Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2021	Feb. 22, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Trading Symbol	CYTK
Entity Registrant Name	CYTOKINETICS, INCORPORATED
Entity Central Index Key	0001061983
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		84,856,037
Entity Public Float			$ 1,443.0
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ
Entity File Number	000-50633
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3291317
Entity Address, Address Line One	350 Oyster Point Boulevard
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	624-3000
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Portions of the Registrant’s Proxy Statement for its 2021 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission, no later than 120 days after the end of the fiscal year, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Redwood City, California

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 112,666	$ 82,985
Short-term investments	358,972	381,075
Accounts receivable	51,819	4,420
Prepaid expenses and other current assets	12,215	5,741
Total current assets	535,672	474,221
Long-term investments	152,050	36,954
Property and equipment, net	73,271	13,346
Operating lease right-of-use assets	73,138	2,924
Other assets	7,188	6,358
Total assets	841,319	533,803
Current liabilities:
Accounts payable	21,087	8,050
Accrued liabilities	34,370	19,315
Short-term operating lease liabilities	14,863	2,785
Other current liabilities	1,540	1,049
Total current liabilities	71,860	31,199
Term loan, net	47,367	46,209
Convertible notes, net	95,471	89,504
Liabilities related to revenue participation right purchase agreement, net	179,072	166,068
Long-term deferred revenue	87,000	87,000
Long-term operating lease liabilities	112,229	440
Other non-current liabilities	4,457	0
Total liabilities	597,456	420,420
Commitments and contingencies	0	0
Stockholders’ equity:
Preferred stock, $0.001 par value: Authorized: 10,000,000 shares; Issued and outstanding: none	0	0
Common stock, $0.001 par value: Authorized: 163,000,000 shares; Issued and outstanding: 84,799,542 shares at December 31, 2021 and 71,015,183 shares at December 31, 2020	84	70
Additional paid-in capital	1,452,268	1,105,470
Accumulated other comprehensive (loss) income	(869)	149
Accumulated deficit	(1,207,620)	(992,306)
Total stockholders’ equity	243,863	113,383
Total liabilities and stockholders’ equity	$ 841,319	$ 533,803

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	163,000,000	163,000,000
Common stock, shares issued	84,799,542	71,015,183
Common stock, shares outstanding	84,799,542	71,015,183

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Total revenues	$ 70,428	$ 55,828	$ 26,868
Operating expenses:
Research and development	159,938	96,951	86,125
General and administrative	96,803	52,820	39,610
Total operating expenses	256,741	149,771	125,735
Operating loss	(186,313)	(93,943)	(98,867)
Interest expense	(16,440)	(15,963)	(6,623)
Non-cash interest expense on liability related to sale of future royalties	(12,892)	(22,713)	(20,737)
Interest and other income, net	331	5,329	4,535
Net loss	$ (215,314)	$ (127,290)	$ (121,692)
Net loss per share — basic and diluted	$ (2.80)	$ (1.97)	$ (2.11)
Weighted-average number of shares used in computing net loss per share — basic and diluted	76,886	64,524	57,575
Other comprehensive loss:
Unrealized (loss) gain on available-for-sale securities, net	$ (1,018)	$ (530)	$ 179
Comprehensive loss	(216,332)	(127,820)	(121,513)
Research and Development Revenues [Member]
Revenues:
Total revenues	10,572	16,527	26,868
License Revenues [Member]
Revenues:
Total revenues	54,856	36,501	0
Milestone Revenues [Member]
Revenues:
Total revenues	$ 5,000	$ 2,800	$ 0

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Underwritten Public Offering	Common Stock [Member]	Common Stock [Member] Underwritten Public Offering	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Underwritten Public Offering	Accumulated Other Comprehensive (Loss) Income [Member]	Accumulated Other Comprehensive (Loss) Income [Member] Underwritten Public Offering	Accumulated Deficit [Member]	Accumulated Deficit [Member] Underwritten Public Offering
Beginning Balance at Dec. 31, 2018	$ 25,934		$ 55		$ 768,703		$ 500		$ (743,324)
Beginning Balance, shares at Dec. 31, 2018			54,717,906
Exercise of stock options, value	1,017		$ 0		1,017		0		0
Exercise of stock options, shares			131,909
Issuance of common stock, net of issuance costs, value	36,214		$ 4		36,210		0		0
Issuance of common stock, net of issuance costs, shares			3,984,849
Issuance under Employee Stock Purchase Plan, value	1,108		$ 0		1,108		0		0
Issuance under Employee Stock Purchase Plan, shares			172,113
Vesting of restricted stock units, net of taxes withheld, value	(732)		$ 0		(732)		0		0
Vesting of restricted stock units, net of taxes withheld, shares			165,347
Issuance of warrants	185		$ 0		185		0		0
Equity component of convertible notes	49,477		0		49,477		0		0
Capped call options associated with convertible notes	(13,386)		0		(13,386)		0		0
Stock-based compensation	10,759		0		10,759		0		0
Other comprehensive income (loss)	179		0		0		179		0
Net loss	(121,692)		0		0		0		(121,692)
Ending Balance at Dec. 31, 2019	(10,937)		$ 59		853,341		679		(865,016)
Ending Balance, shares at Dec. 31, 2019			59,172,124
Exercise of stock options, value	7,611		$ 1		7,610		0		0
Exercise of stock options, shares			943,505
Exercise of warrants, value	0		$ 0		0		0		0
Exercise of warrants, share			104,890
Claims settlement under Section 16(b)	2,151		$ 0		2,151		0		0
Issuance of common stock, net of issuance costs, value		$ 188,883		$ 8		$ 188,875		$ 0		$ 0
Issuance of common stock, net of issuance costs, shares				8,385,417
Issuance of common stock upon private placement, value	36,437		$ 2		36,435		0		0
Issuance of common stock upon private placement, shares			2,000,000
Issuance under Employee Stock Purchase Plan, value	1,509		$ 0		1,509		0		0
Issuance under Employee Stock Purchase Plan, shares			134,684
Vesting of restricted stock units, net of taxes withheld, value	(2,255)		$ 0		(2,255)		0		0
Vesting of restricted stock units, net of taxes withheld, shares			274,563
Issuance of warrants	184		$ 0		184		0		0
Stock-based compensation	17,620		0		17,620		0		0
Other comprehensive income (loss)	(530)		0		0		(530)		0
Net loss	(127,290)		0		0		0		(127,290)
Ending Balance at Dec. 31, 2020	113,383		$ 70		1,105,470		149		(992,306)
Ending Balance, shares at Dec. 31, 2020			71,015,183
Exercise of stock options, value	11,020		$ 3		11,017		0		0
Exercise of stock options, shares			1,304,347
Net share settlement	(418)		$ 0		(418)		0		0
Issuance of common stock, net of issuance costs, value		$ 296,905		$ 11		$ 296,894		$ 0		$ 0
Issuance of common stock, net of issuance costs, shares				11,500,000
Issuance of common stock upon private placement, value	15,144		$ 0		15,144		0		0
Issuance of common stock upon private placement, shares			511,182
Issuance under Employee Stock Purchase Plan, value	1,778		$ 0		1,778		0		0
Issuance under Employee Stock Purchase Plan, shares			108,780
Vesting of restricted stock units, net of taxes withheld, value	(4,449)		$ 0		(4,449)		0		0
Vesting of restricted stock units, net of taxes withheld, shares			360,050
Stock-based compensation	26,832		$ 0		26,832		0		0
Other comprehensive income (loss)	(1,018)		0		0		(1,018)		0
Net loss	(215,314)		0		0		0		(215,314)
Ending Balance at Dec. 31, 2021	$ 243,863		$ 84		$ 1,452,268		$ (869)		$ (1,207,620)
Ending Balance, shares at Dec. 31, 2021			84,799,542

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (215,314)	$ (127,290)	$ (121,692)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Non-cash interest expense on liabilities related to revenue participation right purchase agreement	13,004	22,792	20,737
Non-cash stock-based compensation expense	26,832	17,620	10,759
Non-cash lease expense	7,361	4,221	3,552
Impairment of right-of-use assets	2,844	0	0
Depreciation and amortization of property and equipment	2,276	1,831	1,293
Gain on investment, net	0	(573)	0
Interest receivable and amortization on investments	4,894	(1,194)	(2,587)
Non-cash interest expense related to debt	7,125	6,640	919
Changes in operating assets and liabilities:
Accounts receivable	(47,399)	743	(2,932)
Contract assets	0	0	4,554
Prepaid and other assets	(7,381)	(5,162)	(3,862)
Accounts payable	1,055	(110)	4,396
Accrued and other liabilities	15,060	7,117	(2,168)
Deferred revenue	0	87,000	0
Operating lease liabilities	43,472	(4,692)	(3,876)
Other non-current liabilities	3,649	0	0
Net cash (used in) provided by operating activities	(142,522)	8,943	(90,907)
Cash flows from investing activities:
Purchases of investments	(525,042)	(435,825)	(277,883)
Maturities of investments	422,837	247,301	202,599
Sales of investments	3,300	3,061	3,196
Purchases of property and equipment	(48,872)	(11,052)	(2,619)
Net cash used in investing activities	(147,777)	(196,515)	(74,707)
Cash flows from financing activities:
Proceeds from public offerings of common stock, net of discounts, commissions and offering cost	296,905	188,883	0
Proceeds from private placement, net	15,144	36,225	0
Proceeds from stock-based award activities, net	7,931	6,865	1,393
Claims settlement under Section 16(b)	0	2,151	0
Net proceeds from long-term debt, net of debt discount and issuance costs	0	0	1,710
Net proceeds from convertible notes, net of debt discount and issuance costs	0	0	133,860
Issuance of common stock under at-the-market offering, net of issuance costs	0	0	36,214
Purchase of capped call options associated with convertible notes	0	0	(13,386)
Net cash provided by financing activities	319,980	234,124	159,791
Net increase (decrease) in cash and cash equivalents	29,681	46,552	(5,823)
Cash and cash equivalents, beginning of period	82,985	36,433	42,256
Cash and cash equivalents, end of period	112,666	82,985	36,433
Supplemental cash flow disclosures:
Cash paid for interest	9,175	9,620	4,059
Right-of-use assets recognized in exchange for operating lease obligations	80,395	1,106	10,687
Right-of-use assets recognized in exchange for finance lease obligations	1,294	0	0
Amounts unpaid for purchases of property and equipment	$ 11,982	$ 0	$ 0

Organization and Accounting Policies

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Accounting Policies

Note 1 — Organization and Accounting Policies

Organization

Cytokinetics, Incorporated (the “Company”, “we” or “our”) was incorporated under the laws of the state of Delaware on August 5, 1997. We are a late-stage biopharmaceutical company focused on the discovery and development of novel small molecule therapeutics that modulate muscle function for the potential treatment of serious diseases and medical conditions.

Our financial statements contemplate the conduct of our operations in the normal course of business. We have incurred an accumulated deficit of $1,207.6 million since inception and there can be no assurance that we will attain profitability. We had a net loss of $215.3 million and net cash used in operations of $142.5 million for the year ended December 31, 2021. Cash, cash equivalents and investments increased to $623.7 million as of December 31, 2021 from $501.0 million as of December 31, 2020. We anticipate that we will have operating losses and net cash outflows in future periods.

We are subject to risks common to late-stage biopharmaceutical companies including, but not limited to, development of new drug candidates, dependence on key personnel, and the ability to obtain additional capital as needed to fund our future plans. Our liquidity will be impaired if sufficient additional capital is not available on terms acceptable to us. To date, we have funded operations primarily through sales of our common stock, contract payments under our collaboration agreements, sale of future royalties, debt financing arrangements, government grants and interest income. Until we achieve profitable operations, we intend to continue to fund operations through payments from strategic collaborations, additional sales of equity securities, grants and debt financings. We have never generated revenues from commercial sales of our drugs and may not have drugs to market for at least several years, if ever. Our success is dependent on our ability to enter into new strategic collaborations and/or raise additional capital and to successfully develop and market one or more of our drug candidates. We cannot be certain that sufficient funds will be available from such a financing or through a collaborator when required or on satisfactory terms. Additionally, there can be no assurance that our drug candidates will be accepted in the marketplace or that any future products can be developed or manufactured at an acceptable cost. These factors could have a material adverse effect on our future financial results, financial position and cash flows.

Based on the current status of our research and development activities, we believe that our existing cash, cash equivalents and investments will be sufficient to fund cash requirements for at least the next 12 months after the issuance of these consolidated financial statements. If, at any time, our prospects for financing our research and development programs decline, we may decide to reduce research and development expenses by delaying, discontinuing or reducing our funding of one or more of our research or development programs. Alternatively, we might raise funds through strategic collaborations, public or private financings or other arrangements. Such funding, if needed, may not be available on favorable terms, or at all. The financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. We evaluate our estimates on an ongoing basis. We base our estimates on our historical experience and also on assumptions that we believe are reasonable; however, actual results could significantly differ from those estimates.

Basis of Presentation

The consolidated financial statements include the accounts of Cytokinetics, Incorporated and its wholly-owned subsidiary and have been prepared in accordance with GAAP. Intercompany transactions and balances have been eliminated in consolidation. Certain prior period amounts have been reclassified to conform the prior period presentation to the current year.

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject us to concentrations of risk consist principally of cash and cash equivalents, investments, and accounts receivable.

Our cash, cash equivalents and investments are invested in deposits with two major financial institutions in the United States. Deposits in these banks may exceed the amount of insurance provided on such deposits.

Our exposure to credit risk associated with non-payment is limited to Astellas Pharma Inc. for co-funding one-third of the out-of-pocket clinical development costs which may be incurred in connection with Cytokinetics’ Phase 3 clinical trial, COURAGE-ALS, of reldesemtiv in ALS up to a maximum contribution by Astellas of $12.0 million, to our strategic partner in the People’s Republic of China (including the Hong Kong and Macau Special Administration Districts) (“China”) and Taiwan, Ji Xing Pharmaceuticals Limited (“Ji Xing”), and Royalty Pharma Investments ICAV (“RPI ICAV”), to whom we sold a revenue interest in our net sales of pharmaceutical products containing aficamten under a revenue interest purchase agreement, dated January 7, 2022 (the “RP Aficamten RPA”), as further described in Note 11 below.

Drug candidates we develop may require approvals or clearances from the U.S. Food and Drug Administration (“FDA”) or other regulatory agencies prior to commercial sales. There can be no assurance that our drug candidates will receive any of the required approvals or clearances. If we were to be denied approval, or clearance or any such approval or clearance was to be delayed, it would have a material adverse impact on us.

Cash and Cash Equivalents

We consider all highly liquid investments with a maturity of three months or less at the time of purchase to be cash equivalents.

Investments

Available-for-sale investments. Our investments consist of U.S. Treasury securities, U.S. and non-U.S. government agency bonds, commercial paper, global portfolio of corporate debt and money market funds. We designate all investments as available-for-sale and report them at fair value, based on quoted market prices, with unrealized gains and losses recorded in accumulated other comprehensive income and loss. The cost of securities sold is based on the specific-identification method. Investments with original maturities greater than three months and remaining maturities of one year or less are classified as short-term investments. Investments with remaining maturities greater than one year are classified as long-term investments. The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in Interest and other income, net. Recognized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in Interest and other income, net. Interest and dividends on securities classified as available-for-sale are included in Interest and other income, net.

All of our available-for-sale investments are subject to a periodic impairment review. If an impairment is the result of a credit loss, we recognize an allowance for credit losses (“ACL”). ACL’s reflect management’s current estimate of credit losses that are expected to occur over the remaining life of a financial asset. We recognize an impairment charge when a decline in the fair value of investments below the cost basis is judged to be other-than-temporary. Factors we consider in assessing whether an other-than-temporary impairment has occurred include: the nature of the investment; whether the decline in fair value is attributable to specific adverse conditions affecting the investment; the financial condition of the investee; the severity and the duration of the impairment; and whether we have the intent and ability to hold the investment to maturity. When we determine that an other-than-temporary impairment has occurred, the investment is written down to its market value at the end of the period in which it is determined that an other-than-temporary decline has occurred.

Property and Equipment, net

Property and equipment are stated at cost less accumulated depreciation and are depreciated on a straight-line basis over the estimated useful lives of the related assets, which are generally three years for computer equipment and software, five years for laboratory equipment and office equipment, and seven years for furniture and fixtures. Amortization of leasehold improvements and finance lease right-of-use assets are computed using the straight-line method over the shorter of the remaining lease term or the estimated useful life of the related assets, typically ranging from three to twenty-two years. Upon sale or retirement of assets, the costs and related accumulated depreciation and amortization are removed from the balance sheet and the resulting gain or loss is reflected in operations.

Impairment of Long-lived Assets

We review long-lived assets, including property, equipment and right-of-use assets, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Impairment is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value. We would recognize an impairment loss when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount.

Leases

We determine if the arrangement contains a lease at inception based on whether the contract conveys the right to control the use of an identified asset. The lease classification is determined at lease commencement, which is the date the underlying asset is available for use by the Company, and preliminary based on whether the arrangement is effectively a financed purchase of the underlying asset (finance lease) or not (operating lease). We determined the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. In addition to the fixed minimum lease payments required under the lease arrangements, certain leases include payments of operating expenses that may be revised based on the landlord’s estimate. These variable payments are excluded from the lease payments used to determine the right-of-use asset and lease liability and are recognized when the associated activity occurs.

We recognize right-of-use assets and short-term and long-term lease liabilities on our consolidated balance sheets for operating leases. The right-of-use asset and short-term and long-term lease liabilities for finance leases are recognized in property and equipment, other current liabilities, and other non-current liabilities, respectively, on the consolidated balance sheets.

In determining the present value of lease payments, we estimated our incremental borrowing rate based on information available upon commencement. We base the lease liabilities on the present value of remaining lease payments over the remaining terms of the leases using an estimated rate of interest that we would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The initial right-of-use asset, for both operating and finance leases, is measured based on the lease liability adjusted for any initial direct costs, lease prepayments, and lease incentives.

We recognize rent expense for operating leases on a straight-line basis over the lease term in operating expenses on the consolidated statements of operations. Finance lease right-of-use assets are amortized on a straight-line basis over the shorter of the expected useful life or the lease term, and the carrying amount of the lease liability is adjusted to reflect interest, which is recorded in interest expense.

We exclude from our consolidated balance sheets recognition of leases having a term of 12 months or less (short-term leases). We account for lease and non-lease components as a single component for our operating leases.

Our operating leases consist of the facilities leases with KR Oyster Point 1, LLC (the “Kilroy Lease”) and Britannia Pointe Grand Limited Partnership (the “Britannia Leases”) and our finance leases are for laboratory equipment.

Revenue Recognition

We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration for those goods or services. To recognize revenue from a contract with a customer, we:

(i)

identify our contracts with our customers;

(ii)

identify our distinct performance obligations in each contract;

(iii)

determine the transaction price of each contract;

(iv)

allocate the transaction price to the performance obligations; and

(v)

recognize revenue as we satisfy our performance obligations.

At contract inception, we assess the goods or services promised within each contract and assess whether each promised good or service is distinct and determine those that are performance obligations. We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

Collaborative Arrangements

We enter into collaborative arrangements with partners that typically include payment to us for one of more of the following: (i) license fees; (ii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; (iii) royalties on net sales of licensed products; and (iv) research and development cost reimbursements. Each of these payments results in collaboration or other revenues. Where a portion of non-refundable up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied.

