Blueprint Medicines (BPMC) 10-K 17 Feb 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 14, 2022	Jun. 30, 2021
Cover [Abstract]
Entity Central Index Key	0001597264
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	001-37359
Entity Registrant Name	BLUEPRINT MEDICINES CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3632015
Entity Address, Address Line One	45 Sidney Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	617
Local Phone Number	374-7580
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	BPMC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Listing, Par Value Per Share	$ 0.001
Entity Public Float			$ 5,150,459,010
Entity Common Stock, Shares Outstanding		59,203
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Boston, Massachusetts

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 209,948	$ 684,636
Marketable securities	267,166	187,213
Accounts receivable, net	25,155	7,096
Unbilled accounts receivable	11,875	18,213
Inventory	21,817	8,581
Prepaid expenses and other current assets	18,064	22,020
Total current assets	554,025	927,759
Marketable securities	557,529	677,873
Property and equipment, net	30,700	34,129
Operating lease right-of-use assets, net	90,162	67,539
Restricted cash	5,171	5,168
Other assets	14,638	5,925
Total assets	1,252,225	1,718,393
Current liabilities:
Accounts payable	8,333	4,370
Accrued expenses	121,829	105,938
Current portion of operating lease liabilities	8,093	7,935
Deferred revenue, current	11,510	12,559
Total current liabilities	149,765	130,802
Operating lease liabilities, net of current portion	103,315	81,669
Deferred revenue, net of current portion	25,066	28,599
Other long-term liabilities	3,344	7,235
Total liabilities	281,490	248,305
Commitments and Contingencies (Note 18)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.001 par value; 120,000,000 shares authorized; 59,141,086 and 57,793,533 shares issued and outstanding at December 31, 2021 and December 31, 2020, respectively	59	58
Additional paid-in capital	2,250,250	2,106,600
Accumulated other comprehensive loss	(4,133)	(5,214)
Accumulated deficit	(1,275,441)	(631,356)
Total stockholders' equity	970,735	1,470,088
Total liabilities and stockholders' equity	$ 1,252,225	$ 1,718,393

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Preferred Stock Disclosures
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common Stock Disclosures
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	59,141,086	57,793,533
Common Stock, shares outstanding (in shares)	59,141,086	57,793,533

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Revenue	$ 180,080	$ 793,735	$ 66,512
Cost and operating expenses:
Cost of sales	17,934	425
Research and development	601,033	326,860	331,450
Selling, general and administrative	195,293	157,743	96,388
Collaboration loss sharing	7,801
Total cost and operating expenses	822,061	485,028	427,838
Other income (expense):
Interest income, net	2,386	6,599	13,732
Other expense, net	(1,489)	(366)	(100)
Total other income	897	6,233	13,632
Income (loss) before income taxes	(641,084)	314,940	(347,694)
Income tax expense	3,001	1,058
Net income (loss)	(644,085)	313,882	(347,694)
Other comprehensive income (loss):
Unrealized gain (loss) on pension benefit obligations	4,255	(2,843)	(2,985)
Unrealized gain (loss) on available-for-sale investments	(3,649)	441	671
Currency translation adjustments	475	(278)	(40)
Comprehensive income (loss)	$ (643,004)	$ 311,202	$ (350,048)
Net income (loss) per share - basic (in dollars per share)	$ (11.01)	$ 5.76	$ (7.27)
Net income (loss) per share - diluted (in dollars per share)	$ (11.01)	$ 5.59	$ (7.27)
Weighted-average number of common shares used in net income (loss) per share - basic (in shares)	58,518	54,534	47,829
Weighted-average number of common shares used in net income (loss) per share - diluted (in shares)	58,518	56,168	47,829
Product revenue, net
Revenues:
Revenue	$ 57,687	$ 22,134
Collaboration revenue
Revenues:
Revenue	$ 122,393	$ 771,601	$ 66,512

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common StockFollow-on Public Offering and At-the-market Offering	Common StockPrivate Placement	Common Stock	Additional Paid-In CapitalFollow-on Public Offering and At-the-market Offering	Additional Paid-In CapitalPrivate Placement	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Follow-on Public Offering and At-the-market Offering	Private Placement	Total
Beginning Balance at Dec. 31, 2018			$ 44			$ 1,016,689	$ (180)	$ (597,544)			$ 419,009
Beginning Balance (in shares) at Dec. 31, 2018			44,037,026
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under stock plan			$ 1			12,130					12,131
Issuance of common stock under stock plan (in shares)			552,311
Purchase of common stock under ESPP						1,148					$ 1,148
Purchase of common stock under ESPP (in shares)			20,724								20,724
Stock-based compensation expense						54,653					$ 54,653
Issuance of common stock	$ 4			$ 327,462					$ 327,466
Issuance of common stock (in shares)	4,662,162
Other comprehensive income (loss)							(2,354)				(2,354)
Net income (loss)								(347,694)			(347,694)
Ending Balance at Dec. 31, 2019			$ 49			1,412,082	(2,534)	(945,238)			464,359
Ending Balance (in shares) at Dec. 31, 2019			49,272,223
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under stock plan			$ 1			33,282					33,283
Issuance of common stock under stock plan (in shares)			952,205
Purchase of common stock under ESPP			$ 1			2,153					$ 2,154
Purchase of common stock under ESPP (in shares)			38,516								38,516
Stock-based compensation expense						76,602					$ 76,602
Issuance of common stock	$ 6	$ 1		$ 503,176	$ 79,305				$ 503,182	$ 79,306
Issuance of common stock (in shares)	6,495,070	1,035,519
Other comprehensive income (loss)							(2,680)				(2,680)
Net income (loss)								313,882			313,882
Ending Balance at Dec. 31, 2020			$ 58			2,106,600	(5,214)	(631,356)			$ 1,470,088
Ending Balance (in shares) at Dec. 31, 2020			57,793,533								57,793,533
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under stock plan			$ 1			47,302					$ 47,303
Issuance of common stock under stock plan (in shares)			1,304,386
Purchase of common stock under ESPP						3,313					$ 3,313
Purchase of common stock under ESPP (in shares)			43,167								43,167
Stock-based compensation expense						93,035					$ 93,035
Other comprehensive income (loss)							1,081				1,081
Net income (loss)								(644,085)			(644,085)
Ending Balance at Dec. 31, 2021			$ 59			$ 2,250,250	$ (4,133)	$ (1,275,441)			$ 970,735
Ending Balance (in shares) at Dec. 31, 2021			59,141,086								59,141,086

Consolidated Statements of Cash

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 income (loss)	$ (644,085)	$ 313,882	$ (347,694)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	6,479	6,559	5,259
Noncash lease expense	6,306	5,791	4,991
Stock-based compensation	91,630	75,526	54,653
Acquired in-process research and development	259,957
Accretion of premiums and discounts on investments	1,361	466	(4,949)
Other	3,379	429
Changes in assets and liabilities:
Accounts receivable	(18,143)	(6,387)	(599)
Unbilled accounts receivable	6,338	4,536	(22,597)
Inventory	(12,561)	(6,707)
Prepaid expenses and other current assets	4,693	(12,620)	(3,338)
Other assets	(1,786)	1,440	20
Accounts payable	4,221	(791)	1,448
Accrued expenses	6,095	16,214	36,980
Deferred revenue	(4,582)	(4,915)	(94)
Operating lease liabilities	(7,955)	(6,388)	(2,095)
Net cash provided by (used in) operating activities	(298,653)	387,035	(278,015)
Cash flows from investing activities
Purchases of property and equipment	(3,089)	(3,159)	(14,013)
Purchase of in-process research and development asset, net of cash acquired	(258,152)
Purchases of investments	(655,449)	(969,437)	(738,387)
Maturities of investments	690,830	538,347	735,934
Net cash provided by (used in) investing activities	(225,860)	(434,249)	(16,466)
Cash flows from financing activities
Proceeds from public offerings of common stock, net of issuance cost		503,189	327,466
Net proceeds from stock option exercises and employee stock purchase plan	50,716	35,265	13,288
Issuance of common stock related to collaboration agreement		79,305
Other financing activities			(116)
Net cash provided by financing activities	50,716	617,759	340,638
Net increase (decrease) in cash, cash equivalents, and restricted cash	(473,797)	570,545	46,157
Cash, cash equivalents and restricted cash at beginning of period	689,804	119,604	73,429
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(888)	(345)	18
Cash, cash equivalents and restricted cash at end of period	215,119	689,804	119,604
Supplemental cash flow information
Property and equipment purchases unpaid at period end	149	141	958
Cash paid for taxes, net	$ 694	$ 778	$ 185

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of cash, cash equivalents, and restricted cash
Cash and cash equivalents	$ 209,948	$ 684,636	$ 113,938
Restricted cash included in prepaid expenses and other current assets			500
Restricted cash	5,171	5,168	5,166
Total cash, cash equivalents, and restricted cash shown in condensed consolidated statements of cash flows	$ 215,119	$ 689,804	$ 119,604
Restricted cash, current, consolidated balance sheets position	Prepaid expenses and other current assets	Prepaid expenses and other current assets	Prepaid expenses and other current assets

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Nature of Business	1. Nature of Business Blueprint Medicines Corporation (the Company), a Delaware corporation incorporated on October 14, 2008, is a precision therapy company focused on genomically defined cancers and blood disorders. The Company’s approach is to leverage its novel research engine to systematically and reproducibly identify drivers of diseases in genomically defined patient populations, and to craft highly selective and potent drug candidates that provide significant and durable clinical responses to patients. The Company has two approved precision therapies and is globally advancing multiple programs for systemic mastocytosis, lung cancer and other genomically defined cancers, and cancer immunotherapy. The Company is devoting substantially all of its efforts to research and development for current and future drug candidates and commercialization of AYVAKIT/AYVAKYT, GAVRETO and any current or future drug candidates that obtain marketing approval. The Company is subject to a number of risks similar to those of other companies transitioning to a commercial stage, including but not limited to: successful commercialization of its current and future drugs, either by itself or through collaboration with third parties; establishing safety and efficacy in clinical trials and obtaining regulatory approvals for its drug candidates; competition from other companies; compliance with comprehensive and ongoing regulatory requirements and legislative changes; and the need to obtain adequate additional financing to fund the development of its drug candidates. If the Company is unable to raise capital when needed or on attractive terms, it may be forced to delay, reduce, eliminate or out-license certain of its research and development programs or future commercialization efforts. As of December 31, 2021, the Company had cash, cash equivalents and marketable securities of $1,034.6 million. Based on the Company’s current operating plans, the Company anticipates that its existing cash, cash equivalents and marketable securities will be sufficient to enable it to fund its current operations for at least the next twelve months from the issuance of the financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies and Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Summary of Significant Accounting Policies and Recent Accounting Pronouncements	2. Summary of Significant Accounting Policies and Recent Accounting Pronouncements Basis of Presentation The audited consolidated The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Blueprint Medicines Security Corporation, which is a Massachusetts subsidiary created to buy, sell and hold securities, Blueprint Medicines (Switzerland) GmbH, Blueprint Medicines (Netherlands) B.V., Blueprint Medicines (UK) Ltd, Blueprint Medicines (Germany) GmbH, Blueprint Medicines (Spain) S.L., Blueprint Medicines (France) SAS, Blueprint Medicines (Italy) S.r.L., and Lengo Therapeutics Inc (Lengo), which was acquired on December 30, 2021. All intercompany transactions and balances have been eliminated. Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and in developing the estimates and assumptions that are used in the preparation of the financial statements. Management must apply significant judgment in this process. Management’s estimation process often may yield a range of potentially reasonable estimates and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: revenue recognition, acquisitions, inventory, operating lease right-of-use assets, operating lease liabilities, stock-based compensation expense, accrued expenses, and income taxes. The length of time and full extent to which the ongoing COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including revenues, expenses, reserves and allowances, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, subject to change and difficult to predict, including as a result of new information that may emerge concerning COVID-19, including the identification and spread of new variants, and the actions taken to contain or treat COVID-19, as well as the economic impact thereof on local, regional, national and international customers and markets. The Company considers the impact of COVID-19 while making the estimates within its consolidated financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates. Significant Accounting Policies Revenue Recognition The Company accounts for contracts with customers in accordance with ASC Topic 606, Revenue from Contracts with Customers Product revenue AYVAKIT and GAVRETO its products Product revenue is recognized when the customer takes control of the product, typically upon delivery to the customer. Product revenue is recorded at the net sales price, or transaction price, which includes estimated reserves for variable consideration resulting from chargebacks, government rebates, trade discounts and allowances, product returns and other incentives that are offered within the contract with customers, healthcare providers, payors and other indirect customers relating to the sales of the Company’s product. Reserves are established based on the amounts earned or to be claimed on the related sales. Where appropriate, the Company utilizes the expected value method to determine the appropriate amount for estimates of variable consideration based on factors such as the Company’s current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns, the percentage of our products that are sold via these programs, and our product pricing ​ Chargebacks: expected value method based upon a range of possible outcomes and are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue. Government rebates: Trade discounts and allowances: Product returns: ​ Other deductions: ​ Collaboration revenue At contract inception, the Company analyzes its collaboration arrangements to assess whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities and therefore within the scope of ASC Topic 808, Collaborative Arrangements For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, either by analogy to authoritative accounting literature or by applying a reasonable and rational policy election. The Company evaluates the income statement classification for presentation of amounts due from or owed to other participants associated with multiple activities in a collaboration arrangement based on the nature of each separate activity. For the co-commercialization and marketing activities of certain of the Company’s products and product candidates in a collaboration arrangement, where the Company is the principal on sales transactions with third parties, the Company recognizes revenues, cost of sales and operating expenses on a gross basis in their respective lines in its consolidated statements of operations and comprehensive income (loss). Where the Company is not the principal on sales transactions with third parties, the Company records its share of the revenues, cost of sales and operating expenses on a net basis as revenue (expenses) from the collaboration arrangement in its consolidated statements of operations and comprehensive income (loss). For elements accounted within scope of ASC 606, to determine the appropriate amount of revenue to be recognized for the arrangements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above; and (c) the stand-alone selling price for each performance obligation identified in the contract for the allocation of transaction price in step (iv) above. The Company uses judgment to determine whether milestones or other variable consideration, except for royalties and sales-based milestones, should be included in the transaction price as described further below. The transaction price is allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. Exclusive Licenses. Research and Development Services. Customer Options. Milestone Payments. Royalties. or all of the royalty has been allocated has been satisfied or partially satisfied. To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. Consideration received prior to revenue recognition is recorded as deferred revenue in the consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. If the Company transfer goods or services to a customer before the customer pays consideration or before payment is due, the Company records a contract asset as unbilled accounts receivable on the consolidated balance sheets. For a complete discussion of accounting for collaboration revenues, see Note 11, Collaboration and License Agreements Accounts Receivable, net Accounts receivable arise from product sales and amounts due from the Company’s collaboration partners. The amount from product sales represents amounts due from specialty distributors and specialty pharmacy providers in the U.S. and in the European Union. The Company monitors economic conditions and the financial performance and credit worthiness of its counterparties to identify facts or circumstances that may indicate that its receivables are at risk of collection. The Company provides reserves against accounts receivable for estimated losses that may result from a customer’s inability to pay based on the composition of its accounts receivable, considering past events, current economic conditions, and reasonable and supportable forecasts about the future economic conditions. The contractual life of our accounts receivable is generally short-term. Amounts determined to be uncollectible are charged or written-off against the reserve. For the years ended December 31, 2021 and 2020, the Company did not record any expected credit losses related to outstanding accounts receivable. Inventory Inventories are stated at the lower of cost or estimated net realizable value with cost based on the first-in first-out method. Inventory that can be used in either the production of clinical or commercial products is expensed as research and development costs when identified for use in clinical trials. The Company classifies its inventory costs as long-term when it expects to utilize the inventory beyond its normal operating cycle and includes these costs in other assets in the consolidated balance sheets. Prior to the regulatory approval of its drug candidates, the Company incurs expenses for the manufacture of drug product supplies to support clinical development that could potentially be available to support the commercial launch of those drugs. Until the date at which regulatory approval has been received or is otherwise considered probable, the Company records all such costs as research and development expenses. Fair Value Measurements The Company has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. ● Level 1 — Fair values are determined utilizing quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access; ● Level 2 — Fair values are determined by utilizing quoted prices for identical or similar assets and liabilities in active markets or other market observable inputs such as interest rates, yield curves and foreign currency spot rates; and ● Level 3 — inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s financial assets, which include cash equivalents and marketable securities, have been initially valued at the transaction price, and subsequently revalued at the end of each reporting period, utilizing third-party pricing services. The pricing services utilize industry standard valuation models, including both income and market based approaches, to determine value. There have been no changes to the valuation methods during the years ended December 31, 2021 and 2020. Cash and cash equivalents The Company considers all highly liquid investments purchased with original maturities of 90 days or less from the date of purchase to be cash equivalents. As of December 31, 2021 and 2020, the Company’s cash equivalents comprised of money market funds with less than 90 days from the date of purchase. Cash equivalents are reported at fair value. Available-for-Sale Investments The Company classifies marketable debt securities with a remaining maturity when purchased of greater than three months available-for-sale, and marketable debt securities with a remaining maturity date greater than one year as non-current assets. Available-for-sale marketable debt securities are maintained by an investment manager and mainly consist of U.S. treasury securities and U.S. government agency securities. Available-for-sale marketable debt securities are carried at fair value with the unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders’ equity until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income and/or expense over the life of the instrument. Realized gains and losses are determined using the specific identification method and are included in other income (expense). The Company reviews its portfolio of available-for-sale debt securities, using both quantitative and qualitative factors, to determine if declines in fair value below cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, a loss is recognized in net income, whereas if the decline in fair value is not due to credit-related factors, the loss is recorded in other comprehensive income (loss). Comprehensive Income (Loss) Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Other comprehensive income (loss) consisted of foreign currency translation adjustments, unrealized gains and losses on available-for-sale investments and unrealized gains and losses on pension benefit obligations. Research and Development Expenses Expenditures relating to research and development are expensed in the period incurred. Research and development expenses consist of both internal and external costs associated with the development of the Company’s selective cancer therapies and building of its discovery platform. As part of the process of preparing the consolidated financial statements, the Company accrues costs for clinical trial activities based upon estimates of the services received and related expenses incurred that have yet to be invoiced by the contract research organizations or other clinical trial vendors that perform the activities. ​ In certain circumstances, the Company is required to make nonrefundable advance payments to vendors for goods or services that will be received in the future for use in research and development activities. In such circumstances, the nonrefundable advance payments are deferred and capitalized, even when there is no alternative future use for the research and development, until related goods or services are provided. In circumstances where amounts have been paid in excess of costs incurred, the Company records a prepaid expense. Selling, General and Administrative Expenses Property and Equipment, Net Impairment of Long-Lived Assets not impairment charges Leases Leases are accounted for in accordance with ASC Topic 842, Leases Leases are classified as either finance leases or operating leases. A lease is classified as a finance lease if any one of the following criteria are met: the lease transfers ownership of the asset by the end of the lease term, the lease contains an option to purchase the asset that is reasonably certain to be exercised, the lease term is for a major part of the remaining useful life of the asset or the present value of the lease payments equals or exceeds substantially all of the fair value of the asset. A lease is classified as an operating lease if it does not meet any of these criteria. For all leases at the lease commencement date, a right-of-use asset and a lease liability are recognized. The right-of-use asset represents the right to use the leased asset for the lease term. The lease liability represents the present value of the lease payments under the lease. The right-of-use asset is initially measured at cost, which primarily comprises the initial amount of the lease liability, plus any initial direct costs incurred if any, less any lease incentives received. All right-of-use assets are reviewed for impairment. The lease liability is initially measured at the present value of the lease payments, discounted using the interest rate implicit in the lease or, if that rate cannot be readily determined, the secured incremental borrowing rate for the same term as the underlying lease. Lease payments included in the measurement of the lease liability comprise the following: the fixed noncancelable lease payments, payments for optional renewal periods where it is reasonably certain the renewal period will be exercised, and payments for early termination options unless it is reasonably certain the lease will not be terminated early. Lease cost for operating leases consists of the lease payments plus any initial direct costs, primarily brokerage commissions, and is recognized on a straight-line basis over the lease term. Included in lease cost are any variable lease payments incurred in the period that are not included in the initial lease liability and lease payments incurred in the period for any leases with an initial term of 12 months or less. Lease cost for finance leases consists of the amortization of the right-of-use asset on a straight-line basis over the lease term and interest expense determined on an amortized cost basis. The lease payments are allocated between a reduction of the lease liability and interest expense. The Company has made an accounting policy election to not recognize leases with an initial term of 12 months or less within our consolidated balance sheets and to recognize those lease payments on a straight-line basis in our consolidated statements of income over the lease term. Stock-Based Compensation Expense Stock-based compensation awards are accounted for in accordance with ASC Topic 718, Compensation –Stock Compensation ● expected volatility, which is calculated based on a blend of the Company’s reported volatility data for the length of time that market data is available for the Company’s stock and the historical data for a representative group of publicly traded companies, for which historical information is available. For these analyses, the Company selects companies with comparable characteristics to itself including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. Until a sufficient amount of historical information regarding volatility of the Company’s own share price became available, the Company computed the historical volatility data using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of its stock-based awards ; ● risk-free interest rate, which is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected term assumption; ● expected term, which is calculated using the simplified method, as prescribed by the Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment, as the Company has insufficient historical information regarding its stock options to provide a basis for an estimate. U nder this approach, the weighted-average expected life is presumed to be the average of the contractual term of ten years and the weighted-average vesting term of the stock options, taking into consideration multiple vesting tranches; and ● dividend yield, which is zero based on the fact that the Company never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. common stock purchase Acquisition Business Combinations “business”, requires considerations in the form of two steps: (1) determination of whether “substantially all” of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets (i.e., “screen test”); if not, then (2) evaluate whether the set of transferred assets and activities meets the definition of a business which includes, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. If the assets acquired are not a business, the Company accounts for the transaction as an asset acquisition. If the transaction is a business combination, it is accounted for by applying the acquisition method. In asset acquisitions, the Company allocates the cost of a group of assets acquired to the individual assets acquired or liabilities assumed based on their relative fair values. Goodwill is not recognized in an asset acquisition. Any difference between the cost of an asset acquisition and the fair value of the net assets acquired is allocated to the non-monetary identifiable assets based on their relative fair values. Research and Development Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions using a more-likely-than-not threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in the law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity, and changes in facts or circumstances related to a tax position. Foreign currency translation The financial statements of each of the Company’s subsidiaries with a functional currency other than the U.S. dollar are translated into U.S. dollars using period-end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates for operating results. Translation gains and losses are included in accumulated other comprehensive income (loss) in stockholders’ equity. Foreign currency transaction gains and losses are included in other (expense) income, net in the results of operations. Concentrations of Credit Risk and Off-Balance-Sheet Risk The Company has no significant off-balance-sheet risk such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk primarily consist of cash and cash equivalents, investments, accounts receivable and unbilled account receivables. The Company maintains its cash, cash equivalents and marketable securities in custodian accounts at high quality financial institutions, and as of December 31, 2021 and 2020, substantially all the Company’s cash, cash equivalents and marketable securities were invested in money market funds and U.S. government agency securities and treasury obligations, and consequently, the Company believes that such funds are subject to minimal credit risk. The Company has adopted an investment policy that limits the amounts the Company may invest in any one type of investment. The Company has not experienced any credit losses and does not believe it is exposed to any significant credit risk on these funds. Accounts receivables and unbilled accounts receivables represent amounts arising from product sales and amounts due from the Company’s collaboration partners. The Company monitors economic conditions to identify facts or circumstances that may indicate that its receivables are at risk of collection. Segment and Geographic Information New Accounting Pronouncements Government assistance Government Assistance (Topic 832) – Disclosures by Business Entities about Government Assistance

