SpringWorks Therapeutics (SWTX) 10-K 25 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Document and Entity Information [Abstract]
Entity Registrant Name	SPRINGWORKS THERAPEUTICS, INC.
Entity Central Index Key	0001773427
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity File Number	001-39044
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-4066827
Entity Address, Address Line One	100 Washington Blvd
Entity Address, City or Town	Stamford
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06902
City Area Code	203
Local Phone Number	883-9490
Title of 12(b) Security	Common Stock, $0.0001 Par Value per Share
Trading Symbol	SWTX
Security Exchange Name	NASDAQ
Amendment Flag	false
Current Fiscal Year End Date	--12-31
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 Public Float			$ 897,219,624
Entity Common Stock, Shares Outstanding		48,976,123
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 147,089	$ 327,652
Marketable securities	361,395
Prepaid expenses and other current assets	4,914	3,709
Total current assets	513,398	331,361
Long-term marketable securities	53,336
Property and equipment, net	1,075	795
Operating lease right-of-use assets	1,944
Equity investment	3,871	976
Restricted cash	565	540
Other assets	2,002	1,159
Total assets	576,191	334,831
Current liabilities:
Accounts payable	1,350	2,654
Accrued expenses	14,885	8,953
Operating lease liabilities, current	1,375
Deferred rent		363
Total current liabilities	17,610	11,970
Operating lease liabilities, long-term	1,359
Long-term portion of deferred rent		789
Other long-term liabilities	164
Total liabilities	19,133	12,759
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value, 10,000,000 shares authorized, no shares issued or outstanding at December 31, 2020 and December 31, 2019.
Common stock, $0.0001 par value, 150,000,000 shares authorized, 48,819,591 and 43,006,077 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively.	5	4
Additional paid-in capital	675,615	395,097
Accumulated other comprehensive income	41
Accumulated deficit	(118,603)	(73,029)
Total stockholders' equity	557,058	322,072
Total liabilities and stockholders' equity	$ 576,191	$ 334,831

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Preferred stock, Par value	$ 0.0001	$ 0.0001
Preferred stock, Shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, Shares outstanding	0	0
Common stock, Par value	$ 0.0001	$ 0.0001
Common stock, Shares authorized	150,000,000	150,000,000
Common stock, Shares issued	48,819,591	43,006,077
Common stock, Shares outstanding	48,819,591	43,006,077

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Operations
Licensing revenue	$ 35,000
Revenue, Product and Service [Extensible List]	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 51,859	$ 42,545	$ 9,898
General and administrative	29,465	16,694	8,593
Total operating expenses	81,324	59,239	18,491
Loss from operations	(46,324)	(59,239)	(18,491)
Other income:
Other income	25
Interest income, net	1,330	3,547	678
Total other income	1,355	3,547	678
Equity investment loss	(605)	(2,614)
Net loss	(45,574)	(58,306)	(17,813)
Reconciliation of net loss to net loss attributable to common stockholders and unit holders:
Net loss	(45,574)	(58,306)	(17,813)
Net gain attributable to extinguishment of Series A convertible preferred and Junior Series A convertible preferred units		7,729
Net loss attributable to common stockholders and unit holders, basic and diluted	$ (45,574)	$ (50,577)	$ (17,813)
Net loss per unit, basic and diluted			$ (52.24)
Net loss per share, basic and diluted	$ (1.05)	$ (3.81)
Weighted average common units outstanding, basic and diluted			341,014
Weighted average common shares outstanding, basic and diluted	43,300,063	13,274,836

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Loss
Net loss	$ (45,574)	$ (58,306)	$ (17,813)
Changes in other comprehensive income:
Unrealized gain on marketable securities, net	41
Total changes in other comprehensive income	41
Comprehensive loss	(45,533)	(58,306)	(17,813)
Net gain attributable to extinguishment of Series A convertible preferred and Junior Series A convertible preferred units		7,729
Comprehensive loss attributable to common stockholders	$ (45,533)	$ (50,577)	$ (17,813)

Consolidated Statement of Prefe

Consolidated Statement of Preferred Unit and Members'/Stockholders' Equity/(Deficit) - USD ($) $ in Thousands	Junior Series A Convertible Preferred	Common	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2017	$ 2,014				$ (4,639)	$ (2,625)
Beginning balance (in shares) at Dec. 31, 2017	6,437,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of units, Value			$ 154			154
Shares issued		195,638
Issuance of incentive units, net of forfeitures			915			915
Issuance of incentive units, net of forfeitures (in shares)		2,905,568
Net loss					(17,813)	(17,813)
Ending balance at Dec. 31, 2018	$ 2,014		1,069		(22,452)	(19,369)
Ending balance (in shares) at Dec. 31, 2018	6,437,500	3,101,206
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of units, Value		$ 1	169,729			169,730
Shares issued		10,350,000
Exercise of stock options			21			21
Exercise of stock options (in shares)		9,080
Forfeiture of restricted stock awards (in shares)		(248,568)
Stock-based compensation expense			3,109			3,109
Convertible preferred extinguishment					9,597	9,597
Convertible preferred extinguishment	$ 1,868				(1,868)
Conversion of convertible preferred stock into common stock	$ (3,882)	$ 3	221,169			217,290
Conversion of convertible preferred stock into common stock (in shares)	(6,437,500)	29,794,359
Net loss					(58,306)	(58,306)
Ending balance at Dec. 31, 2019		$ 4	395,097		(73,029)	322,072
Ending balance (in shares) at Dec. 31, 2019		43,006,077
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of convertible preferred shares, net of issuance costs
Issuance of units, Value		$ 1	269,591			269,592
Shares issued		5,637,254
Exercise of stock options			893			893
Exercise of stock options (in shares)		190,484
Forfeiture of restricted stock awards (in shares)		(14,224)
Stock-based compensation expense			10,034			10,034
Other comprehensive income, net of tax				41		41
Net loss					(45,574)	(45,574)
Ending balance at Dec. 31, 2020		$ 5	$ 675,615	$ 41	$ (118,603)	557,058
Ending balance (in shares) at Dec. 31, 2020		48,819,591
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of convertible preferred shares, net of issuance costs

Consolidated Statement of Pre_2

Consolidated Statement of Preferred Unit and Members'/Stockholders' Equity/(Deficit) - Temporary Equity - USD ($) $ in Thousands	Series A convertible preferred stock	Series B convertible preferred stock	Series A and B Convertible Preferred Stock	Junior Series A Convertible Preferred	Total
Beginning balance at Dec. 31, 2017			$ 12,554
Beginning balance (in shares) at Dec. 31, 2017			13,200,001
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred units, net	$ 50,376
Issuance of convertible preferred units, net (in shares)	50,399,999
Ending balance at Dec. 31, 2018			$ 62,930
Ending balance (in shares) at Dec. 31, 2018			63,600,000
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred units, net	$ 39,367	$ 124,590
Issuance of convertible preferred units, net (in shares)	39,400,000	86,639,279
Convertible preferred extinguishment	$ (9,597)		$ (217,290)		$ 9,597
Convertible preferred extinguishment (in shares)			(189,639,279)
Conversion of convertible preferred stock into common stock				$ (3,882)	217,290
Conversion of convertible preferred stock into common stock (in shares)				(6,437,500)
Ending balance at Dec. 31, 2019
Ending balance (in shares) at Dec. 31, 2019

Consolidated Statement of Pre_3

Consolidated Statement of Preferred Unit and Members'/Stockholders' Equity/(Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020
Issuance costs	$ 16,570	$ 17,908
Series B convertible preferred stock
Legal Costs	$ 413

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Net loss	$ (45,574,000)	$ (58,306,000)	$ (17,813,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	349,000	192,000	17,000
Non-cash operating lease expense	1,049,000
Stock compensation expense	10,034,000	3,109,000	1,069,000
Equity investment loss	605,000	2,614,000
Changes in Operating Assets and Liabilities
Prepaid expenses and other current assets	(1,205,000)	(2,327,000)	(1,112,000)
Other assets	(843,000)	(656,000)	(503,000)
Accounts payable	(1,304,000)	1,880,000	491,000
Accrued expenses	5,945,000	6,385,000	2,198,000
Deferred rent		(335,000)	1,487,000
Lease Liability	(1,411,000)
Other long-term liabilities	164,000
Net cash used in operating activities	(32,191,000)	(47,444,000)	(14,166,000)
Investing Activities
Capital expenditures	(642,000)	(670,000)	(293,000)
Equity investments	(3,500,000)	(3,590,000)
Purchases of marketable securities	(442,690,000)
Proceeds from sale and maturity of debt securities	28,000,000
Net cash used in investing activities	(418,832,000)	(4,260,000)	(293,000)
Financing Activities
Proceeds from issuance of common stock, net of issuance costs	269,592,000	169,730,000
Proceeds from issuance of Series A convertible preferred shares, net of issuance costs		39,367,000	50,376,000
Proceeds from issuance of Series B convertible preferred shares, net of issuance costs		124,590,000
Proceeds from stock option exercises	893,000	21,000
Net cash provided by financing activities	270,485,000	333,708,000	50,376,000
Net increase (decrease) in cash and cash equivalents	(180,538,000)	282,004,000	35,917,000
Cash and cash equivalents including Restricted cash, beginning of period	328,192,000	46,188,000	10,271,000
Cash and cash equivalents including Restricted cash, end of period	147,654,000	$ 328,192,000	$ 46,188,000
Supplemental non-cash items not included above resulting from the adoption of ASC 842
Initial recognition of operating lease right of use asset	2,879,000
Initial recognition of lease liabilities	$ (4,030,000)

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2020
Nature of Operations
Nature of Operations	1. Nature of Operations SpringWorks Therapeutics, Inc., or the Company, was formed in Delaware on August 18, 2017. The Company is a clinical-stage biopharmaceutical company applying a precision medicine approach to acquiring, developing and commercializing life-changing medicines for underserved patient populations suffering from devastating rare diseases and cancer. The Company has a differentiated portfolio of small molecule targeted oncology product candidates and is advancing two potentially registrational clinical trials in rare tumor types, as well as several other programs addressing highly prevalent, genetically defined cancers. Two of the programs are late-stage clinical product candidates: nirogacestat and mirdametinib. COVID-19 Pandemic On March 11, 2020, the World Health Organization designated the outbreak of the disease associated with the novel strain of coronavirus known as COVID-19 as a global pandemic. Governments and businesses around the world have taken unprecedented actions to mitigate the spread of COVID-19, including, but not limited to, shelter-in-place orders, quarantines, significant restrictions on travel, as well as restrictions that prohibit many employees from going to work. Uncertainty with respect to the economic impacts of the pandemic has introduced significant volatility in the financial markets. The Company did not observe significant impacts on its business or results of operations for the year ended December 31, 2020 from the global emergence of COVID-19. While the extent to which COVID-19 impacts the Company’s future results will depend on future developments, the pandemic and associated economic impacts could result in a material impact to the Company’s future financial condition, results of operations and cash flows. Follow-On Offering On October 13, 2020, the Company completed the sale of 5,637,254 shares of common stock in an underwritten public offering, including 735,294 shares of common stock sold pursuant to the underwriter's full exercise of their option to purchase additional shares, at an offering price of $51.00 per share, resulting in net proceeds to the Company of $269.5 million. Initial Public Offering On September 12, 2019, the Company completed an initial public offering, or IPO, of its common stock. In connections with its IPO, the Company issued and sold 10,350,000 shares of its common stock at a price to the public of $18.00 per share. The net proceeds from the IPO were approximately $169.7 million after deducting underwriting discounts and commissions of $13.0 million and offering expenses of approximately $3.5 million. At the closing of the IPO, 196,076,779 shares of outstanding convertible preferred stock were automatically converted into 29,794,359 shares of common stock at a conversion rate of 6.5810-for-one. Following the IPO, there were no Reverse Stock Split In August 2019, the Company’s Board of Directors and stockholders approved a one Series B convertible preferred In March 2019, the Company authorized the sale and issuance of up to 86,639,279 shares of Series B convertible preferred stock. The Series B convertible preferred financing was closed in a single tranche at the original price of $1.4428 per share for gross proceeds of $125 million. Issuance costs totaled $0.4 million. The liquidation preference terms of each of the Series A convertible preferred stock and Junior Series A convertible preferred stock changed in connection with the issuance of Series B convertible preferred. Specifically, after receiving one times its original issue price, the Series A convertible preferred does not participate in the distribution with the Junior Series A convertible preferred prior to final distribution to all stockholders, and the Junior Series A convertible preferred does not participate with all other stockholders in the final distribution. The Company concluded that the changes in the Series A convertible preferred and Junior Series A convertible preferred liquidation preferences are a significant change in the economics of those instruments and therefore were accounted for as an extinguishment. Immediately following the extinguishment of Series A convertible preferred and Junior Series A convertible preferred, the same number of shares was reissued at fair value. As a result, the difference between (1) the fair value of the consideration transferred to the holders of the preferred stock and (2) the carrying amount of the extinguished instruments (net of issuance costs) was recorded to retained earnings. Reorganization Prior to March 29, 2019, the Company conducted its business through SpringWorks Therapeutics, LLC, a Delaware limited liability company. On March 29, 2019, the Company completed a series of transactions pursuant to which SpringWorks MergerSub LLC, a wholly owned subsidiary of SpringWorks Therapeutics, Inc., merged with SpringWorks Therapeutics, LLC, with SpringWorks Therapeutics, LLC surviving the merger as a wholly owned subsidiary of SpringWorks Therapeutics, Inc., or the Reorganization. Upon consummation of the Reorganization, the historical consolidated financial statements of SpringWorks Therapeutics, LLC became the historical consolidated financial statements of SpringWorks Therapeutics, Inc. As part of the Reorganization: Holders of Series A convertible preferred Units of SpringWorks Therapeutics, LLC received one share of Series A convertible preferred stock of SpringWorks Therapeutics, Inc. for each Series A convertible preferred unit held immediately prior to the Reorganization; Holders of Junior Series A convertible preferred units of SpringWorks Therapeutics, LLC received one share of Junior Series A convertible preferred stock of Parent for each Junior Series A convertible preferred unit held immediately prior to the Reorganization; Holders of common units received one share of common stock of SpringWorks Therapeutics, Inc. for each common unit held immediately prior to the Reorganization; Each outstanding incentive unit converted into one share of common stock of SpringWorks Therapeutics, Inc. for each incentive unit held immediately prior to the Reorganization, and such common stock is subject to vesting in accordance with the vesting schedule applicable to such incentive units; and Holders of options exercisable to purchase common units, or unit options, of SpringWorks Therapeutics, LLC received one stock option exercisable to purchase common stock of the Company for each unit option held immediately prior to the Reorganization, at the same exercise price of such unit option immediately prior to the Reorganization. Such stock options continue to be subject to vesting in accordance with the vesting schedule applicable to such unit options.