As part of the accounting for these arrangements, we must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligations. The stand-alone selling price may include such items as, forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success, to determine the transaction price to allocate to each performance obligation.

For our collaboration agreements that include more than one performance obligation, such as a license combined with a commitment to perform research and development services, we make judgments to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. We evaluate our progress each reporting period and, if necessary, adjust the measure of a performance obligation and related revenue recognition.

License Fees: If a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front license fees. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

Milestone Payments: We use judgment to determine whether a milestone is considered probable of being reached. Using the most likely amount method, we include the value of a milestone payment in the consideration for a contract at inception if we then conclude achieving the milestone is more likely than not. Otherwise, we exclude the value of a milestone payment from contract consideration at inception and recognize revenue for a milestone at a later date, when we judge that it is probable the milestone will be achieved. If we conclude it is probable that a significant revenue reversal would not occur, the associated milestone is included in the transaction price. We then allocate the transaction price to each performance obligation on a relative stand-alone selling price basis, for which we recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, we re-evaluate the probability of achievement of such milestones and any related constraint, and if necessary, adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration and other revenues and earnings in the period of adjustment.

Royalties: For contracts that include sales-based royalties, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied. To date, we have not recognized any royalty revenues resulting from contracts.

Research and Development Cost Reimbursements: Our joint programs with Astellas under that certain License and Collaboration Agreement for Other Skeletal Sarcomere Activators, dated April 23, 2020, as amended (the “Astellas OSSA Agreement”), and with Amgen under that certain Collaboration and Option Agreement, dated December 29, 2006, as amended (the “Amgen Agreement”) (both of the Astellas OSSA Agreement and the Amgen Agreement having now been terminated), included promises of research and development services. We also entered into the Fast Skeletal Regulatory Activator Agreement with Astellas, dated April 23, 2020 (the “Astellas FSRA Agreement”). Under the Astellas FSRA Agreement, Astellas agreed to pay one-third of the out-of-pocket clinical development costs which may be incurred in connection with the Company’s Phase 3 clinical trial of reldesemtiv in ALS, up to a maximum contribution by Astellas of $12.0 million. We determined that these services collectively were distinct from any licenses provided to Astellas and Amgen under such agreements, and as such, these promises were accounted for as a separate performance obligation recorded over time. We recognized revenue for these services as the performance obligations are satisfied, which we estimated using internal research and development costs incurred.

Accrued Research and Development Expenditures

A substantial portion of our preclinical studies and all of our clinical trials have been performed by third-party contract research organizations (“CROs”) and other vendors and our accruals for expenses for preclinical studies and clinical trials may be significant. For preclinical studies, the significant factors used in estimating accruals include the percentage of work completed to date and contract milestones achieved. For clinical trial expenses, the significant factors used in estimating accruals include the number of patients enrolled, duration of enrollment, milestones achieved and percentage of work completed to date. We monitor patient enrollment levels and related activities to the extent practicable through internal reviews, correspondence and status meetings with CROs, and review of contractual terms. We depend on the timeliness and accuracy of data provided by our CROs and other vendors to accrue expenses. If we receive and rely on incomplete or inaccurate data, accruals and expenses may be too high or too low at a given point in time and corresponding adjustments to accruals and expenses would be made in future periods when the actual expense becomes known.

Revenue Participation Right Purchase Agreements

We have entered into certain revenue participation right purchase agreements with certain investors, pursuant to which such investors purchased rights to royalties from certain revenue streams in exchange for consideration. We typically account for such agreements as debt to be amortized under the effective interest rate method over the life of the related royalty stream, when we have continuing involvement with the underlying R&D. We typically account for such agreements as deferred income to be amortized under the units-of-revenue method, when there is no continuing involvement with the underlying R&D.

Revenue participation right purchase agreements are recognized using significant unobservable inputs. These inputs are derived using internal management estimates developed based on third party data and reflect management’s judgements, current market conditions surrounding competing products, and forecasts. We will periodically assess the amount and timing of expected royalty payments and account for any changes in such estimates on a prospective basis.

Research and Development Expenditures

Research and development costs are charged to operations as incurred. Research and development expenses consist primarily of clinical manufacturing costs, preclinical study expenses, consulting and other third-party costs, employee compensation, supplies and materials, allocation of overhead and occupancy costs, facilities costs and depreciation of equipment.

Income Taxes

We account for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.

We recognize uncertain tax positions taken or expected to be taken on a tax return. Tax positions are initially recognized when it is more likely than not that the position will be sustained upon examination by the tax authorities. Such tax positions are initially and subsequently measured as the largest amount of tax benefit that is more likely than not of being realized upon ultimate settlement with the tax authority assuming full knowledge of the position and relevant facts.

We recognize interest accrued related to unrecognized tax benefits and penalties as income tax expense.

The only aspect of ASU 2019-12 that had a material impact on our consolidated financial statements was the removal of the exception related to intraperiod tax allocation. Starting in 2019, we followed the general intraperiod allocation of tax expense. We have a loss from continuing operations and subsequent to the adoption of ASU 2019-12, we determined the amount attributable to continuing operations without regard to the tax effect of other items. We prospectively applied the ASU 2019-12 amendment related to intraperiod tax allocation.

Had the Company not adopted ASU 2019-12, upon issuance of the convertible notes in 2019 (see Note 6 – Debt) a $12.0 million deferred tax benefit would have been recognized along with corresponding decreases to net loss and accumulated deficit. The Company had no intraperiod tax allocation items in prior years.

Due to our net loss position, the income tax benefit generated without the adoption of ASU 2019-12 was a non-cash benefit. The adoption of ASU 2019-12 did not impact our cash flows.

Stock-Based Compensation

We maintain equity incentive plans under which incentive stock options may be granted to employees and nonqualified stock options, restricted stock awards, performance-based stock units and stock appreciation rights may be granted to employees, directors, consultants and advisors. In addition, we maintain an employee stock purchase plan (“ESPP”) under which employees may purchase shares of our common stock through payroll deductions.

Stock-based compensation expense related to stock options granted to employees and directors is recognized based on the grant date estimated fair values using the Black Scholes option pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense ratably over the requisite service period.

Stock-based compensation expense related to performance-based stock units granted to employees is recognized based on the grant-date fair value of each award and recorded as expense over the vesting period using the ratable method when the underlying performance conditions are deemed probable.

Stock-based compensation expense related to the ESPP is recognized based on the fair value of each award estimated on the first day of the offering period using the Black Scholes option pricing model and recorded as expense over the service period using the straight-line method.

Amortization of Debt Discount and Issuance Costs

Debt discount and issuance costs, consisting of legal and other fees directly related to the debt as well as the discount created by the bifurcation of the equity component and the debt component of the convertible senior notes due 2026 (the “2026 Notes”), are offset against gross proceeds from the issuance of debt and are amortized to interest expense over the estimated life of the debt based on the effective interest method.

Recent Accounting Standards

In August 2020, the FASB issued ASU 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”). Under ASU 2020-06 the embedded conversion features are no longer separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives under Topic 815, Derivatives and Hedging, or that do not result in substantial premiums accounted for as paid-in capital. Consequently, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost and convertible preferred stock will be accounted for as a single equity instrument measured at its historical cost, as long as no other features require bifurcation and recognition as derivatives. By removing those separation models, the interest rate of convertible debt instruments typically will be closer to the coupon interest rate. ASU 2020-06 also provides for certain disclosures with regard to convertible instruments and associated fair values. ASU 2020-06 will be effective for annual reporting periods after December 15, 2021 and interim periods within those annual periods and early adoption is permitted. ASU 2020-06 provides companies with the option to adopt the new standard using either the full retrospective or modified retrospective method.

We will adopt this new guidance using the modified retrospective method as of January 1, 2022 with respect to our convertible senior notes due 2026 (the “2026 Notes”). The adoption of this new guidance is estimated to result in an increase in the carrying value of the 2026 Notes by approximately $38.9 million to reflect the full principal amount of the convertible notes outstanding, net of issuance costs, a decrease in additional paid-in capital of approximately $49.5 million to remove the equity component separately recorded for the conversion feature associated with the convertible notes, a cumulative-effect adjustment of approximately $10.6 million to the beginning balance of our accumulated deficit as of January 1, 2022, and a reversal of the related deferred tax liability of $8.3 million with a corresponding increase in our valuation allowance. The adoption of this new guidance is expected to reduce non-cash interest expense for the year ending December 31, 2022 and until the 2026 Notes have been settled. The remaining debt issuance costs will continue to be amortized over the term of the notes. There is no expected impact to our Consolidated Statement of Cash Flows as a result of the adoption.

Net Loss Per Share

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Net Loss Per Share

Note 2 — Net Loss Per Share

Basic net loss per share is computed by dividing net loss by the weighted average number of vested common shares outstanding during the period. Diluted net loss per share is computed by giving effect to all potentially dilutive common shares, including outstanding stock options, unvested restricted stock, warrants, convertible preferred stock and shares issuable under our ESPP, during the period using the treasury stock method and convertible notes using the if-converted method.

The following instruments were excluded from the computation of diluted net loss per share for the periods presented because their effect would have been antidilutive (in thousands):

	Years Ended December 31,
	2021		2020		2019
Options to purchase common stock		9,373		8,510		7,759
Warrants to purchase common stock		48		48		165
Restricted stock and performance units		1,415		1,117		839
Shares issuable related to the ESPP		8		12		27
Shares issuable upon conversion of convertible notes		16,675		16,675		16,675
Total shares		27,519		26,362		25,465

Research and Development Arrangements

12 Months Ended

Dec. 31, 2021

Research And Development [Abstract]

Research and Development Arrangements

Note 3 — Research and Development Arrangements

License and milestone revenues recognized during 2021, 2020 and 2019 were as follows (in thousands):

	Years Ended December 31,
	2021		2020		2019
License revenues	$	54,856	$	36,501	$	—
Milestone revenues		5,000		2,800		—
	$	59,856	$	39,301	$	—

2021 Ji Xing and RTW Transactions

The Ji Xing OM License Agreement, as defined below, and the sales of common stock to the RTW Investors in December 2021, as described below, (together the “2021 RTW Transactions”) were entered into with parties that are affiliated and in contemplation of one another and, accordingly, we have assessed the accounting for these transactions in the aggregate. We concluded that there were two units of accounting in the 2021 RTW Transactions as further described below. The Company allocated the total consideration in accordance with ASC 820 and ASC 606 as follows (in thousands):

	Allocated Consideration
Units of Accounting:
License and collaboration	$	54,856
Common stock (fair value)		15,144
Total consideration	$	70,000

Ji Xing Omecamtiv Mecarbil License and Collaboration Agreement

On December 20, 2021, we entered into a License and Collaboration Agreement (the “Ji Xing OM License Agreement”) with Ji Xing, pursuant to which we granted to Ji Xing an exclusive license to develop and commercialize omecamtiv mecarbil in China and Taiwan. Under the terms of the Ji Xing OM License Agreement, we are the beneficiary of a nonrefundable $50.0 million payment obligation from Ji Xing comprised of a $40.0 million payment as consideration for the rights granted by us to Ji Xing and $10.0 million attributable to our having submitted to FDA a new drug application (“NDA”) for omecamtiv mecarbil. We may be eligible to receive from Ji Xing additional payments totaling up to $330.0 million for the achievement of certain commercial milestone events in connection to omecamtiv mecarbil. In addition, Ji Xing will pay us tiered royalties in the mid-teens to the low twenties range on the net sales of pharmaceutical products containing omecamtiv mecarbil in China and Taiwan, subject to certain reductions for generic competition, patent expiration and payments for licenses to third party patents.

Ji Xing will be responsible for the development and commercialization of omecamtiv mecarbil at its own cost and is required to use diligent efforts to develop and commercialize omecamtiv mecarbil in China and Taiwan. The development of omecamtiv mecarbil will be initially focused on heart failure with reduced ejection fraction (“HFrEF”), and Ji Xing will have the opportunity to participate in Cytokinetics’ global clinical trials of omecamtiv mecarbil. Cytokinetics will supply omecamtiv mecarbil to Ji Xing either as a finished product or as an active pharmaceutical ingredient.

The Ji Xing OM License Agreement, unless terminated earlier, will continue on a market-by-market basis until expiration of the relevant royalty term. Ji Xing has the right to terminate the Ji Xing OM License Agreement for convenience. Each party may terminate the Ji Xing OM License Agreement for the other party’s uncured material breach, insolvency, or failure to perform due to extended force majeure events. Cytokinetics may also terminate the Ji Xing OM License Agreement if Ji Xing challenges Cytokinetics’ patents or undergoes certain change of control transactions. Rights granted to Ji Xing in relation to omecamtiv mecarbil will revert to Cytokinetics upon termination, and, under certain circumstances, subject to a low single digit royalty payment by the Company to Ji Xing on the net sales of the products containing the compound omecamtiv mecarbil in China and Taiwan. We assessed this arrangement in accordance with ASC 606 and concluded that there is one performance obligation relating to the license of functional intellectual property. The performance obligation was satisfied, and we recognized the residual allocation of arrangement consideration as revenue of $54.9 million for 2021. Due to the nature of development, including the inherent risk of development and approval by regulatory authorities, we are unable to estimate if and when the development milestone payments could be achieved or become due and, accordingly, we consider the milestone payments to be fully constrained and excluded any potential milestone payments from the initial transaction price.

The consideration related to sales-based milestone payments, including royalties, will be recognized when the related sales occur under the sales- and usage-based royalty exception as these amounts have been determined to relate predominantly to the license.

We re-evaluate the probability of achievement of development milestones and any related constraints each reporting period. We will include consideration, without constraint, in the transaction price to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur.

Common Stock Purchase Agreements

On December 20, 2021, as part of the 2021 RTW Transactions, we entered into common stock purchase agreements with each of RTW Master Fund, Ltd., RTW Innovation Master Fund, Ltd. and RTW Venture Fund Limited (collectively, the “RTW Investors”). These common stock purchase agreements provided for the sale and issuance of an aggregate of 511,182 shares of our common stock at a price per share of $39.125 and an aggregate purchase price of $20.0 million. The closing occurred on December 20, 2021. The RTW Investors have agreed to certain trading and other restrictions with respect to the shares of common stock they purchased pursuant to these agreements, including a restriction on sales or other transfers of the shares, subject to certain exceptions, for a period of one year from the closing date. The restrictions resulted in a premium paid by the RTW investors of $4.9 million, which represents the excess amount paid over the fair value of the shares of common stock purchased. The premium was determined by analyzing the restrictions discount applied to the closing stock price as of December 20, 2021, which is a Level 2 fair value input. The cash received less the calculated premium is the $15.1 million fair value of the common stock recorded.

2020 Ji Xing and RTW Transactions

On July 14, 2020, we entered into a series of transactions as described below with RTW Royalty Holdings Designated Activity Company (“RTW Royalty Holdings”) and Ji Xing Pharmaceuticals Limited (“Ji Xing”), related to aficamten, our proprietary small molecule cardiac myosin inhibitor product, a novel cardiac myosin inhibitor, and other assets (together, the “2020 RTW Transactions”). The 2020 RTW Transactions include entering into a licensing and collaboration agreement with Ji Xing, the sale of Cytokinetics common stock to the RTW Investors (as defined below), an agreement to sell to RTW Royalty Holdings our interest in certain future royalties on net sales of products containing the compound mavacamten that is being developed by Bristol-Myers Squibb Company (formerly by MyoKardia, Inc.), and the ability for the Company to obtain additional funding in the future from RTW Royalty Holdings, upon the achievement of certain clinical trial milestones, in exchange for future royalty payments as further discussed below. As a result, we have received and expect to receive a combination of license fees, milestone revenues and sale proceeds from the RTW Investors, RTW Royalty Holdings and Ji Xing.

The 2020 RTW Transactions were entered into with parties that are affiliated and in contemplation of one another and, accordingly, we have assessed the accounting for these transactions in the aggregate. We concluded that there were three units of accounting in the 2020 RTW Transactions as further described below. The Company allocated the total consideration in accordance with ASC 820, Fair Value Measurement, and ASC 606, Revenue from Contracts with Customers, as follows (in thousands):

	Allocated Consideration
Units of Accounting:
License and collaboration (residual)	$	36,501
Royalty (fair value)		87,000
Common stock (fair value)		36,499
Total consideration	$	160,000

Ji Xing Aficamten License and Collaboration Agreement

We entered into a License and Collaboration Agreement (the “Ji Xing Aficamten License Agreement”) with Ji Xing, pursuant to which we granted to Ji Xing an exclusive license to develop and commercialize aficamten in China and Taiwan. Under the terms of the Ji Xing Aficamten License Agreement, we received from Ji Xing a nonrefundable upfront payment of $25.0 million. We may be eligible to receive from Ji Xing milestone payments totaling up to $200.0 million for the achievement of certain development and commercial milestone events in connection to aficamten in the field of obstructive hypertrophic cardiomyopathy (“oHCM”) and/or non-obstructive hypertrophic cardiomyopathy (“nHCM”) and other indications. In addition, Ji Xing will pay us tiered royalties in the low-to-high teens range on the net sales of the products containing aficamten in China and Taiwan, subject to certain reductions for generic competition, patent expiration and payments for licenses to third party patents.

Ji Xing will be responsible for the development and commercialization of aficamten at its own cost and is required to use diligent efforts to develop and commercialize aficamten in China and Taiwan. The development of aficamten will be initially focused on hypertrophic cardiomyopathy, and Ji Xing will have the opportunity to participate in Cytokinetics’ global pivotal clinical trials of aficamten. Cytokinetics or a designated supplier will supply aficamten to Ji Xing either as a finished product or as an active pharmaceutical ingredient.

The Ji Xing Aficamten License Agreement, unless terminated earlier, will continue on a market-by-market basis until expiration of the relevant royalty term. Ji Xing has the right to terminate the Ji Xing Aficamten License Agreement for convenience. Each party may terminate the Ji Xing Aficamten License Agreement for the other party’s uncured material breach, insolvency, or failure to perform due to extended force majeure events. Cytokinetics may also terminate the Ji Xing Aficamten License Agreement if Ji Xing challenges Cytokinetics’ patents or undergoes certain change of control transactions. Rights granted to Ji Xing in relation to aficamten will revert to Cytokinetics upon termination, and, under certain circumstances, subject to a low single digit royalty payment by the Company to Ji Xing on the net sales of the products containing the compound aficamten in China and Taiwan.

We assessed this arrangement in accordance with ASC 606 and concluded that there is one performance obligation relating to the license of functional intellectual property. The performance obligation was satisfied, and we recognized the residual allocation of arrangement consideration as revenue of $36.5 million for 2020. No license revenue was recognized in 2021 related to the Ji Xing Aficamten License Agreement. Due to the nature of development, including the inherent risk of development and approval by regulatory authorities, we are unable to estimate if and when the development milestone payments could be achieved or become due and, accordingly, we consider the milestone payments to be fully constrained and exclude the milestone payments from the initial transaction price.

The consideration related to sales-based milestone payments, including royalties, will be recognized when the related sales occur under the sales- and usage-based royalty exception of ASC 606 as these amounts have been determined to relate predominantly to the license.