Acquisition

Acquisition	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Acquisition	3. Acquisition On November 27, 2021, the Company entered into a merger agreement for the acquisition of all the outstanding shares of Lengo Therapeutics Inc. (“Lengo”), a biopharmaceutical company committed to developing novel, best-in-class precision medicines targeting driver mutations in oncology to improve the lives of patients with cancer. The acquisition was completed on December 30, 2021. Under the terms of the acquisition, the Company agreed to pay Lengo shareholders an upfront consideration of $250.0 million, subject to customary net indebtedness, transaction expenses, and other adjustments, as set forth in the acquisition agreement, and future contingent cash milestone payments of up to $215.0 million, upon achievement of specified regulatory approval and sales milestones. The milestone payments were determined to be contingent consideration which will be recognized when the contingency is resolved, and the consideration is paid or becomes payable. The total net purchase price was $258.4 million upon closing of the transaction, which consists of the $250.0 million upfront payment, and $8.4 million of adjustments associated with net indebtedness, transaction expenses, and other adjustments per the terms of the agreement. The acquisition was accounted for as acquisition of assets that did not meet the definition of a business. The asset acquisition did not constitute a business as substantially all of the fair value of the gross assets acquired was concentrated in Lengo’s lead compound LNG-451, now known as BLU-451. The acquired assets and liabilities were recorded at their relative fair values and the Company immediately expensed the acquired intellectual property in the consolidated statement of operations and comprehensive loss in the amount of $260.0 million as the acquired assets represent in-process research and development with no alternative future use. A summary of the net purchase price and the allocation of the consideration is as follows (in thousands): ​ ​ ​ ​ ​ Purchase price, net of cash acquired ​ $ 258,377 Identifiable assets and liabilities acquired: ​ ​ ​ Net current liabilities ​ ​ (1,580) In-process research and development ​ ​ 259,957 Total identifiable net assets acquired ​ $ 258,377 ​ ​ ​

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Marketable Securities	4. Marketable Securities Marketable securities consisted of the following at December 31, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair December 31, 2021 Cost Gain ​ Losses ​ Value Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ $ 498,582 ​ $ 21 ​ $ (1,460) ​ $ 497,143 U.S. treasury obligations ​ ​ 328,801 ​ ​ — ​ ​ (1,249) ​ ​ 327,552 Total ​ $ 827,383 ​ $ 21 ​ $ (2,709) ​ $ 824,695 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair December 31, 2020 Cost Gain ​ Losses ​ Value Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ $ 746,770 ​ $ 513 ​ $ (14) ​ $ 747,269 U.S. treasury obligations ​ ​ 117,368 ​ ​ 449 ​ ​ — ​ ​ 117,817 Total ​ $ 864,138 ​ $ 962 ​ $ (14) ​ $ 865,086 ​ As of December 31, 2021 and 2020, the Company held 74 and 8 securities, respectively, that were in an unrealized loss position. The aggregate fair value of securities held by the Company in an unrealized loss position for less than twelve months as of December 31, 2021 and 2020 were $750.5 million and $125.7 million, respectively, and there were no securities held by the Company in an unrealized loss position for more than twelve months. The Company has the intent and ability to hold such securities until recovery. As a result, the Company did not impairments . As of December 31, 2021, 56 securities with an aggregate fair value of $557.5 million had remaining maturities between one and five years. As of December 31, 2020, 65 securities with an aggregate fair value of $677.9 million had remaining maturities between one and five years. The Company received proceeds of $690.8 million and $538.3 million from maturities of debt securities for the years ended December 31, 2021 and 2020, respectively. The Company did not realize any gains or losses from maturities of debt securities for the years ended December 31, 2021 and 2020.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Fair Value of Financial Instruments	5. Fair Value of Financial Instruments The following table summarizes the Company’s cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active Observable Unobservable ​ ​ December 31, ​ Markets ​ Inputs ​ Inputs Description ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 118,880 ​ $ 118,880 ​ $ — ​ $ — Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ ​ 497,143 ​ ​ — ​ ​ 497,143 ​ ​ — U.S. treasury obligations ​ ​ 327,552 ​ ​ 327,552 ​ ​ — ​ ​ — Total ​ $ 943,575 ​ $ 446,432 ​ $ 497,143 ​ $ — ​ The following table summarizes the Company’s cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active Observable Unobservable ​ ​ December 31, ​ Markets ​ Inputs ​ Inputs Description ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 420,567 ​ $ 420,567 ​ $ — ​ $ — Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ ​ 747,269 ​ ​ — ​ ​ 747,269 ​ ​ — U.S. treasury obligations ​ ​ 117,817 ​ ​ 117,817 ​ ​ — ​ ​ — Total ​ $ 1,285,653 ​ $ 538,384 ​ $ 747,269 ​ $ — ​

Product Revenue Reserves and Al

Product Revenue Reserves and Allowances	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Product Revenue Reserves and Allowances	​ 6. Product Revenue Reserves and Allowances In January 2020, the U.S. Food and Drug Administration (FDA) approved AYVAKIT for the treatment of adults with unresectable or metastatic gastrointestinal stromal tumor (GIST) harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations. In September 2020, the European Commission granted conditional marketing authorization to AYVAKYT as a monotherapy for the treatment of adult patients with unresectable or metastatic GIST harboring the PDGFRA D842V mutation. In June 2021, the FDA granted a subsequent approval for AYVAKIT, expanding the labeled indications to include adult patients with advanced systemic mastocytosis (Advanced SM), including aggressive SM (ASM), SM with an associated hematological neoplasm (SM-AHN) and mast cell leukemia (MCL). In September 2020, the FDA granted accelerated approval of GAVRETO for the treatment of adult patients with metastatic RET fusion-positive non-small cell lung cancer (NSCLC) as detected by an FDA approved test. In December 2020, the FDA granted a subsequent accelerated approval for GAVRETO, expanding the labeled indications to include adult and pediatric patients 12 years of age and older with advanced or metastatic RET-mutant medullary thyroid cancer (MTC) who require systemic therapy, or with advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are radioactive iodine-refractory (if radioactive iodine is appropriate). The Company recorded net product revenue from the U.S. product sales of GAVRETO through June 30, 2021, and on July 1, 2021, the Company transferred certain responsibilities associated with product sales to customers, pricing and distribution matters related to U.S. product sales of GAVRETO to its collaboration partner and did not Collaboration and License Agreements ​ The following table summarizes revenue recognized from product sales for the years ended December 31, 2021 2020, and 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 AYVAKIT/AYVAKYT ​ $ 52,981 ​ $ 21,262 ​ $ — GAVRETO ​ ​ 4,706 ​ ​ 872 ​ ​ — Total product revenue ​ $ 57,687 ​ $ 22,134 ​ $ — ​ ​ The following table summarizes activity in each of the product revenue allowance and reserve categories for the years ended ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 Beginning balance at January 1 $ 1,192 ​ $ — Provision related to sales in the current period ​ 8,624 ​ ​ 2,515 Adjustment related to prior periods sales (396) ​ — Credits and payments made (5,075) ​ (1,323) Ending balance at December 31 $ 4,345 ​ $ 1,192 ​ ​ The total reserves above, which are included in the Company’s consolidated balance sheets as of December 31, 2021 and 2020, are summarized as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2021 2020 Reduction of accounts receivable, net $ 419 ​ $ 226 Component of accrued expenses 3,926 ​ 966 Total revenue-related reserves $ 4,345 ​ $ 1,192 ​ ​

Inventory

Inventory	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Inventory	7. Inventory Capitalized inventory consists of the following at December 31, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2021 2020 Raw materials ​ $ 10,788 ​ $ — Work in process ​ ​ 17,702 ​ ​ 9,488 Finished goods ​ 3,916 ​ 914 Total ​ $ 32,406 ​ $ 10,402 ​ Balance sheet classification ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2021 2020 Inventory ​ $ 21,817 ​ $ 8,581 Other assets ​ 10,589 ​ 1,821 Total ​ $ 32,406 ​ $ 10,402 ​ ​ Inventory amounts written down as a result of excess, obsolescence, unmarketability or other reasons are charged to cost of sales. For the year ended December 31, 2021, the Company recognized a write-down of $0.6 million. For the year ended December 31, 2020, no write-down was recorded. Long-term inventory, which primarily consists of work in process, is included in other assets in the consolidated balance sheets.

Restricted Cash

Restricted Cash	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Restricted Cash	8. Restricted Cash At December 31, 2021 and 2020, respectively, $5.2 million and $5.2 million, of the Company’s cash is restricted by a bank primarily related to security deposits for the lease agreements for the Company’s current and former corporate headquarters. For additional information, see Note 16, Leases

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Property and Equipment, Net	9. Property and Equipment, Net Property and equipment and related accumulated depreciation are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Estimated ​ ​ ​ ​ ​ ​ ​ ​ Useful Life ​ As of December 31, ​ ​ (Years) ​ 2021 ​ 2020 Lab equipment 5 $ 13,120 $ 11,418 ​ Furniture and fixtures 4 ​ 3,714 ​ 3,420 ​ Computer equipment 3 ​ 1,714 ​ 1,513 ​ Leasehold improvements Term of lease ​ 36,945 ​ 36,946 ​ Software 3 ​ 412 ​ 412 ​ Construction-in-progress ​ ​ ​ ​ 213 ​ ​ 151 ​ Total cost ​ ​ ​ 56,118 ​ 53,860 ​ Less: accumulated depreciation and amortization ​ ​ ​ (25,418) ​ (19,731) ​ Total ​ ​ ​ $ 30,700 ​ $ 34,129 ​ ​ Property, plant and equipment are recorded at historical cost, net of accumulated depreciation. Depreciation expense for the years ended December 31, 2021, 2020 and 2019 was $6.5 million, $6.6 million and $5.3 million, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Accrued Expenses	10. Accrued Expenses Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2021 2020 External research and development ​ $ 68,164 ​ $ 60,255 Employee compensation ​ ​ 29,166 ​ ​ 27,622 Accrued professional fees ​ 12,611 ​ 10,986 Revenue-related reserves ​ 3,926 ​ 966 Other ​ ​ 7,962 ​ ​ 6,109 Total ​ $ 121,829 ​ $ 105,938 ​