Risks and Liquidity

Risks and Liquidity	12 Months Ended
	Dec. 31, 2020
Risks and Liquidity
Risks and Liquidity	2. Risks and Liquidity The Company has incurred losses and negative operating cash flows since inception and had an accumulated deficit of $118.6 million and $73.0 million, and working capital of $495.8 million and $319.4 million at December 31, 2020 and 2019, respectively. To date, we have derived all of our revenue from the nonrefundable upfront payment we received under the asset purchase and license agreement with Jazz Pharmaceuticals Ireland Limited, or Jazz. We do not have any products approved for commercial sale or sources of recurring revenue. The Company is subject to those risks associated with any biopharmaceutical company that has substantial expenditures for development. There can be no assurance that the Company’s development projects will be successful, that products developed will obtain necessary regulatory approval, or that any approved product will be commercially viable. In addition, the Company operates in an environment of rapid technological change and is largely dependent on the services of its employees, advisors, consultants and vendors. ​ The Company had cash, cash equivalents and marketable securities of $561.8 million and $327.7 million as of December 31, 2020 and 2019, respectively. The increase in the cash balance of approximately $234.2 million was primarily driven by net proceeds of $269.5 million from the sale of shares of common stock in an underwritten public offering in October 2020; offset by normal operating activities. Based on the Company’s cash, cash equivalents and marketable securities at December 31, 2020, management estimates that its current liquidity will enable it to meet operating expenses through at least twelve months after the date that these financial statements were issued.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	3. Summary of Significant Accounting Policies Basis of Presentation These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or U.S. GAAP. Principles of Consolidation The consolidated financial statements include the accounts of SpringWorks Therapeutics, Inc. and its subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Investments in business entities in which the Company lacks control but does have the ability to exercise significant influence over operating and financial policies are accounted for using the equity method of accounting. ​ Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, Research and Development expenses and the valuation of equity-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or relevant factors that it believes to be reasonable under the circumstances. Actual results may differ from those estimates. On an ongoing basis, management evaluates its estimates, and adjusts those estimates and assumptions when facts or circumstances change. Changes in estimates are recorded in the period in which they become known. Segment Information Operating segments are defined as components of an entity about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment operating exclusively in the United States. SEC Filing Status The Company became a large accelerated filer on December 31, 2020, based on the market value of the Company's common stock held by non-affiliates as of the last day of the second quarter in 2020. Prior to that, the Company was an emerging growth company, or EGC, as defined in the Jumpstart Our Business Startups Act, or the JOBS Act. Being an EGC allowed the Company to defer adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. The Company had elected to use this extended transition period under the JOBS Act. The Company lost the ability to defer adoption of new or revised accounting pronouncements when it became a large accelerated filer as of December 31, 2020. As a result, the financial statements included in this Annual Report reflect the adoption of new accounting standards effective for calendar year end public companies, including the adoption of Financial Accounting Standards Board Accounting Standards Codification Topic, or ASC, 842, Leases. Refer to the sections titled Recently Adopted Accounting Pronouncements in Footnote 3 and Footnote 7: Leases Cash and Cash Equivalents The Company considers all highly liquid instruments that have maturities of three months or less when acquired to be cash equivalents. The Company had cash and cash equivalents as of December 31, 2020 and 2019 of $147.1 million and $327.7 million, respectively. Marketable Securities Marketable debt securities are reported at fair value with unrealized gains and losses included in Accumulated other comprehensive income. Each reporting period, the Company evaluates whether there are declines in fair value below amortized cost and if these declines are due to credit losses, as well as the Company’s ability and intent to hold the investment until a forecasted recovery occurs. If both criteria regarding the intent or ability to hold are met, any decline in fair value due to credit losses is recorded as an allowance through Other income (expense), net on the Company’s consolidated statements of operations; limited by the amount that the fair value is less than the amortized costs basis. If either criteria is not met, any previously recorded allowance for credit losses and any excess amortized cost basis over fair value is recorded in Other income (expense), net on the Company’s consolidated statements of operations. As of, and for the year ended December 31, 2020, the Company did not have any allowance for credit losses or impairments of its marketable securities. ​ Concentration of Credit Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and available-for-sale marketable securities. The Company maintains each of its cash, cash equivalent balances and marketable securities balances with high quality, financial institutions and the Company’s marketable securities are invested in high-quality, highly liquid debt securities including corporate debt securities, U.S. government securities and commercial paper. Property and Equipment Property and equipment consist of computer equipment, furniture and leasehold improvements and are recorded at cost. Property and equipment are depreciated on a straight-line basis over their estimated useful lives. Revenue The Company recognizes revenue for consideration received related to the development and commercialization of medicines, which is conducted through various means, including in-house development by the Company, joint development or collaboration agreements with third parties, sale or out licensing of product rights, and others. The terms of these arrangements and agreements may contain multiple promised goods and services, which may include licenses, know-how, drug product, related agreements and other deliverables. Payments to the Company under these arrangements may include one or more of the following: upfront license fees; milestone payments; and royalties on future product sales. Arrangements Within the Scope of ASC 606, Revenue from Contracts with Customers The Company recognizes revenue in accordance with ASC 606, which applies to all contracts with customers, except for contracts that are within the scope of other standards, such as collaboration arrangements and leases. Pursuant to ASC 606, the Company recognizes revenue when its customers obtain control of promised goods or services, in an amount that reflects the consideration which the Company determines it expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligation(s). As part of the accounting for these arrangements, the Company may be required to make significant judgments, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each performance obligation. Once a contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within the contract and determines those that are performance obligations. The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and may require management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). In assessing whether a promised good or service is distinct, the Company considers factors such as the research, manufacturing and commercialization capabilities of the customer and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, an entity is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied at a point in time or over time, and if over time based on the use of an output or input method. Licenses of intellectual property: of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. ​ Up-front Fees: ​ Milestone Payments: ​ Royalties: ​ Reimbursement, cost-sharing and profit-sharing payments: ​ Research and Development In accordance with ASC 730, “Research and Development”, expenditures for clinical development, including upfront licensing fees and milestone payments associated with products that have not yet been approved by the U.S. Food and Drug Administration, are charged to research and development expense as incurred. These expenses consist of expenses incurred in performing development activities, including salaries and benefits, equity-based compensation expense, preclinical expenses, clinical trial and related clinical manufacturing expenses, contract services and other outside expenses. Expenses incurred for certain research and development activities, including expenses associated with particular activities performed by contract research organizations, investigative sites in connection with clinical trials and contract manufacturing organizations, are recognized based on an evaluation of the progress or completion of specific tasks using either time-based measures or data such as information provided to the Company by its vendors on actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of expense recognition. Expenses for research and development activities incurred that have yet to be invoiced by the vendors that perform the related activities are reflected in the consolidated financial statements as accrued research and development expenses. Advance payments for goods or services to be received in the future for research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed. General and Administrative General and administrative expenses consist primarily of payroll and employee related costs including salaries and benefits, equity-based compensation expense, rent and utilities, infrastructure, corporate insurance, office expenses and consulting and professional services, including legal, regulatory and compliance. Equity-based compensation expense The Company accounts for employee equity-based compensation in accordance with ASC 718, Compensation — Stock Compensation, which requires all equity-based awards to employees and non-employee directors be recognized as expense in the statement of operations based on the grant date fair value of the awards. The Company’s equity-based awards generally vest over three Stock compensation expense is recognized using the straight-line method, based on the grant date fair value, over the requisite service period of the award, which is generally the vesting term. For awards subject to performance conditions, as well as awards containing both market and performance conditions, the Company recognizes equity award compensation expense using an accelerated recognition method over the remaining service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the expected satisfaction of the performance conditions as of the reporting date. The Company recognizes forfeitures at the time of the actual forfeiture event in accordance with the adoption of the guidance per Accounting Standard Update, or ASU, No. 2016-09. The grant-date fair value of performance-based awards with market conditions is estimated using a Monte Carlo simulation method that incorporates the probability of the performance conditions being met as of the grant date. For stock options issued, the Company estimates the grant date fair value and the resulting stock-based compensation expense using the Black-Scholes option-pricing model. The Black-Scholes option-pricing model requires the use of certain subjective assumptions which determine the fair value of stock-based awards, including the expected term and the price volatility of the underlying stock. Inputs used in the Black-Scholes option-pricing model are: ● Fair value of common stock, which is the current trading price of the Company’s common stock. ● Expected term — The expected term represents the period that the equity-based awards are expected to be outstanding. The Company uses the simplified method to calculate the expected term due to the limited Company-specific historical information available for the Company. ● Expected volatility — The Company lacks Company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until it has adequate historical data regarding the volatility of its own traded stock. ● Risk-free interest rate — The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the awards. ● Expected dividend — The Company has never paid dividends on its common units or stock and has no plans to pay dividends on its common stock. Therefore, the expected dividend yield is zero . For equity-based compensation grants prior to the IPO, the Company estimated the fair value of equity awards granted using the special case of the market approach, including the guideline public company method and precedent transaction method which is known as a backsolve method. This option pricing model was utilized to solve for the implied total equity value that was consistent with the Company’s Series A convertible preferred units “backsolves” to a preferred share price. The backsolve method derives the implied equity value for one type of equity security from a contemporaneous transaction involving another type of security to calculate the equity value. The use of these valuation approaches required management to make assumptions with respect to the expected volatility of its units and stock, time until a liquidity event and risk-free interest rates. Equity value was allocated to the common, incentive and convertible preferred units, and common, restricted and convertible preferred stock using an option-pricing method. Under this method, the common and incentive units and common stock would have had value only if the funds available for distribution exceeded the value of the convertible preferred units’ liquidation preferences at the anticipated time of a liquidity event, such as a strategic sale, merger or IPO. Net Loss per Unit and Share Basic net loss per unit and per share is computed by dividing net loss by the weighted average number of common units and shares outstanding for the period. Diluted net loss per unit and share excludes the potential impact of convertible preferred units, unvested incentive units, convertible preferred stock, unvested restricted stock and stock options because their effect would be anti-dilutive due to the Company’s net loss. Since the Company had a net loss in each of the periods presented, basic and diluted net loss per common unit and share are the same. Income Taxes Income taxes are accounted for using the asset-and-liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized as income in the period that includes the enactment date. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company recognizes deferred tax assets to the extent that it believes that these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company records uncertain tax positions in accordance with ASC 740 on the basis of a two-step process in which (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. These reserves are based on a determination of whether and how much of a tax benefit taken by the Company in its filings or positions is more likely than not to be realized following resolution of any potential contingencies related to the tax benefit. Potential interest related to the underpayment of income taxes will be classified as a component of income tax expense and any related penalties will be classified in income tax expenses in the statement of operations. SpringWorks Therapeutics, LLC elected to be treated under the partnership provisions of the Internal Revenue Service Code prior to the reorganization on March 29, 2019. However, its five wholly owned subsidiaries, SpringWorks Operating Company, SpringWorks Subsidiary 1, SpringWorks Subsidiary 2, SpringWorks Subsidiary 3, and SpringWorks Subsidiary 4, are taxable corporations. Subsequent to the Reorganization, SpringWorks Therapeutics, Inc. became the 100% owner of SpringWorks Therapeutics, LLC, creating a new ultimate parent company, and a consolidated group for income tax reporting. The Reorganization and change in tax status of the reporting entity did not have an impact on the consolidated tax provision. Recently Adopted Accounting Pronouncements Leases In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This standard requires entities that lease assets to recognize on the balance sheet the assets and liabilities of the rights and obligations created by those leases. The Company utilized a package of practical expedients A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term. All other leases are recorded as operating leases. ​ Finance and operating lease assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term using the discount rate implicit in the lease. If the rate implicit is not readily determinable, the Company utilizes its incremental borrowing rate at the lease commencement date. Operating lease assets are further adjusted for prepaid or accrued lease payments. Operating lease payments are expensed using the straight-line method as an operating expense over the lease term. Finance lease assets are amortized to depreciation expense using the straight-line method over the shorter of the useful life of the related asset or the lease term. Finance lease payments are bifurcated into (i) a portion that is recorded as imputed interest expense and (ii) a portion that reduces the finance liability associated with the lease. ​ The Company does not separate lease and non-lease components when determining which lease payments to include in the calculation of its lease assets and liabilities. Variable lease payments are expensed as incurred. If a lease includes an option to extend or terminate the lease, the Company reflects the option in the lease term if it is reasonably certain it will exercise the option. ​ Operating leases are recorded in “Operating lease right-of-use-assets,” “Operating lease liabilities, current” and “Operating lease liabilities, long-term” on the Company’s consolidated balance sheet. The Company had no finance lease obligations for the periods presented. Refer to Footnote 7 for additional lease disclosures. ​ The cumulative effect of applying ASC 842 on the Company’s consolidated balance sheet as of January 1, 2020 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of ​ ​ ​ ​ ​ Balance as of (in thousands) ​ ​ December 31, 2019 * ​ ​ Adjustments ​ ​ January 1, 2020 Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease right-of-use-assets $ — ​ $ 2,848 ​ $ 2,848 Total assets ​ $ — ​ $ 2,848 ​ $ 2,848 Liabilities ​ ​ ​ ​ ​ ​ ​ — Operating lease liabilities, current ​ $ — ​ $ 1,382 ​ $ 1,382 Deferred rent ​ 363 ​ ​ (363) ​ ​ — Operating lease liabilities, long-term ​ ​ — ​ ​ 2,618 ​ ​ 2,618 Long-term portion of deferred rent ​ ​ 789 ​ ​ (789) ​ ​ — Total liabilities ​ $ 1,152 ​ $ 2,848 ​ $ 4,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ *As reported in the Company's 2019 Annual Report on Form 10-K. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Internal-Use Software In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, or ASU 2018-15. The FASB issued ASU 2018-15 to align the requirements for capitalizing implementation costs incurred in a cloud-based hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The Company adopted ASU 2018-15 as of January 1, 2020. The adoption of ASU 2018-15 did not have a significant impact on the Company’s consolidated financial statements. Credit Losses In 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires entities to record expected credit losses for certain financial instruments, including trade receivables, as an allowance that reflects the entity's current estimate of credit losses expected to be incurred. For available-for-sale debt securities with unrealized losses, the standard now requires allowances to be recorded instead of reducing the amortized cost of the investment with certain exceptions. ASU 2016-13 became effective on January 1, 2020. The adoption of ASU 2016-13 did not have a significant impact on the Company’s consolidated financial statements. The Company updated its accounting policy for evaluating impairment of its marketable securities. ​ Recently Issued Accounting Pronouncements In 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740), which simplifies the accounting for income taxes. ASU 2019-12 will be effective for the Company on January 1, 2021 and is not expected to have a significant impact on the Company’s consolidated financial statements .

