Deciphera Pharmaceuticals (DCPH) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 30, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-38219
Entity Registrant Name	DECIPHERA PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	30-1003521
Entity Address, Address Line One	200 Smith Street
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	781
Local Phone Number	209-6400
Title of 12(b) Security	Common Stock, $0.01 Par Value Per Share
Trading Symbol	DCPH
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		56,933,424
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001654151
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 111,154	$ 120,320
Short-term marketable securities	434,171	459,256
Accounts receivable, net	11,814	0
Inventory	4,596	0
Prepaid expenses and other current assets	9,723	13,832
Total current assets	571,458	593,408
Long-term marketable securities	38,989	0
Long-term investments—restricted	2,125	1,510
Property and equipment, net	9,925	6,333
Operating lease assets	37,171	21,158
Total assets	659,668	622,409
Current liabilities:
Accounts payable	10,237	19,575
Accrued expenses and other current liabilities	48,941	38,716
Operating lease liabilities	2,010	1,747
Total current liabilities	61,188	60,038
Operating lease liabilities, net of current portion	29,394	15,904
Total liabilities	90,582	75,942
Commitments and contingencies (Note 7)
Stockholders' equity:
Preferred stock, $0.01 par value per share; 5,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.01 par value per share; 125,000,000 shares authorized; 56,641,065 shares and 51,617,639 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	566	516
Additional paid-in capital	1,260,209	1,033,819
Accumulated other comprehensive income (loss)	39	111
Accumulated deficit	(691,728)	(487,979)
Total stockholders' equity	569,086	546,467
Total liabilities and stockholders' equity	$ 659,668	$ 622,409

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares issued (in shares)	56,641,065	51,617,639
Common stock, shares outstanding (in shares)	56,641,065	51,617,639

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total revenues	$ 15,449	$ 0	$ 22,601	$ 25,000
Cost and operating expenses:
Cost of sales	90	0	98	0
Research and development	49,213	40,374	146,682	110,974
Selling, general, and administrative	30,143	17,979	84,012	44,379
Total cost and operating expenses	79,446	58,353	230,792	155,353
Loss from operations	(63,997)	(58,353)	(208,191)	(130,353)
Other income (expense):
Interest and other income, net	296	2,174	4,442	5,368
Interest expense	0	(17)	0	(55)
Total other income (expense), net	296	2,157	4,442	5,313
Net loss	$ (63,701)	$ (56,196)	$ (203,749)	$ (125,040)
Net loss per share—basic and diluted (in dollars per share)	$ (1.13)	$ (1.28)	$ (3.68)	$ (3.12)
Weighted average common shares outstanding—basic and diluted (in shares)	56,390,748	43,803,508	55,296,775	40,041,321
Comprehensive loss:
Net loss	$ (63,701)	$ (56,196)	$ (203,749)	$ (125,040)
Other comprehensive income (loss):
Unrealized gains (losses) on marketable securities	47	(114)	(72)	61
Total other comprehensive income (loss)	47	(114)	(72)	61
Total comprehensive loss	(63,654)	(56,310)	(203,821)	(124,979)
Product revenues, net
Total revenues	15,164	0	19,989	0
Collaboration revenues
Total revenues	$ 285	$ 0	$ 2,612	$ 25,000

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2018	$ 279,981	$ 0	$ 377	$ 575,327	$ 0	$ (295,723)
Beginning balance (in shares) at Dec. 31, 2018		0	37,676,760
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs (in shares)			12,432,431
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs	431,780		$ 124	431,656
Issuance of common stock upon exercise of stock options (in shares)			934,721
Issuance of common stock upon exercise of stock options	3,706		$ 9	3,697
Stock-based compensation expense	15,065			15,065
Unrealized gains (losses) on marketable securities	61				61
Net loss	(125,040)					(125,040)
Ending balance at Sep. 30, 2019	605,553	$ 0	$ 510	1,025,745	61	(420,763)
Ending balance (in shares) at Sep. 30, 2019		0	51,043,912
Beginning balance at Dec. 31, 2018	279,981	$ 0	$ 377	575,327	0	(295,723)
Beginning balance (in shares) at Dec. 31, 2018		0	37,676,760
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(192,300)
Ending balance at Dec. 31, 2019	546,467	$ 0	$ 516	1,033,819	111	(487,979)
Ending balance (in shares) at Dec. 31, 2019		0	51,617,639
Beginning balance at Jun. 30, 2019	222,878	$ 0	$ 382	586,888	175	(364,567)
Beginning balance (in shares) at Jun. 30, 2019		0	38,215,108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs (in shares)			12,432,431
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs	431,780		$ 124	431,656
Issuance of common stock upon exercise of stock options (in shares)			396,373
Issuance of common stock upon exercise of stock options	2,476		$ 4	2,472
Stock-based compensation expense	4,729			4,729
Unrealized gains (losses) on marketable securities	(114)				(114)
Net loss	(56,196)					(56,196)