Collaboration and License Agree

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Collaboration and License Agreements	11. Collaboration and License Agreements Zai Lab Lab will be responsible for costs related to clinical trials in the Zai Lab territory, other than the specified shared services costs as defined in the Zai Lab agreement which will be shared by the Company and Zai Lab. th second anniversary to determine which of the components of the Zai Lab agreement are performance obligations with a customer The Company evaluated the Zai Lab territory specific licenses and related activities under ASC 606 as these transactions are considered transactions with a customer, and identified three material promises at the outset of the Zai Lab agreement, which consists of the following for each licensed product: (1) the exclusive license, (2) the initial know-how transfer and (3) manufacturing activities related to development and commercial supply of the licensed product in the Zai Lab territory . The Company determined that the exclusive license and the initial know-how transfer were not distinct from each other, as the exclusive license has limited value without the corresponding know-how transfer. As such, for the purposes of ASC 606, the Company determined that these two material promises, the exclusive license and the initial know-how, should be combined into one distinct performance obligation. The Company further evaluated the material promise associated with manufacting activities related to development and commercial supply of the licensed products in the Zai Lab territory, given Zai Lab is not obligated to purchase any minimum amount or quantities of the development and commercial supply from the Company, the Company concluded that, for the purpose of ASC 606, the provision of manufacturing activities related to development and commercial supply of the licensed product in Zai Lab territory was an option but not a performance obligation of the Company at the inception of the Zai Lab collaboration agreement and will be accounted for if and when exercised. The Company also concluded that there is no separate material right in connection with the development and commercial supply of the licensed product, as the expected pricing was not issued at a significant and incremental discount. Therefore, the manufacturing activities were excluded as performance obligation at the outset of the arrangement. The Company evaluated the license under ASC 606 and concluded that the license is a functional intellectual property license. The Company determined that Zai Lab benefited from the license along with the initial know-how transfer at the time of grant, and therefore the related performance obligation is satisfied at a point in time. Additionally, the Company is entitled to sales milestones and royalties from Zai Lab upon future sales of the licensed products in the Zai Lab territory, and revenue will be recognized when the related sales occur. Costs that are incurred associated with Zai Lab territory specific activities are reimbursable from Zai and will be recognized as revenue. million as revenue during the year ended December 31, 2021. The Company will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company will adjust its estimate of the transaction price, and any addition to the transaction price would be recognized as revenue when it becomes probable that inclusion would not lead to a significant revenue reversal. Roche – Pralsetinib Collaboration Under the Roche pralsetinib collaboration agreement, the Company received an upfront cash payment of $675.0 million, and through December 31, 2021, the Company has achieved $105.0 million in specified regulatory and commercialization milestones. In addition to upfront and milestone payments received through December 31, 2021, the Company is eligible to receive up to $822.0 million in contingent payments, including specified development, regulatory and sales-based milestones for pralsetinib and any licensed product containing a next-generation RET compound. In the U.S., the Company and Roche agreed to work together to co-commercialize pralsetinib and equally share responsibilities, profits and losses. In addition, the Company is eligible to receive tiered royalties ranging from high-teens to mid-twenties on annual net sales of pralsetinib outside the U.S., excluding Greater China (the Roche territory). The Company and Roche have also agreed to co-develop pralsetinib globally in RET-altered solid tumors, including non-small cell lung cancer, medullary thyroid carcinoma and other thyroid cancers, as well as other solid tumors. The Company and Roche will share global development costs for pralsetinib at a rate of 45 percent for the Company and 55 percent for Roche up to a specified amount of aggregate joint development costs, after which the Company’s share of global development costs for pralsetinib will be reduced by a specified percentage. The Company and Roche will also share specified global development costs for any next-generation RET compound co-developed under the collaboration in a similar manner. Unless earlier terminated in accordance with its terms, the Roche pralsetinib collaboration agreement will expire on a licensed product-by-licensed product basis (i) in the U.S. upon the expiration of the gross profit sharing term for such licensed product and (ii) outside the U.S. on a country-by-country basis at the end of the applicable royalty term for such licensed product. Roche may terminate the agreement in its entirety or on a licensed product-by-licensed product or country-by-country basis subject to certain notice periods. Either party may terminate the Roche pralsetinib collaboration agreement for the other party’s uncured material breach or insolvency. Subject to the terms of the Roche pralsetinib collaboration agreement, effective upon termination of the agreement, the Company is entitled to retain specified licenses to be able to continue to exploit the licensed products. In connection with the Roche collaboration agreement, on July 13, 2020, the Company also entered into a stock purchase agreement with Roche Holdings, Inc. (Roche Holdings) pursuant to which the Company issued and sold an aggregate of 1,035,519 of shares of common stock to Roche Holdings at a purchase price of $96.57 per share and received $100.0 million in the third quarter of 2020. The closing for a minority portion of the equity investment occurred following the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and other customary closing conditions. The Company considered the ASC 606 criteria for combining contracts and determined that the Roche pralsetinib collaboration agreement and stock purchase agreement should be combined into a single contract because they were negotiated and entered into in contemplation of one another. The Company accounted for the common stock issued to Roche Holdings based on the fair market value of the common stock on the dates of issuance. The fair market value of the common stock issued to Roche Holdings was $79.3 million, based on the closing price of the Company’s common stock on the dates of issuance, resulting in a $20.7 million premium. The Company determined that the premium paid by Roche Holdings for the common stock should be attributed to the transaction price of the Roche pralsetinib collaboration agreement. The Company determined that the Roche pralsetinib collaboration agreement contained four material components: (i) licenses granted to Roche to develop and commercialize pralsetinib worldwide, excluding the CStone territory (pralsetinib license); (ii) the Roche territory-specific commercialization activities for pralsetinib, including manufacturing (Roche territory activities); (iii) the parties’ joint development activities for pralsetinib worldwide, excluding the CStone territory; and (iv) the parties’ joint commercialization activities for pralsetinib in the U.S. The Company considered the guidance in ASC 606 to determine which of the components of the Roche pralsetinib collaboration agreement are performance obligations with a customer and concluded that the pralsetinib license and the Roche territory activities are within the scope of ASC 606 because Roche is the Company’s customer in those transactions. The Company evaluated the Roche pralsetinib license under ASC 606 and concluded that the pralsetinib license is a functional intellectual property license and is a distinct performance obligation. The Company determined that Roche benefited from the pralsetinib license at the time of grant, and therefore the related performance obligation is satisfied at a point in time. The Company evaluated the Roche territory activities under ASC 606 and identified one material promise associated with manufacturing activities related to development and commercial supply of pralsetinib in the Roche territory for up to 24 months. Given that Roche is not obligated to purchase any minimum amount or quantities of the development and commercial supply from the Company, the Company concluded that, for the purpose of ASC 606, the provision of manufacturing activities related to development and commercial supply of pralsetinib in Roche territory was an option but not a performance obligation of the Company at the inception of the Roche collaboration agreement and will be accounted for if and when exercised. The Company also concluded that there is no separate material right in connection with the development and commercial supply of pralsetinib, as the expected pricing was not issued at a significant and incremental discount. Therefore, the manufacturing activities were excluded as performance obligations at the outset of the arrangement. Additionally, the Company is entitled to sales milestones and royalties from Roche upon future sales of pralsetinib in the Roche territory, and revenue will be recognized when the related sales occur. Costs that are incurred associated with the Roche territory activities are reimbursable from Roche and will be recognized as revenue. For the purposes of ASC 606, the transaction price of the Roche collaboration agreement as of the outset of the arrangement was determined to be $695.7 million, which consisted of the upfront cash payment of $675.0 million and the $20.7 million premium on the sale of common stock to Roche Holdings, which was allocated to the performance obligation related to the pralsetinib licenses. During the years ended December 31, 2021 and 2020, cash consideration associated with regulatory or commercialization milestones of $50.0 million and $55.0 million respectively, were added to the estimated transaction price of the Roche pralsetinib agreement and recognized revenue in such periods. The other potential milestone payments that the Company is eligible to receive under the Roche pralsetinib agreement have been excluded from the transaction price, as all the remaining milestone amounts were fully constrained based on the probability of achievement. The Company will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company will adjust its estimate of the transaction price, and any addition to the transaction price would be recognized as revenue when it becomes probable that inclusion would not lead to a significant revenue reversal. The following table summarizes revenue recognized under the Roche pralsetinib collaboration during the years ended December 31, 2021, 2020 and 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 Upfront license revenue ​ $ — $ 695,694 ​ $ — License milestone revenue ​ ​ 50,000 ​ ​ 55,000 ​ ​ — Manufacturing and other services related to Roche territory-specific activities ​ ​ 6,022 ​ ​ 2,406 ​ ​ — Total Roche pralsetinib collaboration revenue ​ $ 56,022 ​ $ 753,100 ​ $ — ​ ​ For the parties’ participation in global development for pralsetinib and the U.S. commercialization activities for GAVRETO, the Company concluded that those activities and cost-sharing payments related to such activities are within the scope of ASC 808, as both parties are active participants in the development, manufacturing and commercialization activities and are exposed to significant risks and rewards of those activities under the Roche pralsetinib collaboration agreement. Payments to or reimbursements from Roche related to the global development activities are accounted for as an increase to or reduction of research and development expenses. Prior to July 1, 2021, the Company was the principal for product sales to customers in the U.S. and recognized revenues on sales to third parties in product revenue, net in its consolidated statements of operations and comprehensive income (loss). On July 1, 2021, Roche took over certain responsibilities associated with product sales to customers, pricing and distribution matters for GAVRETO in the U.S. and became the principal for recording product sales to customers in the U.S., and the Company recognized its portion of the commercial losses sharing as collaboration loss sharing in its consolidated statements of operations and comprehensive income (loss). The following table summarizes the amount from collaboration loss sharing after Roche became the principal for product sales of GAVRETO to customers in the U.S. (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 The Company's share of loss in the U.S. for pralsetinib ​ $ 7,801 $ — $ — ​ The following table summarizes the amounts recognized as reductions to selling, general and administrative expenses related to the commercialization of GAVRETO in the U.S., and reductions to research and development expenses related to global development activities for pralsetinib under the Roche pralsetinib collaboration during the years ended December 31, 2021, 2020 and 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 Reductions to selling, general and administrative expenses ​ $ 18,753 $ 10,631 ​ $ — Reductions to research and development expenses ​ ​ 11,192 ​ ​ 20,459 ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ ​ 2021 ​ 2020 Accounts receivable, net ​ $ 2,679 $ — Unbilled accounts receivable ​ $ 6,802 $ 17,600 ​ Clementia On October 15, 2019, the Company entered into a license agreement (the Clementia agreement) with Clementia Pharmaceuticals, Inc. (Clementia), a wholly-owned subsidiary of Ipsen S.A. Under the Clementia agreement, the Company granted an exclusive, worldwide, royalty-bearing license to Clementia to develop and commercialize BLU- 782, the Company’s oral, highly selective investigational ALK2 inhibitor in clinical development for the treatment of fibrodysplasia ossificans progressive (FOP), as well as specified other compounds related to the BLU-782 program. ​ Under the Clementia agreement, the Company received an upfront cash payment of $25.0 million and through December 31, 2021, the Company has received $20.0 million cash milestone payments. Subject to the terms of the Clementia agreement, in addition to the upfront and milestone payments , the Company is eligible to receive up to $490.0 million in potential development, regulatory and sales-based milestone payments for licensed products. In addition, Clementia is obligated to pay to the Company royalties on aggregate annual worldwide net sales of licensed products at tiered percentage rates ranging from the low- to mid-teens, subject to adjustment in specified circumstances under the Clementia agreement, and Clementia purchased specified manufacturing inventory from the Company for a total of $1.5 million. Unless earlier terminated in accordance with the terms of the Clementia agreement, the agreement will expire on a country-by-country, licensed product-by-licensed product basis on the date when no royalty payments are or will become due. Clementia may terminate the agreement at any time on or after the second anniversary of the effective date of the agreement upon at least 12 months’ prior written notice to the Company, which cannot be delivered before the first anniversary of the effective date. Either party may terminate the agreement for the other party’s uncured material breach or insolvency and in certain other circumstances agreed to by the parties. In certain termination circumstances, the Company is entitled to retain specified licenses to be able to continue to exploit the Clementia licensed products. The Company evaluated the Clementia agreement under ASC 606 as the agreement represented a transaction with a customer. The Company identified the following material promises under the agreement: (1) the exclusive license to develop, manufacture and commercialize BLU-782; (2) the technology transfer of BLU-782 program; (3) the transfer of existing manufacturing inventory; and (4) the transfer of in-process manufacturing inventory. In addition, the Company determined that the exclusive license and technology transfer were not distinct from each other, as the exclusive license has limited value without the corresponding technology transfer. As such, for the purposes of ASC 606, the Company determined that these four material promises, described above, should be combined into three performance obligations: (1) the exclusive license and the technology transfer; (2) the transfer of existing manufacturing inventory; and (3) the transfer of in-process manufacturing inventory. The Company determined that the transaction price as of the outset of the arrangement was $46.5 million, which consisted of the upfront amount of $25.0 million, the $20.0 million cash milestone payment due and received in 2020, the purchase of existing manufacturing inventory of $1.2 million and the purchase of in-process manufacturing inventory of $0.3 million. The other potential milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestone amounts were fully constrained based on the probability of achievement. The transaction price was allocated During the year ended December 31, 2021 and 2020, no material revenue was recognized from the Clementia collaboration. During the year ended December 31, 2019, the Company recognized $46.2 million as revenue for the delivery of the license, the technology transfer and the transfer of existing manufacturing inventory. There was no revenue deferred as a contract liability associated with the Clementia agreement as of December 31, 2021 and 2020. CStone Pharmaceuticals On June 1, 2018, the Company entered into a collaboration and license agreement (the CStone agreement) with CStone Pharmaceuticals (CStone) pursuant to which the Company granted CStone exclusive rights to develop and commercialize the Company’s drug candidates avapritinib, pralsetinib and fisogatinib, including back-up forms and certain other forms thereof, in Mainland China, Hong Kong, Macau and Taiwan (each, a CStone region and collectively, the CStone territory), either as a monotherapy or as part of a combination therapy. The Company received an upfront cash payment of $40.0 million, and through December 31, 2021, the Company has achieved $23.0 million in milestone payments under this collaboration. Subject to the terms of the CStone agreement, in addition to the upfront payments received and milestones achieved through December 31, 2021, the Company will be eligible to receive up to approximately $323.0 million in additional milestone payments, including $95.5 million related to development and regulatory milestones and $227.5 million related to sales-based milestones. In addition, CStone will be obligated to pay the Company tiered percentage royalties on a licensed product-by-licensed product basis ranging from the mid-teens to low twenties on annual net sales of each licensed product in the CStone territory, subject to adjustment in specified circumstances. CStone will be responsible for costs related to the development of the licensed products in the CStone territory, other than specified costs related to the development of fisogatinib as a combination therapy in the CStone territory that will be shared by the Company and CStone. Pursuant to the terms of the CStone agreement, CStone is responsible for conducting all development and commercialization activities in the CStone territory related to the licensed products. Subject to specified exceptions, during the term of the CStone agreement, each party has agreed that neither it nor its affiliates will conduct specified development and commercialization activities in the CStone territory related to selective inhibitors of FGFR4, KIT, PDGFRA and RET. In addition, under the CStone agreement, each party has granted the other party specified intellectual property licenses to enable the other party to perform its obligations and exercise its rights under the CStone agreement, including license grants to enable each party to conduct research, development and commercialization activities pursuant to the terms of the CStone agreement. The CStone agreement will continue on a licensed product-by-licensed product and CStone region-by-CStone region basis until the later of (i) 12 years after the first commercial sale of a licensed product in a CStone region in the CStone territory and (ii) the date of expiration of the last valid patent claim related to the Company’s patent rights or any joint collaboration patent rights for the licensed product that covers the composition of matter, method of use or method of manufacturing such licensed product in such region. Subject to the terms of the CStone agreement, CStone may terminate the CStone agreement in its entirety or with respect to one or more licensed products for convenience by providing written notice to the Company, and CStone may terminate the CStone agreement with respect to a licensed product for convenience at any time by providing written notice to the Company following the occurrence of specified events. In addition, the Company may terminate the CStone agreement under specified circumstances if CStone or certain other parties challenges the Company’s patent rights or any joint collaboration patent rights or if CStone or its affiliates do not conduct any material development or commercialization activities with respect to one or more licensed products for a specified period of time, subject to specified exceptions. Either party may terminate the CStone agreement for the other party’s uncured material breach or insolvency. In certain termination circumstances, the parties are entitled to retain specified licenses to be able to continue to exploit the licensed products, and in the event of termination by CStone for the Company’s uncured material breach, the Company will be obligated to pay CStone a low single digit percentage royalty on a licensed product-by-licensed product basis on annual net sales of such licensed product in the CStone territory, subject to a cap and other specified exceptions. The Company evaluated the CStone agreement to determine whether it is a collaborative arrangement for purposes of ASC 808. The Company determined that there were two material components of the CStone agreement: (i) the CStone territory-specific license and related activities in the CStone territory, and (ii) the parties’ participation in global development of the licensed products. The Company concluded that the CStone territory-specific license and related activities in the CStone territory are not within the scope of ASC 808 because the Company is not exposed to significant risks and rewards. The Company concluded that CStone is a customer with regard to the component that includes the CStone territory-specific license and related activities in CStone territory, which include manufacturing. For the parties’ participation in global development of the licensed products, the Company concluded that the research and development activities and cost-sharing payments related to such activities are within the scope of ASC 808 as both parties are active participants exposed to the risk of the activities under the CStone agreement. The Company concluded that CStone is not a customer with regard to the global development component in the context of the CStone agreement. Therefore, payments received by the Company for global development activities under the CStone agreement, including manufacturing, will be accounted for as a reduction of related expenses. A summary of manufacturing and research and development services related to the global development activities net of expenses payable to CStone during the years ended December 31, 2021, 2020 and 2019 is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 Manufacturing and research and development services related to global development activities, net of expenses payable to CStone ​ $ 2,358 ​ $ 3,060 ​ $ 3,286 ​ The Company evaluated the CStone territory-specific license and related activities in the CStone territory under ASC 606 as these transactions are considered transactions with a customer. The Company identified the following material promises under the arrangement: (1) the three exclusive licenses granted in the CStone territory to develop, manufacture and commercialize the three licensed products; (2) the initial know-how transfer for each licensed product; (3) manufacturing activities related to development and commercial supply of the licensed products; (4) participation in the joint steering committee (JSC) and joint project teams (JPT); (5) regulatory responsibilities; and (6) manufacturing technology and continuing know-how transfers. The Company determined that each licensed product is distinct from the other licensed products. In addition, the Company determined that the exclusive licenses and initial know-how transfers for each licensed product were not distinct from each other, as each exclusive license has limited value without the corresponding initial know-how transfer. For purposes of ASC 606, the Company determined that participation on the JSC and JPTs, the regulatory responsibilities and the manufacturing technology and continuing know-how transfers are qualitatively and quantitatively immaterial in the context of the CStone agreement and therefore are excluded from performance obligations. As such, the Company determined that these six material promises, described above, should be combined into one performance obligation for each of the three candidates. The Company evaluated the provision of manufacturing activities related to development and commercial supply of the licensed products as an option for purposes of ASC 606 to determine whether these manufacturing activities provide CStone with any material rights. The Company concluded that the manufacturing activities were not issued at a significant and incremental discount, and therefore do not provide CStone with any material rights. As such, the manufacturing activities are excluded as performance obligations at the outset of the arrangement. Based on these assessments, the Company identified three distinct performance obligations at the outset of the CStone agreement, which consists of the following for each licensed product: (1) the exclusive license and (2) the initial know-how transfer. Under the CStone agreement, in order to evaluate the transaction price for purposes of ASC 606, the Company determined that the upfront amount of $40.0 million constituted the entirety of the consideration to be included in the transaction price as of the outset of the arrangement, which was allocated to the three performance obligations. The potential milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestone amounts were fully constrained based on the probability of achievement. The Company satisfied the performance obligations upon delivery of the licenses, initial know-how transfers and product trademark and recognized the upfront payment of $40.0 million as revenue during the year ended December 31, 2018. During the years ended December 31, 2021, 2020, and 2019, cash consideration associated with achieved development milestones of $9.0 million, $2.0 million and $12.0 million, respectively, were added to the estimated transaction price for the CStone agreement and recognized as revenue in such periods. The Company will continue to reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company will adjust its estimate of the transaction price, and any addition to the transaction price would be recognized as revenue when it becomes probable that inclusion would not lead to a significant revenue reversal. During the year ended December 31, 2021, the Company entered into commercial supply agreements and an avapritinib manufacturing technology transfer agreement with CStone related to drug substance of avapritinib and drug product of avapritinib and pralsetinib to assist CStone’s commercialization activities conducted specifically for the CStone territory. The manufacturing activities in these agreements were considered as distinct performance obligations from the CStone collaboration agreement and collaboration revenue is recognized upon delivery of the drug substance and drug product to CStone. A summary of revenue recognized under the CStone agreement during the years ended December 31, 2021, 2020 and 2019 is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 License milestone revenue ​ $ 9,000 ​ $ 2,000 ​ $ 12,000 Manufacturing services and royalty revenue related to CStone territory-specific activities ​ ​ 24,395 ​ ​ 1,630 ​ ​ 144 Total CStone collaboration revenue ​ $ 33,395 ​ $ 3,630 ​ $ 12,144 ​ The following table presents the contract assets associated with the CStone collaboration as of December 31, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2021 ​ 2020 Accounts receivable, net ​ $ 8,164 $ 563 Unbilled accounts receivable ​ $ 5,034 $ — ​ As of December 31, 2021, the Company had $4.8 million of deferred revenue as a contract liability associated with the CStone collaboration. This contract liability mainly resulted from advance payments made by CStone in connection with commercial supply of pralsetinib for the CStone territory. The contract liability associated with the CStone collaboration was $6.5 million at December 31, 2020. Roche – Immunotherapy Collaboration In March 2016, the Company entered into a collaboration and license agreement (as amended, the Roche immunotherapy agreement) with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (collectively, Roche) for the discovery, development and commercialization of small molecule therapeutics targeting kinases believed to be important in cancer immunotherapy (including BLU-852, a development candidate for the kinase target MAP4K1, which is believed to play a role in T cell regulation), as single products or possibly in combination with other therapeutics. Under the Roche immunotherapy agreement, Roche was originally granted up to five option rights to obtain an exclusive license to exploit products derived from the collaboration programs in the field of cancer immunotherapy. Such option rights are triggered upon the achievement of Phase 1 proof-of-concept. As a result of amendments to the Roche immunotherapy agreement in prior periods, the Company and Roche are currently conducting activities for up to two programs under the collaboration. For one of the two collaboration programs, if Roche exercises its option, Roche will receive worldwide, exclusive commercialization rights for the licensed product. For the other collaboration program, if Roche exercises its option, the Company will retain commercialization rights in the U.S. for the licensed product, and Roche will receive commercialization rights outside of the U.S. for the licensed product. The Company will also retain worldwide rights to any products for which Roche elects not to exercise its applicable option. Prior to Roche’s exercise of an option, the Company will have the lead responsibility for drug discovery and preclinical development of all collaboration programs. In addition, the Company will have the lead responsibility for the conduct of all Phase 1 clinical trials other than those Phase 1 clinical trials for any p