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2020
Marketable Securities
Marketable Securities	4. Marketable Securities The following table summarizes the Company’s available-for-sale marketable securities as of December 31, 2020 at net book value: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses ​ Estimated Fair Value Marketable securities: ​ ​ ​ ​ ​ Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ $ 157,079 ​ $ 24 ​ $ (1) ​ $ 157,102 Corporate debt securities ​ 74,773 ​ 2 ​ (10) ​ 74,765 Commercial paper ​ ​ 129,528 ​ ​ — ​ ​ — ​ ​ 129,528 Long-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ ​ 53,310 ​ ​ 26 ​ ​ — ​ ​ 53,336 Total ​ $ 414,690 ​ $ 52 ​ $ (11) ​ $ 414,731 ​ The Company’s marketable securities are available-for-sale securities and consist of high-quality, highly liquid debt securities including corporate debt securities, U.S. government securities and commercial paper. The Company’s available-for-sale securities that are classified as short-term marketable securities in the consolidated balance sheet mature within one year or less of the balance sheet date. Marketable securities that mature greater than one year from the balance sheet date are classified as noncurrent. As of December 31, 2020, the Company did not hold any investments that matured beyond five years. As of December 31, 2019, the Company did not

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Measurements
Fair Value Measurements	5. Fair Value Measurements The fair value of the Company’s financial assets measured on a recurring basis are classified based upon a fair value hierarchy consisting of the following three levels: Level 1 — Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets, or liabilities. Level 2 — Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the instrument. Level 3 — Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). The fair value hierarchy is based on inputs to valuation techniques that are used to measure fair value that are either observable or unobservable. Observable inputs reflect assumptions market participants would use in pricing an asset or liability based on market data obtained from independent sources while unobservable inputs reflect a reporting entity's pricing based upon their own market assumptions. The following table sets forth the fair value hierarchy of the Company’s financial assets and liabilities measured on a recurring basis: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 ​ ​ ​ ​ ​ Fair Value Hierarchy (in thousands) Total Level 1 Level 2 ​ Level 3 Financial instruments carried at fair value (asset position): ​ ​ ​ ​ ​ Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 107,723 ​ $ 107,723 ​ $ — ​ $ — Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ 157,102 ​ 157,102 ​ — ​ — Corporate debt securities ​ 74,765 ​ — ​ 74,765 ​ — Commercial paper ​ ​ 129,528 ​ ​ — ​ ​ 129,528 ​ ​ — Long-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ ​ 53,336 ​ ​ 53,336 ​ ​ — ​ ​ — Total ​ $ 522,454 ​ $ 318,161 ​ $ 204,293 ​ $ — ​ As of December 31, 2020, the Company’s financial assets measured at fair value on a recurring basis included cash equivalents, which consist of money market funds, and marketable securities. The Company’s money market funds are readily convertible into cash and the net asset value of each fund on the last day of the quarter is used to determine fair value. The U.S. Government securities are classified as Level 1 and valued utilizing quoted market prices. The Company’s corporate debt securities and commercial paper are classified as Level 2 and valued utilizing various market and industry inputs. The Company had cash and cash equivalents at December 31, 2019 of $327.7 million. As of December 31, 2019, the Company had no other financial assets or liabilities that were measured at fair value on a recurring basis. The Company considers all highly liquid instruments that have maturities of three months or less when acquired to be cash equivalents. The carrying amounts reflected in the Company’s consolidated balance sheets for cash equivalents, accounts payable, and accrued expenses approximate fair value due to their short-term maturities.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2020
Property and Equipment
Property and Equipment	6. Property and Equipment Property and equipment, net consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ (in thousands) ​ 2020 ​ ​ 2019 Useful Life Leasehold improvements ​ $ 1,184 ​ $ 855 ​ Length of lease or 5 years, whichever is shorter Computer equipment ​ ​ 157 ​ ​ 122 ​ 3 years Furniture ​ ​ 97 ​ ​ 31 ​ 5 years Software ​ ​ 62 ​ ​ — ​ 3 years Construction in process ​ ​ 104 ​ ​ — ​ ​ ​ ​ ​ 1,604 ​ ​ 1,008 ​ ​ Less accumulated depreciation ​ ​ (529) ​ ​ (213) ​ ​ ​ ​ $ 1,075 ​ $ 795 ​ ​ ​ Depreciation expense was $349,000, $192,000, and $17,000 for the years ended December 31, 2020, 2019 and 2018, respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases
Leases	7. Leases Operating Leases The company’s operating leases relate to real estate. In October 2018, the Company entered into a lease for its corporate headquarters in Stamford, CT. The lease expires in November 2022. The Company received $1.5 million from the previous tenant in connection with the assumption of the lease. The lease payments increase by 2% in each of the subsequent years. The Company established a security deposit of $0.5 million in the form of a letter-of-credit. In August 2018, the Company entered into a five-year operating lease in Durham, NC (the location of the Company’s clinical development operations), with two five-year renewal options. The lease payments increase by 2.75% in each of the subsequent 4 years. Rental payments under the renewal period will be at current market rates for the premises. In October 2019, the Company entered into a lease for office space in New York, NY. The Company executed an amendment in September 2020, which extended the lease to May 31, 2021. Aggregate Lease Information Related to the Application of ASC 842 Prior to January 1, 2020, the Company accounted for leases under ASC 840. Refer to Footnote 3 for the cumulative effect of applying ASC 842 at adoption. The following information is disclosed in accordance with ASC 842, which was adopted as of January 1, 2020. The components of lease cost recorded in the Company’s consolidated statement of operations were as follows: ​ ​ ​ ​ ​ (in thousands) ​ 2020 Operating lease cost ​ ​ ​ Fixed ​ $ 1,049 Variable ​ 486 Total lease cost ​ $ 1,535 ​ The Company’s leases are included on its consolidated balance sheets as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ As of December 31, 2020 ​ ​ As of December 31, 2019* Operating leases ​ ​ ​ ​ ​ Operating lease right-of-use-assets ​ $ 1,944 ​ $ — Total operating lease assets ​ $ 1,944 ​ $ — ​ ​ ​ ​ ​ Operating lease liabilities, current ​ $ 1,375 ​ $ — Operating lease liabilities, long-term ​ 1,359 ​ — Total operating lease liabilities ​ $ 2,734 ​ $ — ​ ​ ​ ​ ​ ​ ​ *As reported in the Company's 2019 Annual Report on Form 10-K. ​ ​ ​ ​ ​ ​ ​ Maturities of the Company’s operating lease liabilities in accordance with ASC 842 as of December 31, 2020 were as follows: ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ Operating Leases 2021 ​ $ 1,396 2022 ​ 1,298 2023 ​ 135 2024 and thereafter ​ — Total lease payments ​ ​ 2,829 Less: imputed interest ​ ​ (95) Present value of lease liabilities ​ $ 2,734 ​ The weighted-average remaining lease term and discount rate related to the Company’s leases were as follows: ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 Weighted-average remaining lease term (in years) ​ ​ ​ Operating leases ​ ​ 2.0 Weighted-average discount rate ​ ​ ​ Operating leases ​ ​ 3.45% ​ Supplemental cash flow information related to the Company’s leases was as follows: ​ ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ Operating cash flows from operating leases ​ $ 1,411 Right-of-use assets obtained in exchange for new operating lease liabilities ​ ​ 31 ​ ​ ​ ​ The Company recorded rent expense aggregating $1.5 million, $1.6 million and $0.5 million for the years ended December 31, 2020, December 31, 2019, and December 31, 2018, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2020
Accrued Expenses
Accrued Expenses	8. Accrued Expenses Accrued expenses consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, (in thousands) 2020 2019 Accrued professional fees ​ $ 827 ​ $ 793 Accrued compensation and benefits ​ 5,834 ​ 3,147 Accrued research and development ​ ​ 7,922 ​ ​ 4,447 Accrued other ​ 302 ​ 566 Total accrued expenses ​ $ 14,885 ​ $ 8,953 ​