Ending balance at Sep. 30, 2019	605,553	$ 0	$ 510	1,025,745	61	(420,763)
Ending balance (in shares) at Sep. 30, 2019		0	51,043,912
Beginning balance at Dec. 31, 2019	546,467	$ 0	$ 516	1,033,819	111	(487,979)
Beginning balance (in shares) at Dec. 31, 2019		0	51,617,639
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs (in shares)			3,659,090
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs	188,385		$ 37	188,348
Issuance of common stock upon exercise of stock options (in shares)			1,364,336
Issuance of common stock upon exercise of stock options	10,624		$ 13	10,611
Stock-based compensation expense	27,431			27,431
Unrealized gains (losses) on marketable securities	(72)				(72)
Net loss	(203,749)					(203,749)
Ending balance at Sep. 30, 2020	569,086	$ 0	$ 566	1,260,209	39	(691,728)
Ending balance (in shares) at Sep. 30, 2020		0	56,641,065
Beginning balance at Jun. 30, 2020	619,684	$ 0	$ 561	1,247,158	(8)	(628,027)
Beginning balance (in shares) at Jun. 30, 2020		0	56,081,993
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)			559,072
Issuance of common stock upon exercise of stock options	3,228		$ 5	3,223
Stock-based compensation expense	9,828			9,828
Unrealized gains (losses) on marketable securities	47				47
Net loss	(63,701)					(63,701)
Ending balance at Sep. 30, 2020	$ 569,086	$ 0	$ 566	$ 1,260,209	$ 39	$ (691,728)
Ending balance (in shares) at Sep. 30, 2020		0	56,641,065

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (63,701)	$ (56,196)	$ (203,749)	$ (125,040)	$ (192,300)
Adjustments to reconcile net loss to net cash flows used in operating activities:
Stock-based compensation expense			27,431	15,065
Depreciation expense			1,610	385
Noncash lease expense			1,948	433
(Gain) loss on disposal of equipment			(7)	0
Net accretion of discounts on marketable securities			(1,850)	(2,270)
Changes in operating assets and liabilities:
Accounts receivable			(11,814)	0
Inventory			(2,455)	0
Prepaid expenses and other current assets			1,030	(427)
Accounts payable			(9,908)	6,462
Accrued expenses and other current liabilities			8,339	12,038
Operating lease liabilities			(1,130)	(446)
Other long-term liabilities			0	337
Net cash flows used in operating activities			(190,555)	(93,463)
Cash flows from investing activities:
Purchases of marketable securities			(969,005)	(618,190)
Maturities of marketable securities			452,663	137,952
Sales of marketable securities			504,216	21,687
Purchases of property and equipment			(4,886)	(3,210)
Proceeds from sale of equipment			7	0
Increase in restricted investments			(615)	(441)
Net cash flows used in investing activities			(17,620)	(462,202)
Cash flows from financing activities:
Proceeds from public offerings, net of underwriting discounts and commissions			189,037	432,400
Repayment of notes payable to related party			0	(140)
Payments of public offering costs			(652)	(353)
Proceeds from exercise of stock options			10,624	3,706
Net cash flows provided by financing activities			199,009	435,613
Net increase (decrease) in cash and cash equivalents			(9,166)	(120,052)
Cash and cash equivalents at beginning of period			120,320	293,764	293,764
Cash and cash equivalents at end of period	$ 111,154	$ 173,712	111,154	173,712	$ 120,320
Supplemental disclosure of cash flow information:
Cash paid for interest			0	55
Property and equipment purchases included in accounts payable and accrued expenses and other current liabilities			316	883
Offering costs included in accounts payable and accrued expenses and other current liabilities			$ 0	$ 267

Nature of the Business and Summ

Nature of the Business and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Summary of Significant Accounting Policies	Nature of the Business and Summary of Significant Accounting Policies Nature of the Business Deciphera Pharmaceuticals, Inc. (the Company) is a biopharmaceutical company focused on discovering, developing, and commercializing important new medicines to improve the lives of people with cancer. The Company is leveraging its proprietary switch-control kinase inhibitor platform and deep expertise in kinase biology to develop a broad portfolio of innovative medicines. On May 15, 2020, QINLOCK® (ripretinib), referred to as QINLOCK, was approved by the United States (U.S.) Food and Drug Administration (FDA) for the treatment of adult patients with advanced gastrointestinal stromal tumor (GIST) who have received prior treatment with three or more kinase inhibitors, including imatinib. QINLOCK is currently being investigated in a Phase 3 study for the treatment of patients with second-line GIST. In addition to QINLOCK, the Company is advancing multiple drug candidates from its platform in various stages of clinical development. The Company wholly owns its drug and all of its drug candidates with the exception of a development and commercialization out-license agreement for QINLOCK in Mainland China, Hong Kong, Macau, and Taiwan, also referred to as Greater China. The Company is preparing for a potential launch of QINLOCK in