Stockholder's Equity

Stockholder's Equity	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Stockholder's Equity	12. Stockholder’s Equity On January 27, 2020, the Company closed a follow-on public offering of 4,710,144 shares of its common stock at a price to the public of $69.00 per share and received net proceeds of $308.4 million, after deducting underwriting discounts and commissions and offering expenses paid by the Company. On July 30, 2020, the Company entered into the ATM Facility with Cowen, pursuant to which the Company may offer and sell, from time to time at its sole discretion, shares of its common stock having an aggregate offering price of up to $250.0 million through Cowen as sales agent. During the year ended December 31, 2020, the Company issued and sold 1,784,926 shares of its common stock under the ATM Facility and received net proceeds of $194.7 million. The Company did not

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Stock-based Compensation	13. Stock-based Compensation 2015 Stock Option and Incentive Plan In 2015, the Company’s board of directors and stockholders approved the 2015 Stock Option and Incentive Plan (the 2015 Plan), which replaced the Company’s 2011 Stock Option and Grant Plan, as amended (the 2011 Plan). The 2015 Plan includes incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units, unrestricted stock, performance-based awards and cash-based awards. The Company initially reserved a total of 1,460,084 shares of common stock for the issuance of awards under the 2015 Plan. The 2015 Plan provides that the number of shares reserved and available for issuance under the 2015 Plan will be cumulatively increased on January 1 of each calendar year by 4% of the number of shares of common stock issued and outstanding on the immediately preceding December 31 or such lesser amount as specified by the compensation committee of the board of directors. For the calendar years beginning January 1, 2021 and 2022, the number of shares reserved for issuance under the 2015 Plan was increased by 2,311,741 and 2,365,643 shares, respectively. In addition, the total number of shares reserved for issuance is subject to adjustment in the event of a stock split, stock dividend or other change in the Company’s capitalization. As of December 31, 2021, there were 3,027,882 2020 Inducement Plan In March 2020, the Company’s board of directors adopted the 2020 Inducement Plan (the Inducement Plan), pursuant to which the Company may grant, subject to the terms of the Inducement Plan and Nasdaq rules, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards. The Company initially reserved a total of 1,000,000 shares of common stock for the issuance of awards under the Inducement Plan. The number of shares reserved and available for issuance under the Inducement Plan can be increased at any time with the approval of the Company’s board of directors. The Inducement Plan permits the board of directors or a committee thereof to use the stock-based awards available under the Inducement Plan to attract key employees for the growth of the Company. As of December 31, 2021, there were 288,982 shares available for future grant under the Inducement Plan. Stock-based Compensation Expense The Company recognized stock-based compensation expense totaling $91.6 million, $75.5 million and million for the years ended December 31, 2021, 2020 and 2019, respectively. Stock-based compensation expense by award type included within the consolidated statements of operations and comprehensive income (loss) is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 ​ ​ 2019 Stock options $ 57,912 ​ $ 57,237 ​ $ 47,726 Restricted stock units ​ 33,939 ​ ​ 18,407 ​ ​ 6,445 Employee stock purchase plan ​ 1,184 ​ ​ 958 ​ ​ 482 Subtotal ​ 93,035 ​ ​ 76,602 ​ ​ 54,653 Capitalized stock-based compensation costs ​ (1,405) ​ ​ (1,076) ​ ​ — Stock-based compensation expense included in total cost and operating expenses $ 91,630 ​ $ 75,526 ​ $ 54,653 The following table presents stock-based compensation expense that is included in operating expenses by classification within the consolidated statements of operations and comprehensive income (loss) is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 2020 ​ 2019 Research and development $ 39,670 $ 33,642 $ 28,596 ​ Selling, general and administrative 51,960 ​ 41,884 ​ 26,057 ​ Total stock-based compensation expense included in operating expenses $ 91,630 ​ $ 75,526 ​ $ 54,653 ​ ​ ​ At December 31, 2021, there was $199.8 million of total unrecognized compensation cost related to non-vested stock awards, which is expected to be recognized over a weighted-average period of 2.6 years. Stock Options Stock options granted by the Company generally vest ratably over four years, with a one-year cliff for new employee awards and are exercisable from the date of grant for a period of ten years. The fair value of each option issued to employees was estimated at the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2021 ​ 2020 ​ 2019 ​ Risk-free interest rate ​ 0.96 % 1.02 % 2.21 % Expected dividend yield ​ — % — % — % Expected term (years) ​ 6.0 ​ 6.0 ​ 6.0 ​ Expected stock price volatility ​ 58.03 % 60.48 % 63.83 % ​ The following table summarizes the stock option activity for the year ended December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- Remaining Aggregate ​ ​ ​ ​ Average ​ Contractual ​ Intrinsic ​ ​ ​ ​ Exercise ​ Life ​ Value(1) ​ ​ Shares ​ Price ​ (in Years) ​ (in thousands) Outstanding at December 31, 2020 6,030,641 ​ $ 61.28 7.41 ​ $ 306,810 ​ Granted 1,125,514 ​ ​ 98.50 ​ ​ ​ ​ ​ ​ Exercised (982,791) ​ 48.13 ​ ​ ​ ​ ​ ​ Canceled (491,342) ​ 79.27 ​ ​ ​ ​ ​ ​ Outstanding at December 31, 2021 5,682,022 ​ $ 69.37 6.99 ​ $ 214,675 ​ Exercisable at December 31, 2021 3,499,094 ​ $ 61.30 6.13 ​ $ 160,313 ​ (1) Intrinsic value represents the amount by which the fair market value as of December 31, 2021 of the underlying common stock exceeds the exercise price of the option. ​ The weighted-average grant date fair value of options granted in the years ended December 31, 2021, 2020 and 2019 was $52.93, $34.77 and $48.96, respectively. The total intrinsic value of options exercised in the years ended December 31, 2021, 2020, and 2019 was $52.3 million, $43.3 million, and $33.8 million, respectively. At December 31, 2021, the total unrecognized compensation expense related to unvested stock option awards was $93.8 million, which is expected to be recognized over a weighted-average period of approximately 2.4 years. Restricted stock units ​ Restricted stock units granted by the Company generally vest ratably over four years. The following table summarizes the restricted stock units activity for the year ended December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ ​ Grant Date ​ Shares Fair Value Unvested shares at December 31, 2020 1,171,686 ​ $ 65.37 ​ Granted 999,504 ​ 98.62 ​ Vested (321,645) ​ 66.87 ​ Forfeited (259,385) ​ 78.31 ​ Unvested shares at December 31, 2021 1,590,160 ​ $ 83.85 ​ ​ The total fair value of restricted stock units vested during the years ended December 31, 2021, 2020 and 2019 was $31.6 million, $7.4 million and $0.7 million, respectively. As of December 31, 2021, the total unrecognized compensation expense related to unvested restricted stock units was $105.9 million, which is expected to be recognized over a weighted-average period of approximately 2.7 years. 2015 Employee Stock Purchase Plan In 2015, the Company’s board of directors and stockholders approved the 2015 ESPP, which became effective upon the closing of the IPO in May 2015. The Company initially reserved a total of 243,347 shares of common stock for issuance under the 2015 ESPP. The 2015 ESPP provides that the number of shares reserved and available for issuance under the 2015 ESPP will be cumulatively increased on January 1 of each calendar years by 1% of the number of shares of common stock issued and outstanding on the immediately preceding December 31 or such lesser amount as specified by the compensation committee of the board of directors. For the calendar years beginning January 1, 2021 and 2022, the number of shares reserved for issuance under the 2015 ESPP was increased by 577,935 and 591,410 shares, respectively. The Company issued 43,167, 38,516, and 20,724 shares under the ESPP during the years ended December 31, 2021, 2020, and 2019 respectively.

Net Income Per Share

Net Income Per Share	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Net Income Per Share	14. Net income (loss) per share Basic net income (loss) per share (earnings per share, EPS) is calculated by dividing net income (loss) by the weighted average shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net income (loss) per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period. For purposes of the diluted net income (loss) per share calculation, the effect of stock options, unvested restricted stock units and ESPP shares on weighted average number of shares is calculated using the treasury stock method. In periods with reported net operating losses, all common stock equivalents are deemed anti-dilutive such that basic net loss per share and diluted net loss per share are equal. The calculation of net income (loss) and the number of shares used to compute basic and diluted net income (loss) per share for the years ended December 31, 2021, 2020 and 2019 are as follows (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 ​ 2020 2019 Net income (loss) - basic and diluted ​ $ (644,085) ​ $ 313,882 $ (347,694) Weighted average shares outstanding - basic ​ ​ 58,518 ​ ​ 54,534 ​ ​ 47,829 Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Stock options ​ ​ — ​ ​ 1,303 ​ ​ — Restricted stock units ​ ​ — ​ ​ 331 ​ ​ — Weighted average shares outstanding - diluted ​ ​ 58,518 ​ ​ 56,168 ​ ​ 47,829 Net income (loss) per share - basic ​ $ (11.01) ​ $ 5.76 ​ $ (7.27) Net income (loss) per share - diluted ​ ​ (11.01) ​ ​ 5.59 ​ ​ (7.27) ​ For the years ended December 31, 2021, 2020 and 2019, the following dilutive securities were not included in the computation of net income (loss) per share because the effect would be anti-dilutive (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 2020 ​ 2019 Stock options 5,682 4,480 5,796 ​ Restricted stock units 1,590 13 420 ​ ESPP shares ​ 24 ​ 19 ​ 14 ​ Total 7,296 4,512 ​ 6,230 ​ ​

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Income Taxes	15. Income Taxes A reconciliation of the U.S. statutory income tax rate to the Company’s effective tax rate is as follows for the years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2021 2020 ​ 2019 Federal income tax (benefit) at statutory rate ​ 21.00 % 21.00 % 21.00 % Permanent differences 0.07 ​ (0.47) ​ 1.11 ​ In-process research and development ​ (8.53) ​ — ​ — ​ Federal research and development credits 0.76 ​ (0.96) ​ 0.77 ​ Federal orphan drug credits ​ 4.02 ​ (10.35) ​ 6.90 ​ State income tax, net of federal benefit 1.26 ​ 0.08 ​ 7.46 ​ Other (0.05) ​ 1.50 ​ 2.13 ​ Foreign rate differential ​ (0.10) ​ 0.37 ​ (0.03) ​ Deferred rate change ​ 0.79 ​ 2.60 ​ (0.08) ​ Foreign tax credit ​ 0.39 ​ — ​ — ​ Change in valuation allowance (20.08) ​ (13.42) ​ (39.26) ​ Effective income tax rate (0.47) % 0.35 % — % ​ The Company’s deferred tax assets and liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 ​ 2019 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ ​ Net operating loss carryforwards $ 243,670 ​ $ 140,769 ​ $ 219,935 Research and development credit carryforwards 36,345 ​ 23,679 ​ 19,240 Orphan drug credit carryforwards ​ 150,859 ​ ​ 125,153 ​ ​ 92,538 Accrued expenses and other 40,617 ​ 32,206 ​ 25,842 Deferred revenue ​ 6,598 ​ ​ 7,317 ​ ​ 10,971 Deferred lease incentive ​ — ​ ​ — ​ ​ — Deferred rent ​ 24,798 ​ 19,308 ​ 26,196 Jublient license ​ 448 ​ ​ — ​ ​ — Interest expense 29 ​ — ​ — Total gross deferred tax asset 503,364 ​ 348,432 ​ 394,722 Deferred tax liability ​ ​ ​ ​ ​ ​ ​ Depreciation ​ (5,157) ​ (5,451) ​ (4,474) Right of use assets ​ (20,059) ​ ​ (14,539) ​ ​ (19,869) UNICAP (1,966) ​ — ​ — Prepaid expenses ​ (2) ​ ​ — ​ ​ — Valuation allowance (476,180) ​ (328,442) ​ (370,379) Net deferred tax asset $ — ​ $ — ​ $ — ​ ​ Management has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets and has determined that it is more likely than not that the Company will not recognize the benefits of its net federal, foreign and state deferred tax assets, and as a result, a valuation allowance of $476.2 million, $328.4 million and $370.4 million has been established at December 31, 2021, 2020 and 2019, respectively. The change in the valuation allowance was $147.7 million, ($42.0) million and $136.9 million for the years ended December 31, 2021, 2020 and 2019, respectively. The increase of deferred tax asset between December 31, 2021 and 2020 is primarily driven by increased net operating losses (NOL) and credits generated from R&D activities during the year. The Company has incurred NOL since inception with the exception of year 2020. As of December 31, 2021, the Company had federal and state NOL carryforwards of $872.6 million and $997.1 million, respectively, which begin to expire in 2030, and of which $851.1 million of the Company’s federal NOL is post 2017 NOL that will be carried forward indefinitely. As a result of Lengo acquisition (a stock acquisition for tax purposes) in 2021, the Company has a carryover inside tax basis in Lengo’s assets and liabilities, including its tax attributes. The Company acquired $66.6 million and $67.1 million of the federal and state NOL carryforwards, respectively, from the acquisition of Lengo. All such acquired NOL is post 2017 NOL and will be carried forward indefinitely for federal purposes. As of December 31, 2021, the Company had federal and state research and development tax credit carryforwards of $19.4 million and $17.7 million, respectively, which begin to expire in 2030. The Company acquired $0.3 million and $0.2 million of the federal and state research development tax credit carryforwards, respectively, from the acquisition of Lengo. As of December 31, 2021, the Company had federal orphan drug credits of $150.9 million, which begin to expire in 2035 and state investment tax credits of $0.6 million, which have begun to expire in 2021. As of December 31, 2021, the Company has foreign tax credits of $2.5 million which will expire in 2031. The Company has analyzed and validated its research and development tax credits as well as its orphan drug credits for 2011-2020. The Company generated research credits in 2021 but has not conducted a formal study to document its qualified activities. This study may result in an adjustment to the Company’s research and development credit carryforwards. No amounts are being presented as an uncertain tax position as of December 31, 2021 until such study is completed and the adjustment is known. A valuation allowance has been provided against the Company’s research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carry-forwards and the valuation allowance. The Internal Revenue Code of 1986, as amended (the Code), provides for a limitation of the annual use of NOL and other tax attributes (such as research and development tax credit carryforwards) following certain ownership changes (as defined by the Code) that could limit the Company’s ability to utilize these carryforwards. We may have experienced such ownership changes in the past, and we may experience ownership changes in the future as a result of shifts in our stock ownership, some of which are outside our control. Approximately $2 million of the Company’s NOL carryforwards may not be available for utilization within their applicable carryforward periods based on the Section 382 study in 2020. In addition, U.S. tax laws limit the time during which these carryforwards may be applied against future taxes. Therefore, the Company may not be able to take full advantage of these carryforwards for federal or state income tax purposes. With respect to the net operating losses and research and development tax credit carryforwards acquired from the acquisition of Lengo, the Company has not completed a study to assess whether an ownership change under Section 382 of the Code has occurred, or whether there have been multiple ownership changes since Lengo’s formation. Accordingly, the Company’s ability to utilize the aforementioned carryforwards may be limited and in turn, may not be able to take full advantage of these carryforwards for federal or state income tax purposes. Interest and penalty charges, if any, related to unrecognized tax benefits would be classified as income tax expense in the accompanying statements of operations and comprehensive loss. As of December 31, 2021 and 2020, the Company has no unrecognized tax benefits or accrued interest related to unrecognized tax benefits. As of December 31, 2021, the Company was open to examination in the U.S. federal and certain state jurisdictions for all of the Company’s tax years since the net operating losses may potentially be utilized in future years to reduce taxable income. Since the Company is in a loss carryforward position, it is generally subject to examination by the U.S. federal, state, and local income tax authorities for all tax years in which a loss carryforward is available.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Leases	16. Leases 38 Sidney Street On February 12, 2015, the Company entered into a lease for approximately 39,000 rentable square feet of office and laboratory space at 38 Sidney Street in Cambridge, Massachusetts, which the initial term of the lease agreement will expire on October 31, 2022. On December 15, 2021, the Company extended the lease term to expire on November 30, 2029, and agreed to pay an initial annual base rent of approximately $4.5 million, which rises annually until it reaches approximately $5.5 million. The lease extension provided the Company with an allowance for leasehold improvements of $0.8 million improvements to be made to the premises. Security deposit of $0.9 million was recorded as restricted cash on the Company’s consolidated balance sheet as of December 31, 2021. The Company is subleasing the space to third parties and the term of the subleases will expire on February 28, 2022 and September 30, 2022. 45 Sidney Street On April 28, 2017, the Company entered into a lease agreement for approximately 99,833 rentable square feet of office and laboratory space located at 45 Sidney Street in Cambridge, Massachusetts. On September 19, 2018, the Company entered into an amendment to the lease agreement to expand the rentable square footage to approximately 139,216 square feet. The initial term of the lease agreement will expire on November 30, 2029, unless terminated sooner. The lease agreement also provides the Company with an option to extend the lease agreement for two consecutive five-year periods at the then fair market annual rent, as defined in the lease agreement. The Company has agreed to pay for the 99,833 rentable square feet an initial annual base rent of approximately $7.7 million, which increases annually until it reaches approximately $10.6 million in the last year of the initial term. The Company has also agreed to pay an initial annual base rent of approximately $3.2 million for the expansion premises, which increases annually until it reaches approximately $4.2 million in the last year of the initial term for the expansion premises. The amended lease provided the Company with a total tenant improvement allowance of approximately $17.4 million for improvements to be made to the premises. Security deposit of $3.8 million was recorded as restricted cash on the Company’s consolidated balance sheet as of December 31, 2021. ​ The lease agreements do not contain residual value guarantees and t he components of lease cost for the years ended December 31, 2021, 2020 and 2019 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Operating leases: 2021 ​ 2020 ​ 2019 Lease cost $ 18,299 ​ $ 17,600 ​ $ 16,162 Sublease income ​ (2,174) ​ ​ (2,919) ​ ​ (2,834) Net lease cost $ 16,125 ​ $ 14,681 ​ $ 13,328 ​ The Company has not entered into any material short-term leases or financing leases as of December 31, 2021. Supplemental cash flow information related to leases for the years ended December 31, 2021 and 2020 was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities: $ 14,896 ​ $ 14,444 Lease liabilities arising from obtaining right-of-use assets: ​ ​ ​ ​ ​ Operating leases $ 28,929 ​ $ 479 ​ The weighted average remaining lease term and weighted average discount rate of the operating leases are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases Weighted average remaining lease term in years ​ ​ ​ ​ 7.8 Weighted average discount rate ​ ​ ​ ​ 7.4% ​ Future minimum lease payments under non-cancellable leases as of December 31, 2021 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 ​ ​ 15,825 2023 ​ ​ 17,691 2024 ​ ​ 18,183 2025 ​ ​ 18,557 2026 ​ ​ 19,089 Thereafter ​ ​ 58,912 Total future minimum lease payments ​ ​ 148,257 Less imputed interest ​ ​ (36,849) Total ​ $ 111,408 ​ * Minimum lease payments have not been reduced by minimum net sublease receivables of $2.0 million due in the future under the Company’s non-cancelable subleases for the office and laboratory space located at 38 Sidney Street, Cambridge, Massachusetts.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Employee Benefit Plans	17. Employee Benefit Plans 401(k) Savings Plan The Company maintains a 401(k) plan for employees (the 401(k) Plan). The 401(k) Plan is intended to qualify under Section 401(k) of the Code, so that contributions to the 401(k) Plan by employees or by the Company, and the investment earnings on contributions, are not taxable to the employees until withdrawn from the 401(k) Plan, and so that contributions by the Company, if any, will be deductible by the Company when made. Under the 401(k) Plan, employees may elect to reduce their current compensation by up to the statutorily prescribed annual limit and to have the amount of such reduction contributed to the 401(k) Plan. The 401(k) Plan permits the Company to make contributions up to the limits allowed by law on behalf of all eligible employees. The expense related to the 401(k) Plan primarily consists of the Company’s matching contributions. The expenses related to the 401(k) Plan for the years ended December 31, 2021, 2020 and 2019 were $3.0 million, $1.9 million and $1.2 million, respectively. Switzerland Defined Benefit Plan The Company maintains a pension plan Switzerland