Equity-Based Compensation

Equity-Based Compensation	12 Months Ended
	Dec. 31, 2020
Equity-Based Compensation
Equity-Based Compensation	9. Equity Based Compensation The Company recorded total equity-based compensation expense for the periods presented as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (in thousands) ​ 2020 ​ 2019 ​ ​ 2018 Research and development ​ $ 3,055 ​ $ 731 ​ $ 164 General and administrative ​ ​ 6,979 ​ ​ 2,378 ​ ​ 905 Total equity compensation expense ​ $ 10,034 ​ $ 3,109 ​ $ 1,069 ​ 2019 Equity Incentive Plan The 2019 Equity Incentive Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards and dividend equivalent rights to the Company’s officers, employees, directors and other key persons (including consultants). The number of shares initially reserved for issuance under the 2019 Equity Incentive Plan was 3,537,225 shares and is cumulatively increased each January 1, through and including January 1, 2030, by 5% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s compensation committee. Effective January 1, 2020, the number of shares reserved for issuance under the 2019 Equity Incentive Plan was increased by 2,150,304 shares. The terms of stock options and restricted stock awards, including vesting requirements, are determined by the Board of Directors or its delegates, subject to the provisions of the 2019 Equity Incentive Plan. Stock options and restricted stock awards granted by the Company to employees and directors generally vest over four years. As of December 31, 2020, there were 4,256,747 shares available for future issuance under the 2019 Equity Incentive Plan. 2019 Private Company Plan On March 29, 2019, the Company adopted the 2019 Stock Option and Incentive Plan, or the 2019 Private Company Plan, in connection with the Reorganization. The 2019 Private Company Plan originally had 5,292,355 shares available for issuance. In connection with the adoption of the 2019 Private Company Plan, all outstanding incentive units and unit options, granted under the 2018 Equity Plan, were exchanged for stock options and restricted stock under the 2019 Private Company Plan. The restricted common stock was issued with the same vesting terms as the unvested incentive units held immediately prior to the Reorganization. On June 4, 2019, the total shares available for issuance under the 2019 Private Company Plan was increased to 5,382,828 shares. On July 29, 2019, the total shares available for issuance was increased to 6,700,197. In connection with the IPO no modification was triggered for the 2019 Private Company Plan and upon the effectiveness of the 2019 Public Company Plan no further grants can be made under the 2019 Private Company Plan. However, the shares of common stock underlying any awards that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire or are otherwise terminated (other than by exercise) under the 2019 Private Company Plan will be added back to the shares of common stock available for issuance under the 2019 Public Company Plan. 2018 Equity Plan In January 2018, the Company adopted the 2018 Equity Incentive Plan, or the 2018 Equity Plan. There were 2,738,929 incentive units, or incentive units, initially available for issuance under the 2018 Equity Plan. The 2018 Plan was increased by 269,716 units for an aggregate of 3,008,645 as of December 31, 2018. On March 19, 2019, the Company modified its operating agreement to allow for the award of unit options. In connection with the adoption of the 2019 Private Company Plan, as noted above, all outstanding awards were exchanged for identical awards under the 2019 Private Company Plan. No further grants can be made under the 2018 Equity Plan. 2019 Employee Stock Purchase Plan On August 30, 2019, the Company’s stockholders approved the 2019 Employee Stock Purchase Plan, or the ESPP, which became effective immediately preceding the effectiveness of the Company’s registration statement on September 12, 2019 in connection with the IPO. A total of 442,153 shares of common stock were reserved for issuance under the ESPP. In addition, the number of shares of common stock that may be issued under the ESPP will automatically increase each January 1, through and including January 1, 2028, by the lesser of (i) 663,229 shares of common stock, (ii) 1% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or (iii) such lesser number of shares determined by the administrator of the Company’s ESPP. Effective January 1, 2020, the number of shares reserved for issuance under the ESPP was increased by 430,061 shares. No offering periods under the ESPP had been initiated as of December 31, 2020. Stock Options A summary of the changes in the Company’s stock options from December 31, 2018 through December 31, 2020 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ ​ ​ Weighted ​ Remaining ​ ​ ​ ​ ​ ​ ​ Average ​ Contractual ​ Aggregate ​ ​ ​ ​ ​ Exercise ​ Life ​ Intrinsic ​ Shares ​ Price (Years)​ Value Outstanding at December 31, 2018 ​ — ​ ​ — ​ — ​ — Granted ​ — ​ ​ — ​ — ​ — Outstanding at March 29, 2019 ​ 148,415 ​ $ 1.65 ​ — ​ — Granted ​ 3,177,233 ​ ​ 5.21 ​ — ​ — Exercised ​ (9,080) ​ ​ 2.30 ​ — ​ — Forfeited/cancelled ​ (90,843) ​ ​ 2.18 ​ — ​ — Outstanding at December 31, 2019 3,225,725 ​ ​ 5.08 9.4 ​ 107,771,472 Granted 1,580,788 ​ ​ 35.90 — ​ — Exercised ​ (190,484) ​ ​ 4.69 ​ — ​ — Forfeited/cancelled (110,483) ​ ​ 23.49 — ​ — Outstanding at December 31, 2020 4,505,546 ​ ​ 15.51 ​ 8.7 ​ 256,860,405 Exercisable at December 31, 2020 ​ 1,402,718 ​ ​ 8.25 ​ 8.5 ​ 90,150,057 ​ Aggregate intrinsic value is calculated by subtracting the exercise price of the option from the closing price of the Company’s common stock on closing date, multiplied by the number of shares per each option. Assumptions used in determining the fair value of the stock options granted in 2020 include risk-free interest rate 0.31% – 1.73%, expected dividend yield of 0.00%, expected life in years of 5.50 - 6.08 and expected volatility of 70.0% - 75.0%. 2019 CEO Performance Award In June 2019, the Company’s CEO received an award of 176,411 stock options, or the 2019 CEO Performance Award. The 2019 CEO Performance Award can vest over 48 monthly installments based on four years of service, a performance condition (a liquidity event, such as an IPO) and market conditions, assuming continued employment and service through each vesting date. During the vesting period of four years, the 2019 CEO Performance Award is not earned unless the market condition is achieved on each vesting date. If the market condition is not achieved on a vesting date, but is achieved on a future vesting date, the award is earned for the entire period since the last date that such market condition was achieved. All or a portion of the award can be earned following the initial four-year service period if the market condition is next achieved after such four-year service period and Mr. Islam remains in continuous service. The market condition and performance condition are satisfied when the Company’s common stock is listed on a U.S. national securities exchange and achieves a 60-trading day average closing price of at least $28.49 per share (as adjusted for stock splits, recapitalizations, and similar events). During the year ended December 31, 2020, 73,502 options of the CEO performance award became exercisable upon the satisfaction of the market condition applicable to this award. At December 31, 2020, the total unrecognized compensation expense related to unvested stock options was $34.2 million, which the Company expects to recognize over a weighted-average remaining period of approximately 2.80 years. For the year ended December 31, 2020, total stock option compensation expense for outstanding stock options was $9.7 million. Restricted Stock A summary of the changes in the Company’s restricted stock from December 31, 2018 through December 31, 2020 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ Number ​ ​ Grant Date ​ of Shares ​ Fair Value Unvested and outstanding at December 31, 2018 ​ 2,503,744 ​ $ 1.25 Vested ​ (228,209) ​ ​ 0.81 Forfeited ​ (12,570) ​ ​ 1.45 Unvested and outstanding at March 29, 2019 ​ 2,262,965 ​ ​ 1.24 Vested ​ (737,530) ​ ​ 1.26 Forfeited ​ (235,998) ​ ​ 1.36 Unvested and outstanding at December 31, 2019 1,289,437 ​ ​ 1.21 Vested (588,345) ​ ​ 1.14 Forfeited (14,224) ​ ​ 1.45 Unvested and outstanding at December 31, 2020 686,868 ​ ​ 1.26 ​ At December 31, 2020, the total unrecognized compensation expense related to unvested restricted stock was $0.3 million, which the Company expects to recognize over a weighted-average remaining period of approximately 0.86 years. For the year ended December 31, 2020, total restricted stock compensation expense was $0.3 million.

License and Collaboration Agree

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2020
License and Collaboration Agreements
License and Collaboration Agreements	10. License and Collaboration Agreements Pfizer Inc. In August and October 2017, the Company entered into four license agreements with Pfizer Inc., or Pfizer, for rights to certain technologies, or the License Agreements. Under the License Agreements, the Company obtained from Pfizer the right to use research, develop, manufacture and commercialize certain products, including nirogacestat and mirdametinib. In connection with the License Agreements, the Company issued 6,437,500 units of Junior Series A convertible preferred units to Pfizer (see Note 1). No The Company is required to pay Pfizer milestones payments of up to an aggregate of $232.5 million for nirogacestat and up to an aggregate of $229.8 million for mirdametinib, each upon achievement of certain commercial milestone events. Royalties are also payable under each License Agreement based on a specified percentage of net sales ranging from mid-single digit percentages to low 20s, Royalty payments under each License Agreement continue until the expiration of the last to expire licensed patent applicable to such product, but not less than ten years after the first commercial sale on a country-by-country basis. BeiGene, Ltd. In August 2018, the Company entered into a clinical collaboration agreement with BeiGene Ltd., or BeiGene to conduct a clinical study of the combination of mirdametinib and a BeiGene compound designated as lifirafenib. In accordance with the terms of the agreement, the Company and BeiGene share equally the costs associated with the clinical study. BeiGene is required to supply the BeiGene compound and the Company is required to supply mirdametinib to conduct the clinical study. The collaboration is guided by a joint steering committee. Specified areas of development require unanimous agreement among all members of the joint steering committee. The Company recorded expense of $0.9 million and $1.0 million for the years ended December 31, 2020 and December 31, 2019, respectively, in connection with this collaboration agreement, which are classified as research and development expenses in the Company’s statement of operations. GSK clinical collaboration agreement In June 2019, the Company entered into a clinical collaboration agreement with GlaxoSmithKline, or GSK, or the GSK Collaboration Agreement, to evaluate the safety, tolerability and preliminary efficacy of nirogacestat and belantamab mafodotin. Under the terms of the GSK Collaboration Agreement, GSK will sponsor and conduct the adaptive Phase 1b study of nirogacestat, in combination with GSK’s B-cell maturation antigen, or BCMA antibody-drug conjugate, belantamab mafodotin, in patients with relapsed or refractory multiple myeloma. GSK will assume all development costs associated with the study. The Company agreed to manufacture and supply the Company compound for purposes of the study. Pursuant to the GSK Collaboration Agreement, GSK is responsible for administering the clinical trial and is responsible for all costs associated with the direct conduct of the clinical trial, other than the manufacture and supply of nirogacestat and certain expenses related to intellectual property rights. The collaboration is managed by a joint development committee of equal representation by the Company and GSK. Following completion of the clinical trial, within a specified period of time, either party may propose new agreements for the purpose of performing one or more additional clinical trials of the combination therapy for the treatment of relapsed and refractory multiple myeloma. If a party proposes to conduct an additional clinical trial, the parties will negotiate in good faith, without obligation, the details of a definitive agreement to provide for the expansion of the clinical collaboration. If the parties do not reach an agreement, and only one party wishes to proceed with an additional clinical trial, it may do so if the other party does not object to the protocol based on safety concerns. Allogene clinical collaboration agreement In January 2020, the Company entered into a clinical trial collaboration and supply agreement with Allogene Therapeutics, or Allogene, to evaluate nirogacestat in combination with ALLO-715, Allogene’s investigational allogeneic BCMA-targeted chimeric antigen receptor, or CAR, T cell product, in patients with relapsed or refractory multiple myeloma. Allogene is responsible for administering the Phase 1 clinical trial and is responsible for all costs associated with the direct conduct of the clinical trial, other than the manufacture and supply of nirogacestat and certain expenses related to intellectual property rights. The collaboration is managed by a joint development committee of equal representation by the Company and Allogene. Janssen clinical collaboration agreement In September 2020, the Company entered into a clinical collaboration and supply agreement with Janssen Biotech, Inc., or Janssen, to evaluate the Company’s investigational gamma secretase inhibitor, or GSI, nirogacestat, in combination with Janssen’s bispecific antibody targeting BCMA, and CD3, teclistamab, in patients with relapsed or refractory multiple myeloma. Janssen is responsible for administering the Phase 1 clinical trial and is responsible for all costs associated with the direct conduct of the clinical trial, other than the manufacture and supply of nirogacestat and certain expenses related to intellectual property rights. The collaboration is managed by a joint oversight committee of equal representation by the Company and Janssen. Precision BioSciences clinical collaboration agreement In September 2020, the Company entered into a clinical trial collaboration agreement with Precision BioSciences, Inc., or Precision, to evaluate nirogacestat in combination with PBCAR269A, an investigational allogeneic, or CAR-T cell therapy candidate targeting BCMA, in patients with relapsed or refractory multiple myeloma. ​ Precision is responsible for administering the Phase 1/2a clinical trial and is responsible for all costs associated with the direct conduct of the clinical trial, other than the manufacture and supply of nirogacestat and certain expenses related to intellectual property rights. The collaboration is managed by a joint steering committee of equal representation by the Company and Precision. ​ Pfizer clinical collaboration agreement In October 2020, the Company entered into a clinical trial collaboration and supply agreement with Pfizer to evaluate nirogacestat in combination with Pfizer’s bispecific antibody targeting BCMA and CD3, elranatamab, in patients with relapsed or refractory multiple myeloma. ​ Pfizer is responsible for administering the Phase 1b/2 clinical trial and is responsible for all costs associated with the direct conduct of the clinical trial, other than the manufacture and supply of nirogacestat and certain expenses related to intellectual property rights. The collaboration is managed by a joint development committee of equal representation by the Company and Pfizer. ​ Jazz Pharmaceuticals asset purchase and exclusive license agreement ​ In October 2020, the Company and Jazz announced an asset purchase and exclusive license agreement, pursuant to which Jazz acquired the Company’s fatty acid amide hydrolase, or FAAH, inhibitor program including PF-04457845. The FAAH inhibitor program was obtained by the Company as part of the License Agreements in 2017. Jazz made an upfront payment of $35 million to the Company with potential future payments of up to $375 million based upon the achievement of certain clinical development, regulatory, and commercial milestones. In addition, Jazz is obligated to pay the Company tiered sales-based royalties on future net sales of PF-04457845 in the single-digit range. ​ Pursuant to the Jazz Agreement, Jazz is obligated to use commercially reasonable efforts to develop and seek regulatory approval for at least one product in the United States and if regulatory approval is obtained, to commercialize such product in the United States. Consideration received under the Jazz Agreement The Company evaluated the Jazz Agreement under ASC 606, and determined there was a single performance obligation and the license was the predominant item in a bundle of goods that was distinct. The Company transferred all items in the bundle of goods, including the license, in the period ended December 31, 2020. The license is functional intellectual property, given the functionality of the intellectual property is not expected to change substantially as a result of the Company’s ongoing activities, and accordingly, revenue should be recognized at a point in time. The Company recognized the upfront payment as revenue in the period ended December 31, 2020. The Company will not recognize development or regulatory approval milestones until the related activity has been achieved; and royalties, including commercial milestone payments based on the level of sales, will be recognized at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all the royalty has been allocated has been satisfied (or partially satisfied), which for the Jazz Agreement will be the period when the related sales occur.