We re-evaluate the probability of achievement of development milestones and any related constraints each reporting period. We will include consideration, without constraint, in the transaction price to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur.

We earned a $2.5 million milestone from Ji Xing as of December 31, 2020 for the first patient dosed in Cohort 2 of REDWOOD-HCM (Randomized Evaluation of Dosing With CK-274 in Obstructive Outflow Disease in HCM). We determined recognition of the milestone during 2020 was appropriate based on clinical trial progress. Our determination that we expected to earn the $2.5 million milestone resulted in a change in the overall transaction price of the collaboration agreement, as it was probable that a significant reversal of cumulative revenue would not occur. A corresponding contract asset was recorded in other current assets in our consolidated balance sheet as of December 31, 2020 and was released in the first quarter of 2021 upon receipt of cash.

We recognized a $5.0 million milestone from Ji Xing during the third quarter of 2021 for initiation of a phase 3 clinical trial for aficamten in obstructive HCM. Although our contractual right to payment has not yet arisen under the Ji Xing Aficamten License Agreement, we determined recognition of the milestone in accordance with ASC 606 during the third quarter of 2021 was appropriate based on our expected initiation of a phase 3 clinical trial of aficamten in obstructive HCM and recorded a corresponding contract asset in other current assets in our consolidated balance sheet as of December 31, 2021.

Royalty Purchase Agreement

We entered into a Royalty Purchase Agreement (the “RTW Royalty Purchase Agreement”) with RTW Royalty Holdings, pursuant to which we sold our right to receive certain payments on the net sales of products containing the compound mavacamten, a cardiac myosin inhibitor (the “Mavacamten Royalty”), under the Research Collaboration Agreement, dated August 24, 2012, between us and MyoKardia, Inc. to RTW Royalty Holdings for a one-time payment of $85.0 million. The RTW Royalty Purchase Agreement transaction closed on November 13, 2020. On March 31, 2021, RTW Royalty Holdings assigned its rights and obligations under the RTW Royalty Purchase Agreement to its affiliate, RTW Investments ICAV for RTW Fund 1 (“RTW ICAV”).

The allocation of the consideration for the 2020 RTW Transactions resulted in $87.0 million being allocated to the RTW Royalty Purchase Agreement representing its fair value. The fair value was determined using an income approach method based on management’s estimates of the discounted cash flows to be received over the term of the related royalty agreement, which are Level 3 fair value inputs. Management’s estimates included significant unobservable inputs. These inputs are derived using internal management estimates developed based on third party data and reflect management’s judgements, current market conditions surrounding competing products, and forecasts. The significant unobservable inputs include the estimated patient population, estimated selling price, estimated peak sales and sales ramp, the expected term of the royalty stream, and timing of the expected launch. The $87.0 million recorded as deferred revenue will be amortized using the units-of-revenue method.

We will recognize revenue related to the sale of the Mavacamten Royalty using the units-of-revenue method. Under the units-of-revenue method, the revenue to be recognized for a period is calculated by computing a ratio of the Mavacamten Royalty paid to RTW Royalty Holdings for a given period to the total payments expected to be made to RTW Royalty Holdings over the term of the agreement, and then applying that ratio to the period's cash payment. We will record any adjustments due to changes in the underlying royalties on a cumulative catch-up basis.

Common Stock Purchase Agreements

On July 14, 2020, we entered into common stock purchase agreements with each of RTW Master Fund, Ltd., RTW Innovation Master Fund, Ltd. and RTW Venture Fund Limited (collectively, the “RTW Investors”). These common stock purchase agreements provided for the sale and issuance of an aggregate of 2.0 million shares of common stock of Cytokinetics at a price per share of $25.00 and an aggregate purchase price of $50.0 million. The closing occurred on July 14, 2020. The RTW Investors have agreed to certain trading and other restrictions with respect to the shares of common stock they purchased pursuant to these agreements, including a restriction on sales or other transfers of the shares, subject to certain exceptions, for a period of two years from the closing date, which period will be extended if certain conditions are met. The restrictions resulted in a premium paid by RTW investors of $13.5 million which represents the excess amount paid over the fair value of the shares of common stock purchased. The premium was determined by analyzing the holding period discount applied to the 30-day average stock price as of July 14, 2020, which is a Level 2 fair value input. The cash received less the calculated premium is the $36.5 million fair value of the common stock recorded.

Funding Agreement

During July 2020, we also entered into a Funding Agreement (the “Funding Agreement”) with RTW Royalty Holdings. Pursuant to the Funding Agreement, RTW Royalty Holdings has committed to provide up to $90.0 million (the “Funding Commitment”) to fund our development and commercialization of aficamten in nHCM and oHCM.

On January 7, 2022, we announced that we had elected to unilaterally terminate the Funding Agreement in connection with our entry into the RP Aficamten RPA. At the time of its termination, we had not exercised any rights to sell any revenue interest in aficamten under the Funding Agreement.

Astellas

Our strategic alliance with Astellas to advance novel therapies for diseases and medical conditions associated with skeletal muscle impairment and weakness commenced in 2013 under the License and Collaboration Agreement, dated June 21, 2013 between the parties (the “Astellas Agreement”).

On April 23, 2020, we and Astellas entered into the two agreements referenced below which, taken together, amend and restate the Company’s research, development and commercialization collaboration with Astellas under the Astellas Agreement.

Fast Skeletal Regulatory Activator Agreement

The Company and Astellas entered into a Fast Skeletal Regulatory Activator Agreement, dated April 23, 2020 (the “Astellas FSRA Agreement”). As a result of the Astellas FSRA Agreement, the Company will now have exclusive control and responsibility for the Company's future development and commercialization of reldesemtiv, CK-601 and other fast skeletal regulatory activator (collectively “FSRA”) compounds and products, and accordingly, Astellas has agreed to terminate its license to all FSRA compounds and related products.

Under the Astellas FSRA Agreement, Astellas agreed to pay one-third of the out-of-pocket clinical development costs which may be incurred in connection with the Company’s Phase 3 clinical trial of reldesemtiv in ALS, up to a maximum contribution by Astellas of $12 million. In addition, Astellas agreed to non-cash contributions to the Company, which include the transfer of its existing inventories of active pharmaceutical ingredient of reldesemtiv and CK-601. Astellas has also agreed to the continued conduct of ongoing stability studies pertaining to such existing inventories of active pharmaceutical ingredient, at Astellas’ cost. In exchange, the Company will pay Astellas a low- to mid- single digit royalty on sales of reldesemtiv in the United States, Canada, United Kingdom and the European Union until the later of (i) ten years following the first commercial sale of such product in a major market country, or (ii) December 31, 2034, subject to certain royalty reduction provisions. The Company will not owe Astellas royalties on sales of reldesemtiv in any other country, or on the sale of any FSRA compounds or related products other than reldesemtiv.

License and Collaboration Agreement for Other Skeletal Sarcomere Activators

The Company and Astellas also entered into that certain License and Collaboration Agreement for Other Skeletal Sarcomere Activators, dated April 23, 2020 (the “Astellas OSSA Agreement”), which is an amendment and restatement of the Astellas Agreement and removes the FSRA compounds and related products from the collaboration.

On April 27, 2021, we received written notice of termination from Astellas of the Astellas OSSA Agreement. The termination of the Astellas OSSA Agreement was effective November 1, 2021.

We recognized research revenue for reimbursements from Astellas of internal costs of certain full-time employee equivalents, supporting collaborative research and development programs, and of other costs related to those programs through March 31, 2021 when the research term of the Astellas OSSA Agreement expired.

Research and development revenues from Astellas for 2021, 2020 and 2019 were $3.2 million, $6.6 million, and $13.1 million, respectively.

We had accounts receivable from Astellas of $1.8 million as of December 31, 2021 and $2.7 million as of December 31, 2020.

Amgen

On November 23, 2020, we received written notice of termination from Amgen of that certain Collaboration and Option Agreement, dated December 29, 2006, as amended (the “Amgen Agreement”) pertaining to the discovery, development and commercialization of novel small molecule therapeutics, including omecamtiv mecarbil, a novel cardiac myosin activator, and CK-136 (formerly AMG 594), a novel cardiac troponin activator. The termination of the Amgen Agreement was effective May 20, 2021.

We recognized research and development revenue for reimbursements from Amgen of both internal costs of certain full-time employee equivalents and other costs related to the Amgen Agreement, which terminated effective May 20, 2021. Research and development revenue from Amgen was $7.4 million in 2021, $10.0 million in 2020 and $13.8 million in 2019 and consists of reimbursement of costs we incurred related to METEORIC-HF.

We had no accounts receivable from Amgen as of December 31, 2021. Accounts receivable from Amgen was $1.7 million as of December 31, 2020.

Fair Value Measurements

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 4 — Fair Value Measurements

We value our financial assets and liabilities at fair value, defined as the price that would be received for assets when sold or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We utilize market data or assumptions that we believe market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs can be readily observable, market corroborated or generally unobservable.

We primarily apply the market approach for recurring fair value measurements and endeavor to utilize the best information reasonably available. Accordingly, we use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible and consider the security issuers’ and the third-party issuers’ credit risk in our assessment of fair value.

We classify fair value based on the observability of those inputs using a hierarchy that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement):

Level 1 — Observable inputs, such as quoted prices in active markets for identical assets or liabilities;

Level 2 — Inputs, other than the quoted prices in active markets, that are observable either directly or through corroboration with observable market data; and

Level 3 — Unobservable inputs, for which there is little or no market data for the assets or liabilities, such as internally-developed valuation models.

Fair Value of Financial Assets

The follow tables set forth the fair value of our financial assets, which consists of cash equivalents and investments classified as available-for-sale securities, that were measured on a recurring basis (in thousands):

	December 31, 2021
	Fair Value Hierarchy Level	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	Level 1	$	115,937	$	—	$	—		$	115,937
U.S. Treasury securities	Level 1		133,498		1		(268	)		133,231
U.S. and non-U.S. government agency bonds	Level 2		33,489		—		(53	)		33,436
Commercial paper	Level 2		169,622		6		(19	)		169,609
U.S. and non-U.S. corporate obligations	Level 2		175,282		—		(536	)		174,746
		$	627,828	$	7	$	(876	)	$	626,959

	December 31, 2020
	Fair Value Hierarchy Level	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	Level 1	$	80,050	$	—	$	—		$	80,050
U.S. Treasury securities	Level 1		274,407		147		(8	)		274,546
U.S. government agency bonds	Level 2		51,581		15		(3	)		51,593
Commercial paper	Level 2		49,500		3		(1	)		49,502
U.S. and non-U.S. corporate obligations	Level 2		42,392		7		(11	)		42,388
		$	497,930	$	172	$	(23	)	$	498,079

The available-for-sale securities in our consolidated balance sheet are as follows (in thousands):

	December 31, 2021		December 31, 2020
Cash equivalents	$	115,937	$	80,050
Short-term investments		358,972		381,075
Long-term investments		152,050		36,954
	$	626,959	$	498,079

Interest income was $1.0 million, $5.3 million and $4.5 million in 2021, 2020 and 2019, respectively.

No credit losses on debt securities were recognized in either 2021 or 2020. In its evaluation to determine expected credit losses, management considered all available historical and current information, expectations of future economic conditions, the type of security, the credit rating of the security, and the size of the loss position, as well as other relevant information. The Company does not intend to sell, and is unlikely to be required to sell, any of these available-for-sale investments before their effective maturity or market price recovery.

The carrying amount of our accounts receivable and accounts payable approximate fair value due to the short-term nature of these instruments.

Fair Value of Financial Liabilities:

As of December 31, 2021, the fair value of our term loan approximated its carrying value of $47.4 million based upon a market observable interest rate, which is a Level 2 input (see Note 6 – “Debt”).

As of December 31, 2021, the estimated fair value of our convertible notes was $618.9 million and was based upon observable, Level 2 inputs, including pricing information from recent trades of the convertible notes (see Note 6 – “Debt”).

As of December 31, 2021, the fair value of the liability related to the sale of future royalties to RPI Finance Trust (“RPFT”) is consistent with its carrying value of $179.1 million, and is based on our current estimates of future royalties expected to be paid to RPFT under the Royalty Purchase Agreement (the “RP OM RPA”), over the life of the arrangement, which are considered Level 3 inputs (see Note 7 – “Liabilities Related to Revenue Participation Right Purchase Agreements”).

There were no transfers between Level 1, Level 2, and Level 3 during the periods presented.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Components

Note 5 — Balance Sheet Components

Our property and equipment consisted of (in thousands):

	December 31,
	2021			2020
Property and equipment, net:
Laboratory equipment	$	18,837		$	18,160
Computer equipment and software		4,605			2,940
Office equipment, furniture and fixtures		4,042			1,885
Leasehold improvements		60,343			5,872
Construction in progress		224			9,130
Right-of-use assets, finance lease		1,409			—
Total property and equipment		89,460			37,987
Less: Accumulated depreciation and amortization		(16,189	)		(24,641	)
	$	73,271		$	13,346

Depreciation expense was $2.3 million, $1.8 million and $1.3 million for 2021, 2020 and 2019, respectively.

The balance of property and equipment increased significantly in 2021 primarily due to our relocation from our existing headquarters to our new facilities at Oyster Point in the fourth quarter of 2021 (see Note 9 – Commitments and Contingencies).

Our accrued liabilities were as follows (in thousands):

	December 31,
	2021		2020
Accrued liabilities:
Clinical and preclinical costs	$	13,872	$	6,124
Compensation related		14,930		11,787
Other accrued expenses		5,568		1,404
Total accrued liabilities	$	34,370	$	19,315

We sponsor a 401(k) defined contribution plan covering all employees and contributed $1.1 million, $0.9 million and $0.6 million to this plan in 2021, 2020 and 2019 respectively.

Debt

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Debt

Note 6 — Debt

Term Loan

Prior to May 17, 2019, we maintained a loan and security agreement dated as of October 19, 2015, as amended (the “Original Loan Agreement”) with Silicon Valley Bank and Oxford Finance LLC (“Oxford”) (the “Lenders”) to fund our working capital and other general corporate needs.

On May 17, 2019, we entered into a new loan and security agreement (the “Term Loan Agreement”) with the Lenders for $45.0 million (the “Term Loan”) and terminated the Original Loan Agreement. The proceeds of the Term Loan were used in part to repay in full all of the outstanding term loans under the Original Loan Agreement in an aggregate principal amount of $42.0 million. On November 6, 2019, and November 7, 2019, the Company entered into a First Amendment and a Second Amendment to the Term Loan Agreement. The Term Loan Agreement, as amended, permits the issuance of the Convertible Notes and Capped Call Transactions discussed below. On July 16, 2020, the Company and the Lenders entered into the Third Amendment to the Term Loan Agreement, which amended the Term Loan Agreement to permit (i) the sale of the Mavacamten Royalty under the RTW Royalty Purchase Agreement and (ii) subject to entry into an intercreditor agreement between Oxford (as security agent for the Lenders) and RTW Royalty Holdings in form and substance reasonably satisfactory to the Lenders and RTW Royalty Holdings, permits the draw of funding under the Funding Agreement and the grant of a security interest to RTW Royalty Holdings in the intellectual property located in the United States and accounts receivable related to aficamten. On June 30, 2021, the Company and the Lenders entered into the Fourth Amendment to the Term Loan Agreement, which amended the Term Loan Agreement to permit our ability to incur lease obligations for equipment, software and other property that may be leased under our lease agreements not to exceed $3.0 million in the aggregate. As of December 31, 2021, the Company has drawn approximately $1.4 million under such lease agreements.

The Term Loan was accounted for as a debt modification in a non-troubled debt restructuring based on a comparison of the present value of the cash flows under the terms of the debt immediately before and after the effective date of the Term Loan, which resulted in a change of less than 10%. As a result, issuance costs paid to the Lenders in connection with the Term Loan were recorded as a reduction of the carrying amount of the debt liability and were not significant. Unamortized issuance costs as of the date of the modification were amortized to interest expense over the repayment term of Term Loan.

Both borrowings under the Original Loan Agreement and Term Loan bear interest at an annual rate equal to the greater of (a) 8.05% or (b) the sum of 6.81% plus the 30-day U.S. LIBOR rate. The borrowing under the Original Loan Agreement was repayable in monthly interest-only payments through November 2019 followed by 35 months of monthly payments of interest and principal. The borrowing under the Term Loan was repayable in monthly interest-only payments through December 31, 2020. The interest-only period was automatically extended until July 1, 2021 as a result of the Company’s initiation of a Phase 2 trial for aficamten in cardiomyopathy and has been extended through December 31, 2021 as a result of the achievement of positive results in GALACTIC-HF, the trial of omecamtiv mecarbil in chronic heart failure as announced on October 8, 2020. The ultimate interest-only period will be followed by equal monthly payments of principal and interest to the maturity date in December 2023. We are required to make a final payment upon loan maturity of 6.00% of the notes payable, which we accrete over the life of the Term Loan. Our obligations under the Term Loan Agreement are secured by substantially all our current and future assets, other than our intellectual property.

Interest expense for the Term Loan was $4.8 million, $4.9 million and $5.2 million for 2021, 2020 and 2019 respectively. As of December 31, 2021, the interest rate applicable to borrowings under the Term Loan was 8.05%.

Future minimum payments under the Term Loan Agreement are (in thousands):

Years ending December 31:
2022	$	23,595
2023		30,108
Future minimum payments		53,703
Less: Interest and final payment		(8,703	)
Term Loan, gross	$	45,000

The Term Loan Agreement was terminated and all amounts thereunder repaid in connection to our entry into that certain Development Funding Loan Agreement, dated January 7, 2022 (the “RP Loan Agreement”), between us and Royalty Pharma Development Funding, LLC (“RPDF”), as further described in Note 11 below. The term loan was classified as non-current in our consolidated balance sheet at December 31, 2021, because short-term obligations expected to be refinanced on a long-term basis are not expected to require the use of working capital during the ensuing fiscal year.

Convertible Notes

On November 13, 2019, the Company issued $138.0 million aggregate principal amount of 4.0% convertible senior notes due 2026 (the “2026 Notes”). The 2026 Notes are unsecured obligations and bear interest at an annual rate of 4.0% per year, payable semi-annually on May 15 and December 15 of each year, beginning May 15, 2020. The 2026 Notes are governed by an indenture between the Company and U.S. Bank National Association, as trustee. The 2026 Notes will mature on November 15, 2026, unless earlier repurchased or redeemed by the Company or converted at the option of the holders. The Company may redeem the 2026 Notes prior to the maturity date but is not required to and no sinking fund is provided for the 2026 Notes. The 2026 Notes may be converted, under certain circumstances as described below, based on an initial conversion rate of 94.7811 shares of common stock per $1,000 principal amount (which represents an initial conversion price of $10.55 per share). The conversion rate for the 2026 Notes will be subject to adjustment upon the occurrence of certain specified events. In addition, upon the occurrence of a make-whole fundamental change (as defined in the indenture), the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its notes in connection with such make-whole fundamental change. The Company received approximately $133.9 million in net proceeds, after deducting the initial purchasers’ discount, from the issuance of the 2026 Notes.