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Commitments and Contingencies	18. Commitments and Contingencies Purchase Commitments Associated with Commercial Supply Agreements In connection with the commercialization of AYVAKIT/AYVAKYT and GAVRETO, the Company has negotiated manufacturing agreements with certain vendors that require the Company to meet minimum purchase obligations on an annual basis. The aggregate amount of future minimum purchase obligations under these manufacturing agreements over the period of next five years is approximately $34.2 million as of December 31, 2021. Legal Proceedings The Company is not currently a party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses the costs related to its legal proceedings as they are incurred. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and senior management that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not not crued any liabilities related to such obligations in its consolidated financial statements as of December 31, 2021 or 2020.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
Disclosure Text Block
Subsequent Events	19. Subsequent Events During the first quarter of 2022, a $30.0 million development milestone was achieved under our license agreement with Clementia.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Policies)	12 Months Ended
	Dec. 31, 2021
Policy Text Blocks
Basis of Presentation	Basis of Presentation The audited consolidated The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Blueprint Medicines Security Corporation, which is a Massachusetts subsidiary created to buy, sell and hold securities, Blueprint Medicines (Switzerland) GmbH, Blueprint Medicines (Netherlands) B.V., Blueprint Medicines (UK) Ltd, Blueprint Medicines (Germany) GmbH, Blueprint Medicines (Spain) S.L., Blueprint Medicines (France) SAS, Blueprint Medicines (Italy) S.r.L., and Lengo Therapeutics Inc (Lengo), which was acquired on December 30, 2021. All intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and in developing the estimates and assumptions that are used in the preparation of the financial statements. Management must apply significant judgment in this process. Management’s estimation process often may yield a range of potentially reasonable estimates and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: revenue recognition, acquisitions, inventory, operating lease right-of-use assets, operating lease liabilities, stock-based compensation expense, accrued expenses, and income taxes. The length of time and full extent to which the ongoing COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including revenues, expenses, reserves and allowances, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, subject to change and difficult to predict, including as a result of new information that may emerge concerning COVID-19, including the identification and spread of new variants, and the actions taken to contain or treat COVID-19, as well as the economic impact thereof on local, regional, national and international customers and markets. The Company considers the impact of COVID-19 while making the estimates within its consolidated financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates.
Revenue Recognition	Revenue Recognition The Company accounts for contracts with customers in accordance with ASC Topic 606, Revenue from Contracts with Customers Product revenue AYVAKIT and GAVRETO its products Product revenue is recognized when the customer takes control of the product, typically upon delivery to the customer. Product revenue is recorded at the net sales price, or transaction price, which includes estimated reserves for variable consideration resulting from chargebacks, government rebates, trade discounts and allowances, product returns and other incentives that are offered within the contract with customers, healthcare providers, payors and other indirect customers relating to the sales of the Company’s product. Reserves are established based on the amounts earned or to be claimed on the related sales. Where appropriate, the Company utilizes the expected value method to determine the appropriate amount for estimates of variable consideration based on factors such as the Company’s current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns, the percentage of our products that are sold via these programs, and our product pricing ​ Chargebacks: expected value method based upon a range of possible outcomes and are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue. Government rebates: Trade discounts and allowances: Product returns: ​ Other deductions: ​ Collaboration revenue At contract inception, the Company analyzes its collaboration arrangements to assess whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities and therefore within the scope of ASC Topic 808, Collaborative Arrangements For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, either by analogy to authoritative accounting literature or by applying a reasonable and rational policy election. The Company evaluates the income statement classification for presentation of amounts due from or owed to other participants associated with multiple activities in a collaboration arrangement based on the nature of each separate activity. For the co-commercialization and marketing activities of certain of the Company’s products and product candidates in a collaboration arrangement, where the Company is the principal on sales transactions with third parties, the Company recognizes revenues, cost of sales and operating expenses on a gross basis in their respective lines in its consolidated statements of operations and comprehensive income (loss). Where the Company is not the principal on sales transactions with third parties, the Company records its share of the revenues, cost of sales and operating expenses on a net basis as revenue (expenses) from the collaboration arrangement in its consolidated statements of operations and comprehensive income (loss). For elements accounted within scope of ASC 606, to determine the appropriate amount of revenue to be recognized for the arrangements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above; and (c) the stand-alone selling price for each performance obligation identified in the contract for the allocation of transaction price in step (iv) above. The Company uses judgment to determine whether milestones or other variable consideration, except for royalties and sales-based milestones, should be included in the transaction price as described further below. The transaction price is allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. Exclusive Licenses. Research and Development Services. Customer Options. Milestone Payments. Royalties. or all of the royalty has been allocated has been satisfied or partially satisfied. To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. Consideration received prior to revenue recognition is recorded as deferred revenue in the consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. If the Company transfer goods or services to a customer before the customer pays consideration or before payment is due, the Company records a contract asset as unbilled accounts receivable on the consolidated balance sheets. For a complete discussion of accounting for collaboration revenues, see Note 11, Collaboration and License Agreements
Accounts Receivable, net	Accounts Receivable, net Accounts receivable arise from product sales and amounts due from the Company’s collaboration partners. The amount from product sales represents amounts due from specialty distributors and specialty pharmacy providers in the U.S. and in the European Union. The Company monitors economic conditions and the financial performance and credit worthiness of its counterparties to identify facts or circumstances that may indicate that its receivables are at risk of collection. The Company provides reserves against accounts receivable for estimated losses that may result from a customer’s inability to pay based on the composition of its accounts receivable, considering past events, current economic conditions, and reasonable and supportable forecasts about the future economic conditions. The contractual life of our accounts receivable is generally short-term. Amounts determined to be uncollectible are charged or written-off against the reserve. For the years ended December 31, 2021 and 2020, the Company did not record any expected credit losses related to outstanding accounts receivable.
Inventory	Inventory Inventories are stated at the lower of cost or estimated net realizable value with cost based on the first-in first-out method. Inventory that can be used in either the production of clinical or commercial products is expensed as research and development costs when identified for use in clinical trials. The Company classifies its inventory costs as long-term when it expects to utilize the inventory beyond its normal operating cycle and includes these costs in other assets in the consolidated balance sheets. Prior to the regulatory approval of its drug candidates, the Company incurs expenses for the manufacture of drug product supplies to support clinical development that could potentially be available to support the commercial launch of those drugs. Until the date at which regulatory approval has been received or is otherwise considered probable, the Company records all such costs as research and development expenses.
Fair Value Measurements	Fair Value Measurements The Company has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. ● Level 1 — Fair values are determined utilizing quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access; ● Level 2 — Fair values are determined by utilizing quoted prices for identical or similar assets and liabilities in active markets or other market observable inputs such as interest rates, yield curves and foreign currency spot rates; and ● Level 3 — inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s financial assets, which include cash equivalents and marketable securities, have been initially valued at the transaction price, and subsequently revalued at the end of each reporting period, utilizing third-party pricing services. The pricing services utilize industry standard valuation models, including both income and market based approaches, to determine value. There have been no changes to the valuation methods during the years ended December 31, 2021 and 2020.
Cash and cash equivalents	Cash and cash equivalents The Company considers all highly liquid investments purchased with original maturities of 90 days or less from the date of purchase to be cash equivalents. As of December 31, 2021 and 2020, the Company’s cash equivalents comprised of money market funds with less than 90 days from the date of purchase. Cash equivalents are reported at fair value.
Available-for-sale Investments	Available-for-Sale Investments The Company classifies marketable debt securities with a remaining maturity when purchased of greater than three months available-for-sale, and marketable debt securities with a remaining maturity date greater than one year as non-current assets. Available-for-sale marketable debt securities are maintained by an investment manager and mainly consist of U.S. treasury securities and U.S. government agency securities. Available-for-sale marketable debt securities are carried at fair value with the unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders’ equity until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income and/or expense over the life of the instrument. Realized gains and losses are determined using the specific identification method and are included in other income (expense). The Company reviews its portfolio of available-for-sale debt securities, using both quantitative and qualitative factors, to determine if declines in fair value below cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, a loss is recognized in net income, whereas if the decline in fair value is not due to credit-related factors, the loss is recorded in other comprehensive income (loss).
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Other comprehensive income (loss) consisted of foreign currency translation adjustments, unrealized gains and losses on available-for-sale investments and unrealized gains and losses on pension benefit obligations.
Research and Development Expenses	Research and Development Expenses Expenditures relating to research and development are expensed in the period incurred. Research and development expenses consist of both internal and external costs associated with the development of the Company’s selective cancer therapies and building of its discovery platform. As part of the process of preparing the consolidated financial statements, the Company accrues costs for clinical trial activities based upon estimates of the services received and related expenses incurred that have yet to be invoiced by the contract research organizations or other clinical trial vendors that perform the activities. ​ In certain circumstances, the Company is required to make nonrefundable advance payments to vendors for goods or services that will be received in the future for use in research and development activities. In such circumstances, the nonrefundable advance payments are deferred and capitalized, even when there is no alternative future use for the research and development, until related goods or services are provided. In circumstances where amounts have been paid in excess of costs incurred, the Company records a prepaid expense.
Selling, General and Administrative Expenses	Selling, General and Administrative Expenses
Property and Equipment, Net	Property and Equipment, Net
Impairment of Long Lived Assets	Impairment of Long-Lived Assets not impairment charges
Leases	Leases Leases are accounted for in accordance with ASC Topic 842, Leases Leases are classified as either finance leases or operating leases. A lease is classified as a finance lease if any one of the following criteria are met: the lease transfers ownership of the asset by the end of the lease term, the lease contains an option to purchase the asset that is reasonably certain to be exercised, the lease term is for a major part of the remaining useful life of the asset or the present value of the lease payments equals or exceeds substantially all of the fair value of the asset. A lease is classified as an operating lease if it does not meet any of these criteria. For all leases at the lease commencement date, a right-of-use asset and a lease liability are recognized. The right-of-use asset represents the right to use the leased asset for the lease term. The lease liability represents the present value of the lease payments under the lease. The right-of-use asset is initially measured at cost, which primarily comprises the initial amount of the lease liability, plus any initial direct costs incurred if any, less any lease incentives received. All right-of-use assets are reviewed for impairment. The lease liability is initially measured at the present value of the lease payments, discounted using the interest rate implicit in the lease or, if that rate cannot be readily determined, the secured incremental borrowing rate for the same term as the underlying lease. Lease payments included in the measurement of the lease liability comprise the following: the fixed noncancelable lease payments, payments for optional renewal periods where it is reasonably certain the renewal period will be exercised, and payments for early termination options unless it is reasonably certain the lease will not be terminated early. Lease cost for operating leases consists of the lease payments plus any initial direct costs, primarily brokerage commissions, and is recognized on a straight-line basis over the lease term. Included in lease cost are any variable lease payments incurred in the period that are not included in the initial lease liability and lease payments incurred in the period for any leases with an initial term of 12 months or less. Lease cost for finance leases consists of the amortization of the right-of-use asset on a straight-line basis over the lease term and interest expense determined on an amortized cost basis. The lease payments are allocated between a reduction of the lease liability and interest expense. The Company has made an accounting policy election to not recognize leases with an initial term of 12 months or less within our consolidated balance sheets and to recognize those lease payments on a straight-line basis in our consolidated statements of income over the lease term.
Stock-Based Compensation Expense	Stock-Based Compensation Expense Stock-based compensation awards are accounted for in accordance with ASC Topic 718, Compensation –Stock Compensation ● expected volatility, which is calculated based on a blend of the Company’s reported volatility data for the length of time that market data is available for the Company’s stock and the historical data for a representative group of publicly traded companies, for which historical information is available. For these analyses, the Company selects companies with comparable characteristics to itself including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. Until a sufficient amount of historical information regarding volatility of the Company’s own share price became available, the Company computed the historical volatility data using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of its stock-based awards ; ● risk-free interest rate, which is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected term assumption; ● expected term, which is calculated using the simplified method, as prescribed by the Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment, as the Company has insufficient historical information regarding its stock options to provide a basis for an estimate. U nder this approach, the weighted-average expected life is presumed to be the average of the contractual term of ten years and the weighted-average vesting term of the stock options, taking into consideration multiple vesting tranches; and ● dividend yield, which is zero based on the fact that the Company never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. common stock purchase
Acquisition	Acquisition Business Combinations “business”, requires considerations in the form of two steps: (1) determination of whether “substantially all” of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets (i.e., “screen test”); if not, then (2) evaluate whether the set of transferred assets and activities meets the definition of a business which includes, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. If the assets acquired are not a business, the Company accounts for the transaction as an asset acquisition. If the transaction is a business combination, it is accounted for by applying the acquisition method. In asset acquisitions, the Company allocates the cost of a group of assets acquired to the individual assets acquired or liabilities assumed based on their relative fair values. Goodwill is not recognized in an asset acquisition. Any difference between the cost of an asset acquisition and the fair value of the net assets acquired is allocated to the non-monetary identifiable assets based on their relative fair values. Research and Development
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions using a more-likely-than-not threshold for recognizing and resolving uncertain tax positions. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in the law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity, and changes in facts or circumstances related to a tax position.
Foreign currency translation	Foreign currency translation The financial statements of each of the Company’s subsidiaries with a functional currency other than the U.S. dollar are translated into U.S. dollars using period-end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates for operating results. Translation gains and losses are included in accumulated other comprehensive income (loss) in stockholders’ equity. Foreign currency transaction gains and losses are included in other (expense) income, net in the results of operations.
Concentrations of Credit Risk and Off-Balance-Sheet Risk	Concentrations of Credit Risk and Off-Balance-Sheet Risk The Company has no significant off-balance-sheet risk such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk primarily consist of cash and cash equivalents, investments, accounts receivable and unbilled account receivables. The Company maintains its cash, cash equivalents and marketable securities in custodian accounts at high quality financial institutions, and as of December 31, 2021 and 2020, substantially all the Company’s cash, cash equivalents and marketable securities were invested in money market funds and U.S. government agency securities and treasury obligations, and consequently, the Company believes that such funds are subject to minimal credit risk. The Company has adopted an investment policy that limits the amounts the Company may invest in any one type of investment. The Company has not experienced any credit losses and does not believe it is exposed to any significant credit risk on these funds. Accounts receivables and unbilled accounts receivables represent amounts arising from product sales and amounts due from the Company’s collaboration partners. The Company monitors economic conditions to identify facts or circumstances that may indicate that its receivables are at risk of collection.
Segment and Geographic Information	Segment and Geographic Information
New Accounting Pronouncements	New Accounting Pronouncements Government assistance Government Assistance (Topic 832) – Disclosures by Business Entities about Government Assistance