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Investments
Investments	11. Investments MapKure In June 2019, the Company announced the formation of MapKure, an entity jointly owned by the Company and BeiGene. BeiGene licensed to MapKure exclusive rights to BGB-3245, an oral, small molecule selective inhibitor of specific BRAF driver mutations and genetic fusions. MapKure is advancing BGB-3245 through clinical development for solid tumor patients harboring BRAF driver mutations and genetic fusions that were observed to be sensitive to the compound in preclinical studies. In addition to the Company’s equity ownership in MapKure, the Company has appointed a member to each of MapKure’s joint steering committee and board of directors. The Company also contributes to clinical development and other operational activities for BGB-3245 through a service agreement with MapKure. ​ In conjunction with the formation of MapKure in June 2019, the Company purchased 3,500,000 Series A preferred units of MapKure, or a 25% ownership interest, for $3.5 million, and BeiGene received 10,000,000 Series A preferred units as payment for its contributed intellectual property, or a 71.4% ownership interest. Two individuals each purchased ownership In June 2020, the Company purchased an additional 3,500,000 Series A preferred units of MapKure for $3.5 million, as required by the terms of the initial investment in MapKure. As of December 31, 2020, the Company’s ownership interest in MapKure is 38.9%. The Company determined that MapKure is a variable interest entity. The Company is not the primary beneficiary, as the Company does not have the power to direct the activities that most significantly impact the economic performance of MapKure. Accordingly, the Company does not consolidate the financial statements of this entity and accounts for this investment using the equity method of accounting. The Company reaffirmed its assessment as of December 31, 2020. In accordance with ASC 323-10-35-6, the Company records its portion of MapKure’s earnings or losses based on a one quarter lag. For the year ended December 31, 2020, the Company recognized a $0.6 million loss for its portion of MapKure’s losses. The Company’s investment in MapKure is included in “Equity method investments” in the consolidated balance sheet. The balance of the Company’s investment was $3.9 million at December 31, 2020, representing the maximum exposure to loss as a result of the Company’s involvement with MapKure.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies
Commitments and Contingencies	12. Commitments and Contingencies As of December 31, 2020, the Company had obligations consisting of operating leases for facilities. Refer to Footnote 7: Leases The Company enters into contracts in the normal course of business for clinical trials, preclinical studies, manufacturing and other services and products for operating purposes. These contracts generally provide for termination following a certain period after notice and therefore the Company believes that non-cancelable obligations under these agreements are not material. ​ Additionally, the Company has excluded milestone or royalty payments or other contractual payment obligations as the timing and amount of such obligations are unknown or uncertain. ​ Contingencies From time to time, the Company may be involved in disputes or regulatory inquiries that arise in the ordinary course of business. When the Company determines that a loss is both probable and reasonably estimable, a liability is recorded and disclosed if the amount is material to the financial statements taken as a whole. When a material loss contingency is only reasonably possible, the Company does not record a liability, but instead discloses the nature and the amount of the claim, and an estimate of the loss or range of loss, if such an estimate can reasonably be made. As of December 31, 2020, and December 31, 2019, there was no litigation or contingency that created at least a reasonable possibility of a material loss.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Taxes
Income Taxes	13. Income Taxes Prior to the Reorganization, SpringWorks Therapeutics, LLC elected to be treated under the partnership provisions of the Internal Revenue Service code. However, its five wholly owned subsidiaries, SpringWorks Operating Company, SpringWorks Subsidiary 1, SpringWorks Subsidiary 2, SpringWorks Subsidiary 3, and SpringWorks Subsidiary 4, or Combined Subsidiaries, are taxable corporations. Subsequent to the Reorganization, SpringWorks Therapeutics, Inc. became the 100% owner of SpringWorks Therapeutics, LLC, creating a new ultimate parent company, and a consolidated group for income tax reporting. The Reorganization and change in tax status of the reporting entity did not have an impact on the consolidated tax provision. For the years ended December 31, 2020 and December 31, 2019, the Company did not have a current or deferred income tax expense or benefit as the Company has incurred losses since inception. As of December 31, 2020, the Company has federal, state and city net operating loss carryforwards of $110.9 million, $0.6 million and $3.7 million, respectively, which are available to reduce future taxable income. Federal net operating loss carryforwards of $34.8 million, $55.9 million and $16.0 million reported in 2020, 2019 and 2018, will be available to offset 80% of taxable income for an indefinite period of time, until fully utilized. Federal net operating loss carryforwards of $4.3 million reported in 2017 and the state and city net operating loss carryforwards expire at various dates through 2038. The Company also has federal tax credits of The net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions and other provisions within the Internal Revenue Code. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to an ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has not recorded any reserves for uncertain tax positions as of December 31, 2020 or December 31, 2019. The Company has completed a study for the research and development credit carryforwards through December 31, 2019, and has not yet conducted a study of research and development credit carryforwards for the year ended December 31, 2020. The 2020 study, once completed, may result in an adjustment to the Company’s research and development credit carryforwards. A full 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 valuation allowance. Thus, there would be no impact to the balance sheets or statements of operations and comprehensive loss if an adjustment were required. Interest and penalty charges, if any, related to unrecognized tax benefits will be classified as income tax expense in the accompanying statements of operations and comprehensive loss. As of December 31, 2020, the Company had no 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. The Company is not currently under examination by the Internal Revenue Service or any other jurisdictions for any tax years. The principal components of the Subsidiaries deferred tax assets are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (in thousands) 2020 2019 Deferred tax assets: ​ ​ Net operating loss carryforwards ​ $ 23,630 ​ $ 16,252 Research and development credits ​ 1,673 ​ 706 Orphan drug credit ​ ​ 5,519 ​ ​ 71 Deferred rent ​ — ​ 242 Accrued expenses ​ 1,225 ​ 212 Depreciation ​ ​ 71 ​ ​ 34 Stock compensation ​ ​ 1,972 ​ ​ 496 Operating lease liabilities ​ 574 ​ — Total deferred tax assets ​ 34,664 ​ 18,013 Deferred tax liability: ​ ​ ​ ​ Operating lease right-of-use assets ​ ​ (408) ​ ​ — Valuation allowance ​ (34,256) ​ (18,013) Net deferred tax assets ​ $ — ​ $ — ​ ASC 740 requires a valuation allowance to reduce the deferred tax assets reported if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. After consideration of all the evidence, both positive and negative, the Company has recorded a full valuation allowance against its deferred tax assets at December 31, 2020 and December 31, 2019 because the Company’s management has determined that it is more likely than not that these assets will not be realized. The increase in the valuation allowance of $16.2 million in 2020 primarily relates to the net loss incurred by the Company as well as federal research and orphan drug credits generated. The effective tax rate for the Company for the years ended December 31, 2020, December 31, 2019 and December 31, 2018 was zero percent. A reconciliation of the income tax expense at the federal statutory tax rate to the Company’s effective income tax rate follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 ​ 2019 ​ 2018 Statutory tax rate 21.00 % ​ 21.00 % ​ 21.00 % Federal and state return to provision adjustments 0.03 ​ (0.01) ​ ​ (1.08) ​ Stock-based compensation ​ 0.55 ​ ​ — ​ ​ — ​ Research and development credit 2.12 ​ 0.57 ​ ​ 2.02 ​ Orphan drug credit ​ 11.95 ​ ​ — ​ ​ — ​ Other (0.01) ​ (0.03) ​ ​ (0.04) ​ Change in valuation allowance (35.64) ​ (21.53) ​ ​ (21.90) ​ Effective tax rate — % ​ — % ​ — % ​