The 2026 Notes may be converted at the option of the holder under any of the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on March 31, 2020 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter exceeds 127.5% of the last reported sale price of the Company’s common stock on November 7, 2019; (2) during the 5 consecutive business days immediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “measurement period”) if the trading price per $1,000 principal amount of 2026 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company’s common stock on such trading day and the conversion rate on such trading day; (3) upon the occurrence of certain corporate events or distributions on the Company’s common stock; (4) if the Company calls the 2026 Notes for redemption; and (5) at any time from, and including, July 15, 2026 until the close of business on the scheduled trading day immediately before the maturity date, November 15, 2026. The Company will settle conversions by paying or delivering, as applicable, cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s election, based on the applicable conversion rate.

The 2026 Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after November 20, 2023 and, in the case of any partial redemption, on or before the 60th scheduled trading day before the maturity date, at a cash redemption price equal to the principal amount of the 2026 Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date but only if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price on (1) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice; and (2) the trading day immediately before the date the Company sends such notice. If a “fundamental change” (as defined in the indenture) occurs, then, subject to certain exceptions, holders may require the Company to repurchase their 2026 Notes at a cash repurchase price equal to the principal amount of the 2026 Notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the fundamental change repurchase date.

In accounting for the issuance of the 2026 Notes, the Company separated the 2026 Notes into liability and equity components. The carrying amount of the liability component of approximately $84.2 million was calculated by using a discount rate of 12.0%, which was estimated to be the Company’s borrowing rate on the date of the issuance of the notes for a similar debt instrument without the conversion feature. The carrying amount of the equity component of approximately $49.5 million, representing the conversion option, was determined by deducting the fair value of the liability component from the par value of the 2026 Notes. The equity component of the 2026 Notes is included in additional paid-in capital in the consolidated balance sheets and is not remeasured as long as it continues to meet the conditions for equity classification. The difference between the principal amount of the 2026 Notes and the liability component (the “debt discount”) is amortized to interest expense using the effective interest method over the term of the 2026 Notes.

Debt issuance costs for the issuance of the 2026 Notes were approximately $5.0 million, consisting of initial purchasers' discount and other issuance costs. In accounting for the transaction costs, the Company allocated the total amount incurred to the liability and equity components using the same proportions as the proceeds from the 2026 Notes. Transaction costs attributable to the liability component were approximately $3.1 million, were recorded as debt issuance cost (presented as contra debt in the consolidated balance sheet) and are being amortized to interest expense over the term of the 2026 Notes. The transaction costs attributable to the equity component were approximately $1.9 million and were netted with the equity component in stockholders’ equity. As of December 31, 2021, unamortized debt issuance cost for the 2026 Notes were $2.5 million.

Interest expense recognized on the 2026 Notes for 2021, 2020 and 2019 (in thousands) is as follows:

	Years Ended December 31,
	2021		2020		2019
Contractual interest expense	$	5,520	$	5,520	$	721
Accretion of debt discount		5,907		5,246		673
Accretion of debt issuance costs		59		52		6
Total interest costs recognized	$	11,486	$	10,818	$	1,400

The effective interest rate on the liability component of the 2026 Notes was 12.5% for the year ended December 31, 2021, which remains unchanged from the date of issuance. The remaining unamortized debt discount was $40.1 million as of December 31, 2021 and will be amortized over approximately 4.9 years. If the 2026 Notes were to be converted on December 31, 2021, the holders of the 2026 Notes would receive common shares of 16.7 million with an aggregate value of $760.0 million based on the Company’s closing stock price of $45.58 as of December 31, 2021. The if-converted value of the 2026 Notes exceeded its principal amount by $622.0 million as of December 31, 2021.

Capped Call Transactions

In connection with the offering of the 2026 Notes, the Company entered into privately-negotiated capped call transactions with one of the underwriters in the offering or its affiliate. The Company used approximately $13.4 million of the net proceeds from the offering of the 2026 Notes to pay the cost of the capped call transactions. The capped call transactions are expected generally to reduce potential dilution to the Company’s common stock upon any conversion of the 2026 Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted 2026 Notes, as the case may be, in the event that the market value per share of the Company’s common stock, as measured under the terms of the capped call transactions at the time of exercise, is greater than the strike price of the capped call transactions (which initially corresponds to the initial conversion price of the 2026 Notes, and is subject to certain adjustments), with such reduction and/or offset subject to a cap initially equal to approximately $14.07 per share (which represents a premium of approximately 70% over the last reported sale price of the Company’s common stock on November 7, 2019), subject to certain adjustments. The capped call transactions are separate transactions, entered into by the Company and are not part of the terms of the 2026 Notes.

Given that the transactions meet certain accounting criteria, the convertible note capped call transactions are recorded in stockholders’ equity, and they are not accounted for as derivatives and are not remeasured each reporting period. As of December 31, 2021, the Company had not purchased any shares under the convertible note capped call transactions.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

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+ Details

Liabilities Related to Revenue Participation Right Purchase Agreements

12 Months Ended

Dec. 31, 2021

Royalty Liability [Abstract]

Note 7 — Liabilities Related to Revenue Participation Right Purchase Agreements

We have a number of revenue participation right purchase agreements in place, including the Royalty Purchase Agreement entered into with RTW Royalty Holdings (the “RTW Royalty Purchase Agreement”) in 2020 and the Royalty Purchase Agreement (the “RP OM RPA”) entered into with RPI Finance Trust (“RPFT”) in 2017.

Royalty Purchase Agreement with RPFT

In February 2017, we entered into the RP OM RPA pursuant to which we sold a portion of our right to receive royalties from Amgen on future net sales of omecamtiv mecarbil to RPFT for a one-time payment of $90 million, which is non-refundable even if omecamtiv mecarbil is never commercialized. Concurrently, we entered into a common stock purchase agreement with RPFT through which RPFT purchased 875,656 shares of the Company’s common stock for $10.0 million. We allocated the consideration and issuance costs on a relative fair value basis to our liability to RPFT related to sale of future royalties under the RP OM RPA (the “RP OM Liability”) and the common stock sold to RPFT, which resulted in the RP OM Liability being initially recognized at $92.3 million. The RP OM RPA provides for the sale of a royalty to RPFT of 4.5% on worldwide net sales of omecamtiv mecarbil, subject to a potential increase of up to an additional 1% under certain circumstances.

As a result of the termination of the Amgen Agreement and pursuant to our obligations under the RP OM RPA, we and RPFT entered into Amendment No. 1 to Royalty Purchase Agreement, dated January 7, 2022 to preserve RPFT’s rights under the RP OM RPA by providing for direct payments by us to RPFT of 4.5% of our and our affiliates and licensees worldwide net sales of omecamtiv mecarbil, subject to a potential increase of up to an additional 1% under certain circumstances (if FDA approves omecamtiv mecarbil on its target PDUFA date of November 30, 2022, the royalty owed to RPFT will be 4.9% of worldwide net sales of omecamtiv mecarbil). Amendment No. 1 to Royalty Purchase Agreement, dated January 7, 2022 had no impact on the original accounting for the $92.3 million associated with the RP OM Liability established in February 2017.

We account for the RP OM Liability as a liability primarily because we have significant continuing involvement in generating the related revenue stream from which the liability will be repaid. If and when omecamtiv mecarbil is commercialized and royalties become due, we will recognize the portion of royalties paid to RPFT as a decrease to the RP OM Liability and a corresponding reduction in cash.

The carrying amount of the RP OM Liability is based on our estimate of the future royalties to be paid to RPFT over the life of the arrangement as discounted using an imputed rate of interest. The excess of future estimated royalty payments over the $92.3 million of allocated proceeds, less issuance costs, is recognized as non-cash interest expense using the effective interest method. The imputed rate of interest on the unamortized portion of the RP OM Liability was approximately 10% as of December 31, 2021 and 15% as of December 31, 2020.

We periodically assess the amount and timing of expected royalty payments using a combination of internal projections and forecasts from external sources. To the extent such payments are greater or less than our initial estimates or the timing of such payments is materially different than its original estimates, we will prospectively adjust the amortization of the RP OM Liability and the effective interest rate.

There are a number of factors that could materially affect the amount and timing of royalty payments, most of which are not within our control. The RP OM Liability is recognized using significant unobservable inputs. These inputs are derived using internal management estimates developed based on third party data, including data historically provided by Amgen, and reflect management’s judgements, current market conditions surrounding competing products, and forecasts. The significant unobservable inputs include the estimated patient population, estimated selling price, estimated peak sales and sales ramp, the expected term of the royalty stream, timing of the expected launch and its impact on the royalty rate as well as the overall probability of success. A significant change in unobservable inputs could result in a material increase or decrease to the effective interest rate of the RP OM Liability.

During the year ended December 31, 2021, we updated our analyses for the amount and timing of sales and royalties associated with omecamtiv mecarbil as a result of ongoing market research in the U.S. and to reflect other adjustments in connection with our anticipated commercialization plans. Our estimates regarding the amount of future royalty payments decreased and the time periods within which we anticipated that such payments will be due changed. Each of these adjustments is accounted for on a prospective basis in our liability calculation and resulted in a decline in our imputed interest rate and noncash interest expenses from 15% and $22.7 million in 2020 to 10% and $12.9 million in 2021, respectively. In 2021, the change in estimate had no impact on revenue and reduced the net loss by $11.5 million. The change in accounting estimate reduced net loss per share by $0.15 in 2021. We review our assumptions on a quarterly basis and our estimates may change in the future as we refine and reassess our assumptions.

Changes to the RP OM Liability related to the sale of future royalties are as follows (in thousands):

	2021		2020
Beginning balance, January 1	$	166,068	$	143,276
Interest accretion		12,892		22,713
Amortization of issuance costs		112		79
Ending balance, December 31	$	179,072	$	166,068

We recognized $12.9 million, $22.7 million and $20.7 million in non-cash interest expense in 2021, 2020 and 2019, respectively, related to the RP OM RPA.

On January 7, 2022 we announced that we had sold a revenue interest in our net sales of pharmaceutical products containing aficamten to RPI ICAV under the RP Aficamten RPA, as further described in Note 11 below.

Stockholders' Equity

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Stockholders' Equity

Note 8 — Stockholders’ Equity

Public Offering of Common Stock

In July 2021, we closed an underwritten public offering of 11,500,000 shares of our common stock at a public offering price of $27.50, which included the exercise in full by the underwriters of their option to purchase up to 1,500,000 shares of our common stock at the same price. The gross proceeds were $316.3 million and net proceeds were approximately $296.9 million, after deducting the applicable underwriting discounts and commissions.

Equity Incentive Plan

Our amended and restated 2004 Equity Incentive Plan (the “2004 Plan”) provides for us to grant incentive stock options, nonstatutory stock options, restricted stock, stock appreciation rights, restricted stock units, performance shares and performance units to employees, directors and consultants. We may grant options for terms of up to ten years at prices not lower than 100% of the fair market value of our common stock on the date of grant. Options granted to new employees generally vest 25% after one year and monthly thereafter over a period of four years. Options granted to existing employees generally vest monthly over a period of four years.

In May 2019, our stockholders approved an amendment to the Amended and Restated 2004 Equity Incentive Plan (the “2004 Plan”) to increase the number of authorized shares reserved for issuance under the 2004 Plan by 4.1 million shares. In May 2020, our board of directors approved an amendment to the 2004 Plan to increase the number of authorized shares reserved for issuance under the 2004 Plan by 0.8 million shares for inducement grants to new employees. In May 2021, our stockholders approved an amendment to the 2004 Plan to increase the number of authorized shares reserved for issuance under the 2004 Plan by 5.2 million shares to 21.5 million shares (excluding an additional 0.8 million then authorized for issuance as inducement grants to new employees). In August 2021, the Company’s board of directors approved another amendment to the 2004 plan and increased the number of shares reserved for issuance for inducement grants to new employees from the 0.8 million to 1.9 million. We started granting inducement grants in September 2020. As of December 31, 2021, the total authorized shares under the 2004 Plan of 5.7 million were available for grant.

Stock option activity in 2021 was as follows:

	Stock Options Outstanding			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in millions)
Balance at December 31, 2019		7,759,012		$	8.59
Granted		1,944,562			15.59
Exercised		(967,571	)		8.27
Forfeited		(234,054	)		16.06
Balance at December 31, 2020		8,501,949		$	10.02
Granted		2,513,350			22.43
Exercised		(1,346,194	)		9.01
Forfeited		(296,146	)		14.56
Balance at December 31, 2021		9,372,959		$	13.35		6.8	$	302.1
Exercisable at December 31, 2021		5,828,902		$	9.99		5.6	$	207.4

We expect all outstanding options to vest. The intrinsic value of stock options exercised, calculated based on the difference between the market value at the date of exercise and the exercise price, was $29.3 million for 2021, $14.0 million for 2020 and $0.5 million for 2019. The intrinsic value of stock options outstanding at December 31, 2021 was $302.1 million.

Restricted stock unit (“RSU”), including Performance Stock Units (“PSUs”), activity in 2021 was as follows:

	Number of Restricted Stock Units			Weighted Average Award Date Fair Value per Share
Balance at December 31, 2019		839,075		$	7.49
Granted		731,225			14.40
Exercised		(435,450	)		7.72
Forfeited		(18,208	)		10.37
Balance at December 31, 2020		1,116,642		$	11.88
Granted		1,093,450			21.69
Exercised		(606,240	)		11.13
Forfeited		(189,025	)		21.32
Balance at December 31, 2021		1,414,827		$	18.52

RSUs generally vest annually over two to three years. For 2021, the fair value of RSUs vested, calculated based on the units vested multiplied by the closing price of our common stock on the date of vesting, was $11.6 million.

Performance Stock Units

In May 2021, the Compensation and Talent Committee of the Company’s Board of Directors (“the Compensation Committee”) granted a total of 375,000 Performance Stock Units (“PSUs”) to certain employees with a weighted average grant date fair value of $25.32 per unit. The fair value of the PSUs was determined on the grant date based on the fair value of the Company’s common stock at such time. The PSUs consist of two equal tranches with 50% of each tranche vesting upon achieving certain performance criteria and 50% vesting at the one-year anniversary of such achievement provided the recipient has been continuously employed by the Company. The first tranche vests upon certification by the Compensation Committee that the new drug application (“NDA”) for omecamtiv mecarbil has been filed and accepted by the U.S. Food and Drug Administration (“FDA”) and the second tranche vests upon certification by the Compensation Committee that the FDA approval of the NDA is with an approved label that is consistent with the expectations underlying the Company’s commercial launch plans for omecamtiv mecarbil in effect immediately prior to such approval. As the FDA accepted our NDA for omecamtiv mecarbil subsequent to the year ended 2021, it resulted in change of estimate of the probability of meeting the performance conditions for the PSU grants during the fourth quarter of 2021. The previous estimate was based on assumptions that were the best available information at the time. The change of estimate resulted in a cancellation of 91,250 PSUs and decrease of $0.5 million in stock-based compensation expense for the year ended December 31, 2021.

In 2021, the Company recognized expense of $1.4 million for the first tranche of PSUs. No expense has been recognized for the second tranche. As of December 31, 2021, there were 273,750 PSUs outstanding and $0.9 million unamortized stock-based compensation, which may vest and recognized with respect to the achievement of the performance goals and service period. The Company will assess the likelihood of achieving the performance conditions quarterly and the expense recognized will be adjusted accordingly.

Employee Stock Purchase Plan

Under our 2015 Employee Stock Purchase Plan (the “ESPP”), employees may purchase common stock up to a specified maximum amount at a price equal to 85% of the fair market value at certain plan-defined dates. In May 2020, the Company’s stockholders approved an amendment to the ESPP to increase the number of common stock shares reserved for issuance under the ESPP by 0.5 million shares.

We issued 108,780 shares at an average price of $16.33 per share during 2021, 134,684 shares at an average price of $11.21 per share in 2020, and 172,113 shares at an average price of $6.43 per share in 2019 pursuant to the ESPP. At December 31, 2021, we have 338,040 shares of common stock reserved for issuance under the ESPP.

Stock-Based Compensation Expense

We use the Black-Scholes option pricing model to determine the fair value of stock option grants to employees and directors and employee stock purchase plan shares. The fair value of share-based payments was estimated on the date of grant based on the following assumptions:

Year Ended December

31, 2021

Year Ended December

31, 2020

Year Ended December

31, 2019

Options

ESPP

Options

ESPP

Options

ESPP

Risk-free interest rate

0.58% to 1.28%

0.05%

0.42% to 1.8%

0.11% to 1.8%

1.6% to 3.0%

1.8% to 2.4%

Volatility

66% to 67%

74% to 75%

73% to 76%

Expected term in years

6.4 to 6.5

0.5

6.5 to 6.6

0.5

6.5

0.6

Expected dividend yield

0%

We use U.S. Treasury zero-coupon issues with remaining terms similar to the expected terms of the options for the risk-free interest rate. We use our own volatility history based on its stock’s trading history and our own historical exercise and forfeiture activity to estimate expected term for option grants. We do not anticipate paying dividends in the foreseeable future and use an expected dividend yield of zero. We do not estimate forfeitures in our stock-based compensation.

We measure compensation expense for restricted stock units at fair value on the date of grant and recognize the expense over the expected vesting period. We recognize stock-based compensation expense on a ratable basis over the requisite service period, generally the vesting period of the award for share-based awards.

Stock-based compensation expense for 2021 and 2020 was as follows (in thousands):

	Years Ended December 31,
	2021		2020		2019
Research and development	$	10,463	$	6,949	$	4,260
General and administrative		16,369		10,671		6,499
	$	26,832	$	17,620	$	10,759

Stock-based compensation expense for share-based awards to non-employees was $0.2 million in 2021, 2020, and 2019.

As of December 31, 2021, we expect to recognize $44.5 million of unrecognized compensation cost related to unvested stock options over a weighted-average period of 2.7 years, $11.5 million of unrecognized compensation cost related to unvested restricted stock over a weighted-average period of 1.4 years, and $0.9 million of unrecognized compensation cost related to unvested PSUs, which may vest and recognized with respect to the achievement of the performance goals and service period.

Warrants

Pursuant to the Term Loan agreement described in Note 6 - Debt, we issued a warrant with an exercise price of $9.76 per share to purchase 23,065 shares of our common stock in 2019. The warrant was fully exercisable and expires in May 2029. As of December 31, 2019, warrants to purchase 165,424 shares of our common stock with a weighted average exercise price of $7.25 per share were outstanding. All outstanding warrants are fully exercisable and expire ten years after issuance.

During the first quarter of 2020, in connection with the Term Loan Agreement further described in Note 6 - Debt, we issued a warrant with an exercise price of $10.42 per share to purchase 21,595 shares of our common stock. The warrant was issued in connection with achieving the interest-only extension milestone 1 in the Term Loan Agreement. The warrant was fully exercisable and expires in January 2030. The $0.2 million fair value of the warrant related to the Term Loan was recorded as interest expense during the first quarter of 2020.

In July 2020, OTA LLC, an assignee of Oxford, exercised 51,214 warrants with a strike price of $6.59 per share, 48,892 warrants with a strike price of $6.903 per share, and 25,352 warrants with a strike price of $7.10 per share and elected the cashless settlement method. Accordingly, in July 2020, we issued to OTA LLC a total of 95,932 shares of our common stock.