Acquisition (Tables)

Acquisition (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Summary of the net purchase price and the allocation of the consideration	​ ​ ​ ​ ​ Purchase price, net of cash acquired ​ $ 258,377 Identifiable assets and liabilities acquired: ​ ​ ​ Net current liabilities ​ ​ (1,580) In-process research and development ​ ​ 259,957 Total identifiable net assets acquired ​ $ 258,377 ​

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Schedule of marketable securities	Marketable securities consisted of the following at December 31, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair December 31, 2021 Cost Gain ​ Losses ​ Value Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ $ 498,582 ​ $ 21 ​ $ (1,460) ​ $ 497,143 U.S. treasury obligations ​ ​ 328,801 ​ ​ — ​ ​ (1,249) ​ ​ 327,552 Total ​ $ 827,383 ​ $ 21 ​ $ (2,709) ​ $ 824,695 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair December 31, 2020 Cost Gain ​ Losses ​ Value Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ $ 746,770 ​ $ 513 ​ $ (14) ​ $ 747,269 U.S. treasury obligations ​ ​ 117,368 ​ ​ 449 ​ ​ — ​ ​ 117,817 Total ​ $ 864,138 ​ $ 962 ​ $ (14) ​ $ 865,086

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Schedule of financial instruments measured at fair value	The following table summarizes the Company’s cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active Observable Unobservable ​ ​ December 31, ​ Markets ​ Inputs ​ Inputs Description ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 118,880 ​ $ 118,880 ​ $ — ​ $ — Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ ​ 497,143 ​ ​ — ​ ​ 497,143 ​ ​ — U.S. treasury obligations ​ ​ 327,552 ​ ​ 327,552 ​ ​ — ​ ​ — Total ​ $ 943,575 ​ $ 446,432 ​ $ 497,143 ​ $ — ​ The following table summarizes the Company’s cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Active Observable Unobservable ​ ​ December 31, ​ Markets ​ Inputs ​ Inputs Description ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 420,567 ​ $ 420,567 ​ $ — ​ $ — Marketable securities, available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government agency securities ​ ​ 747,269 ​ ​ — ​ ​ 747,269 ​ ​ — U.S. treasury obligations ​ ​ 117,817 ​ ​ 117,817 ​ ​ — ​ ​ — Total ​ $ 1,285,653 ​ $ 538,384 ​ $ 747,269 ​ $ —

Product Revenue Reserves and _2

Product Revenue Reserves and Allowances (Tables) - Product revenue, net	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Summary of revenue recognized	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 AYVAKIT/AYVAKYT ​ $ 52,981 ​ $ 21,262 ​ $ — GAVRETO ​ ​ 4,706 ​ ​ 872 ​ ​ — Total product revenue ​ $ 57,687 ​ $ 22,134 ​ $ — ​
Schedule of product revenue allowance and reserve categories	​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 Beginning balance at January 1 $ 1,192 ​ $ — Provision related to sales in the current period ​ 8,624 ​ ​ 2,515 Adjustment related to prior periods sales (396) ​ — Credits and payments made (5,075) ​ (1,323) Ending balance at December 31 $ 4,345 ​ $ 1,192 ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2021 2020 Reduction of accounts receivable, net $ 419 ​ $ 226 Component of accrued expenses 3,926 ​ 966 Total revenue-related reserves $ 4,345 ​ $ 1,192 ​

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Schedule of capitalized inventory	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2021 2020 Raw materials ​ $ 10,788 ​ $ — Work in process ​ ​ 17,702 ​ ​ 9,488 Finished goods ​ 3,916 ​ 914 Total ​ $ 32,406 ​ $ 10,402 ​ Balance sheet classification ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2021 2020 Inventory ​ $ 21,817 ​ $ 8,581 Other assets ​ 10,589 ​ 1,821 Total ​ $ 32,406 ​ $ 10,402 ​

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Schedule of property and equipment	Property and equipment and related accumulated depreciation are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Estimated ​ ​ ​ ​ ​ ​ ​ ​ Useful Life ​ As of December 31, ​ ​ (Years) ​ 2021 ​ 2020 Lab equipment 5 $ 13,120 $ 11,418 ​ Furniture and fixtures 4 ​ 3,714 ​ 3,420 ​ Computer equipment 3 ​ 1,714 ​ 1,513 ​ Leasehold improvements Term of lease ​ 36,945 ​ 36,946 ​ Software 3 ​ 412 ​ 412 ​ Construction-in-progress ​ ​ ​ ​ 213 ​ ​ 151 ​ Total cost ​ ​ ​ 56,118 ​ 53,860 ​ Less: accumulated depreciation and amortization ​ ​ ​ (25,418) ​ (19,731) ​ Total ​ ​ ​ $ 30,700 ​ $ 34,129 ​

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Schedule of accrued expenses	Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2021 2020 External research and development ​ $ 68,164 ​ $ 60,255 Employee compensation ​ ​ 29,166 ​ ​ 27,622 Accrued professional fees ​ 12,611 ​ 10,986 Revenue-related reserves ​ 3,926 ​ 966 Other ​ ​ 7,962 ​ ​ 6,109 Total ​ $ 121,829 ​ $ 105,938

Collaboration and License Agr_2

Collaboration and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Summary of manufacturing and research and development services related to the global development activities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 Manufacturing and research and development services related to global development activities, net of expenses payable to CStone ​ $ 2,358 ​ $ 3,060 ​ $ 3,286
Schedule of collaboration loss sharing	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 The Company's share of loss in the U.S. for pralsetinib ​ $ 7,801 $ — $ — ​
Schedule of amounts recognized as reductions to expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 Reductions to selling, general and administrative expenses ​ $ 18,753 $ 10,631 ​ $ — Reductions to research and development expenses ​ ​ 11,192 ​ ​ 20,459 ​ ​ — ​
Roche, Collaboration (Pralsetnib) Agreement
Table Text Blocks
Summary of revenue recognized	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 Upfront license revenue ​ $ — $ 695,694 ​ $ — License milestone revenue ​ ​ 50,000 ​ ​ 55,000 ​ ​ — Manufacturing and other services related to Roche territory-specific activities ​ ​ 6,022 ​ ​ 2,406 ​ ​ — Total Roche pralsetinib collaboration revenue ​ $ 56,022 ​ $ 753,100 ​ $ — ​
Summary of contract assets and/or contract liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ ​ 2021 ​ 2020 Accounts receivable, net ​ $ 2,679 $ — Unbilled accounts receivable ​ $ 6,802 $ 17,600 ​
Roche, Collaboration and License (Immunotherapy) Agreement
Table Text Blocks
Summary of revenue recognized	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 ​ 2020 2019 Roche collaboration research and development services revenue ​ $ 7,636 ​ $ 14,580 ​ $ 8,165
Roche, Collaboration and License (Immunotherapy) Agreement | Collaboration revenue
Table Text Blocks
Summary of contract assets and/or contract liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 ​ 2020 2019 Amounts included in the contract liability at the beginning of the period ​ $ 5,080 $ 11,546 ​ $ 4,578
C Stone
Table Text Blocks
Summary of revenue recognized	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 ​ 2019 License milestone revenue ​ $ 9,000 ​ $ 2,000 ​ $ 12,000 Manufacturing services and royalty revenue related to CStone territory-specific activities ​ ​ 24,395 ​ ​ 1,630 ​ ​ 144 Total CStone collaboration revenue ​ $ 33,395 ​ $ 3,630 ​ $ 12,144
C Stone | Collaboration revenue
Table Text Blocks
Summary of contract assets and/or contract liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2021 ​ 2020 Accounts receivable, net ​ $ 8,164 $ 563 Unbilled accounts receivable ​ $ 5,034 $ —

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Assumptions used in estimating fair value of stock options on grant date	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2021 ​ 2020 ​ 2019 ​ Risk-free interest rate ​ 0.96 % 1.02 % 2.21 % Expected dividend yield ​ — % — % — % Expected term (years) ​ 6.0 ​ 6.0 ​ 6.0 ​ Expected stock price volatility ​ 58.03 % 60.48 % 63.83 %
Summary of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- Remaining Aggregate ​ ​ ​ ​ Average ​ Contractual ​ Intrinsic ​ ​ ​ ​ Exercise ​ Life ​ Value(1) ​ ​ Shares ​ Price ​ (in Years) ​ (in thousands) Outstanding at December 31, 2020 6,030,641 ​ $ 61.28 7.41 ​ $ 306,810 ​ Granted 1,125,514 ​ ​ 98.50 ​ ​ ​ ​ ​ ​ Exercised (982,791) ​ 48.13 ​ ​ ​ ​ ​ ​ Canceled (491,342) ​ 79.27 ​ ​ ​ ​ ​ ​ Outstanding at December 31, 2021 5,682,022 ​ $ 69.37 6.99 ​ $ 214,675 ​ Exercisable at December 31, 2021 3,499,094 ​ $ 61.30 6.13 ​ $ 160,313 ​ (1) Intrinsic value represents the amount by which the fair market value as of December 31, 2021 of the underlying common stock exceeds the exercise price of the option. ​
Summary of restricted stock units activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ ​ Grant Date ​ Shares Fair Value Unvested shares at December 31, 2020 1,171,686 ​ $ 65.37 ​ Granted 999,504 ​ 98.62 ​ Vested (321,645) ​ 66.87 ​ Forfeited (259,385) ​ 78.31 ​ Unvested shares at December 31, 2021 1,590,160 ​ $ 83.85 ​
Summary of stock-based compensation expense, allocation by type of awards and recognition in statements of operations	Stock-based compensation expense by award type included within the consolidated statements of operations and comprehensive income (loss) is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 ​ ​ 2019 Stock options $ 57,912 ​ $ 57,237 ​ $ 47,726 Restricted stock units ​ 33,939 ​ ​ 18,407 ​ ​ 6,445 Employee stock purchase plan ​ 1,184 ​ ​ 958 ​ ​ 482 Subtotal ​ 93,035 ​ ​ 76,602 ​ ​ 54,653 Capitalized stock-based compensation costs ​ (1,405) ​ ​ (1,076) ​ ​ — Stock-based compensation expense included in total cost and operating expenses $ 91,630 ​ $ 75,526 ​ $ 54,653 The following table presents stock-based compensation expense that is included in operating expenses by classification within the consolidated statements of operations and comprehensive income (loss) is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 2020 ​ 2019 Research and development $ 39,670 $ 33,642 $ 28,596 ​ Selling, general and administrative 51,960 ​ 41,884 ​ 26,057 ​ Total stock-based compensation expense included in operating expenses $ 91,630 ​ $ 75,526 ​ $ 54,653 ​ ​

Net Income Per Share (Tables)

Net Income Per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Schedule of net income (loss) and the number of shares used to compute basic and diluted net income (loss) per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 ​ 2020 2019 Net income (loss) - basic and diluted ​ $ (644,085) ​ $ 313,882 $ (347,694) Weighted average shares outstanding - basic ​ ​ 58,518 ​ ​ 54,534 ​ ​ 47,829 Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Stock options ​ ​ — ​ ​ 1,303 ​ ​ — Restricted stock units ​ ​ — ​ ​ 331 ​ ​ — Weighted average shares outstanding - diluted ​ ​ 58,518 ​ ​ 56,168 ​ ​ 47,829 Net income (loss) per share - basic ​ $ (11.01) ​ $ 5.76 ​ $ (7.27) Net income (loss) per share - diluted ​ ​ (11.01) ​ ​ 5.59 ​ ​ (7.27)
Schedule of common stock equivalents excluded from calculation of diluted net loss per share applicable to common stockholders	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 2020 ​ 2019 Stock options 5,682 4,480 5,796 ​ Restricted stock units 1,590 13 420 ​ ESPP shares ​ 24 ​ 19 ​ 14 ​ Total 7,296 4,512 ​ 6,230 ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Schedule of the reconciliation of the effective tax rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2021 2020 ​ 2019 Federal income tax (benefit) at statutory rate ​ 21.00 % 21.00 % 21.00 % Permanent differences 0.07 ​ (0.47) ​ 1.11 ​ In-process research and development ​ (8.53) ​ — ​ — ​ Federal research and development credits 0.76 ​ (0.96) ​ 0.77 ​ Federal orphan drug credits ​ 4.02 ​ (10.35) ​ 6.90 ​ State income tax, net of federal benefit 1.26 ​ 0.08 ​ 7.46 ​ Other (0.05) ​ 1.50 ​ 2.13 ​ Foreign rate differential ​ (0.10) ​ 0.37 ​ (0.03) ​ Deferred rate change ​ 0.79 ​ 2.60 ​ (0.08) ​ Foreign tax credit ​ 0.39 ​ — ​ — ​ Change in valuation allowance (20.08) ​ (13.42) ​ (39.26) ​ Effective income tax rate (0.47) % 0.35 % — %
Schedule of the deferred tax assets and liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 ​ 2019 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ ​ Net operating loss carryforwards $ 243,670 ​ $ 140,769 ​ $ 219,935 Research and development credit carryforwards 36,345 ​ 23,679 ​ 19,240 Orphan drug credit carryforwards ​ 150,859 ​ ​ 125,153 ​ ​ 92,538 Accrued expenses and other 40,617 ​ 32,206 ​ 25,842 Deferred revenue ​ 6,598 ​ ​ 7,317 ​ ​ 10,971 Deferred lease incentive ​ — ​ ​ — ​ ​ — Deferred rent ​ 24,798 ​ 19,308 ​ 26,196 Jublient license ​ 448 ​ ​ — ​ ​ — Interest expense 29 ​ — ​ — Total gross deferred tax asset 503,364 ​ 348,432 ​ 394,722 Deferred tax liability ​ ​ ​ ​ ​ ​ ​ Depreciation ​ (5,157) ​ (5,451) ​ (4,474) Right of use assets ​ (20,059) ​ ​ (14,539) ​ ​ (19,869) UNICAP (1,966) ​ — ​ — Prepaid expenses ​ (2) ​ ​ — ​ ​ — Valuation allowance (476,180) ​ (328,442) ​ (370,379) Net deferred tax asset $ — ​ $ — ​ $ — ​

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Table Text Blocks
Summary of lease expenses and cash flow and weighted average information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Operating leases: 2021 ​ 2020 ​ 2019 Lease cost $ 18,299 ​ $ 17,600 ​ $ 16,162 Sublease income ​ (2,174) ​ ​ (2,919) ​ ​ (2,834) Net lease cost $ 16,125 ​ $ 14,681 ​ $ 13,328 ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities: $ 14,896 ​ $ 14,444 Lease liabilities arising from obtaining right-of-use assets: ​ ​ ​ ​ ​ Operating leases $ 28,929 ​ $ 479 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases Weighted average remaining lease term in years ​ ​ ​ ​ 7.8 Weighted average discount rate ​ ​ ​ ​ 7.4%
Schedule of future minimum lease payments	​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 ​ ​ 15,825 2023 ​ ​ 17,691 2024 ​ ​ 18,183 2025 ​ ​ 18,557 2026 ​ ​ 19,089 Thereafter ​ ​ 58,912 Total future minimum lease payments ​ ​ 148,257 Less imputed interest ​ ​ (36,849) Total ​ $ 111,408

Nature of Business (Details)

Nature of Business (Details) $ in Millions	Dec. 31, 2021USD ($)
Cash, cash equivalents and marketable securities
Cash, cash equivalents and marketable securities	$ 1,034.6

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Selling, General and Administrative Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Selling, General and Administrative Expenses
Advertising costs	$ 13.5	$ 9.4	$ 3.3

Summary of Significant Accoun_4

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Impairment of Long-Lived Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Impairment of Long Lived Assets
Long-lived asset impairment	$ 0	$ 0	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Stock-Based Compensation Expense (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock Options
Stock-based compensation
Expected dividend yield	0.00%	0.00%	0.00%
Award expiration period	10 years	10 years	10 years
Employee Stock
Stock-based compensation
Purchase price on common stock (as a percent)	85.00%	85.00%	85.00%
Discount on fair value, offering date (as a percent)	15.00%	15.00%	15.00%
Discount on fair value, purchase date (as a percent)	15.00%	15.00%	15.00%
Award expiration period	180 days	180 days	180 days

Summary of Significant Accoun_6

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Segment and Geographic Information (Details) - segment	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment and Geographic Information
Number of operating segments	1	1	1