Europe and the Company has, and intends in the future to, enter into select distributor arrangements to offer QINLOCK in geographies where the Company does not intend to build a local presence, such as Australia and Canada. The Company is subject to risks and uncertainties common to companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, market acceptance and the successful commercialization of QINLOCK or any of the Company's current or future drug candidates for which it receives marketing approval, competition for QINLOCK or any of the Company's current or future drug candidates for which it receives marketing approval, protection of proprietary technology, ability to complete late-stage clinical trials, ability to obtain and maintain regulatory approvals, compliance with government regulations, the impact of the novel coronavirus (COVID-19) pandemic on its operations, and the ability to secure additional capital to fund operations. QINLOCK and the Company's drug candidates currently under development will require significant additional research and development efforts, including extensive preclinical and/or clinical testing and regulatory approval. In addition to supporting its research and development efforts, the Company will be required to invest in the Company's commercial capabilities and infrastructure, to support its launch and commercialization of QINLOCK, the Company's first and recently approved drug in the U.S., and any current or future drug candidate for which the Company obtains marketing approval. These efforts require significant amounts of additional capital, adequate personnel and infrastructure, and extensive compliance-reporting capabilities. Even if the Company's drug development and commercialization efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales of QINLOCK or any current or future drug candidates for which it receives marketing approval. The full extent to which the COVID-19 pandemic, or the future outbreak of any other highly infectious or contagious diseases, may impact the Company's business, including its preclinical studies, clinical trial operations, or commercialization efforts, will depend on continuously changing circumstances, which are highly uncertain and cannot be predicted at this time, such as the duration of such pandemic including future waves of infection, the actions taken to contain the pandemic or mitigate its impact, and the direct and indirect economic effects of the pandemic and containment measures, among others. The Company is continuing to monitor the long-term impact of COVID-19, if any, on its financial condition and results of operations. The ongoing fluidity of this situation precludes any prediction as to the full impact of the COVID-19 pandemic but it could have a material adverse effect on the Company's business, financial condition, and results of operations. The COVID-19 pandemic may also have the effect of heightening the risks to which the Company is subject, including various aspects of the Company's preclinical studies and ongoing clinical trials, the reliance on third parties in the Company's supply chain for materials and manufacturing of the Company's drug and drug candidates, disruptions in health regulatory agencies' operations globally, the volatility of the Company's common stock, and its ability to access capital markets, and the Company's ability to successfully launch, commercialize, and generate revenue from sales of QINLOCK. In June 2018, the Company issued and sold 4,945,000 shares of its common stock in a follow-on public offering at a public offering price of $40.00 per share, resulting in net proceeds of $185.3 million after deducting underwriting discounts and commissions and other offering expenses. In the third quarter of 2019, the Company issued and sold 12,432,431 shares of its common stock in a follow-on public offering at a public offering price of $37.00 per share, resulting in net proceeds of $431.8 million after deducting underwriting discounts and commissions and other offering expenses. In February 2020, the Company issued and sold 3,659,090 shares of its common stock in a follow-on public offering at a public offering price of $55.00 per share, resulting in net proceeds of $188.4 million after deducting underwriting discounts and commissions and other offering expenses. In August 2020, the Company entered into an Open Market Sale Agreement℠ (the Sales Agreement) with Jefferies LLC (Jefferies), pursuant to which the Company may issue and sell shares of its common stock having aggregate offering proceeds of up to $200.0 million (the Shares) from time to time through Jefferies as its sales agent. Upon delivery of a placement notice and subject to the terms and conditions of the Sales Agreement, Jefferies may sell the Shares by any method permitted by law deemed to be an "at the market offering" as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended. The Company may sell the Shares in amounts and at