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2020
401(k) Plan
401(k) Plan	14. 401(k) Plan In 2017, the Company adopted a tax-qualified employee savings and retirement plan, or the 401(k) Plan, that covers all of its full-time employees who are at least 21 years of age. Pursuant to the 401(k) Plan, participants may elect to contribute up to the federally allowed maximum limits of their pretax earnings to the 401(k) Plan. As of December 31, 2020, the Company has not made any matching contributions.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions
Related Party Transactions	15. Related Party Transactions Pfizer is a significant shareholder of the Company and a former Pfizer employee is a member of the Board of Directors. See Note 9 for further details on transactions entered into with Pfizer. Prior to the IPO, the Company regarded the Board of Directors, or BOD, as related parties. The Company recorded consulting and BOD expenses totaling $0.2 million for the period January 1, 2019 through the date of the IPO. For the year ended December 31, 2018, the Company recorded consulting and BOD expenses totaling $0.3 million.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2020
Net Loss per Share
Net Loss per Share	16. Net Loss per Share Basic and diluted net loss per unit and share is calculated as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands, except share and per-share data) 2020 2019 ​ 2018 Numerator: ​ ​ ​ ​ Net loss ​ $ (45,574) ​ $ (58,306) ​ $ (17,813) Net gain attributable to extinguishment of Series A convertible preferred and Junior Series A convertible preferred units ​ — ​ 7,729 ​ — Net loss attributable to common stockholders  ​ $ (45,574) ​ $ (50,577) ​ $ (17,813) Denominator: ​ ​ ​ ​ ​ Weighted average units outstanding, basic and diluted ​ ​ — ​ ​ — ​ ​ 341,014 Weighted average shares outstanding, basic and diluted ​ 43,300,063 ​ 13,274,836 ​ — Net loss per unit, basic and diluted ​ $ — ​ $ — ​ $ 52.24 Net loss per share, basic and diluted ​ $ (1.05) ​ $ (3.81) ​ $ — ​ Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2020 2019 Common stock options issued and outstanding 4,505,546 3,225,725 Restricted stock subject to future vesting 686,868 1,289,437 Total potentially dilutive securities 5,192,414 4,515,162 ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or U.S. GAAP.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of SpringWorks Therapeutics, Inc. and its subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Investments in business entities in which the Company lacks control but does have the ability to exercise significant influence over operating and financial policies are accounted for using the equity method of accounting.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, Research and Development expenses and the valuation of equity-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or relevant factors that it believes to be reasonable under the circumstances. Actual results may differ from those estimates. On an ongoing basis, management evaluates its estimates, and adjusts those estimates and assumptions when facts or circumstances change. Changes in estimates are recorded in the period in which they become known.
Segment Information	Segment Information Operating segments are defined as components of an entity about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment operating exclusively in the United States.
SEC Filing Status	SEC Filing Status The Company became a large accelerated filer on December 31, 2020, based on the market value of the Company's common stock held by non-affiliates as of the last day of the second quarter in 2020. Prior to that, the Company was an emerging growth company, or EGC, as defined in the Jumpstart Our Business Startups Act, or the JOBS Act. Being an EGC allowed the Company to defer adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. The Company had elected to use this extended transition period under the JOBS Act. The Company lost the ability to defer adoption of new or revised accounting pronouncements when it became a large accelerated filer as of December 31, 2020. As a result, the financial statements included in this Annual Report reflect the adoption of new accounting standards effective for calendar year end public companies, including the adoption of Financial Accounting Standards Board Accounting Standards Codification Topic, or ASC, 842, Leases. Refer to the sections titled Recently Adopted Accounting Pronouncements in Footnote 3 and Footnote 7: Leases
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid instruments that have maturities of three months or less when acquired to be cash equivalents. The Company had cash and cash equivalents as of December 31, 2020 and 2019 of $147.1 million and $327.7 million, respectively.
Marketable Securities	Marketable Securities Marketable debt securities are reported at fair value with unrealized gains and losses included in Accumulated other comprehensive income. Each reporting period, the Company evaluates whether there are declines in fair value below amortized cost and if these declines are due to credit losses, as well as the Company’s ability and intent to hold the investment until a forecasted recovery occurs. If both criteria regarding the intent or ability to hold are met, any decline in fair value due to credit losses is recorded as an allowance through Other income (expense), net on the Company’s consolidated statements of operations; limited by the amount that the fair value is less than the amortized costs basis. If either criteria is not met, any previously recorded allowance for credit losses and any excess amortized cost basis over fair value is recorded in Other income (expense), net on the Company’s consolidated statements of operations. As of, and for the year ended December 31, 2020, the Company did not have any allowance for credit losses or impairments of its marketable securities.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and available-for-sale marketable securities. The Company maintains each of its cash, cash equivalent balances and marketable securities balances with high quality, financial institutions and the Company’s marketable securities are invested in high-quality, highly liquid debt securities including corporate debt securities, U.S. government securities and commercial paper.
Property and Equipment	Property and Equipment Property and equipment consist of computer equipment, furniture and leasehold improvements and are recorded at cost. Property and equipment are depreciated on a straight-line basis over their estimated useful lives.
Revenue	Revenue The Company recognizes revenue for consideration received related to the development and commercialization of medicines, which is conducted through various means, including in-house development by the Company, joint development or collaboration agreements with third parties, sale or out licensing of product rights, and others. The terms of these arrangements and agreements may contain multiple promised goods and services, which may include licenses, know-how, drug product, related agreements and other deliverables. Payments to the Company under these arrangements may include one or more of the following: upfront license fees; milestone payments; and royalties on future product sales. Arrangements Within the Scope of ASC 606, Revenue from Contracts with Customers The Company recognizes revenue in accordance with ASC 606, which applies to all contracts with customers, except for contracts that are within the scope of other standards, such as collaboration arrangements and leases. Pursuant to ASC 606, the Company recognizes revenue when its customers obtain control of promised goods or services, in an amount that reflects the consideration which the Company determines it expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligation(s). As part of the accounting for these arrangements, the Company may be required to make significant judgments, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each performance obligation. Once a contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within the contract and determines those that are performance obligations. The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and may require management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). In assessing whether a promised good or service is distinct, the Company considers factors such as the research, manufacturing and commercialization capabilities of the customer and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, an entity is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied at a point in time or over time, and if over time based on the use of an output or input method. Licenses of intellectual property: of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. ​ Up-front Fees: ​ Milestone Payments: ​ Royalties: ​ Reimbursement, cost-sharing and profit-sharing payments:
Research and Development	Research and Development In accordance with ASC 730, “Research and Development”, expenditures for clinical development, including upfront licensing fees and milestone payments associated with products that have not yet been approved by the U.S. Food and Drug Administration, are charged to research and development expense as incurred. These expenses consist of expenses incurred in performing development activities, including salaries and benefits, equity-based compensation expense, preclinical expenses, clinical trial and related clinical manufacturing expenses, contract services and other outside expenses. Expenses incurred for certain research and development activities, including expenses associated with particular activities performed by contract research organizations, investigative sites in connection with clinical trials and contract manufacturing organizations, are recognized based on an evaluation of the progress or completion of specific tasks using either time-based measures or data such as information provided to the Company by its vendors on actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of expense recognition. Expenses for research and development activities incurred that have yet to be invoiced by the vendors that perform the related activities are reflected in the consolidated financial statements as accrued research and development expenses. Advance payments for goods or services to be received in the future for research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed.
General and Administrative	General and Administrative General and administrative expenses consist primarily of payroll and employee related costs including salaries and benefits, equity-based compensation expense, rent and utilities, infrastructure, corporate insurance, office expenses and consulting and professional services, including legal, regulatory and compliance.
Equity-based compensation expense	Equity-based compensation expense The Company accounts for employee equity-based compensation in accordance with ASC 718, Compensation — Stock Compensation, which requires all equity-based awards to employees and non-employee directors be recognized as expense in the statement of operations based on the grant date fair value of the awards. The Company’s equity-based awards generally vest over three Stock compensation expense is recognized using the straight-line method, based on the grant date fair value, over the requisite service period of the award, which is generally the vesting term. For awards subject to performance conditions, as well as awards containing both market and performance conditions, the Company recognizes equity award compensation expense using an accelerated recognition method over the remaining service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the expected satisfaction of the performance conditions as of the reporting date. The Company recognizes forfeitures at the time of the actual forfeiture event in accordance with the adoption of the guidance per Accounting Standard Update, or ASU, No. 2016-09. The grant-date fair value of performance-based awards with market conditions is estimated using a Monte Carlo simulation method that incorporates the probability of the performance conditions being met as of the grant date. For stock options issued, the Company estimates the grant date fair value and the resulting stock-based compensation expense using the Black-Scholes option-pricing model. The Black-Scholes option-pricing model requires the use of certain subjective assumptions which determine the fair value of stock-based awards, including the expected term and the price volatility of the underlying stock. Inputs used in the Black-Scholes option-pricing model are: ● Fair value of common stock, which is the current trading price of the Company’s common stock. ● Expected term — The expected term represents the period that the equity-based awards are expected to be outstanding. The Company uses the simplified method to calculate the expected term due to the limited Company-specific historical information available for the Company. ● Expected volatility — The Company lacks Company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until it has adequate historical data regarding the volatility of its own traded stock. ● Risk-free interest rate — The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the awards. ● Expected dividend — The Company has never paid dividends on its common units or stock and has no plans to pay dividends on its common stock. Therefore, the expected dividend yield is zero . For equity-based compensation grants prior to the IPO, the Company estimated the fair value of equity awards granted using the special case of the market approach, including the guideline public company method and precedent transaction method which is known as a backsolve method. This option pricing model was utilized to solve for the implied total equity value that was consistent with the Company’s Series A convertible preferred units “backsolves” to a preferred share price. The backsolve method derives the implied equity value for one type of equity security from a contemporaneous transaction involving another type of security to calculate the equity value. The use of these valuation approaches required management to make assumptions with respect to the expected volatility of its units and stock, time until a liquidity event and risk-free interest rates. Equity value was allocated to the common, incentive and convertible preferred units, and common, restricted and convertible preferred stock using an option-pricing method. Under this method, the common and incentive units and common stock would have had value only if the funds available for distribution exceeded the value of the convertible preferred units’ liquidation preferences at the anticipated time of a liquidity event, such as a strategic sale, merger or IPO.
Net Loss per Unit and Share	Net Loss per Unit and Share Basic net loss per unit and per share is computed by dividing net loss by the weighted average number of common units and shares outstanding for the period. Diluted net loss per unit and share excludes the potential impact of convertible preferred units, unvested incentive units, convertible preferred stock, unvested restricted stock and stock options because their effect would be anti-dilutive due to the Company’s net loss. Since the Company had a net loss in each of the periods presented, basic and diluted net loss per common unit and share are the same.
Income Taxes	Income Taxes Income taxes are accounted for using the asset-and-liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized as income in the period that includes the enactment date. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company recognizes deferred tax assets to the extent that it believes that these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company records uncertain tax positions in accordance with ASC 740 on the basis of a two-step process in which (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. These reserves are based on a determination of whether and how much of a tax benefit taken by the Company in its filings or positions is more likely than not to be realized following resolution of any potential contingencies related to the tax benefit. Potential interest related to the underpayment of income taxes will be classified as a component of income tax expense and any related penalties will be classified in income tax expenses in the statement of operations. SpringWorks Therapeutics, LLC elected to be treated under the partnership provisions of the Internal Revenue Service Code prior to the reorganization on March 29, 2019. However, its five wholly owned subsidiaries, SpringWorks Operating Company, SpringWorks Subsidiary 1, SpringWorks Subsidiary 2, SpringWorks Subsidiary 3, and SpringWorks Subsidiary 4, are taxable corporations. Subsequent to the Reorganization, SpringWorks Therapeutics, Inc. became the 100% owner of SpringWorks Therapeutics, LLC, creating a new ultimate parent company, and a consolidated group for income tax reporting. The Reorganization and change in tax status of the reporting entity did not have an impact on the consolidated tax provision.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Leases In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This standard requires entities that lease assets to recognize on the balance sheet the assets and liabilities of the rights and obligations created by those leases. The Company utilized a package of practical expedients A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term. All other leases are recorded as operating leases. ​ Finance and operating lease assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term using the discount rate implicit in the lease. If the rate implicit is not readily determinable, the Company utilizes its incremental borrowing rate at the lease commencement date. Operating lease assets are further adjusted for prepaid or accrued lease payments. Operating lease payments are expensed using the straight-line method as an operating expense over the lease term. Finance lease assets are amortized to depreciation expense using the straight-line method over the shorter of the useful life of the related asset or the lease term. Finance lease payments are bifurcated into (i) a portion that is recorded as imputed interest expense and (ii) a portion that reduces the finance liability associated with the lease. ​ The Company does not separate lease and non-lease components when determining which lease payments to include in the calculation of its lease assets and liabilities. Variable lease payments are expensed as incurred. If a lease includes an option to extend or terminate the lease, the Company reflects the option in the lease term if it is reasonably certain it will exercise the option. ​ Operating leases are recorded in “Operating lease right-of-use-assets,” “Operating lease liabilities, current” and “Operating lease liabilities, long-term” on the Company’s consolidated balance sheet. The Company had no finance lease obligations for the periods presented. Refer to Footnote 7 for additional lease disclosures. ​ The cumulative effect of applying ASC 842 on the Company’s consolidated balance sheet as of January 1, 2020 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of ​ ​ ​ ​ ​ Balance as of (in thousands) ​ ​ December 31, 2019 * ​ ​ Adjustments ​ ​ January 1, 2020 Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease right-of-use-assets $ — ​ $ 2,848 ​ $ 2,848 Total assets ​ $ — ​ $ 2,848 ​ $ 2,848 Liabilities ​ ​ ​ ​ ​ ​ ​ — Operating lease liabilities, current ​ $ — ​ $ 1,382 ​ $ 1,382 Deferred rent ​ 363 ​ ​ (363) ​ ​ — Operating lease liabilities, long-term ​ ​ — ​ ​ 2,618 ​ ​ 2,618 Long-term portion of deferred rent ​ ​ 789 ​ ​ (789) ​ ​ — Total liabilities ​ $ 1,152 ​ $ 2,848 ​ $ 4,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ *As reported in the Company's 2019 Annual Report on Form 10-K. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Internal-Use Software In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, or ASU 2018-15. The FASB issued ASU 2018-15 to align the requirements for capitalizing implementation costs incurred in a cloud-based hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The Company adopted ASU 2018-15 as of January 1, 2020. The adoption of ASU 2018-15 did not have a significant impact on the Company’s consolidated financial statements. Credit Losses In 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires entities to record expected credit losses for certain financial instruments, including trade receivables, as an allowance that reflects the entity's current estimate of credit losses expected to be incurred. For available-for-sale debt securities with unrealized losses, the standard now requires allowances to be recorded instead of reducing the amortized cost of the investment with certain exceptions. ASU 2016-13 became effective on January 1, 2020. The adoption of ASU 2016-13 did not have a significant impact on the Company’s consolidated financial statements. The Company updated its accounting policy for evaluating impairment of its marketable securities. ​ Recently Issued Accounting Pronouncements In 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740), which simplifies the accounting for income taxes. ASU 2019-12 will be effective for the Company on January 1, 2021 and is not expected to have a significant impact on the Company’s consolidated financial statements .

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
ASU 2016-02
Recently Adopted Accounting Pronouncements
Schedule of the cumulative effect of applying ASC 842	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of ​ ​ ​ ​ ​ Balance as of (in thousands) ​ ​ December 31, 2019 * ​ ​ Adjustments ​ ​ January 1, 2020 Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease right-of-use-assets $ — ​ $ 2,848 ​ $ 2,848 Total assets ​ $ — ​ $ 2,848 ​ $ 2,848 Liabilities ​ ​ ​ ​ ​ ​ ​ — Operating lease liabilities, current ​ $ — ​ $ 1,382 ​ $ 1,382 Deferred rent ​ 363 ​ ​ (363) ​ ​ — Operating lease liabilities, long-term ​ ​ — ​ ​ 2,618 ​ ​ 2,618 Long-term portion of deferred rent ​ ​ 789 ​ ​ (789) ​ ​ — Total liabilities ​ $ 1,152 ​ $ 2,848 ​ $ 4,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ *As reported in the Company's 2019 Annual Report on Form 10-K. ​ ​ ​ ​ ​ ​ ​ ​ ​

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2020
Marketable Securities
Summary of available-for-sale marketable securities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses ​ Estimated Fair Value Marketable securities: ​ ​ ​ ​ ​ Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ $ 157,079 ​ $ 24 ​ $ (1) ​ $ 157,102 Corporate debt securities ​ 74,773 ​ 2 ​ (10) ​ 74,765 Commercial paper ​ ​ 129,528 ​ ​ — ​ ​ — ​ ​ 129,528 Long-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ ​ 53,310 ​ ​ 26 ​ ​ — ​ ​ 53,336 Total ​ $ 414,690 ​ $ 52 ​ $ (11) ​ $ 414,731

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Measurements
Schedule of financial assets subject to fair value measurements	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 ​ ​ ​ ​ ​ Fair Value Hierarchy (in thousands) Total Level 1 Level 2 ​ Level 3 Financial instruments carried at fair value (asset position): ​ ​ ​ ​ ​ Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 107,723 ​ $ 107,723 ​ $ — ​ $ — Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ 157,102 ​ 157,102 ​ — ​ — Corporate debt securities ​ 74,765 ​ — ​ 74,765 ​ — Commercial paper ​ ​ 129,528 ​ ​ — ​ ​ 129,528 ​ ​ — Long-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Government securities ​ ​ 53,336 ​ ​ 53,336 ​ ​ — ​ ​ — Total ​ $ 522,454 ​ $ 318,161 ​ $ 204,293 ​ $ —

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property and Equipment
Property and equipment, net	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ (in thousands) ​ 2020 ​ ​ 2019 Useful Life Leasehold improvements ​ $ 1,184 ​ $ 855 ​ Length of lease or 5 years, whichever is shorter Computer equipment ​ ​ 157 ​ ​ 122 ​ 3 years Furniture ​ ​ 97 ​ ​ 31 ​ 5 years Software ​ ​ 62 ​ ​ — ​ 3 years Construction in process ​ ​ 104 ​ ​ — ​ ​ ​ ​ ​ 1,604 ​ ​ 1,008 ​ ​ Less accumulated depreciation ​ ​ (529) ​ ​ (213) ​ ​ ​ ​ $ 1,075 ​ $ 795 ​ ​

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases
Schedule of components of lease costs	​ ​ ​ ​ ​ (in thousands) ​ 2020 Operating lease cost ​ ​ ​ Fixed ​ $ 1,049 Variable ​ 486 Total lease cost ​ $ 1,535
Schedule of operating lease assets and liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ As of December 31, 2020 ​ ​ As of December 31, 2019* Operating leases ​ ​ ​ ​ ​ Operating lease right-of-use-assets ​ $ 1,944 ​ $ — Total operating lease assets ​ $ 1,944 ​ $ — ​ ​ ​ ​ ​ Operating lease liabilities, current ​ $ 1,375 ​ $ — Operating lease liabilities, long-term ​ 1,359 ​ — Total operating lease liabilities ​ $ 2,734 ​ $ — ​ ​ ​ ​ ​ ​ ​ *As reported in the Company's 2019 Annual Report on Form 10-K. ​ ​ ​ ​ ​ ​
Schedule of future minimum lease obligations	​ ​ ​ ​ ​ ​ ​ (in thousands) ​ Operating Leases 2021 ​ $ 1,396 2022 ​ 1,298 2023 ​ 135 2024 and thereafter ​ — Total lease payments ​ ​ 2,829 Less: imputed interest ​ ​ (95) Present value of lease liabilities ​ $ 2,734
Schedule of weighted-average remaining lease terms and discount rates	​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020 Weighted-average remaining lease term (in years) ​ ​ ​ Operating leases ​ ​ 2.0 Weighted-average discount rate ​ ​ ​ Operating leases ​ ​ 3.45%
Schedule of supplemental cash flow information	​ ​ ​ ​ ​ (in thousands) ​ ​ December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ Operating cash flows from operating leases ​ $ 1,411 Right-of-use assets obtained in exchange for new operating lease liabilities ​ ​ 31