Summary of Significant Accoun_7

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - New Accounting Pronouncements (Details) - Accounting Standards Update 2021-10 - Subsequent Event	Feb. 16, 2022
Summary of Significant Accounting Policies and Recent Accounting Pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2022
Change in Accounting Principle, Accounting Standards Update, Early Adoption	false

Acquisition - General Informati

Acquisition - General Information (Details) - Lengo Therapeutics Inc.	Dec. 30, 2021	Nov. 27, 2021
Acquisition
Asset Acquisition, Date of Acquisition Agreement		Nov. 27, 2021
Asset Acquisition, Effective Date of Acquisition	Dec. 30, 2021

Acquisition - Consideration Tra

Acquisition - Consideration Transferred (Details) - Lengo Therapeutics Inc. $ in Thousands	Dec. 30, 2021USD ($)
Acquisition
Upfront payment	$ 250,000
Future contingent cash milestone payments	215,000
Total net purchase price	258,377
Adjustments associated with net indebtedness, transaction expenses, and other adjustments	$ 8,400

Acquisition - Acquired Intellec

Acquisition - Acquired Intellectual Property (Details) - USD ($) $ in Thousands	Dec. 30, 2021	Dec. 31, 2021
Acquisition
Acquired in-process research and development		$ 259,957
Lengo Therapeutics Inc.
Acquisition
Acquired in-process research and development	$ 260,000

Acquisition - Purchase Price (D

Acquisition - Purchase Price (Details) $ in Thousands	Dec. 30, 2021USD ($)
Lengo Therapeutics Inc.
Acquisition
Purchase price, net of cash acquired	$ 258,377

Acquisition - Identifiable Net

Acquisition - Identifiable Net Assets Acquired (Details) - Lengo Therapeutics Inc. $ in Thousands	Dec. 30, 2021USD ($)
Acquisition
Net current liabilities	$ (1,580)
In-process research and development	259,957
Total identifiable net assets acquired	$ 258,377

Marketable Securities - Tabular

Marketable Securities - Tabular Disclosure (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Marketable securities, available-for-sale:
Amortized cost	$ 827,383	$ 864,138
Unrealized gain	21	962
Unrealized losses	(2,709)	(14)
Fair value	824,695	865,086
U.S. government agency securities
Marketable securities, available-for-sale:
Amortized cost	498,582	746,770
Unrealized gain	21	513
Unrealized losses	(1,460)	(14)
Fair value	497,143	747,269
U.S. Treasury obligations
Marketable securities, available-for-sale:
Amortized cost	328,801	117,368
Unrealized gain		449
Unrealized losses	(1,249)
Fair value	$ 327,552	$ 117,817

Marketable Securities - Unreali

Marketable Securities - Unrealized Loss Position (Details) $ in Millions	Dec. 31, 2021USD ($)security	Dec. 31, 2020USD ($)security
Unrealized loss position, number of positions
Number of held securities in an unrealized loss position for less than 12 months	74	8
Number of held securities in an unrealized loss position for 12 months or longer	0	0
Unrealized loss position, aggregate fair value
Unrealized loss position for less than 12 months | $	$ 750.5	$ 125.7

Marketable Securities - Other-t

Marketable Securities - Other-than-temporary Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Other-than-temporary impairment loss, debt securities, available-for-sale securities
Other-than-temporary impairment loss, debt securities, available-for-sale	$ 0	$ 0

Marketable Securities - Remaini

Marketable Securities - Remaining Maturities (Details) $ in Millions	Dec. 31, 2021USD ($)security	Dec. 31, 2020USD ($)security
Investments, available-for-sale
Securities with remaining maturities greater than one year | security	56	65
Aggregate fair value with remaining maturities greater than one year | $	$ 557.5	$ 677.9

Marketable Securities - Proceed

Marketable Securities - Proceeds from Maturities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Proceeds from the maturities of debt securities
Proceeds from the maturities of debt securities	$ 690,830	$ 538,347	$ 735,934

Marketable Securities - Realize

Marketable Securities - Realized Gains (Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Realized gains (losses) from maturities of debt securities
Realized gains (losses) from maturities of debt securities	$ 0	$ 0

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value of Financial Instruments
Marketable securities, available-for-sale	$ 824,695	$ 865,086
U.S. government agency securities
Fair Value of Financial Instruments
Marketable securities, available-for-sale	497,143	747,269
U.S. Treasury obligations
Fair Value of Financial Instruments
Marketable securities, available-for-sale	327,552	117,817
Recurring
Fair Value of Financial Instruments
Total	943,575	1,285,653
Recurring | U.S. government agency securities
Fair Value of Financial Instruments
Marketable securities, available-for-sale	497,143	747,269
Recurring | U.S. Treasury obligations
Fair Value of Financial Instruments
Marketable securities, available-for-sale	327,552	117,817
Recurring | Money market funds
Fair Value of Financial Instruments
Cash equivalents	118,880	420,567
Recurring | Active Markets (Level 1)
Fair Value of Financial Instruments
Total	446,432	538,384
Recurring | Active Markets (Level 1) | U.S. Treasury obligations
Fair Value of Financial Instruments
Marketable securities, available-for-sale	327,552	117,817
Recurring | Active Markets (Level 1) | Money market funds
Fair Value of Financial Instruments
Cash equivalents	118,880	420,567
Recurring | Observable Inputs (Level 2)
Fair Value of Financial Instruments
Total	497,143	747,269
Recurring | Observable Inputs (Level 2) | U.S. government agency securities
Fair Value of Financial Instruments
Marketable securities, available-for-sale	$ 497,143	$ 747,269

Product Revenue Reserves and _3

Product Revenue Reserves and Allowances - Product Revenue (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Revenue		$ 180,080	$ 793,735	$ 66,512
Product revenue, net
Revenues
Revenue		57,687	22,134
AYVAKIT and AYVAKYT
Revenues
Revenue		52,981	21,262
GAVRETO
Revenues
Revenue	$ 0	$ 4,706	$ 872

Product Revenue Reserves and _4

Product Revenue Reserves and Allowances - Product Revenue Allowance and Reserve (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Product revenue allowance and reserve
Beginning balance	$ 1,192	$ 0
Provision related to sales in the current period	8,624	2,515
Adjustment related to prior periods sales	(396)
Credits and payments made	(5,075)	(1,323)
Ending balance	$ 4,345	$ 1,192

Product Revenue Reserves and _5

Product Revenue Reserves and Allowances - Revenue-related Reserves (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue-related reserves
Revenue-related reserves	$ 4,345	$ 1,192	$ 0
Accounts Receivable, Net
Revenue-related reserves
Revenue-related reserves	419	226
Accrued Expenses
Revenue-related reserves
Revenue-related reserves	$ 3,926	$ 966

Inventory - Capitalized (Detail

Inventory - Capitalized (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Inventory, Noncurrent [Abstract]
Raw materials	$ 10,788
Work in process	17,702	$ 9,488
Finished goods	3,916	914
Total	$ 32,406	$ 10,402

Inventory - Balance Sheet Class

Inventory - Balance Sheet Classification (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Inventory
Inventory	$ 21,817	$ 8,581
Other assets	10,589	1,821
Total	$ 32,406	$ 10,402

Inventory - Write-down (Details

Inventory - Write-down (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Inventory
Inventory write-down	$ 600	$ 0

Restricted Cash (Details)

Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Restricted cash
Restricted cash	$ 5.2	$ 5.2

Property and Equipment, Net - E

Property and Equipment, Net - Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2021
Lab equipment
Property and Equipment, Net
Estimated Useful Life (Years)	5 years
Furniture and fixtures
Property and Equipment, Net
Estimated Useful Life (Years)	4 years
Computer equipment
Property and Equipment, Net
Estimated Useful Life (Years)	3 years
Leasehold improvements
Property and Equipment, Net
Estimated Useful Life	Term of lease
Software
Property and Equipment, Net
Estimated Useful Life (Years)	3 years

Property and Equipment, Net - P

Property and Equipment, Net - Property and Equipment and Related Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property and Equipment, Net
Total cost	$ 56,118	$ 53,860
Less: accumulated depreciation and amortization	(25,418)	(19,731)
Total	30,700	34,129
Lab equipment
Property and Equipment, Net
Total cost	13,120	11,418
Furniture and fixtures
Property and Equipment, Net
Total cost	3,714	3,420
Computer equipment
Property and Equipment, Net
Total cost	1,714	1,513
Leasehold improvements
Property and Equipment, Net
Total cost	36,945	36,946
Software
Property and Equipment, Net
Total cost	412	412
Construction-in-progress
Property and Equipment, Net
Total cost	$ 213	$ 151

Property and Equipment, Net - D

Property and Equipment, Net - Depreciation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Depreciation expense
Depreciation expense	$ 6.5	$ 6.6	$ 5.3

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued Expenses
External research and development	$ 68,164	$ 60,255
Employee compensation	29,166	27,622
Accrued professional fees	12,611	10,986
Revenue-related reserves	3,926	966
Other	7,962	6,109
Total	$ 121,829	$ 105,938

Collaboration and License Agr_3

Collaboration and License Agreements - General Information (Details) - Collaborative Arrangement $ in Millions	Oct. 15, 2019USD ($)	Jun. 01, 2018USD ($)item	Jul. 31, 2020USD ($)	Mar. 31, 2016USD ($)item	Dec. 31, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2021USD ($)item	Dec. 31, 2020USD ($)	Dec. 31, 2021USD ($)	Nov. 08, 2021USD ($)	Jul. 13, 2020
Zai Lab (Shanghai) Co., Ltd.
Collaboration Agreements
Collaborative arrangement, upfront payment, cash payment received					$ 25
Collaborative arrangement, milestones, contingent payments eligible to receive										$ 590
Collaborative arrangement, termination, counterparty written notice period, period from effective date							2 years
Collaborative arrangement, termination, counterparty written notice period, period from effective date, given after first commercial sale of licensed product in counterparty territory							12 months
Collaborative arrangement, termination, counterparty written notice period, period from effective date, given prior to first commercial sale of licensed product in counterparty territory							9 months
Roche, Collaboration (Pralsetnib) Agreement
Collaboration Agreements
Collaborative arrangement, upfront payment, cash payment received						$ 675
Collaborative arrangement, milestones, contingent payments eligible to receive					822		$ 822		$ 822
Collaborative arrangement, milestones, specified regulatory and commercialization milestones, achieved							50	$ 55	105
Collaborative arrangement, percentage of global development costs shared, entity (as a percent)											45.00%
Collaborative arrangement, percentage of global development costs shared, counterparty (as a percent)											55.00%
Roche, Collaboration and License (Immunotherapy) Agreement
Collaboration Agreements
Collaborative arrangement, upfront payment, cash payment received				$ 45
Collaborative arrangement, option fees and milestones, pre-clinical and clinical development events prior to licensing, contingent payments eligible to receive					319.3		319.3		319.3
Collaborative arrangement, milestones, research milestones, achieved					23.5		$ 23.5		23.5
Collaborative arrangement, license option rights, number | item				5			5
Collaborative arrangement, collaboration programs, number | item							2
Collaborative arrangement, collaboration programs, licensed products, commercialization rights, counterparty exercises option, counterparty receives worldwide exclusivity, number | item				1
Collaborative arrangement, collaboration programs, licensed products, commercialization rights, counterparty exercises option, entity retains domestic and counterparty receives international, number | item							1
Collaborative arrangement, termination, counterparty written notice period				120 days
Collaborative arrangement, termination, counterparty written notice period, after option exercise, if licensed products have not been commercially sold				120 days
Collaborative arrangement, termination, counterparty written notice period, after option exercise, if licensed products have been commercially sold				180 days
Clementia
Collaboration Agreements
Collaborative arrangement, upfront payment, cash payment received	$ 25
Collaborative arrangement, milestones, cash payments received			$ 20			$ 20
Collaborative arrangement, milestones, contingent payments eligible to receive	490
Collaborative arrangement, inventory purchased by counterparty	$ 1.5
Collaborative arrangement, termination, counterparty written notice period	12 months
C Stone
Collaboration Agreements
Collaborative arrangement, upfront payment, cash payment received		$ 40
Collaborative arrangement, milestones, cash payments received							$ 23
Collaborative arrangement, milestones, contingent payments eligible to receive					323		323		323
Collaborative arrangement, milestones, development and regulatory milestones, contingent payments eligible to receive					95.5		95.5		95.5
Collaborative arrangement, milestones, sales-based milestones, contingent payments eligible to receive					$ 227.5		$ 227.5		$ 227.5
Collaborative arrangement, licensed product term from first commercial sale		12 years
Collaborative arrangement, license option rights, number | item		3
Collaborative arrangement, collaboration programs with exclusive commercialization rights, number | item		3

Collaboration and License Agr_4

Collaboration and License Agreements - Transaction Price (Details) - Collaborative Arrangement - USD ($) $ in Millions	Jul. 13, 2020	Oct. 15, 2019	Jun. 01, 2018	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Zai Lab (Shanghai) Co., Ltd.
Collaboration Agreements
Collaborative arrangement, transaction price				$ 25
Roche, Collaboration (Pralsetnib) Agreement
Collaboration Agreements
Collaborative arrangement, transaction price	$ 695.7
Collaborative arrangement, transaction price, upfront payment	675
Collaborative arrangement, transaction price, stock issued, premium on sale of stock to counterparty	$ 20.7
Roche, Collaboration and License (Immunotherapy) Agreement
Collaboration Agreements
Collaborative arrangement, transaction price, milestone payments received and receivable					$ 23.5
Clementia
Collaboration Agreements
Collaborative arrangement, transaction price		$ 46.5
Collaborative arrangement, transaction price, upfront payment		25
Collaborative arrangement, transaction price, milestone payments receivable		20
Collaborative arrangement, transaction price, inventory purchased by counterparty, existing manufacturing inventory		1.2
Collaborative arrangement, transaction price, inventory purchased by counterparty, in-process manufacturing inventory		$ 0.3
C Stone
Collaboration Agreements
Collaborative arrangement, transaction price			$ 40
Collaborative arrangement, transaction price, cash consideration received					$ 9	$ 2	$ 12

Collaboration and License Agr_5

Collaboration and License Agreements - Sale of Stock (Details) - Private Placement - USD ($) $ / shares in Units, $ in Thousands	Jul. 13, 2020	Sep. 30, 2020	Dec. 31, 2020
Sale of Stock
Stock issued (in shares)		1,035,519
Share price (in dollars per share)		$ 96.57
Purchase consideration		$ 100,000
Issuance of common stock	$ 79,300		$ 79,306
Share purchase consideration, premium	$ 20,700

Collaboration and License Agr_6

Collaboration and License Agreements - Manufacturing and Research and Development Services (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangement | C Stone
Collaboration Agreements
Manufacturing and research and development services related to global development activities, net of expenses payable	$ 2,358	$ 3,060	$ 3,286

Collaboration and License Agr_7

Collaboration and License Agreements - Revenue Recognized (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Revenue		$ 180,080	$ 793,735	$ 66,512
Collaboration revenue
Revenues
Revenue		122,393	771,601	66,512
Collaborative Arrangement | Zai Lab (Shanghai) Co., Ltd.
Revenues
Revenue		25,000
Collaborative Arrangement | Collaboration revenue | Roche, Collaboration (Pralsetnib) Agreement
Revenues
Revenue		56,022	753,100
Collaborative Arrangement | Collaboration revenue | Roche, Collaboration and License (Immunotherapy) Agreement
Revenues
Revenue		7,636	14,580	8,165
Collaborative Arrangement | Collaboration revenue | Clementia
Revenues
Revenue				46,200
Collaborative Arrangement | Collaboration revenue | C Stone
Revenues
Revenue	$ 40,000	33,395	3,630	12,144
Collaborative Arrangement | Upfront license revenue | Roche, Collaboration (Pralsetnib) Agreement
Revenues
Revenue			695,694
Collaborative Arrangement | License milestone revenue | Roche, Collaboration (Pralsetnib) Agreement
Revenues
Revenue		50,000	55,000
Collaborative Arrangement | License milestone revenue | C Stone
Revenues
Revenue		9,000	2,000	12,000
Collaborative Arrangement | Territory-specific activities, services | Roche, Collaboration (Pralsetnib) Agreement
Revenues
Revenue		6,022	2,406
Collaborative Arrangement | Territory-specific activities, manufacturing services and royalty | C Stone
Revenues
Revenue		$ 24,395	$ 1,630	$ 144

Collaboration and License Agr_8

Collaboration and License Agreements - Collaboration Loss Sharing (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Collaboration Agreements
Collaboration loss sharing	$ 7,801
Collaborative Arrangement | Roche, Collaboration (Pralsetnib) Agreement
Collaboration Agreements
Collaboration loss sharing	$ 7,801

Collaboration and License Agr_9

Collaboration and License Agreements - Reduction in Expenses (Details) - Collaborative Arrangement - Roche, Collaboration (Pralsetnib) Agreement - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Collaboration Agreements
Collaborative arrangement, commercialization, reduction in selling, general and administrative expenses	$ 18,753	$ 10,631
Collaborative arrangement, global development activities, reduction in research and development expenses	$ 11,192	$ 20,459

Collaboration and License Ag_10

Collaboration and License Agreements - Change in Contract with Customer, Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangement | Roche, Collaboration and License (Immunotherapy) Agreement
Change in Contract with Customer, Liability
Amounts included in the contact liability at the beginning of the period	$ 5,080	$ 11,546	$ 4,578

Collaboration and License Ag_11

Collaboration and License Agreements - Contract Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Collaboration Agreements
Accounts receivable, net	$ 25,155	$ 7,096
Unbilled accounts receivable	11,875	18,213
Collaborative Arrangement | Roche, Collaboration (Pralsetnib) Agreement
Collaboration Agreements
Accounts receivable, net	2,679
Unbilled accounts receivable	6,802	17,600
Collaborative Arrangement | C Stone
Collaboration Agreements
Accounts receivable, net	8,164	$ 563
Unbilled accounts receivable	$ 5,034

Collaboration and License Ag_12

Collaboration and License Agreements - Contract Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Contract Liability
Deferred revenue, current	$ 11,510	$ 12,559
Collaborative Arrangement | Clementia
Contract Liability
Deferred revenue	0	0
Collaborative Arrangement | C Stone
Contract Liability
Deferred revenue	4,800	6,500
Collaborative Arrangement | Roche, Collaboration and License (Immunotherapy) Agreement
Contract Liability
Deferred revenue	31,400	34,700
Deferred revenue, current	$ 6,300	$ 6,100