In October 2020, OTA LLC exercised 13,839 warrants with a strike price of $9.755 per share and elected cashless settlement method. Accordingly, in October 2020, we issued OTA LLC a total of 8,958 shares of our common stock.

As of December 31, 2021, we had outstanding warrants issued pursuant to the Original Loan Agreement and Term Loan Agreement with a weighted average exercise price of $9.12 per share to purchase 47,722 shares of our common stock.

Committed Equity Offering

In 2019, we terminated our original Controlled Equity Offering^SM Sales Agreement (the “ATM Facility”) with Cantor Fitzgerald & Co. (“Cantor”) for the sale, in our sole discretion, of shares of our common stock, having an aggregate offering price of up to $75.0 million through Cantor and we entered into a new sales agreement (the “New ATM Facility”) with Cantor, which provides for the sale, in our sole discretion, of shares of our common stock having an aggregate offering price of up to $85.0 million through Cantor, as our sales agent. The issuance and sale of these shares by us pursuant to the New ATM Facility are deemed “at the market” offerings and are registered under the Securities Act of 1933, as amended. We pay a commission of up to 3.0% of gross sales proceeds of any common stock sold under the New ATM Facility. As of 2019, we issued 3,984,849 shares of common stock for net proceeds of $36.2 million under the New ATM Facility.

Claims Settlement

In the first quarter of 2020, we received $2.2 million from a claims settlement with certain institutional investors that were beneficial owners of our common stock related to the disgorgement of short swing profits pursuant to Section 16(b) of the Securities Exchange Act of 1934, as amended. This settlement was recognized in equity as additional paid-in capital.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 9 — Commitments and Contingencies

Operating Leases

In May 2021, we amended the lease agreement for buildings 250, 256 and 280 East Grand Avenue, South San Francisco, California for our existing facilities and extended the lease term until June 30, 2022, which was accounted for as a lease modification in accordance with Topic 842. Pursuant to such guidance, the Company remeasured the modified lease using the revised term as of the modification date. Adjustments were made to reflect the remeasured liability with the offset to the right-of-use asset. The lease includes rental payments and payment of certain operating expenses. Under the lease terms, we have minimum rental fee payment obligations of $0.5 million per month through the remaining term.

As of December 31, 2021, the remaining lease term is 0.5 years and the discount rate used to determine the operating lease liability was 6.8% for buildings 250, 256 and 280 East Grand Avenue, South San Francisco, California.

In July 2019, we entered into a lease agreement for approximately 234,892 square feet of office and laboratory space at a facility located in South San Francisco, California and in May 2020, January 2021 and November 2021, we entered into first, second and third amendments to the lease (collectively the “Oyster Point Lease”).

The Oyster Point Lease commenced on March 31, 2021 and upon commencement, we recognized a right-of-use asset of $77.9 million, a short-term lease liability of $3.7 million and a long-term lease liability of $85.3 million. The long-term lease liability includes $11.1 million of tenant improvement reimbursements as of March 31, 2021. The Oyster Point Lease had an initial expiration date of September 30, 2033 and we have two consecutive five-year options to extend the lease. The options to extend the lease term were not included as part of the right-of-use asset or lease liability as the exercise of the options were not reasonably assured at the inception of the lease. During the third quarter of 2021, we amended the lease payment schedule and will be required to start making rent payments in January 2022. The lease term is extended until October 31, 2033. The amendment was accounted for as a lease modification in accordance with Topic 842.

As of December 31, 2021, the remaining lease term of the Oyster Point Lease is 11.8 years and the discount rate used to determine the related lease liability was 10.1%. We paid a total security deposit of $5.1 million in December 2019 and December 2020. The landlord will provide a tenant improvement allowance of $43.6 million in aggregate for costs relating to the initial design and construction of the improvements. As of December 31, 2021, the total commitment of undiscounted lease payments for the Oyster Point Lease was $230.5 million.

During the fourth quarter of 2021, we officially relocated from our existing headquarters located at 250, 256, and 280 East Grand Avenue, South San Francisco to our new facilities at Oyster Point. As a result of the relocation, we considered ceasing use of the existing headquarters, which triggered an impairment assessment. In connection with this assessment, we recorded an impairment loss of $2.8 million, consisting of right-of-use assets of the existing headquarters, which is included in operating expenses on the consolidated statement of operations for the year ended December 31, 2021. We are subject to the fixed rental fee payments for the existing headquarters through the remaining term until June 2022.

As of December 31, 2021, the weighted average remaining lease term for the operating leases is 11.7 years and the weighted average discount rate used to determine the operating lease liability is 10.0%

Cash paid for amounts included in the measurement of operating lease liabilities for the years ended December 31, 2021 and 2020 was $6.1 million and $6.7 million, respectively, and was included in net cash used in operating activities in our consolidated statements of cash flows.

Finance Leases

During the third quarter of 2021, we entered into a master lease agreement for laboratory equipment leases that was partially commenced in the fourth quarter of 2021. The leases have an initial term of 3 years and are expected to commence through the second quarter of 2022. The master lease agreement provides a purchase option with a bargain purchase price, which we expect to exercise at the end of the term. The Company classified the leases as finance leases.

Finance leases are accounted for on the consolidated balance sheets with right-of-use assets and lease liabilities recognized in property and equipment, other current liabilities, and other non-current liabilities, respectively. The finance lease cost is recognized as a combination of the amortization expense for the right-of-use assets calculated on a straight-line basis over the five-year estimated useful life for laboratory equipment and interest expense for the outstanding lease liabilities using the determined discount rates. As of December 31, 2021, we have recognized finance lease right-of-use assets of $1.4 million, short-term finance lease liabilities of $0.5 million, and long-term finance lease liabilities of $0.8 million.

As of December 31, 2021, the weighted average remaining lease term for the finance leases is 4.9 years and the weighted average discount rate used to determine the finance lease liabilities is 9.47%.

There was no cash paid for amounts included in the measurement of finance lease liabilities for the year ended December 31, 2021.

The undiscounted future non-cancellable lease payments under all our operating and finance lease agreements as of December 31, 2021 is as follows (in thousands):

Years ending December 31:	Operating Leases			Finance Leases
2022	$	15,611		$	513
2023		17,060			479
2024		17,620			479
2025		18,199			—
2026		18,799			—
Thereafter		146,193			—
Total undiscounted future lease payments		233,482			1,471
Less: Present value adjustments		(106,390	)		(166	)
Total lease liability	$	127,092		$	1,305

The lease obligations for the finance leases that have not yet commenced as of December 31, 2021 is approximately $1.9 million, which are not included in the table above. These leases will commence through the second quarter of 2022 and expire in 2025.

Rent expenses for the operating leases and finance leases were $23.1 million, $5.7 million and $5.1 million for 2021, 2020 and 2019, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

Note 10 — Income Taxes

We did not record an income tax provision in 2021, 2020 and 2019 because we had net taxable losses. Our significant jurisdictions are the United States and California.

The following reconciles the statutory federal income tax rate to our effective tax rate:

	Years Ended December 31,
	2021			2020			2019
Tax at federal statutory tax rate		21	%		21	%		21	%
State tax, net of federal benefits		0	%		1	%		3	%
Change in state effected rates		(1	)%		(2	)%		4	%
Tax credits, net		3	%		3	%		3	%
Change in valuation allowance		(24	)%		(23	)%		(30	)%
Stock-based compensation		2	%		1	%		(1	)%
Other		(1	)%		(1	)%		0	%
Total		0	%		0	%		0	%

Deferred tax assets, net, reflecting the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, were as follows (in thousands):

	As of December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	181,977		$	162,514
Tax credits		77,366			71,976
Liability related to sale of future royalties		38,302			36,989
Reserves and accruals		15,409			10,876
Capitalized R&D		1,115			2,370
Long-term lease liability		26,223			718
Deferred revenue		18,608			—
Depreciation and amortization		—			746
Total noncurrent deferred tax assets		359,000			286,189
Deferred tax liabilities:
Depreciation and amortization		(7,664	)		—
Accounting method change		—			(927	)
Operating lease right-of-use assets		(15,643	)		(651	)
Convertible notes		(8,296	)		(9,832	)
Total noncurrent deferred tax liabilities		(31,603	)		(11,410	)
Less: Valuation allowance		(327,397	)		(274,779	)
Net deferred tax assets	$	—		$	—

Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Based upon the weight of available evidence, which includes our historical operating performance, reported cumulative net losses since inception, expected future losses, and difficulty in accurately forecasting our future results and an assessment of both positive and negative evidence when determining whether it is more likely than not that deferred tax assets are recoverable, we maintained a full valuation allowance on the net deferred tax assets as of December 31, 2021 and 2020. The valuation allowance increased by $52.6 million in 2021 and increased by $28.9 million in 2020.

At December 31, 2021 federal NOL carryforwards were $753.8 million and apportioned state NOL carryforwards before federal benefits were $323.1 million. If not utilized, federal and state operating loss carryforwards incurred prior to 2018 will begin to expire in various amounts beginning 2022 and 2028, respectively.

At December 31, 2021, tax credits of $73.6 million and $17.8 million for federal and state income tax purposes, respectively consisted of Research and Development Credits and Orphan Drug Credits. If not utilized, the federal carryforwards will expire in various amounts beginning in 2021. California based credit carryforwards do not expire.

In general, under Section 382 of the Internal Revenue Code (“Section 382”), a corporation that undergoes an ‘ownership change’ is subject to limitations on its ability to utilize its pre-change net operating losses and tax credits to offset future taxable income. We do not believe it has experienced an ownership change since 2006, however, a portion of its NOLs and tax credits prior to 2007 will be subject to limitations under Section 382.

Activity related to our gross unrecognized tax benefits were (in thousands):

	Years Ended December 31,
	2021			2020			2019
Balance at the beginning of the year	$	10,522		$	9,922		$	9,475
Decrease related to prior year tax positions		(29	)		(3	)		—
Increase related to current year tax positions		802			603			447
Balance at the end of the year	$	11,295		$	10,522		$	9,922

We are subject to income tax examination for all fiscal years with unutilized NOLs and tax credit carryforwards. Included in the balance of unrecognized tax benefits as of December 31, 2021, 2020 and 2019 are $10.3 million, $9.6 million and $9.1 million of tax benefits, respectively, that, if recognized, would result in adjustments to other tax accounts, primarily deferred taxes.

On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security (CARES) Act was signed into law making several changes to the Internal Revenue Code, including provisions addressing the carryback of net operating losses for specific periods, refunds of alternative minimum tax credits, temporary modifications to limitations placed on the tax deductibility of net interest expenses, and technical amendments for qualified improvement property. Additionally, the CARES Act provides for refundable employee retention tax credits and the deferral of the employer-paid portion of Social Security taxes. For the years ended December 31, 2021 and 2020, respectively, the Company’s income tax provision was not significantly impacted by the CARES Act. The Company will continue to closely monitor any effects from future legislation.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

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+ Details

Subsequent Events

12 Months Ended

Dec. 31, 2021

Subsequent Events [Abstract]

Subsequent Events

Note 11 — Subsequent Events

2022 Royalty Pharma Transactions

On January 7, 2022, we announced that we had entered into the RP Loan Agreement and the RP Aficamten RPA with RPDF and RPI ICAV respectively, each of which are affiliated with Royalty Pharma International plc.

Under the RP Loan Agreement, we are entitled to receive up to $300.0 million in term loans, $50.0 million of which was disbursed to us on closing and the remaining $250.0 available to us upon our satisfaction of customary disbursement conditions and certain development conditions by specific deadlines, as follows:

•

$50.0 million of tranche 2 term loans during the one year period following the receipt on or prior to December 31, 2022 of marketing approval from FDA of omecamtiv mecarbil;

•

$25.0 million of tranche 3 term loans during the one year period following the commercial availability of a diagnostic test measuring levels of omecamtiv mecarbil to support the final FDA label language applicable to such drug, subject to such commercial availability and the conditions to the tranche 2 term loans having occurred on or prior to December 31, 2022;

•

$75.0 million of tranche 4 term loans during the one year period following the receipt on or prior to September 30, 2024 of positive results from SEQUOIA-HCM, the Phase 3 trial for aficamten; and

•

$100.0 million of tranche 5 term loans during the one year period following the acceptance by the FDA on or prior to March 31, 2025 of an NDA for aficamten, subject to the conditions to the tranche 4 term loans having occurred on or prior to September 30, 2024.

Each term loan under the RP Loan Agreement matures on the 10 year anniversary of the funding date for such term loan and is repayable in quarterly installments of principal, interest and fees commencing on the last business day of the seventh full calendar quarter following the calendar quarter of the applicable funding date for such Term Loan, with the aggregate amount payable in respect of each term loan (including interest and other applicable fees) equal to 190% of the principal amount of the term loan (such amount with respect to each Term Loan, “Final Payment Amount”).

We may prepay the term loans in full (but not in part) at any time at our option by paying an amount equal to the unpaid portion of Final Payment Amount for the outstanding Term Loans; provided that if the conditions for either the tranche 4 term loans or the tranche 5 term loans have been met, we must have borrowed at least $25 million principal amount of the tranche 4 or 5 term loans. In addition, the term loans under the RP Loan Agreement are repayable in full at the option of either us or the lender in an amount equal to the unpaid portion of Final Payment Amount for the outstanding term loans upon a change of control of Cytokinetics.

In addition, on January 7, 2022, we entered into the RP Aficamten RPA with RPI ICAV, pursuant to which RPI ICAV purchased rights to certain revenue streams from net sales of pharmaceutical products containing aficamten by us, our affiliates and our licensees in exchange for up to $150.0 million in consideration, $50.0 million of which was paid on the closing date, $50.0 million of which is payable following the initiation of the first pivotal trial in oHCM for aficamten and $50.0 million of which is payable following the initiation of the first pivotal clinical trial in nHCM for aficamten. The RP Aficamten ARPA also provides that the parties will negotiate terms for additional funding if we achieve proof of concept results in certain other indications for aficamten, with a reduction in the applicable royalty if we and RPI ICAV fail to agree on such terms in certain circumstances.

Pursuant to the RP Aficamten RPA, RPI ICAV purchased the right to receive a percentage of net sales equal to 4.5% for annual worldwide net sales of pharmaceutical products containing aficamten up to $1 billion and 3.5% for annual worldwide net sales of pharmaceutical products containing aficamten in excess of $1 billion, subject to reduction in certain circumstances.

Commensurate with our entry into the RP Loan Agreement and RP Aficamten RPA, we terminated the Term Loan Agreement with the Lenders and repaid all amounts outstanding thereunder.

Organization and Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization

Cytokinetics, Incorporated (the “Company”, “we” or “our”) was incorporated under the laws of the state of Delaware on August 5, 1997. We are a late-stage biopharmaceutical company focused on the discovery and development of novel small molecule therapeutics that modulate muscle function for the potential treatment of serious diseases and medical conditions.

Our financial statements contemplate the conduct of our operations in the normal course of business. We have incurred an accumulated deficit of $1,207.6 million since inception and there can be no assurance that we will attain profitability. We had a net loss of $215.3 million and net cash used in operations of $142.5 million for the year ended December 31, 2021. Cash, cash equivalents and investments increased to $623.7 million as of December 31, 2021 from $501.0 million as of December 31, 2020. We anticipate that we will have operating losses and net cash outflows in future periods.

We are subject to risks common to late-stage biopharmaceutical companies including, but not limited to, development of new drug candidates, dependence on key personnel, and the ability to obtain additional capital as needed to fund our future plans. Our liquidity will be impaired if sufficient additional capital is not available on terms acceptable to us. To date, we have funded operations primarily through sales of our common stock, contract payments under our collaboration agreements, sale of future royalties, debt financing arrangements, government grants and interest income. Until we achieve profitable operations, we intend to continue to fund operations through payments from strategic collaborations, additional sales of equity securities, grants and debt financings. We have never generated revenues from commercial sales of our drugs and may not have drugs to market for at least several years, if ever. Our success is dependent on our ability to enter into new strategic collaborations and/or raise additional capital and to successfully develop and market one or more of our drug candidates. We cannot be certain that sufficient funds will be available from such a financing or through a collaborator when required or on satisfactory terms. Additionally, there can be no assurance that our drug candidates will be accepted in the marketplace or that any future products can be developed or manufactured at an acceptable cost. These factors could have a material adverse effect on our future financial results, financial position and cash flows.

Based on the current status of our research and development activities, we believe that our existing cash, cash equivalents and investments will be sufficient to fund cash requirements for at least the next 12 months after the issuance of these consolidated financial statements. If, at any time, our prospects for financing our research and development programs decline, we may decide to reduce research and development expenses by delaying, discontinuing or reducing our funding of one or more of our research or development programs. Alternatively, we might raise funds through strategic collaborations, public or private financings or other arrangements. Such funding, if needed, may not be available on favorable terms, or at all. The financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. We evaluate our estimates on an ongoing basis. We base our estimates on our historical experience and also on assumptions that we believe are reasonable; however, actual results could significantly differ from those estimates.

Basis of Presentation

The consolidated financial statements include the accounts of Cytokinetics, Incorporated and its wholly-owned subsidiary and have been prepared in accordance with GAAP. Intercompany transactions and balances have been eliminated in consolidation. Certain prior period amounts have been reclassified to conform the prior period presentation to the current year.

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject us to concentrations of risk consist principally of cash and cash equivalents, investments, and accounts receivable.

Our cash, cash equivalents and investments are invested in deposits with two major financial institutions in the United States. Deposits in these banks may exceed the amount of insurance provided on such deposits.

Our exposure to credit risk associated with non-payment is limited to Astellas Pharma Inc. for co-funding one-third of the out-of-pocket clinical development costs which may be incurred in connection with Cytokinetics’ Phase 3 clinical trial, COURAGE-ALS, of reldesemtiv in ALS up to a maximum contribution by Astellas of $12.0 million, to our strategic partner in the People’s Republic of China (including the Hong Kong and Macau Special Administration Districts) (“China”) and Taiwan, Ji Xing Pharmaceuticals Limited (“Ji Xing”), and Royalty Pharma Investments ICAV (“RPI ICAV”), to whom we sold a revenue interest in our net sales of pharmaceutical products containing aficamten under a revenue interest purchase agreement, dated January 7, 2022 (the “RP Aficamten RPA”), as further described in Note 11 below.

Drug candidates we develop may require approvals or clearances from the U.S. Food and Drug Administration (“FDA”) or other regulatory agencies prior to commercial sales. There can be no assurance that our drug candidates will receive any of the required approvals or clearances. If we were to be denied approval, or clearance or any such approval or clearance was to be delayed, it would have a material adverse impact on us.

Cash and Cash Equivalents

We consider all highly liquid investments with a maturity of three months or less at the time of purchase to be cash equivalents.

Investments

Available-for-sale investments. Our investments consist of U.S. Treasury securities, U.S. and non-U.S. government agency bonds, commercial paper, global portfolio of corporate debt and money market funds. We designate all investments as available-for-sale and report them at fair value, based on quoted market prices, with unrealized gains and losses recorded in accumulated other comprehensive income and loss. The cost of securities sold is based on the specific-identification method. Investments with original maturities greater than three months and remaining maturities of one year or less are classified as short-term investments. Investments with remaining maturities greater than one year are classified as long-term investments. The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in Interest and other income, net. Recognized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in Interest and other income, net. Interest and dividends on securities classified as available-for-sale are included in Interest and other income, net.