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Accrued Expenses
Schedule of accrued expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, (in thousands) 2020 2019 Accrued professional fees ​ $ 827 ​ $ 793 Accrued compensation and benefits ​ 5,834 ​ 3,147 Accrued research and development ​ ​ 7,922 ​ ​ 4,447 Accrued other ​ 302 ​ 566 Total accrued expenses ​ $ 14,885 ​ $ 8,953

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of equity-based compensation expense related to restricted stock and stock options	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (in thousands) ​ 2020 ​ 2019 ​ ​ 2018 Research and development ​ $ 3,055 ​ $ 731 ​ $ 164 General and administrative ​ ​ 6,979 ​ ​ 2,378 ​ ​ 905 Total equity compensation expense ​ $ 10,034 ​ $ 3,109 ​ $ 1,069
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of the changes in the Company's options during the period	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ ​ ​ Weighted ​ Remaining ​ ​ ​ ​ ​ ​ ​ Average ​ Contractual ​ Aggregate ​ ​ ​ ​ ​ Exercise ​ Life ​ Intrinsic ​ Shares ​ Price (Years)​ Value Outstanding at December 31, 2018 ​ — ​ ​ — ​ — ​ — Granted ​ — ​ ​ — ​ — ​ — Outstanding at March 29, 2019 ​ 148,415 ​ $ 1.65 ​ — ​ — Granted ​ 3,177,233 ​ ​ 5.21 ​ — ​ — Exercised ​ (9,080) ​ ​ 2.30 ​ — ​ — Forfeited/cancelled ​ (90,843) ​ ​ 2.18 ​ — ​ — Outstanding at December 31, 2019 3,225,725 ​ ​ 5.08 9.4 ​ 107,771,472 Granted 1,580,788 ​ ​ 35.90 — ​ — Exercised ​ (190,484) ​ ​ 4.69 ​ — ​ — Forfeited/cancelled (110,483) ​ ​ 23.49 — ​ — Outstanding at December 31, 2020 4,505,546 ​ ​ 15.51 ​ 8.7 ​ 256,860,405 Exercisable at December 31, 2020 ​ 1,402,718 ​ ​ 8.25 ​ 8.5 ​ 90,150,057
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of the changes in the Company's restricted stock	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ Number ​ ​ Grant Date ​ of Shares ​ Fair Value Unvested and outstanding at December 31, 2018 ​ 2,503,744 ​ $ 1.25 Vested ​ (228,209) ​ ​ 0.81 Forfeited ​ (12,570) ​ ​ 1.45 Unvested and outstanding at March 29, 2019 ​ 2,262,965 ​ ​ 1.24 Vested ​ (737,530) ​ ​ 1.26 Forfeited ​ (235,998) ​ ​ 1.36 Unvested and outstanding at December 31, 2019 1,289,437 ​ ​ 1.21 Vested (588,345) ​ ​ 1.14 Forfeited (14,224) ​ ​ 1.45 Unvested and outstanding at December 31, 2020 686,868 ​ ​ 1.26

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Taxes
Schedule of principal components of the Subsidiaries deferred tax assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (in thousands) 2020 2019 Deferred tax assets: ​ ​ Net operating loss carryforwards ​ $ 23,630 ​ $ 16,252 Research and development credits ​ 1,673 ​ 706 Orphan drug credit ​ ​ 5,519 ​ ​ 71 Deferred rent ​ — ​ 242 Accrued expenses ​ 1,225 ​ 212 Depreciation ​ ​ 71 ​ ​ 34 Stock compensation ​ ​ 1,972 ​ ​ 496 Operating lease liabilities ​ 574 ​ — Total deferred tax assets ​ 34,664 ​ 18,013 Deferred tax liability: ​ ​ ​ ​ Operating lease right-of-use assets ​ ​ (408) ​ ​ — Valuation allowance ​ (34,256) ​ (18,013) Net deferred tax assets ​ $ — ​ $ —
Schedule of reconciliation of U.S. statutory income tax rate to effective tax rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 ​ 2019 ​ 2018 Statutory tax rate 21.00 % ​ 21.00 % ​ 21.00 % Federal and state return to provision adjustments 0.03 ​ (0.01) ​ ​ (1.08) ​ Stock-based compensation ​ 0.55 ​ ​ — ​ ​ — ​ Research and development credit 2.12 ​ 0.57 ​ ​ 2.02 ​ Orphan drug credit ​ 11.95 ​ ​ — ​ ​ — ​ Other (0.01) ​ (0.03) ​ ​ (0.04) ​ Change in valuation allowance (35.64) ​ (21.53) ​ ​ (21.90) ​ Effective tax rate — % ​ — % ​ — %

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Net Loss per Share
Schedule of Basic and diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands, except share and per-share data) 2020 2019 ​ 2018 Numerator: ​ ​ ​ ​ Net loss ​ $ (45,574) ​ $ (58,306) ​ $ (17,813) Net gain attributable to extinguishment of Series A convertible preferred and Junior Series A convertible preferred units ​ — ​ 7,729 ​ — Net loss attributable to common stockholders  ​ $ (45,574) ​ $ (50,577) ​ $ (17,813) Denominator: ​ ​ ​ ​ ​ Weighted average units outstanding, basic and diluted ​ ​ — ​ ​ — ​ ​ 341,014 Weighted average shares outstanding, basic and diluted ​ 43,300,063 ​ 13,274,836 ​ — Net loss per unit, basic and diluted ​ $ — ​ $ — ​ $ 52.24 Net loss per share, basic and diluted ​ $ (1.05) ​ $ (3.81) ​ $ —
Schedule of potential common shares not included in the calculation of the diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2020 2019 Common stock options issued and outstanding 4,505,546 3,225,725 Restricted stock subject to future vesting 686,868 1,289,437 Total potentially dilutive securities 5,192,414 4,515,162

Nature of Operations (Details)

Nature of Operations (Details) $ / shares in Units, $ in Thousands	Oct. 13, 2020USD ($)$ / sharesshares	Sep. 12, 2019USD ($)$ / sharesshares	Sep. 12, 2019$ / sharesshares	Oct. 31, 2020USD ($)	Aug. 31, 2019	Dec. 31, 2020USD ($)itemshares	Dec. 31, 2019USD ($)shares
Subsidiary, Sale of Stock [Line Items]
Number of clinical trials | item						2
Shares issued | shares	5,637,254
Share Price | $ / shares	$ 51
Proceeds from issuance of common stock, net of issuance costs | $	$ 269,500					$ 269,592	$ 169,730
Conversion rate | shares			6.5810
Preferred stock outstanding | shares						0	0
Reverse stock split					0.1520
Accumulated deficit | $						$ (118,603)	$ (73,029)
Working Capital | $						495,800	319,400
Cash, cash equivalents and marketable securities | $						$ 561,800	$ 327,700
IPO
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares		10,350,000
Share Price | $ / shares		$ 18	$ 18
Net proceeds from the IPO | $		$ 169,700
Underwriting discounts and commissions | $		13,000
Proceeds from issuance of common stock, net of issuance costs | $				$ 269,500
Issuance costs | $		$ 3,500
Number of shares converted | shares		196,076,779
Number of shares issued upon conversion | shares		29,794,359	29,794,359
Preferred stock outstanding | shares		0	0
Underwriter's option
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares	735,294

Nature of Operations - Series B

Nature of Operations - Series B convertible preferred (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Mar. 31, 2019	Oct. 13, 2020
Class of Stock [Line Items]
Price per unit		$ 51
Series B convertible preferred stock
Class of Stock [Line Items]
Number of shares authorized to issue	86,639,279
Price per unit	$ 1.4428
Proceeds from issuance of convertible preferred shares, net of issuance costs	$ 125
Issuance costs	$ 0.4

Nature of Operations - Reorgani

Nature of Operations - Reorganization (Details)	Mar. 29, 2019shares
Series A convertible preferred unit
Reorganizations [Line Items]
Number of stock per unit	1
Junior Series A convertible preferred unit
Reorganizations [Line Items]
Number of stock per unit	1
Common units
Reorganizations [Line Items]
Number of stock per unit	1
Incentive units
Reorganizations [Line Items]
Number of stock per unit	1
Unit options
Reorganizations [Line Items]
Number of stock per unit	1

Risks and Liquidity (Details)

Risks and Liquidity (Details) - USD ($) $ in Thousands	Oct. 13, 2020	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Risks and Liquidity
Accumulated deficit			$ (118,603)	$ (73,029)
Working Capital			495,800	319,400
Cash, cash equivalents and marketable securities			561,800	327,700
Increase in the cash balance			234,200
Proceeds from issuance of common stock, net of issuance costs	$ 269,500		269,592	169,730
Proceeds from issuance of Series A convertible preferred shares, net of issuance costs				39,367	$ 50,376
Proceeds from issuance of Series B convertible preferred shares, net of issuance costs				124,590
Net loss			$ (45,574)	$ (58,306)	$ (17,813)
IPO
Risks and Liquidity
Proceeds from issuance of common stock, net of issuance costs		$ 269,500
Asset Purchase and Exclusive License Agreement | Jazz Pharmaceuticals Ireland Limited
Risks and Liquidity
Upfront payment		$ 35,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Unaudited Pro Forma Information, Segment Information & Cash and Cash Equivalents (Details)	12 Months Ended
	Dec. 31, 2020USD ($)segment	Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)
Summary of Significant Accounting Policies
Number of Operating Segments | segment	1
Cash and cash equivalents	$ 147,089,000		$ 327,652,000
Entity Public Float		$ 897,219,624

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Equity-based compensation expense (Details)	12 Months Ended
	Dec. 31, 2020USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	$ 0
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)subsidiary	Dec. 31, 2019USD ($)
Recently Adopted Accounting Pronouncements
Lease, Practical Expedients, Package [true false]	true
Operating lease right-of-use assets	$ 1,944
Total assets	576,191	$ 334,831
Operating lease liabilities, current	1,375
Deferred rent		363
Operating lease liabilities, long-term	1,359
Long-term portion of deferred rent		789
Total deferred rent		1,152
Total liabilities	19,133	12,759
Total operating lease liabilities	$ 2,734
Income Taxes
Number of wholly owned taxable subsidiaries | subsidiary	5
Spring Works Therapeutics, LLC
Income Taxes
Ownership percentage	100.00%
ASU 2016-02 | Cumulative Effect Adjustment
Recently Adopted Accounting Pronouncements
Operating lease right-of-use assets		2,848
Total assets		2,848
Operating lease liabilities, current		1,382
Deferred rent		(363)
Operating lease liabilities, long-term		2,618
Long-term portion of deferred rent		(789)
Total liabilities		2,848
ASU 2016-02 | Cumulative Effect Adjusted Balance
Recently Adopted Accounting Pronouncements
Operating lease right-of-use assets		2,848
Total assets		2,848
Operating lease liabilities, current		1,382
Operating lease liabilities, long-term		2,618
Total operating lease liabilities		$ 4,000

Marketable Securities (Details)

Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Amortized Cost	$ 414,690
Gross Unrealized Gains	52
Gross Unrealized Losses	(11)
Estimated Fair Value	414,731	$ 0
Investments with maturity beyond five years	0
Short-term investments | U.S. Government securities
Marketable Securities [Line Items]
Amortized Cost	157,079
Gross Unrealized Gains	24
Gross Unrealized Losses	(1)
Estimated Fair Value	157,102
Short-term investments | Corporate debt securities
Marketable Securities [Line Items]
Amortized Cost	74,773
Gross Unrealized Gains	2
Gross Unrealized Losses	(10)
Estimated Fair Value	74,765
Short-term investments | Commercial paper
Marketable Securities [Line Items]
Amortized Cost	129,528
Estimated Fair Value	129,528
Long-term investments | U.S. Government securities
Marketable Securities [Line Items]
Amortized Cost	53,310
Gross Unrealized Gains	26
Estimated Fair Value	$ 53,336

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Measurements
Cash and cash equivalents	$ 147,089	$ 327,652
Recurring
Fair Value Measurements
Total financial assets	522,454
Recurring | Money market funds
Fair Value Measurements
Cash equivalents	107,723
Recurring | U.S. Government securities
Fair Value Measurements
Short-term investments	157,102
Long-term investment	53,336
Recurring | Corporate debt securities
Fair Value Measurements
Short-term investments	74,765
Recurring | Commercial paper
Fair Value Measurements
Short-term investments	129,528
Level 1 | Recurring
Fair Value Measurements
Total financial assets	318,161
Level 1 | Recurring | Money market funds
Fair Value Measurements
Cash equivalents	107,723
Level 1 | Recurring | U.S. Government securities
Fair Value Measurements
Short-term investments	157,102
Long-term investment	53,336
Level 2 | Recurring
Fair Value Measurements
Total financial assets	204,293
Level 2 | Recurring | Corporate debt securities
Fair Value Measurements
Short-term investments	74,765
Level 2 | Recurring | Commercial paper
Fair Value Measurements
Short-term investments	$ 129,528