Collaboration and License Ag_13

Collaboration and License Agreements - Performance Obligations (Details) - Collaborative Arrangement	12 Months Ended
	Dec. 31, 2021item
Zai Lab (Shanghai) Co., Ltd.
Performance Obligations
Collaborative arrangement, material promises, number	3
Collaborative arrangement, material promises, combined into distinct performance obligation, number	2
Collaborative arrangement, material components, number	2
Roche, Collaboration (Pralsetnib) Agreement
Performance Obligations
Collaborative arrangement, material promises, number	1
Collaborative arrangement, material promises, manufacturing activities, term	24 months
Collaborative arrangement, material components, number	4
Roche, Collaboration and License (Immunotherapy) Agreement
Performance Obligations
Revenue, performance obligation, performance obligations, number	1
Roche, Collaboration and License (Immunotherapy) Agreement | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Performance Obligations
Revenue, remaining performance obligation, expected timing of satisfaction, period	3 years 3 months
Clementia
Performance Obligations
Collaborative arrangement, material promises, number	4
Revenue, performance obligation, performance obligations, number	3
C Stone
Performance Obligations
Collaborative arrangement, material promises, combined into distinct performance obligation, number	6
Collaborative arrangement, material components, number	2
Revenue, performance obligation, performance obligations, number	3

Stockholder's Equity (Details)

Stockholder's Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 27, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 31, 2020
Sale of Stock
Proceeds from issuance of common stock, net of underwriting discounts and commissions and estimated offering expenses			$ 503,189	$ 327,466
Follow-on Public Offering
Sale of Stock
Stock issued (in shares)	4,710,144
Share price (in dollars per share)	$ 69
Proceeds from issuance of common stock, net of underwriting discounts and commissions and estimated offering expenses	$ 308,400
At-the-market Offering
Sale of Stock
Aggregate offering price					$ 250,000
Stock issued (in shares)		0	1,784,926
Proceeds from issuance of common stock, net of underwriting discounts and commissions and estimated offering expenses			$ 194,700

Stock-based Compensation - 2015

Stock-based Compensation - 2015 Stock Option and Incentive Plan (Details) - 2015 Stock Option and Incentive Plan - shares	Jan. 01, 2022	Jan. 01, 2021	Dec. 31, 2021	Apr. 08, 2015
Stock-based compensation
Initial shares of common stock authorized for issuance of stock awards (in shares)				1,460,084
Increase in number of shares available for grant (as a percent)			4.00%
Increase in number of shares available for grant (in shares)	2,365,643	2,311,741
Number of shares available for grant (in shares)			3,027,882

Stock-based Compensation - 2020

Stock-based Compensation - 2020 Inducement Plan (Details) - 2020 Inducement Plan - shares	Dec. 31, 2021	Mar. 31, 2020
Stock-based compensation
Initial shares of common stock authorized for issuance of stock awards (in shares)		1,000,000
Number of shares available for grant (in shares)	288,982

Stock-based Compensation - Stoc

Stock-based Compensation - Stock-based Compensation Expense - General Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Total stock based compensation expense
Stock-based compensation expense	$ 91,630	$ 75,526	$ 54,653

Stock-based Compensation - St_2

Stock-based Compensation - Stock-based Compensation Expense - By Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Total stock based compensation expense
Subtotal	$ 93,035	$ 76,602	$ 54,653
Capitalized stock-based compensation costs	(1,405)	(1,076)
Stock-based compensation expense included in total cost and operating expenses	91,630	75,526	54,653
Stock Options
Total stock based compensation expense
Subtotal	57,912	57,237	47,726
Restricted Stock Units
Total stock based compensation expense
Subtotal	33,939	18,407	6,445
Employee Stock
Total stock based compensation expense
Subtotal	$ 1,184	$ 958	$ 482

Stock-based Compensation - St_3

Stock-based Compensation - Stock-based Compensation Expense - By Classification (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Total stock based compensation expense
Stock-based compensation expense	$ 91,630	$ 75,526	$ 54,653
Research and Development
Total stock based compensation expense
Stock-based compensation expense	39,670	33,642	28,596
Selling, General and Administrative
Total stock based compensation expense
Stock-based compensation expense	$ 51,960	$ 41,884	$ 26,057

Stock-based Compensation - Unre

Stock-based Compensation - Unrecognized Compensation Costs (Details) $ in Millions	Dec. 31, 2021USD ($)
Stock-based compensation
Total unrecognized compensation cost related to non-vested stock awards	$ 199.8
Total unrecognized compensation cost related to non-vested stock option awards	$ 93.8
Weighted-average period over which unrecognized compensation cost will be recognized	2 years 7 months 6 days
Stock Options
Stock-based compensation
Weighted-average period over which unrecognized compensation cost will be recognized	2 years 4 months 24 days
Restricted Stock Units
Stock-based compensation
Total unrecognized compensation cost related to non-vested non-option awards	$ 105.9
Weighted-average period over which unrecognized compensation cost will be recognized	2 years 8 months 12 days

Stock-based Compensation - Awar

Stock-based Compensation - Awards - General Information (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock Options
Stock-based compensation
Award expiration period	10 years	10 years	10 years
2015 Stock Option and Incentive Plan | Stock Options
Stock-based compensation
Award vesting period	4 years	4 years	4 years
Cliff vesting period for new employees	1 year	1 year	1 year
Award expiration period	10 years	10 years	10 years
2015 Stock Option and Incentive Plan | Restricted Stock Units
Stock-based compensation
Award vesting period	4 years	4 years	4 years

Stock-based Compensation - St_4

Stock-based Compensation - Stock Options - Weighted Average Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assumptions used in estimating the fair value of stock options granted
Risk-free interest rate	0.96%	1.02%	2.21%
Expected dividend yield	0.00%	0.00%	0.00%
Expected term (in years)	6 years	6 years	6 years
Expected stock price volatility	58.03%	60.48%	63.83%

Stock-based Compensation - St_5

Stock-based Compensation - Stock Options - Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Shares
Outstanding at beginning of period (in shares)	6,030,641
Granted (in shares)	1,125,514
Exercised (in shares)	(982,791)
Cancelled (in shares)	(491,342)
Outstanding at end of period (in shares)	5,682,022	6,030,641
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 61.28
Granted (in dollars per share)	98.50
Exercised (in dollars per share)	48.13
Cancelled (in dollars per share)	79.27
Outstanding at end of period (in dollars per share)	$ 69.37	$ 61.28
Additional disclosures
Shares - Exercisable (in shares)	3,499,094
Weighted-Average Exercise Price - Exercisable (in dollars per share)	$ 61.30
Remaining Contractual Life - Outstanding	6 years 11 months 26 days	7 years 4 months 28 days
Remaining Contractual Life - Exercisable	6 years 1 month 17 days
Aggregate Intrinsic Value - Outstanding	$ 214,675	$ 306,810
Aggregate Intrinsic Value - Exercisable	$ 160,313

Stock-based Compensation - St_6

Stock-based Compensation - Stock Options - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Additional disclosures
Weighted-average grant date fair value of options granted	$ 52.93	$ 34.77	$ 48.96
Total intrinsic value of options exercised	$ 52.3	$ 43.3	$ 33.8

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock Units - Activity (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Shares
Unvested at beginning of period (in shares) | shares	1,171,686
Granted (in shares) | shares	999,504
Vested (in shares) | shares	(321,645)
Forfeited (in shares) | shares	(259,385)
Unvested at end of period (in shares) | shares	1,590,160
Weighted-Average Grant Date Fair Value
Unvested at beginning or period (in dollars per share) | $ / shares	$ 65.37
Granted (in dollars per share) | $ / shares	98.62
Vested (in dollars per share) | $ / shares	66.87
Forfeited (in dollars per share) | $ / shares	78.31
Unvested at end of period (in dollars per share) | $ / shares	$ 83.85

Stock-based Compensation - Re_2

Stock-based Compensation - Restricted Stock Units - Additional Information (Details) - Restricted Stock Units - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-based Compensation
Total fair value of restricted stock units that vested	$ 31.6	$ 7.4	$ 0.7
Vested (in shares)	321,645

Stock-based Compensation - Empl

Stock-based Compensation - Employee Stock Purchase Plan (Details) - Employee Stock - shares	1 Months Ended
	May 31, 2015	Jan. 01, 2022	Jan. 01, 2021
Stock-based compensation
Number of common shares reserved for future issuance (in shares)	243,347
Annual increase for common stock for issuance (as a percent)	1.00%
Increase of common shares reserved for future issuance (in shares)		591,410	577,935

Net Income Per Share - Net Inco

Net Income Per Share - Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net income (loss) - basic and diluted
Net loss	$ (644,085)	$ 313,882	$ (347,694)
Net income (loss) - basic	(644,085)	313,882	(347,694)
Net income (loss) - diluted	$ (644,085)	$ 313,882	$ (347,694)
Weighted average shares outstanding
Weighted average shares outstanding - basic (in shares)	58,518	54,534	47,829
Effect of dilutive securities:
Weighted average shares outstanding - diluted (in shares)	58,518	56,168	47,829
Net income (loss) per share - basic
Net income (loss) per share - basic (in dollars per share)	$ (11.01)	$ 5.76	$ (7.27)
Net income (loss) per share - diluted
Net income (loss) per share - diluted (in dollars per share)	$ (11.01)	$ 5.59	$ (7.27)
Stock Options
Effect of dilutive securities:
Effect of dilutive securities (in shares)		1,303
Restricted Stock Units
Effect of dilutive securities:
Effect of dilutive securities (in shares)		331

Net Income Per Share - Anti-dil

Net Income Per Share - Anti-dilutive Securities (Details) - 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
Antidilutive securities excluded from computation of earnings per share	7,296	4,512	6,230
Stock Options
Antidilutive securities excluded from computation of earnings per share
Antidilutive securities excluded from computation of earnings per share	5,682	4,480	5,796
Restricted Stock Units
Antidilutive securities excluded from computation of earnings per share
Antidilutive securities excluded from computation of earnings per share	1,590	13	420
Employee Stock
Antidilutive securities excluded from computation of earnings per share
Antidilutive securities excluded from computation of earnings per share	24	19	14

Income Taxes - Reconciliation (

Income Taxes - Reconciliation (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
A reconciliation of the U.S. statutory income tax rate to the Company's effective tax rate
Federal income tax (benefit) at statutory rate	21.00%	21.00%	21.00%
Permanent differences	0.07%	(0.47%)	1.11%
In-process research and development	(8.53%)
Federal research and development credits	0.76%	(0.96%)	0.77%
Federal orphan drug credits	4.02%	(10.35%)	6.90%
State income tax, net of federal benefit	1.26%	0.08%	7.46%
Other	(0.05%)	1.50%	2.13%
Foreign rate differential	(0.10%)	0.37%	(0.03%)
Deferred rate change	0.79%	2.60%	(0.08%)
Foreign tax credit	0.39%
Change in valuation allowance	(20.08%)	(13.42%)	(39.26%)
Effective income tax rate	(0.47%)	0.35%	0.00%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 243,670	$ 140,769	$ 219,935
Research and development credit carryforwards	36,345	23,679	19,240
Orphan drug credit carryforwards	150,859	125,153	92,538
Accrued expenses and other	40,617	32,206	25,842
Deferred revenue	6,598	7,317	10,971
Deferred rent	24,798	19,308	26,196
Jublient license	448
Interest expense	29
Total gross deferred tax asset	503,364	348,432	394,722
Deferred tax liability
Depreciation	(5,157)	(5,451)	(4,474)
Right of use assets	(20,059)	(14,539)	(19,869)
UNICAP	(1,966)
Prepaid expenses	(2)
Valuation allowance	(476,180)	(328,442)	(370,379)
Net deferred tax asset	$ 0	$ 0	$ 0

Income Taxes - Valuation Allowa

Income Taxes - Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Valuation allowance
Valuation allowance	$ 476,180	$ 328,442	$ 370,379
Change in valuation allowance	$ 147,700	$ (42,000)	$ 136,900

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss Carryforwards (Details) $ in Millions	Dec. 31, 2021USD ($)
Net Operating Loss Carryforwards
Net operating loss carryforwards, limitations on use, available for utilization	$ 2
Federal
Net Operating Loss Carryforwards
Net operating loss carryforwards	872.6
Net operating loss carryforwards, unlimited	851.1
Federal | Lengo Therapeutics Inc.
Net Operating Loss Carryforwards
Net operating loss carryforwards	66.6
State
Net Operating Loss Carryforwards
Net operating loss carryforwards	997.1
State | Lengo Therapeutics Inc.
Net Operating Loss Carryforwards
Net operating loss carryforwards	$ 67.1

Income Taxes - Tax Credit Carry

Income Taxes - Tax Credit Carryforwards (Details) $ in Millions	Dec. 31, 2021USD ($)
Foreign
Tax Credit Carryforwards
Tax credit carryforwards	$ 2.5
Research and Development Tax Credit | Federal
Tax Credit Carryforwards
Tax credit carryforwards	17.7
Research and Development Tax Credit | Federal | Lengo Therapeutics Inc.
Tax Credit Carryforwards
Tax credit carryforwards	0.3
Research and Development Tax Credit | State and Local Jurisdiction [Member]
Tax Credit Carryforwards
Tax credit carryforwards	19.4
Research and Development Tax Credit | State and Local Jurisdiction [Member] | Lengo Therapeutics Inc.
Tax Credit Carryforwards
Tax credit carryforwards	0.2
Orphan Drug Tax Credit | Federal
Tax Credit Carryforwards
Tax credit carryforwards	150.9
Investment Tax Credit | State and Local Jurisdiction [Member]
Tax Credit Carryforwards
Tax credit carryforwards	$ 0.6

Income Taxes - Uncertain Tax Po

Income Taxes - Uncertain Tax Positions (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Uncertain tax positions
Accrued interest related to uncertain tax positions	$ 0	$ 0

Leases - General Information (D

Leases - General Information (Details) $ in Thousands	Dec. 15, 2021USD ($)	Sep. 19, 2018USD ($)ft²	Apr. 28, 2017USD ($)ft²	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 18, 2018USD ($)	Feb. 12, 2015ft²
Leases
Initial lease commitments				$ 148,257
Restricted cash				5,200	$ 5,200
Corporate Headquarters Lease
Leases
Area leased (in square feet) | ft²							39,000
Base annual rent, initial	$ 4,500
Base annual rent, maximum	5,500
Allowance for leasehold improvements	$ 800
Security deposit				900
Office and Laboratory Space in Cambridge Massachusetts, 45 Sidney Street
Leases
Area leased (in square feet) | ft²		139,216	99,833
Extension period of lease term			5 years
Lessee, Operating Lease, Existence of Option to Extend			true
Base annual rent, initial			$ 7,700
Base annual rent, maximum			$ 10,600
Allowance for leasehold improvements						$ 17,400
Office and Laboratory Space in Cambridge, Massachusetts, 45 Sidney Street, Expansion Premises
Leases
Base annual rent, initial		$ 3,200
Base annual rent, maximum		$ 4,200
Security deposit				$ 3,800

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating leases cost:
Lease cost	$ 18,299	$ 17,600	$ 16,162
Sublease income	(2,174)	(2,919)	(2,834)
Net lease cost	$ 16,125	$ 14,681	$ 13,328

Leases - Cash Flow Information

Leases - Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases
Cash paid for amounts included in the measurement of lease liabilities, operating cash flows from operating leases	$ 14,896	$ 14,444
Lease liabilities arising from obtaining right-of-use assets, operating leases	$ 28,929	$ 479

Leases - Weighted Average Remai

Leases - Weighted Average Remaining Lease-term and Weighted Average Discount Rate (Details)	Dec. 31, 2021
Leases
Weighted average remaining lease term in years	7 years 9 months 18 days
Weighted average discount rate	7.40%

Leases - Future Minimum Lease P

Leases - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2021USD ($)
Future minimum lease payments
2022	$ 15,825
2023	17,691
2024	18,183
2025	18,557
2026	19,089
Thereafter	58,912
Total future minimum lease payments	$ 148,257

Leases - Total Lease Liability

Leases - Total Lease Liability (Details) $ in Thousands	Dec. 31, 2021USD ($)
Leases
Total future minimum lease payments	$ 148,257
Less imputed interest	(36,849)
Total	$ 111,408

Leases - Future Minimum Net Sub

Leases - Future Minimum Net Sublease Receivables Due (Details) $ in Millions	Dec. 31, 2021USD ($)
Sublease
Future minimum net sublease receivables due	$ 2

Employee Benefit Plans - 401(k)

Employee Benefit Plans - 401(k) Savings Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
401(k) Savings Plan
401(k) Plan expenses	$ 3	$ 1.9	$ 1.2

Employee Benefit Plans - Switze

Employee Benefit Plans - Switzerland Defined Benefit Plan (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)
Additional information
Defined Benefit Plan, Type	us-gaap:PensionPlansDefinedBenefitMember
Defined Benefit Plan, Sponsor Location	country:CH
Unfunded status
Unfunded net pension obligation	$ 3.4
Accumulated benefit obligation in excess of plan assets
Plan assets	4.5
Projected benefit obligation	7.9
Accumulated benefit obligation	6.5
Net periodic benefit cost
Net periodic benefit cost	$ 2

Commitments and Contingencies -

Commitments and Contingencies - Purchase Commitments (Details) - Manufacturing Agreement, October 2020 $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)
Manufacturing Agreements
Unrecorded unconditional purchase obligation, term	5 years
Unrecorded unconditional purchase obligation, future minimum purchase obligations	$ 34.2

Commitments and Contingencies_2

Commitments and Contingencies - Indemnification Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Indemnification Agreement
Indemnification Agreements
Loss contingency accrual	$ 0	$ 0

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Feb. 16, 2022USD ($)
Collaborative Arrangement | Subsequent Event | Clementia
Subsequent Events
Collaborative arrangement, milestones, development milestones, achieved	$ 30