All of our available-for-sale investments are subject to a periodic impairment review. If an impairment is the result of a credit loss, we recognize an allowance for credit losses (“ACL”). ACL’s reflect management’s current estimate of credit losses that are expected to occur over the remaining life of a financial asset. We recognize an impairment charge when a decline in the fair value of investments below the cost basis is judged to be other-than-temporary. Factors we consider in assessing whether an other-than-temporary impairment has occurred include: the nature of the investment; whether the decline in fair value is attributable to specific adverse conditions affecting the investment; the financial condition of the investee; the severity and the duration of the impairment; and whether we have the intent and ability to hold the investment to maturity. When we determine that an other-than-temporary impairment has occurred, the investment is written down to its market value at the end of the period in which it is determined that an other-than-temporary decline has occurred.

Property and Equipment, net

Property and equipment are stated at cost less accumulated depreciation and are depreciated on a straight-line basis over the estimated useful lives of the related assets, which are generally three years for computer equipment and software, five years for laboratory equipment and office equipment, and seven years for furniture and fixtures. Amortization of leasehold improvements and finance lease right-of-use assets are computed using the straight-line method over the shorter of the remaining lease term or the estimated useful life of the related assets, typically ranging from three to twenty-two years. Upon sale or retirement of assets, the costs and related accumulated depreciation and amortization are removed from the balance sheet and the resulting gain or loss is reflected in operations.

Impairment of Long-lived Assets

We review long-lived assets, including property, equipment and right-of-use assets, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Impairment is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value. We would recognize an impairment loss when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount.

Leases

We determine if the arrangement contains a lease at inception based on whether the contract conveys the right to control the use of an identified asset. The lease classification is determined at lease commencement, which is the date the underlying asset is available for use by the Company, and preliminary based on whether the arrangement is effectively a financed purchase of the underlying asset (finance lease) or not (operating lease). We determined the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. In addition to the fixed minimum lease payments required under the lease arrangements, certain leases include payments of operating expenses that may be revised based on the landlord’s estimate. These variable payments are excluded from the lease payments used to determine the right-of-use asset and lease liability and are recognized when the associated activity occurs.

We recognize right-of-use assets and short-term and long-term lease liabilities on our consolidated balance sheets for operating leases. The right-of-use asset and short-term and long-term lease liabilities for finance leases are recognized in property and equipment, other current liabilities, and other non-current liabilities, respectively, on the consolidated balance sheets.

In determining the present value of lease payments, we estimated our incremental borrowing rate based on information available upon commencement. We base the lease liabilities on the present value of remaining lease payments over the remaining terms of the leases using an estimated rate of interest that we would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The initial right-of-use asset, for both operating and finance leases, is measured based on the lease liability adjusted for any initial direct costs, lease prepayments, and lease incentives.

We recognize rent expense for operating leases on a straight-line basis over the lease term in operating expenses on the consolidated statements of operations. Finance lease right-of-use assets are amortized on a straight-line basis over the shorter of the expected useful life or the lease term, and the carrying amount of the lease liability is adjusted to reflect interest, which is recorded in interest expense.

We exclude from our consolidated balance sheets recognition of leases having a term of 12 months or less (short-term leases). We account for lease and non-lease components as a single component for our operating leases.

Our operating leases consist of the facilities leases with KR Oyster Point 1, LLC (the “Kilroy Lease”) and Britannia Pointe Grand Limited Partnership (the “Britannia Leases”) and our finance leases are for laboratory equipment.

Revenue Recognition

We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration for those goods or services. To recognize revenue from a contract with a customer, we:

(i)

identify our contracts with our customers;

(ii)

identify our distinct performance obligations in each contract;

(iii)

determine the transaction price of each contract;

(iv)

allocate the transaction price to the performance obligations; and

(v)

recognize revenue as we satisfy our performance obligations.

At contract inception, we assess the goods or services promised within each contract and assess whether each promised good or service is distinct and determine those that are performance obligations. We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

Collaborative Arrangements

We enter into collaborative arrangements with partners that typically include payment to us for one of more of the following: (i) license fees; (ii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; (iii) royalties on net sales of licensed products; and (iv) research and development cost reimbursements. Each of these payments results in collaboration or other revenues. Where a portion of non-refundable up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied.

As part of the accounting for these arrangements, we must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligations. The stand-alone selling price may include such items as, forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success, to determine the transaction price to allocate to each performance obligation.

For our collaboration agreements that include more than one performance obligation, such as a license combined with a commitment to perform research and development services, we make judgments to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. We evaluate our progress each reporting period and, if necessary, adjust the measure of a performance obligation and related revenue recognition.

License Fees: If a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front license fees. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

Milestone Payments: We use judgment to determine whether a milestone is considered probable of being reached. Using the most likely amount method, we include the value of a milestone payment in the consideration for a contract at inception if we then conclude achieving the milestone is more likely than not. Otherwise, we exclude the value of a milestone payment from contract consideration at inception and recognize revenue for a milestone at a later date, when we judge that it is probable the milestone will be achieved. If we conclude it is probable that a significant revenue reversal would not occur, the associated milestone is included in the transaction price. We then allocate the transaction price to each performance obligation on a relative stand-alone selling price basis, for which we recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, we re-evaluate the probability of achievement of such milestones and any related constraint, and if necessary, adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration and other revenues and earnings in the period of adjustment.

Royalties: For contracts that include sales-based royalties, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied. To date, we have not recognized any royalty revenues resulting from contracts.

Research and Development Cost Reimbursements: Our joint programs with Astellas under that certain License and Collaboration Agreement for Other Skeletal Sarcomere Activators, dated April 23, 2020, as amended (the “Astellas OSSA Agreement”), and with Amgen under that certain Collaboration and Option Agreement, dated December 29, 2006, as amended (the “Amgen Agreement”) (both of the Astellas OSSA Agreement and the Amgen Agreement having now been terminated), included promises of research and development services. We also entered into the Fast Skeletal Regulatory Activator Agreement with Astellas, dated April 23, 2020 (the “Astellas FSRA Agreement”). Under the Astellas FSRA Agreement, Astellas agreed to pay one-third of the out-of-pocket clinical development costs which may be incurred in connection with the Company’s Phase 3 clinical trial of reldesemtiv in ALS, up to a maximum contribution by Astellas of $12.0 million. We determined that these services collectively were distinct from any licenses provided to Astellas and Amgen under such agreements, and as such, these promises were accounted for as a separate performance obligation recorded over time. We recognized revenue for these services as the performance obligations are satisfied, which we estimated using internal research and development costs incurred.

Accrued Research and Development Expenditures

A substantial portion of our preclinical studies and all of our clinical trials have been performed by third-party contract research organizations (“CROs”) and other vendors and our accruals for expenses for preclinical studies and clinical trials may be significant. For preclinical studies, the significant factors used in estimating accruals include the percentage of work completed to date and contract milestones achieved. For clinical trial expenses, the significant factors used in estimating accruals include the number of patients enrolled, duration of enrollment, milestones achieved and percentage of work completed to date. We monitor patient enrollment levels and related activities to the extent practicable through internal reviews, correspondence and status meetings with CROs, and review of contractual terms. We depend on the timeliness and accuracy of data provided by our CROs and other vendors to accrue expenses. If we receive and rely on incomplete or inaccurate data, accruals and expenses may be too high or too low at a given point in time and corresponding adjustments to accruals and expenses would be made in future periods when the actual expense becomes known.

Revenue Participation Right Purchase Agreements

We have entered into certain revenue participation right purchase agreements with certain investors, pursuant to which such investors purchased rights to royalties from certain revenue streams in exchange for consideration. We typically account for such agreements as debt to be amortized under the effective interest rate method over the life of the related royalty stream, when we have continuing involvement with the underlying R&D. We typically account for such agreements as deferred income to be amortized under the units-of-revenue method, when there is no continuing involvement with the underlying R&D.

Revenue participation right purchase agreements are recognized using significant unobservable inputs. These inputs are derived using internal management estimates developed based on third party data and reflect management’s judgements, current market conditions surrounding competing products, and forecasts. We will periodically assess the amount and timing of expected royalty payments and account for any changes in such estimates on a prospective basis.

Research and Development Expenditures

Research and development costs are charged to operations as incurred. Research and development expenses consist primarily of clinical manufacturing costs, preclinical study expenses, consulting and other third-party costs, employee compensation, supplies and materials, allocation of overhead and occupancy costs, facilities costs and depreciation of equipment.

Income Taxes

We account for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.

We recognize uncertain tax positions taken or expected to be taken on a tax return. Tax positions are initially recognized when it is more likely than not that the position will be sustained upon examination by the tax authorities. Such tax positions are initially and subsequently measured as the largest amount of tax benefit that is more likely than not of being realized upon ultimate settlement with the tax authority assuming full knowledge of the position and relevant facts.

We recognize interest accrued related to unrecognized tax benefits and penalties as income tax expense.

The only aspect of ASU 2019-12 that had a material impact on our consolidated financial statements was the removal of the exception related to intraperiod tax allocation. Starting in 2019, we followed the general intraperiod allocation of tax expense. We have a loss from continuing operations and subsequent to the adoption of ASU 2019-12, we determined the amount attributable to continuing operations without regard to the tax effect of other items. We prospectively applied the ASU 2019-12 amendment related to intraperiod tax allocation.

Had the Company not adopted ASU 2019-12, upon issuance of the convertible notes in 2019 (see Note 6 – Debt) a $12.0 million deferred tax benefit would have been recognized along with corresponding decreases to net loss and accumulated deficit. The Company had no intraperiod tax allocation items in prior years.

Due to our net loss position, the income tax benefit generated without the adoption of ASU 2019-12 was a non-cash benefit. The adoption of ASU 2019-12 did not impact our cash flows.

Stock-Based Compensation

We maintain equity incentive plans under which incentive stock options may be granted to employees and nonqualified stock options, restricted stock awards, performance-based stock units and stock appreciation rights may be granted to employees, directors, consultants and advisors. In addition, we maintain an employee stock purchase plan (“ESPP”) under which employees may purchase shares of our common stock through payroll deductions.

Stock-based compensation expense related to stock options granted to employees and directors is recognized based on the grant date estimated fair values using the Black Scholes option pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense ratably over the requisite service period.

Stock-based compensation expense related to performance-based stock units granted to employees is recognized based on the grant-date fair value of each award and recorded as expense over the vesting period using the ratable method when the underlying performance conditions are deemed probable.

Stock-based compensation expense related to the ESPP is recognized based on the fair value of each award estimated on the first day of the offering period using the Black Scholes option pricing model and recorded as expense over the service period using the straight-line method.

Amortization of Debt Discount and Issuance Costs

Debt discount and issuance costs, consisting of legal and other fees directly related to the debt as well as the discount created by the bifurcation of the equity component and the debt component of the convertible senior notes due 2026 (the “2026 Notes”), are offset against gross proceeds from the issuance of debt and are amortized to interest expense over the estimated life of the debt based on the effective interest method.

Recent Accounting Standards

In August 2020, the FASB issued ASU 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”). Under ASU 2020-06 the embedded conversion features are no longer separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives under Topic 815, Derivatives and Hedging, or that do not result in substantial premiums accounted for as paid-in capital. Consequently, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost and convertible preferred stock will be accounted for as a single equity instrument measured at its historical cost, as long as no other features require bifurcation and recognition as derivatives. By removing those separation models, the interest rate of convertible debt instruments typically will be closer to the coupon interest rate. ASU 2020-06 also provides for certain disclosures with regard to convertible instruments and associated fair values. ASU 2020-06 will be effective for annual reporting periods after December 15, 2021 and interim periods within those annual periods and early adoption is permitted. ASU 2020-06 provides companies with the option to adopt the new standard using either the full retrospective or modified retrospective method.

We will adopt this new guidance using the modified retrospective method as of January 1, 2022 with respect to our convertible senior notes due 2026 (the “2026 Notes”). The adoption of this new guidance is estimated to result in an increase in the carrying value of the 2026 Notes by approximately $38.9 million to reflect the full principal amount of the convertible notes outstanding, net of issuance costs, a decrease in additional paid-in capital of approximately $49.5 million to remove the equity component separately recorded for the conversion feature associated with the convertible notes, a cumulative-effect adjustment of approximately $10.6 million to the beginning balance of our accumulated deficit as of January 1, 2022, and a reversal of the related deferred tax liability of $8.3 million with a corresponding increase in our valuation allowance. The adoption of this new guidance is expected to reduce non-cash interest expense for the year ending December 31, 2022 and until the 2026 Notes have been settled. The remaining debt issuance costs will continue to be amortized over the term of the notes. There is no expected impact to our Consolidated Statement of Cash Flows as a result of the adoption.

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Instruments Excluded from the Computation of Diluted Net Loss Per Share

The following instruments were excluded from the computation of diluted net loss per share for the periods presented because their effect would have been antidilutive (in thousands):

	Years Ended December 31,
	2021		2020		2019
Options to purchase common stock		9,373		8,510		7,759
Warrants to purchase common stock		48		48		165
Restricted stock and performance units		1,415		1,117		839
Shares issuable related to the ESPP		8		12		27
Shares issuable upon conversion of convertible notes		16,675		16,675		16,675
Total shares		27,519		26,362		25,465

Research and Development Arrangements (Tables)

12 Months Ended

Dec. 31, 2021

Research And Development [Abstract]

Summary of License Revenues and Milestone Revenues

License and milestone revenues recognized during 2021, 2020 and 2019 were as follows (in thousands):

	Years Ended December 31,
	2021		2020		2019
License revenues	$	54,856	$	36,501	$	—
Milestone revenues		5,000		2,800		—
	$	59,856	$	39,301	$	—

Schedule of Allocated Consideration

The Ji Xing OM License Agreement, as defined below, and the sales of common stock to the RTW Investors in December 2021, as described below, (together the “2021 RTW Transactions”) were entered into with parties that are affiliated and in contemplation of one another and, accordingly, we have assessed the accounting for these transactions in the aggregate. We concluded that there were two units of accounting in the 2021 RTW Transactions as further described below. The Company allocated the total consideration in accordance with ASC 820 and ASC 606 as follows (in thousands):

	Allocated Consideration
Units of Accounting:
License and collaboration	$	54,856
Common stock (fair value)		15,144
Total consideration	$	70,000

The 2020 RTW Transactions were entered into with parties that are affiliated and in contemplation of one another and, accordingly, we have assessed the accounting for these transactions in the aggregate. We concluded that there were three units of accounting in the 2020 RTW Transactions as further described below. The Company allocated the total consideration in accordance with ASC 820, Fair Value Measurement, and ASC 606, Revenue from Contracts with Customers, as follows (in thousands):

	Allocated Consideration
Units of Accounting:
License and collaboration (residual)	$	36,501
Royalty (fair value)		87,000
Common stock (fair value)		36,499
Total consideration	$	160,000

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Summary of Fair Value of Financial Assets Consists of Cash Equivalents and Investments Classified as Available-for-sale Securities Measured on Recurring Basis

The follow tables set forth the fair value of our financial assets, which consists of cash equivalents and investments classified as available-for-sale securities, that were measured on a recurring basis (in thousands):

	December 31, 2021
	Fair Value Hierarchy Level	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	Level 1	$	115,937	$	—	$	—		$	115,937
U.S. Treasury securities	Level 1		133,498		1		(268	)		133,231
U.S. and non-U.S. government agency bonds	Level 2		33,489		—		(53	)		33,436
Commercial paper	Level 2		169,622		6		(19	)		169,609
U.S. and non-U.S. corporate obligations	Level 2		175,282		—		(536	)		174,746
		$	627,828	$	7	$	(876	)	$	626,959

	December 31, 2020
	Fair Value Hierarchy Level	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	Level 1	$	80,050	$	—	$	—		$	80,050
U.S. Treasury securities	Level 1		274,407		147		(8	)		274,546
U.S. government agency bonds	Level 2		51,581		15		(3	)		51,593
Commercial paper	Level 2		49,500		3		(1	)		49,502
U.S. and non-U.S. corporate obligations	Level 2		42,392		7		(11	)		42,388
		$	497,930	$	172	$	(23	)	$	498,079

The available-for-sale securities in our consolidated balance sheet are as follows (in thousands):

	December 31, 2021		December 31, 2020
Cash equivalents	$	115,937	$	80,050
Short-term investments		358,972		381,075
Long-term investments		152,050		36,954
	$	626,959	$	498,079

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Summary of Property and Equipment

Our property and equipment consisted of (in thousands):

	December 31,
	2021			2020
Property and equipment, net:
Laboratory equipment	$	18,837		$	18,160
Computer equipment and software		4,605			2,940
Office equipment, furniture and fixtures		4,042			1,885
Leasehold improvements		60,343			5,872
Construction in progress		224			9,130
Right-of-use assets, finance lease		1,409			—
Total property and equipment		89,460			37,987
Less: Accumulated depreciation and amortization		(16,189	)		(24,641	)
	$	73,271		$	13,346

Summary of Accrued Liabilities

Our accrued liabilities were as follows (in thousands):

	December 31,
	2021		2020
Accrued liabilities:
Clinical and preclinical costs	$	13,872	$	6,124
Compensation related		14,930		11,787
Other accrued expenses		5,568		1,404
Total accrued liabilities	$	34,370	$	19,315

Debt (Tables)

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Schedule of Future Minimum Payments under Term Loan Agreement

Future minimum payments under the Term Loan Agreement are (in thousands):

Years ending December 31:
2022	$	23,595
2023		30,108
Future minimum payments		53,703
Less: Interest and final payment		(8,703	)
Term Loan, gross	$	45,000

Schedule of Interest Expense on 2026 Notes

Interest expense recognized on the 2026 Notes for 2021, 2020 and 2019 (in thousands) is as follows:

	Years Ended December 31,
	2021		2020		2019
Contractual interest expense	$	5,520	$	5,520	$	721
Accretion of debt discount		5,907		5,246		673
Accretion of debt issuance costs		59		52		6
Total interest costs recognized	$	11,486	$	10,818	$	1,400

Liabilities Related to Revenue Participation Right Purchase Agreements (Tables)

12 Months Ended

Dec. 31, 2021

Royalty Liability [Abstract]

Schedule of Activity within Liabilities Related to Revenue Participation Right Purchase Agreements

Changes to the RP OM Liability related to the sale of future royalties are as follows (in thousands):

	2021		2020
Beginning balance, January 1	$	166,068	$	143,276
Interest accretion		12,892		22,713
Amortization of issuance costs		112		79
Ending balance, December 31	$	179,072	$	166,068

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Summary of Stock Option Activity

Stock option activity in 2021 was as follows:

	Stock Options Outstanding			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in millions)
Balance at December 31, 2019		7,759,012		$	8.59
Granted		1,944,562			15.59
Exercised		(967,571	)		8.27
Forfeited		(234,054	)		16.06
Balance at December 31, 2020		8,501,949		$	10.02
Granted		2,513,350			22.43
Exercised		(1,346,194	)		9.01
Forfeited		(296,146	)		14.56
Balance at December 31, 2021		9,372,959		$	13.35		6.8	$	302.1
Exercisable at December 31, 2021		5,828,902		$	9.99		5.6	$	207.4