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property and Equipment
Property, Plant and Equipment, Gross	$ 1,604	$ 1,008
Less accumulated depreciation	(529)	(213)
Property, Plant and Equipment, Net	1,075	795
Leasehold improvements
Property and Equipment
Property, Plant and Equipment, Gross	$ 1,184	$ 855
Property, Plant and Equipment, Useful Life	5 years	5 years
Computer equipment
Property and Equipment
Property, Plant and Equipment, Gross	$ 157	$ 122
Property, Plant and Equipment, Useful Life	3 years	3 years
Furniture
Property and Equipment
Property, Plant and Equipment, Gross	$ 97	$ 31
Property, Plant and Equipment, Useful Life	5 years	5 years
Software
Property and Equipment
Property, Plant and Equipment, Gross	$ 62
Property, Plant and Equipment, Useful Life	3 years	3 years
Construction in Progress
Property and Equipment
Property, Plant and Equipment, Gross	$ 104

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property and Equipment
Depreciation expense	$ 349,000	$ 192,000	$ 17,000

Leases (Details)

Leases (Details)	1 Months Ended		12 Months Ended
	Oct. 31, 2018USD ($)	Aug. 31, 2018USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Leases
Rent expense			$ 1,500,000	$ 1,600,000	$ 500,000
Durham, NC
Leases
Lease term		5 years
Number of renewal options		2
Renewal term		5 years
Annual increase in lease payments (as a percent)		2.75%
Number of years the lease payment will increase		4 years
Stamford, CT
Leases
Annual increase in lease payments (as a percent)	2.00%
Cash received from previous tenant	$ 1,500,000
Security deposit	$ 500,000

Leases - Statement of Operation

Leases - Statement of Operations (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Operating lease cost
Fixed	$ 1,049
Variable	486
Total lease cost	$ 1,535

Leases - Balance Sheet (Details

Leases - Balance Sheet (Details) $ in Thousands	Dec. 31, 2020USD ($)
Leases
Operating lease right-of-use assets	$ 1,944
Operating lease liabilities, current	1,375
Operating lease liabilities, long-term	1,359
Total operating lease liabilities	$ 2,734

Leases - Future Lease Obligatio

Leases - Future Lease Obligations (Details) $ in Thousands	Dec. 31, 2020USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2021	$ 1,396
2022	1,298
2023	135
Total lease payments	2,829
Less: imputed interest	(95)
Present value of lease liabilities	$ 2,734

Leases - Supplemental Informati

Leases - Supplemental Information (Details)	Dec. 31, 2020
Leases
Operating leases -Weighted-average remaining lease term (in years)	2 years
Operating leases - Weighted-average discount rate	3.45%

Leases - Cash Flow Statement (D

Leases - Cash Flow Statement (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Leases
Operating cash flows from operating leases	$ 1,411
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 31

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Expenses
Accrued professional fees	$ 827	$ 793
Accrued compensation and benefits	5,834	3,147
Accrued research and development	7,922	4,447
Accrued other	302	566
Accrued expenses	$ 14,885	$ 8,953

Equity-Based Compensation - Equ

Equity-Based Compensation - Equity-based compensation expense related to restricted stock and stock options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total equity compensation expenses	$ 10,034	$ 3,109	$ 1,069
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total equity compensation expenses	3,055	731	164
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total equity compensation expenses	$ 6,979	$ 2,378	$ 905

Equity-Based Compensation - 201

Equity-Based Compensation - 2019 Equity Incentive Plan (Details) - 2019 Equity Incentive Plan - shares	Jan. 01, 2020	Aug. 30, 2019	Dec. 31, 2019	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance			3,537,225	4,256,747
Percentage of annual increase in the shares			5.00%
Number of additional shares reserved for issuance	2,150,304
Employee and Non employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years

Equity-Based Compensation - 2_2

Equity-Based Compensation - 2019 Private Company Plan (Details) - shares	Jul. 29, 2019	Jun. 04, 2019	Mar. 29, 2019
Stock options | 2019 Stock Option and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units authorized	6,700,197	5,382,828	5,292,355

Equity-Based Compensation - 2_3

Equity-Based Compensation - 2018 Equity Plan (Details) - Incentive units - 2018 Equity Incentive Plan - shares	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units authorized	3,008,645	2,738,929
Increase in number of units	269,716

Equity-Based Compensation - 2_4

Equity-Based Compensation - 2019 Employee Stock Purchase Plan (Details) - 2019 Employee Stock Purchase Plan - shares	Jan. 01, 2020	Aug. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance	430,061	442,153
Automatic increase in to shares authorized by the number of shares		663,229
Automatic increase in to shares authorized as percentage of outstanding stock		1.00%

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock options (Details) - USD ($)	9 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Stock compensation expense		$ 10,034,000	$ 3,109,000	$ 1,069,000
Stock options
Number of Award
Outstanding at the beginning		3,225,725
Granted	3,177,233	1,580,788
Exercised	(9,080)	(190,484)
Forfeited/cancelled	(90,843)	(110,483)
Outstanding at the end	3,225,725	4,505,546	3,225,725
Exercisable		1,402,718
Weighted Average Exercise Price
Outstanding at the beginning (in dollars per share)		$ 5.08
Granted (in dollars per share)	$ 5.21	35.90
Exercised (in dollars per share)	2.30	4.69
Forfeited/cancelled (in dollars per share)	2.18	23.49
Outstanding at the end (in dollars per share)	$ 5.08	15.51	$ 5.08
Exercisable (in dollars per share)		$ 8.25
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Outstanding at the end (in years)	9 years 4 months 24 days	8 years 8 months 12 days
Exercisable (in years)		8 years 6 months
Outstanding at the end (in dollars)	$ 107,771,472	$ 256,860,405	$ 107,771,472
Exercisable (in dollars)		$ 90,150,057
Stock options | 2019 Stock Option and Incentive Plan
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Minimum risk-free interest rate		0.31%
Maximum risk-free interest rate		1.73%
Expected dividend yield		0.00%
Stock options | 2019 Stock Option and Incentive Plan | Minimum
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Expected term		5 years 6 months
Expected volatility		70.00%
Stock options | 2019 Stock Option and Incentive Plan | Maximum
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Expected term		6 years 29 days
Expected volatility		75.00%
Unit options
Number of Award
Outstanding at the beginning	148,415
Weighted Average Exercise Price
Outstanding at the beginning (in dollars per share)	$ 1.65

Equity-Based Compensation - CEO

Equity-Based Compensation - CEO performance Award (Details) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2019installment$ / sharesshares	Dec. 31, 2019$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense | $			$ 10,034	$ 3,109	$ 1,069
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive units issued		3,177,233	1,580,788
Exercise price of option | $ / shares		$ 5.21	$ 35.90
Exercisable			1,402,718
Stock options | CEO Performance Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive units issued	176,411
Service of CEO	4 years
Vesting period	4 years
Vesting period , number of monthly installments | installment	48
Number of trading day on which average closing price is based	60 days
Average closing price | $ / shares	$ 28.49
Stock compensation expense | $			$ 9,700
Unrecognized compensation expense, options | $			$ 34,200
Share compensation recognition period			2 years 9 months 18 days
Exercisable			73,502

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 29, 2019	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted Average Grant Date Fair Valued
Stock compensation expense			$ 10,034	$ 3,109	$ 1,069
Restricted stock
Number of Units
Outstanding at the beginning	2,503,744	2,262,965	1,289,437	2,503,744
Vested	228,209	737,530	588,345
Vested	(228,209)	(737,530)	(588,345)
Forfeited	(12,570)	(235,998)	(14,224)
Unvested and outstanding at the end	2,262,965	1,289,437	686,868	1,289,437	2,503,744
Weighted Average Grant Date Fair Valued
Outstanding at the beginning (in dollars per share)	$ 1.25	$ 1.24	$ 1.21	$ 1.25
Vested (in dollars per share)	0.81	1.26	1.14
Forfeited (in dollars per share)	1.45	1.36	1.45
Unvested and outstanding at the end (in dollars per share)	$ 1.24	$ 1.21	$ 1.26	$ 1.21	$ 1.25
Unrecognized compensation expense, options			$ 300
Share compensation recognition period			10 months 9 days
Stock compensation expense			$ 300

License and Collaboration Agr_2

License and Collaboration Agreements (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2020USD ($)	Oct. 31, 2017USD ($)itemshares	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Preferred stock, shares issued | shares			0	0
Research and development expenses			$ 51,859	$ 42,545	$ 9,898
Pfizer | License agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of license agreements with rights to certain technologies | item		4
Minimum period after first commercial sale on country-by-country basis		10 years
Pfizer | License agreement | Nirogacestat
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Maximum milestone payments under agreement		$ 232,500
Pfizer | License agreement | Mirdametinib
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Maximum milestone payments under agreement		$ 229,800
Pfizer | License agreement | Junior Series A convertible preferred unit
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Preferred stock, shares issued | shares		6,437,500
Gross cash proceeds from issuance		$ 0
BeiGene | Clinical collaboration agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expenses			$ 900	$ 1,000
Asset Purchase and Exclusive License Agreement | Jazz Pharmaceuticals Ireland Limited
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront payment	$ 35,000
Asset Purchase and Exclusive License Agreement | Jazz Pharmaceuticals Ireland Limited | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential future payments	$ 375,000

Investments (Details)

Investments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jun. 30, 2020USD ($)shares	Jun. 30, 2019USD ($)individualshares
Number of individuals under the equity method investments | individual				2
Investment in Mapkure	$ 3,871	$ 976
Equity investment loss	605	$ 2,614
BeiGene | Series A Preferred Units
Shares purchased | shares				10,000,000
Ownership Interest				71.40%
Individual One | Series A Preferred Units
Shares purchased | shares				250,000
Ownership Interest				1.80%
Individual Two | Series A Preferred Units
Shares purchased | shares				250,000
Ownership Interest				1.80%
MapKure
Investment in Mapkure	3,900
Equity investment loss	$ 600
MapKure | Series A Preferred Units
Shares purchased | shares			3,500,000	3,500,000
Investment in Mapkure			$ 3,500	$ 3,500
Ownership Interest	38.90%			25.00%

Income Taxes - Deferred Taxes (

Income Taxes - Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 23,630	$ 16,252
Research and development credits	1,673	706
Orphan drug credit	5,519	71
Deferred rent		242
Accrued expenses	1,225	212
Depreciation	71	34
Stock compensation	1,972	496
Operating lease liabilities	574
Total deferred tax assets	34,664	18,013
Operating lease right-of-use assets	(408)
Valuation allowance	$ (34,256)	$ (18,013)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of U.S. Statutory Income Tax Rate to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the U.S. statutory income tax rate to the Company's effective tax rate
Statutory tax rate	21.00%	21.00%	21.00%
Federal and state return to provision adjustments	0.03%	(0.01%)	(1.08%)
Stock-based compensation	0.55%
Research and development credit	2.12%	0.57%	2.02%
Orphan drug credit	11.95%
Other	(0.01%)	(0.03%)	(0.04%)
Change in valuation allowance	(35.64%)	(21.53%)	(21.90%)
Effective tax rate	0.00%	0.00%	0.00%

Income Taxes - Additional infor

Income Taxes - Additional information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)subsidiary	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Income Taxes
Number of wholly owned taxable subsidiaries | subsidiary	5
Corporate tax rate (as a percent)	21.00%	21.00%	21.00%
Increase in valuation allowance	$ 16.2
Effective tax rate	0.00%	0.00%	0.00%
Accrued interest or penalties	$ 0
Spring Works Therapeutics, LLC
Income Taxes
Ownership percentage	100.00%
Internal revenue service
Income Taxes
Net operating loss carryforwards	$ 110.9
Federal net operating loss carryforwards	$ 34.8	$ 55.9	$ 16	$ 4.3
Available to offset	80.00%
Tax credit carryforwards	$ 7.2
State
Income Taxes
Net operating loss carryforwards	0.6
City
Income Taxes
Net operating loss carryforwards	$ 3.7

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	8 Months Ended	12 Months Ended
	Sep. 12, 2019	Dec. 31, 2018
Director
Related Party Transaction [Line Items]
Consulting and BOD expenses	$ 0.2	$ 0.3

Net Loss per Share - Basic and

Net Loss per Share - Basic and diluted net loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Loss per Share
Net loss attributable to common stockholders	$ (45,574)	$ (58,306)	$ (17,813)
Net gain attributable to extinguishment of Series A convertible preferred and Junior Series A convertible preferred units		7,729
Net loss attributable to common stockholders and unit holders, basic and diluted	$ (45,574)	$ (50,577)	$ (17,813)
Weighted average common units outstanding, basic and diluted			341,014
Weighted average common shares outstanding, basic and diluted	43,300,063	13,274,836
Net loss per unit, basic and diluted			$ (52.24)
Net loss per share, basic and diluted	$ (1.05)	$ (3.81)

Net Loss per Share - Potential

Net Loss per Share - Potential common units not included in the calculation of the diluted net loss per unit and share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive securities	5,192,414	4,515,162
Common
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive securities	4,505,546	3,225,725
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive securities	686,868	1,289,437