Summary of Restricted Stock Unit Activity Including Performance Stock Units

Restricted stock unit (“RSU”), including Performance Stock Units (“PSUs”), activity in 2021 was as follows:

	Number of Restricted Stock Units			Weighted Average Award Date Fair Value per Share
Balance at December 31, 2019		839,075		$	7.49
Granted		731,225			14.40
Exercised		(435,450	)		7.72
Forfeited		(18,208	)		10.37
Balance at December 31, 2020		1,116,642		$	11.88
Granted		1,093,450			21.69
Exercised		(606,240	)		11.13
Forfeited		(189,025	)		21.32
Balance at December 31, 2021		1,414,827		$	18.52

Fair Value of Share-Based Payments was Estimated on Date of Grant Based on Assumptions

We use the Black-Scholes option pricing model to determine the fair value of stock option grants to employees and directors and employee stock purchase plan shares. The fair value of share-based payments was estimated on the date of grant based on the following assumptions:

Year Ended December

31, 2021

Year Ended December

31, 2020

Year Ended December

31, 2019

Options

ESPP

Options

ESPP

Options

ESPP

Risk-free interest rate

0.58% to 1.28%

0.05%

0.42% to 1.8%

0.11% to 1.8%

1.6% to 3.0%

1.8% to 2.4%

Volatility

66% to 67%

74% to 75%

73% to 76%

Expected term in years

6.4 to 6.5

0.5

6.5 to 6.6

0.5

6.5

0.6

Expected dividend yield

0%

Summary of Stock-Based Compensation Expense

Stock-based compensation expense for 2021 and 2020 was as follows (in thousands):

	Years Ended December 31,
	2021		2020		2019
Research and development	$	10,463	$	6,949	$	4,260
General and administrative		16,369		10,671		6,499
	$	26,832	$	17,620	$	10,759

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Schedule of Undiscounted Future Non-cancellable Lease Payments under the Operating and Finance Lease Agreements

The undiscounted future non-cancellable lease payments under all our operating and finance lease agreements as of December 31, 2021 is as follows (in thousands):

Years ending December 31:	Operating Leases			Finance Leases
2022	$	15,611		$	513
2023		17,060			479
2024		17,620			479
2025		18,199			—
2026		18,799			—
Thereafter		146,193			—
Total undiscounted future lease payments		233,482			1,471
Less: Present value adjustments		(106,390	)		(166	)
Total lease liability	$	127,092		$	1,305

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Reconciliation of Statutory Federal Income Tax Rate to Effective Tax Rate

The following reconciles the statutory federal income tax rate to our effective tax rate:

	Years Ended December 31,
	2021			2020			2019
Tax at federal statutory tax rate		21	%		21	%		21	%
State tax, net of federal benefits		0	%		1	%		3	%
Change in state effected rates		(1	)%		(2	)%		4	%
Tax credits, net		3	%		3	%		3	%
Change in valuation allowance		(24	)%		(23	)%		(30	)%
Stock-based compensation		2	%		1	%		(1	)%
Other		(1	)%		(1	)%		0	%
Total		0	%		0	%		0	%

Summary of Deferred Tax Assets, Net

Deferred tax assets, net, reflecting the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, were as follows (in thousands):

	As of December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	181,977		$	162,514
Tax credits		77,366			71,976
Liability related to sale of future royalties		38,302			36,989
Reserves and accruals		15,409			10,876
Capitalized R&D		1,115			2,370
Long-term lease liability		26,223			718
Deferred revenue		18,608			—
Depreciation and amortization		—			746
Total noncurrent deferred tax assets		359,000			286,189
Deferred tax liabilities:
Depreciation and amortization		(7,664	)		—
Accounting method change		—			(927	)
Operating lease right-of-use assets		(15,643	)		(651	)
Convertible notes		(8,296	)		(9,832	)
Total noncurrent deferred tax liabilities		(31,603	)		(11,410	)
Less: Valuation allowance		(327,397	)		(274,779	)
Net deferred tax assets	$	—		$	—

Schedule of Activity Related to our Gross Unrecognized Tax Benefits

Activity related to our gross unrecognized tax benefits were (in thousands):

	Years Ended December 31,
	2021			2020			2019
Balance at the beginning of the year	$	10,522		$	9,922		$	9,475
Decrease related to prior year tax positions		(29	)		(3	)		—
Increase related to current year tax positions		802			603			447
Balance at the end of the year	$	11,295		$	10,522		$	9,922

Organization and Accounting Policies - Additional Information (Detail) $ in Thousands		12 Months Ended
	Jan. 01, 2022 USD ($)	Dec. 31, 2021 USD ($) Financial_Institution Obligation	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit incurred		$ (1,207,620)	$ (992,306)
Net loss		(215,314)	(127,290)	$ (121,692)
Net cash provided by (used in) operating activities		142,522	(8,943)	90,907
Cash, cash equivalents and investments		$ 623,700	$ 501,000
Cash requirements term		12 months
Number of major financial institutions \| Financial_Institution		2
Without Adoption of ASU 2019-12 [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred tax benefit				$ 12,000
ASU 2020-06 [Member] \| Subsequent Event [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
Decrease in additional paid-in capital	$ 49,500
Deferred tax liability reversal	8,300
ASU 2020-06 [Member] \| Subsequent Event [Member] \| 2026 Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Increase in carrying value	38,900
ASU 2020-06 [Member] \| Cumulative-Effect Adjustment [Member] \| Subsequent Event [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated accumulated deficit	$ (10,600)
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of performance obligation \| Obligation		1
Computer Equipment and Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		3 years
Laboratory Equipment and Office Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		5 years
Furniture and Fixtures [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		7 years
Leasehold Improvements [Member] \| Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		3 years
Leasehold Improvements [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		22 years
Astellas [Member] \| Astellas FSRA Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Payment of development costs for clinical trials of reldesemtiv		$ 12,000

Net Loss Per Share - Instruments Excluded from the Computation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares	27,519	26,362	25,465
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares	9,373	8,510	7,759
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares	48	48	165
Restricted Stock and Performance Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares	1,415	1,117	839
Shares Issuable Related to the ESSP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares	8	12	27
Shares Issuable Upon Conversion of Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares	16,675	16,675	16,675

Research and Development Arrangements - Summary of License Revenue and Milestone Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total revenues	$ 70,428	$ 55,828	$ 26,868
License Revenues [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total revenues	54,856	36,501	0
Collaborative Arrangement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total revenues	59,856	39,301	0
Collaborative Arrangement [Member] \| License Revenues [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total revenues	54,856	36,501	0
Collaborative Arrangement [Member] \| Milestone Revenues [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total revenues	$ 5,000	$ 2,800	$ 0

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Research and Development Arrangements - Schedule of Allocated Consideration (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Jul. 14, 2020	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Total revenues			$ 70,428	$ 55,828	$ 26,868
Collaborative Arrangement [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Total revenues			$ 59,856	$ 39,301	$ 0
RTW [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Total consideration		$ 70,000
RTW [Member] \| Collaborative Arrangement [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Total consideration	$ 160,000
RTW [Member] \| Common Stock [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Fair value of common stock		15,144
RTW [Member] \| Common Stock [Member] \| Collaborative Arrangement [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Fair value of common stock	36,499
RTW [Member] \| License And Collaboration [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Total revenues		$ 54,856
RTW [Member] \| License And Collaboration [Member] \| Collaborative Arrangement [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Total revenues	36,501
RTW [Member] \| Royalty [Member] \| Collaborative Arrangement [Member]
Allocated Transaction Prices Of Collaborative Arrangements [Line Items]
Fair Value of Royalty	$ 87,000

Research and Development Arrangements - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended	12 Months Ended
	Dec. 20, 2021	Jul. 14, 2020	Apr. 23, 2020	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues					$ 70,428	$ 55,828	$ 26,868
Net proceeds of issuance of common stock					0	0	36,214
Amount received as milestone payment				$ 5,000		2,500
Long-term deferred revenue					87,000	87,000
Accounts receivable					51,819	4,420
Astellas [Member] \| Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable					1,800	2,700
License Revenues [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues					54,856	36,501	0
Research and Development Revenues [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues					10,572	16,527	26,868
Research and Development Revenues [Member] \| Astellas [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues					3,200	6,600	13,100
Research And Development Milestone Grant And Other Revenues Net \| Amgen
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues					7,400	10,000	$ 13,800
Accounts receivable					0	1,700
Ji Xing Omecamtiv Mecarbil License and Collaboration Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable payment obligation	$ 50,000
Ji Xing Omecamtiv Mecarbil License and Collaboration Agreement [Member] \| Rights Granted [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable payment obligation	40,000
Ji Xing Omecamtiv Mecarbil License and Collaboration Agreement [Member] \| New Drug Application [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable payment obligation	$ 10,000
Common Stock Purchase Agreements [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Issuance of common stock upon private placement, shares	511,182	2,000,000.0
Shares Issued, price per share	$ 39.125	$ 25.00
Net proceeds of issuance of common stock	$ 20,000	$ 50,000
Common stock purchase agreement date	Dec. 20, 2021	Jul. 14, 2020
Excess amount paid over the fair value of the shares	$ 4,900	$ 13,500
Fair value of common stock	15,100	36,500
Ji Xing Aficamten License and Collaboration Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received		25,000
Ji Xing Aficamten License and Collaboration Agreement [Member] \| License Revenues [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues					0	36,500
Royalty Purchase Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Sale of interest in future royalties						85,000
Fair Value of Royalty						$ 87,000
Long-term deferred revenue					$ 87,000
Maximum [Member] \| Two Thousand Sixteen Amendment
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment of development costs for clinical trials of reldesemtiv			$ 12,000
Maximum [Member] \| Ji Xing Omecamtiv Mecarbil License and Collaboration Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential additional payments receivable	$ 330,000
Maximum [Member] \| Ji Xing Aficamten License and Collaboration Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential additional payments receivable		200,000
Maximum [Member] \| Funding Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone receivable		$ 90,000

Fair Value Measurements - Summary of Fair Value of Financial Assets Consists of Cash Equivalents and Investments Classified as Available-for-sale Securities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 626,959	$ 498,079
Long-term Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	152,050	36,954
Cash Equivalents [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	115,937	80,050
Short-term Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	358,972	381,075
Fair Value, Measurements, Recurring [Member] \| Cash and Cash Equivalents and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	627,828	497,930
Unrealized Gains	7	172
Unrealized Losses	(876)	(23)
Fair Value	626,959	498,079
Money Market Funds [Member] \| Fair Value Measurements Using Level 1 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cash and Cash Equivalents and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	115,937	80,050
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	115,937	80,050
U.S. Treasury Securities [Member] \| Fair Value Measurements Using Level 1 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cash and Cash Equivalents and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	133,498	274,407
Unrealized Gains	1	147
Unrealized Losses	(268)	(8)
Fair Value	133,231	274,546
U.S. and Non-U.S. Government Agency Bonds [Member] \| Fair Value Measurements Using Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cash and Cash Equivalents and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	33,489
Unrealized Gains	0
Unrealized Losses	(53)
Fair Value	33,436
U.S. Government Agency Bonds [Member] \| Fair Value Measurements Using Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cash and Cash Equivalents and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost		51,581
Unrealized Gains		15
Unrealized Losses		(3)
Fair Value		51,593
Commercial Paper [Member] \| Fair Value Measurements Using Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cash and Cash Equivalents and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	169,622	49,500
Unrealized Gains	6	3
Unrealized Losses	(19)	(1)
Fair Value	169,609	49,502
U.S. and Non-U.S. Corporate Obligations [Member] \| Fair Value Measurements Using Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Cash and Cash Equivalents and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	175,282	42,392
Unrealized Gains	0	7
Unrealized Losses	(536)	(11)
Fair Value	$ 174,746	$ 42,388

Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Interest Income	$ 1,000,000.0	$ 5,300,000	$ 4,500,000
Credit losses on debt securities	0	0
Long-term debt, fair value	47,400,000
Convertible debt, fair value	618,900,000
Liability related to the sale of future royalties, net	179,072,000	$ 166,068,000	$ 143,276,000
Fair value of liabilities transferred from level 1 to level 2	0
Fair value of liabilities transferred from level 2 to level 1	0
Fair value of liabilities transferred into level 3	0
Fair value of liabilities transferred from level 3	$ 0

Balance Sheet Components - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Total property and equipment	$ 89,460	$ 37,987
Less: Accumulated depreciation and amortization	(16,189)	(24,641)
Total property and equipment, net	73,271	13,346
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	18,837	18,160
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	4,605	2,940
Office Equipment, Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	4,042	1,885
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	60,343	5,872
Construction in Progress [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	224	9,130
Right-of-Use Assets, Finance Lease [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,409	$ 0

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Depreciation expense	$ 2.3	$ 1.8	$ 1.3
Employer contributions under the plan	$ 1.1	$ 0.9	$ 0.6

Balance Sheet Components - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued liabilities:
Clinical and preclinical costs	$ 13,872	$ 6,124
Compensation related	14,930	11,787
Other accrued expenses	5,568	1,404
Total accrued liabilities	$ 34,370	$ 19,315

Debt - Additional Information (Detail)				12 Months Ended
Debt - Additional Information (Detail)	Jun. 30, 2021 USD ($)	Nov. 13, 2019 USD ($) $ / shares shares	Nov. 07, 2019 $ / shares	Dec. 31, 2021 USD ($) Installment Day $ / shares shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	May 17, 2019 USD ($)
Debt Instrument [Line Items]
Interest expense				$ 16,440,000	$ 15,963,000	$ 6,623,000
Net proceeds from convertible notes, net of debt discount and issuance costs				0	0	133,860,000
Purchase of capped call options associated with convertible notes				0	0	13,386,000
Cap price of capped call transactions \| $ / shares			$ 14.07
Capped call premium percentage of sale price of common stock			70.00%
Oxford and Silicon Valley Bank [Member] \| Term Loan Agreement [Member]
Debt Instrument [Line Items]
Principal amount of original loan							$ 45,000,000.0
Oxford and Silicon Valley Bank [Member] \| Term Loan Agreement [Member] \| Equipment Software and Other Property [Member]
Debt Instrument [Line Items]
Amount drawn under lease agreement				1,400,000
Oxford and Silicon Valley Bank [Member] \| Term Loan Agreement [Member] \| Maximum [Member] \| Equipment Software and Other Property [Member]
Debt Instrument [Line Items]
Drawn amount future exceed limit	$ 3,000,000.0
Oxford and Silicon Valley Bank [Member] \| 2019 Term Loan [Member] \| Term Loan Agreement [Member]
Debt Instrument [Line Items]
Principal amount of original loan							$ 42,000,000.0
Interest expense				$ 4,800,000	$ 4,900,000	$ 5,200,000
Stated interest rate on the amounts borrowed under the Agreement				8.05%
Oxford and Silicon Valley Bank [Member] \| 2019 Term Loan [Member] \| Amended Loan Agreement [Member]
Debt Instrument [Line Items]
Loan repayment terms				The borrowing under the Original Loan Agreement was repayable in monthly interest-only payments through November 2019 followed by 35 months of monthly payments of interest and principal.
Number of instalments description				35 months of monthly payments of interest and principal
Number of instalments \| Installment				35
Debt instrument, applicable interest rate for scenario 1				8.05%
Debt instrument, base interest rate for scenario 2				6.81%
Interest rate description				Both borrowings under the Original Loan Agreement and Term Loan bear interest at an annual rate equal to the greater of (a) 8.05% or (b) the sum of 6.81% plus the 30-day U.S. LIBOR rate
Debt instrument, maturity year and month				2023-12
Oxford and Silicon Valley Bank [Member] \| 2019 Term Loan [Member] \| New Loan and Security Agreement [Member]
Debt Instrument [Line Items]
Loan repayment terms				The borrowing under the Term Loan was repayable in monthly interest-only payments through December 31, 2020. The interest-only period was automatically extended until July 1, 2021 as a result of the Company’s initiation of a Phase 2 trial for aficamten in cardiomyopathy and has been extended through December 31, 2021 as a result of the achievement of positive results in GALACTIC-HF, the trial of omecamtiv mecarbil in chronic heart failure as announced on October 8, 2020. The ultimate interest-only period will be followed by equal monthly payments of principal and interest to the maturity date in December 2023.
Final payment fee percentage				6.00%
2026 Notes [Member]
Debt Instrument [Line Items]
Principal amount of original loan		$ 138,000,000.0
Number of instalments description					payable semi-annually on May 15 and December 15 of each year, beginning May 15, 2020
Convertible notes, interest rate		4.00%
Convertible notes, maturity date		Nov. 15, 2026
Convertible notes, sinking fund		$ 0
Convertible notes, shares issued \| shares		94.7811
Convertible notes, principal amount		$ 1,000
Convertible notes, initial conversion price \| $ / shares		$ 10.55
Convertible notes, type of equity security issued				common stock
Net proceeds from convertible notes, net of debt discount and issuance costs		$ 133,900,000
Convertible notes, conversion description				The 2026 Notes may be converted at the option of the holder under any of the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on March 31, 2020 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter exceeds 127.5% of the last reported sale price of the Company’s common stock on November 7, 2019; (2) during the 5 consecutive business days immediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “measurement period”) if the trading price per $1,000 principal amount of 2026 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company’s common stock on such trading day and the conversion rate on such trading day; (3) upon the occurrence of certain corporate events or distributions on the Company’s common stock; (4) if the Company calls the 2026 Notes for redemption; and (5) at any time from, and including, July 15, 2026 until the close of business on the scheduled trading day immediately before the maturity date, November 15, 2026. The Company will settle conversions by paying or delivering, as applicable, cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s election, based on the applicable conversion rate.
Convertible notes, redemption description				The 2026 Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after November 20, 2023 and, in the case of any partial redemption, on or before the 60th scheduled trading day before the maturity date, at a cash redemption price equal to the principal amount of the 2026 Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date but only if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price on (1) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice; and (2) the trading day immediately before the date the Company sends such notice. If a “fundamental change” (as defined in the indenture) occurs, then, subject to certain exceptions, holders may require the Company to repurchase their 2026 Notes at a cash repurchase price equal to the principal amount of the 2026 Notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the fundamental change repurchase date.
Carrying amount of the liability component		$ 84,200,000
Debt instrument interest, discount rate		12.00%
Carrying amount of the equity component		$ 49,500,000
Debt issuance costs		5,000,000.0
Unamortized debt issuance cost				$ 2,500,000
Debt instrument, unamortized discount				$ 40,100,000
Unamortized debt discount amortization period				4 years 10 months 24 days
Conversion of units \| shares				16.7
Conversion of units				$ 760,000,000.0
Stock price \| $ / shares				$ 45.58
If-converted value in excess of principal amount				$ 622,000,000.0
2026 Notes [Member] \| Equity [Member]
Debt Instrument [Line Items]
Debt issuance costs		1,900,000
2026 Notes [Member] \| Liability [Member]
Debt Instrument [Line Items]
Debt issuance costs		$ 3,100,000
Debt instrument effective interest rate				12.50%
2026 Notes [Member] \| Debt Instrument Convertible Covenant One [Member]
Debt Instrument [Line Items]
Convertible notes, percentage of conversion price				127.50%
Convertible notes, trading days \| Day				20
Convertible notes, consecutive trading days \| Day				30
2026 Notes [Member] \| Debt Instrument Convertible Covenant Two [Member]
Debt Instrument [Line Items]
Convertible notes, percentage of last reported sale price of common stock				98.00%
Convertible notes, trading days \| Day				5
Convertible notes, consecutive trading days \| Day				10

Debt - Schedule of Future Minimum Payments under Term Loan Agreement (Detail) - Term Loan Agreement [Member] - Oxford and Silicon Valley Bank [Member] $ in Thousands	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
2022	$ 23,595
2023	30,108
Future minimum payments	53,703
Long-term debt, alternative
Future minimum payments	53,703
Less: Interest and final payment	(8,703)
Term Loan, gross	$ 45,000

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References + Details

Debt - Schedule of Interest Expense on 2026 Notes (Detail) - 2026 Notes [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Contractual interest expense	$ 5,520	$ 5,520	$ 721
Accretion of debt discount	5,907	5,246	673
Accretion of debt issuance costs	59	52	6
Total interest costs recognized	$ 11,486	$ 10,818	$ 1,400

Liabilities Related to Revenue Participation Right Purchase Agreements - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2017	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Nov. 30, 2022
Liabilities Related To Revenue Participation Right Purchase Agreements [Line Items]
Purchase of common stock shares		84,799,542	71,015,183
Liabilities		$ 597,456	$ 420,420
Royalty Purchase Finance Trust Agreement [Member]
Liabilities Related To Revenue Participation Right Purchase Agreements [Line Items]
Imputed rate of interest on unamortized liability		10.00%	15.00%
Non-cash interest expense recognized		$ 12,900	$ 22,700	$ 20,700
Cash payment under royalty agreement	$ 90,000
Purchase of common stock shares	875,656
Stock issued during period, value, issued for services	$ 10,000
Liabilities	$ 92,300
Royalty Purchase Finance Trust Agreement [Member] \| Minimum [Member]
Liabilities Related To Revenue Participation Right Purchase Agreements [Line Items]
Percent of royalty on net sale	4.50%
Royalty Purchase Finance Trust Agreement [Member] \| Maximum [Member]
Liabilities Related To Revenue Participation Right Purchase Agreements [Line Items]
Additional percent of royalty on net sale	1.00%
Royalty Purchase Finance Trust Agreement [Member] \| Forecast [Member] \| Minimum [Member]
Liabilities Related To Revenue Participation Right Purchase Agreements [Line Items]
Percent of royalty on net sale					4.90%
Change in Accounting Estimate [Member]
Liabilities Related To Revenue Participation Right Purchase Agreements [Line Items]
Imputed rate of interest on unamortized liability		10.00%	15.00%
Non-cash interest expense recognized		$ 12,900	$ 22,700
Reduction in net loss		$ (11,500)
Reduction in net loss per share		$ 0.15

Liabilities Related to Revenue Participation Right Purchase Agreements - Schedule Represents Allocation of Transaction Consideration on a Relative Fair Value Basis to the Liability and the Common Stock (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Royalty Liability [Abstract]
Liability related to sale of future royalties beginning balance	$ 166,068	$ 143,276
Interest accretion	12,892	22,713
Amortization of issuance costs	112	79
Liability related to sale of future royalties ending balance	$ 179,072	$ 166,068

Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended					3 Months Ended		12 Months Ended
	Jul. 31, 2021 USD ($) $ / shares shares	May 31, 2021 Tranche $ / shares shares	Oct. 31, 2020 $ / shares shares	Jul. 31, 2020 $ / shares shares	May 31, 2020 shares	Dec. 31, 2021 USD ($) $ / shares shares	Mar. 31, 2020 USD ($)	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Aug. 31, 2021 shares	May 31, 2019 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Intrinsic value of stock options outstanding \| $						$ 302,100		$ 302,100
Allocated share based compensation expense \| $								$ 26,832	$ 17,620	$ 10,759
Warrants outstanding to purchase upon exercise of common stock						23,065		23,065
Warrants exercise price \| $ / shares						$ 9.76		$ 9.76
Warrants expiration date								2029-05
Outstanding warrants						165,424		165,424
Outstanding warrants, weighted average exercise price \| $ / shares						$ 7.25		$ 7.25
Expiry period of warrants after date of issuance								10 years
Common stock, shares issued						84,799,542		84,799,542	71,015,183
Commision of gross sales proceeds								3.00%
Net proceeds of issuance of common stock \| $								$ 0	$ 0	36,214
Claims settlement \| $							$ 2,200	$ 0	$ 2,151	$ 0
OTA LLC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares issued			8,958	95,932
Warrant 1 [Member] \| OTA LLC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants exercise price \| $ / shares			$ 9.755	$ 6.59
Exercise of stock options, shares			13,839	51,214
Warrant 2 [Member] \| OTA LLC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants exercise price \| $ / shares				$ 6.903
Exercise of stock options, shares				48,892
Warrant 3 [Member] \| OTA LLC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants exercise price \| $ / shares				$ 7.10
Exercise of stock options, shares				25,352
New ATM Facility [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, net of issuance costs, shares										3,984,849
Common stock, shares issued										3,984,849
Net proceeds of issuance of common stock \| $										$ 36,200
Oxford and Silicon Valley Bank [Member] \| New Loan and Security Agreement [Member] \| 2019 Term Loan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding to purchase upon exercise of common stock									21,595
Warrants exercise price \| $ / shares									$ 10.42
Warrants expiration date									2030-01
Outstanding warrants						47,722		47,722
Outstanding warrants, weighted average exercise price \| $ / shares						$ 9.12		$ 9.12
Amortization of discount on debt \| $									$ 200
Maximum [Member] \| ATM Facility [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock offering price \| $						$ 75,000		$ 75,000
Maximum [Member] \| New ATM Facility [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock offering price \| $						85,000		85,000
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, vested restricted stock units, total fair value \| $								11,600
Unamortized/unrecognized stock-based compensation expense \| $						$ 11,500		$ 11,500
Weighted-average period								1 year 4 months 24 days
Restricted Stock Units (RSUs) \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period								2 years
Restricted Stock Units (RSUs) \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period								3 years
Performance Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for grant		375,000
Per unit weighted average grant date fair value \| $ / shares		$ 25.32
Number of tranche \| Tranche		2
Number of shares cancelled						91,250
Decrease in allocated share based compensation expense \| $								$ 500
Number of shares outstanding						273,750		273,750
Unamortized/unrecognized stock-based compensation expense \| $						$ 900		$ 900
Performance Stock Units \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share based payment award award vesting rights percentage		50.00%
Allocated share based compensation expense \| $								1,400
Performance Stock Units \| Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share based payment award award vesting rights percentage		50.00%
Allocated share based compensation expense \| $								0
Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unamortized/unrecognized stock-based compensation expense \| $						$ 44,500		$ 44,500
Weighted-average period								2 years 8 months 12 days
2004 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option grant prices as percentage of the fair market value of the common stock								100.00%
Term to grant nonstatutory stock options and incentive stock options								10 years
Percentage of options grant to new employees								25.00%
Increase in number of authorized shares reserved for issuance		5,200,000			800,000						1,900,000	4,100,000
Number of authorized shares reserved for issuance		21,500,000
Shares available for grant						5,700,000		5,700,000
Share based compensation, options exercised, total intrinsic value \| $								$ 29,300	$ 14,000	$ 500
Intrinsic value of stock options outstanding \| $						$ 302,100		$ 302,100
2004 Plan [Member] \| New Employee [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting right								Options granted to new employees generally vest 25% after one year and monthly thereafter over a period of four years
Period from percentage of stock option vested								1 year
Vesting period								4 years
2004 Plan [Member] \| Existing Employee [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting right								Options granted to existing employees generally vest monthly over a period of four years
Vesting period								4 years
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option grant prices as percentage of the fair market value of the common stock								85.00%
Number of authorized shares reserved for issuance						338,040		338,040
Increase in common stock shares reserved for issuance					500,000
Issuance of common stock pursuant to ESPP, shares								108,780	134,684	172,113
Issuance of common stock pursuant to ESPP, per share \| $ / shares								$ 16.33	$ 11.21	$ 6.43
Non-employee Stock-Based Compensation [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated share based compensation expense \| $								$ 200	$ 200	$ 200
Underwritten Public Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sales of common stock, number of shared issued	11,500,000
Sale of stock, price per share \| $ / shares	$ 27.50
Issuance of common stock, net of issuance costs, shares	1,500,000
Gross proceeds, consideration received on transaction \| $	$ 316,300
Net proceeds, consideration received on transaction \| $	$ 296,900
Common stock, shares issued	1,500,000

Stockholders' Equity - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Options Outstanding, Beginning Balance	8,501,949	7,759,012
Stock Options Outstanding, Granted	2,513,350	1,944,562
Stock Options Outstanding, Forfeited	(296,146)	(234,054)
Stock Options Outstanding, Ending Balance	9,372,959	8,501,949
Stock Options Outstanding, Exercisable	5,828,902
Weighted Average Exercise Price per Share, Beginning Balance	$ 10.02	$ 8.59
Weighted Average Exercise Price per Share, Granted	22.43	15.59
Weighted Average Exercise Price per Share, Exercised	9.01	8.27
Weighted Average Exercise Price per Share, Forfeited	14.56	16.06
Weighted Average Exercise Price per Share, Ending Balance	13.35	$ 10.02
Weighted Average Exercise Price per Share, Exercisable	$ 9.99
Weighted Average Remaining Contractual Life	6 years 9 months 18 days
Weighted Average Remaining Contractual Life, Exercisable at December 31, 2021	5 years 7 months 6 days
Aggregate Intrinsic Value	$ 302.1
Aggregate Intrinsic Value, Exercisable at December 31, 2021	$ 207.4
Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Options Outstanding, Exercised	(1,346,194)	(967,571)

Stockholders' Equity - Summary of Restricted Stock Unit Activity Including Performance Stock Units (Detail) - Restricted Stock Units (RSUs) Including Performance Stock Units (PSUs) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Restricted Stock Units, Beginning Balance	1,116,642	839,075
Number of Restricted Stock Units, Granted	1,093,450	731,225
Number of Restricted Stock Units, Exercised	(606,240)	(435,450)
Number of Restricted Stock Units, Forfeited	(189,025)	(18,208)
Number of Restricted Stock Units, Ending Balance	1,414,827	1,116,642
Weighted Average Award Date Fair Value per Share, Beginning Balance	$ 11.88	$ 7.49
Weighted Average Award Date Fair Value per Share, Granted	21.69	14.40
Weighted Average Award Date Fair Value per Share, Exercised	11.13	7.72
Weighted Average Award Date Fair Value per Share, Forfeited	21.32	10.37
Weighted Average Award Date Fair Value per Share, Ending Balance	$ 18.52	$ 11.88

Stockholders' Equity - Fair Value of Share-Based Payments was Estimated on Date of Grant Based on Assumptions (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Options [Member]
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Risk-free interest rate, minimum	0.58%	0.42%	1.60%
Risk-free interest rate, maximum	1.28%	1.80%	3.00%
Volatility, minimum	66.00%	74.00%	73.00%
Volatility, maximum	67.00%	75.00%	76.00%
Expected term in years			6 years 6 months
Expected dividend yield	0.00%	0.00%	0.00%
Minimum [Member] \| Options [Member]
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Expected term in years	6 years 4 months 24 days	6 years 6 months
Maximum [Member] \| Options [Member]
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Expected term in years	6 years 6 months	6 years 7 months 6 days
ESPP [Member]
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Risk-free interest rate, minimum		0.11%	1.80%
Risk-free interest rate, maximum		1.80%	2.40%
Risk-free interest rate	0.05%
Volatility, minimum	66.00%	74.00%	73.00%
Volatility, maximum	67.00%	75.00%	76.00%
Expected term in years	6 months	6 months	7 months 6 days
Expected dividend yield	0.00%	0.00%	0.00%

Stockholders' Equity - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 26,832	$ 17,620	$ 10,759
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	10,463	6,949	4,260
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 16,369	$ 10,671	$ 6,499

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021 USD ($) ft²	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets	$ 73,138,000	$ 2,924,000
Operating lease, short-term lease liability	14,863,000	2,785,000
Operating lease, long-term lease liability	112,229,000	440,000
Impairment of right-of-use assets	$ 2,844,000	0	$ 0
Finance lease, contractual lease term	3 years
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	us-gaap:OtherAssets
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other non-current liabilities
Lease obligations for finance leases not yet commenced	$ 1,900,000
Rent expenses for the operating leases and finance leases	$ 23,100,000	5,700,000	5,100,000
Lease Agreement
Lessee Lease Description [Line Items]
Operating lease, weighted average remaining lease term	11 years 8 months 12 days
Operating lease, weighted average discount rate	10.00%
Operating lease, cash paid included in net cash used in operating activities	$ 6,100,000	6,700,000
Financial lease estimated life	5 years
Finance Lease, Right-of-Use Asset	$ 1,400,000
Short term finance lease liability	500,000
Long term finance lease liability	$ 800,000
Finance lease, weighted average remaining lease term	4 years 10 months 24 days
Finance lease, weighted average discount rate	9.47%
Finance lease payments	$ 0
Current Lease [Member]
Lessee Lease Description [Line Items]
Operating lease, lease expiration date	Jun. 30, 2022
Operating lease, weighted average remaining lease term	6 months
Operating lease, weighted average discount rate	6.80%
Current Lease [Member] \| Minimum [Member]
Lessee Lease Description [Line Items]
Operating lease, payments monthly	$ 500,000
Oyster Point Lease [Member] \| California [Member]
Lessee Lease Description [Line Items]
Operating lease, lease expiration date	Sep. 30, 2033
Operating lease, weighted average remaining lease term	11 years 9 months 18 days
Operating lease, weighted average discount rate	10.10%
Operating lease, area of land under lease agreement \| ft²	234,892
Operating lease, commencement period	2021-03
Operating lease right-of-use assets	$ 77,900,000
Operating lease, short-term lease liability	3,700,000
Operating lease, long-term lease liability	85,300,000
Operating lease, tenant improvement reimbursements	11,100,000
Operating lease, security deposit liability		$ 5,100,000	$ 5,100,000
Operating lease agreement allowances for tenant improvements	43,600,000
Operating lease undiscounted lease payments	$ 230,500,000
Operating lease, term description	We have two consecutive five-year options to extend the lease.

Commitments and Contingencies - Schedule of Undiscounted Future Non-cancellable Lease Payments under the Operating and Finance Lease Agreements (Detail) $ in Thousands	Dec. 31, 2021 USD ($)
Leases [Abstract]
2022	$ 15,611
2023	17,060
2024	17,620
2025	18,199
2026	18,799
Thereafter	146,193
Total undiscounted future lease payments	233,482
Less: Present value adjustments	(106,390)
Total lease liability	127,092
2022	513
2023	479
2024	479
2025	0
2026	0
Thereafter	0
Total undiscounted future lease payments	1,471
Less: Present value adjustments	(166)
Total lease liability	$ 1,305

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Provision for income tax	$ 0	$ 0	$ 0
Increase (decrease) in valuation allowance	$ 52,600,000	28,900,000
Research and development credits and orphan drug credits, federal carryforwards will expire	2021
Unrecognized tax benefits	$ 10,300,000	$ 9,600,000	$ 9,100,000
Federal Tax [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 753,800,000
Net operating loss carryforwards expiration	2022
Credit carryforwards for federal and state	$ 73,600,000
Federal and State Tax [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 323,100,000
Net operating loss carryforwards expiration	2028
Credit carryforwards for federal and state	$ 17,800,000

Income Taxes - Reconciliation of Statutory Federal Income Tax Rate to Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Tax at federal statutory tax rate	21.00%	21.00%	21.00%
State tax, net of federal benefits	0.00%	1.00%	3.00%
Change in state effected rates	(1.00%)	(2.00%)	4.00%
Tax credits, net	3.00%	3.00%	3.00%
Change in valuation allowance	(24.00%)	(23.00%)	(30.00%)
Stock-based compensation	2.00%	1.00%	(1.00%)
Other	(1.00%)	(1.00%)	0.00%
Total	0.00%	0.00%	0.00%

Income Taxes - Summary of Deferred Tax Assets, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforwards	$ 181,977	$ 162,514
Tax credits	77,366	71,976
Liability related to sale of future royalties	38,302	36,989
Reserves and accruals	15,409	10,876
Capitalized R&D	1,115	2,370
Long-term lease liability	26,223	718
Deferred revenue	18,608	0
Depreciation and amortization	0	746
Total noncurrent deferred tax assets	359,000	286,189
Deferred tax liabilities:
Depreciation and amortization	(7,664)	0
Accounting method change	0	(927)
Operating lease right-of-use assets	(15,643)	(651)
Convertible notes	(8,296)	(9,832)
Total noncurrent deferred tax liabilities	(31,603)	(11,410)
Less: Valuation allowance	(327,397)	(274,779)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Schedule of Activity Related to our Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Balance at the beginning of the year	$ 10,522	$ 9,922	$ 9,475
Decrease related to prior year tax positions	(29)	(3)	0
Increase related to current year tax positions	802	603	447
Balance at the end of the year	$ 11,295	$ 10,522	$ 9,922

Subsequent Events - Additional Information (Detail) - 2022 Royalty Pharma Transactions [Member] - Subsequent Event [Member]	Jan. 07, 2022 USD ($)
RP Loan Agreement [Member]
Subsequent Event [Line Items]
Term loan, maximum borrowing capacity	$ 300,000,000.0
Term loan, current borrowing capacity	50,000,000.0
Term loan, remaining borrowing capacity	$ 250,000,000.0
Term loan, maturity year	10 years
Debt instrument effective interest rate	190.00%
Principal amount of original loan	$ 25,000,000
RP Loan Agreement [Member] \| Term Loan Tranche 2 [Member]
Subsequent Event [Line Items]
Long term debt	50,000,000.0
RP Loan Agreement [Member] \| Term Loan Tranche 3 [Member]
Subsequent Event [Line Items]
Long term debt	25,000,000.0
RP Loan Agreement [Member] \| Term Loan Tranche 4 [Member]
Subsequent Event [Line Items]
Long term debt	75,000,000.0
RP Loan Agreement [Member] \| Term Loan Tranche 5 [Member]
Subsequent Event [Line Items]
Long term debt	100,000,000.0
RP Aficamten RPA, RPI ICAV [Member]
Subsequent Event [Line Items]
Purchased rights to certain revenue streams from net sales in consideration payment	$ 50,000,000.0
Percentage of net sales payable	4.50%
4.5% of net revenue to be receivable from annual worldwide net sales	$ 1,000,000,000
Percentage of net sales payable for excess of annual worldwide net sales	3.50%
3.5% of net sales payable for excess of annual worldwide net sales	$ 1,000,000,000
RP Aficamten RPA, RPI ICAV [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Purchased rights to certain revenue streams from net sales in consideration payment	150,000,000.0
RP Aficamten RPA, RPI ICAV [Member] \| oHCM [Member]
Subsequent Event [Line Items]
Amount payable of first pivotal clinical trail	50,000,000.0
RP Aficamten RPA, RPI ICAV [Member] \| nHCM [Member]
Subsequent Event [Line Items]
Amount payable of first pivotal clinical trail	$ 50,000,000.0