times to be determined by the Company from time to time subject to the terms and conditions of the Sales Agreement, but it has no obligation to sell any Shares under the Sales Agreement. The Company or Jefferies may suspend or terminate the offering of Shares upon notice to the other party and subject to other conditions. As of September 30, 2020, the Company had not made any sales of Shares pursuant to the Sales Agreement. Basis of Presentation The accompanying consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets, and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has incurred recurring losses including net losses of $203.7 million and $192.3 million for the nine months ended September 30, 2020 and the year ended December 31, 2019, respectively. As of September 30, 2020, the Company had an accumulated deficit of $691.7 million. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash, cash equivalents, and marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements through at least 12 months from the issuance date of these consolidated financial statements. The future viability of the Company is dependent on its ability to raise additional capital to fund its operations. The Company will need to obtain substantial additional funding in connection with continuing operations. If the Company is unable to raise capital when needed, or on attractive terms, it could be forced to delay, reduce, or eliminate its research or drug development programs or certain commercialization efforts. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. These consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated. Unaudited Interim Financial Information These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (GAAP). The consolidated balance sheet as of December 31, 2019 was derived from audited financial statements, but does not include all disclosures required by GAAP. The accompanying unaudited consolidated financial statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (SEC) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. These consolidated financial statements should be read in conjunction with the Company's audited financial statements and the notes thereto for the year ended December 31, 2019 included in the Company's Annual Report on Form 10-K (Form 10-K) on file with the SEC. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company's consolidated financial position as of September 30, 2020 and consolidated results of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019 and consolidated cash flows for the nine months ended September 30, 2020 and 2019 have been made. The consolidated results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2020. Certain prior year amounts have been reclassified to conform to current year presentation. The significant accounting policies used in preparation of these consolidated financial statements for the three and nine months ended September 30, 2020 are consistent with those discussed in Note 2, Summary of Significant Accounting Policies, to the consolidated financial statements in the Company's Form 10-K for the year ended December 31, 2019, except as noted within the section "Significant Accounting Policies" with respect to the Company's accounting policies for product revenues, accounts receivable, and inventory and within the section "Recently Issued Accounting Pronouncements." Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, the accrual for research and development expenses, and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts, and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. Net Loss per Share Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted average number of common shares outstanding for the period. Diluted net income (loss) per share is computed by dividing the diluted net income (loss) by the weighted average number of common shares, including potential dilutive common shares assuming the dilutive effect as determined using the treasury stock method. For periods in which the Company has reported net losses, diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported a net loss for the three and nine months ended September 30, 2020 and 2019. The following potential dilutive securities, presented based on amounts outstanding at the end of each reporting period, have been excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive impact: As of September 30, 2020 2019 Options to purchase common stock 6,351,397 6,891,125 Unvested time-based restricted common stock units 419,235 67,000 Unvested performance-based restricted common stock units 55,200 — Unvested employee stock purchase plan shares 39,600 — Total 6,865,432 6,958,125 Significant Accounting Policies Product Revenues In May 2020, the Company began generating product revenue from sales of QINLOCK to specialty distributors and specialty pharmacies in the U.S. following the approval of QINLOCK by the FDA on May 15, 2020 for the treatment of adult patients with advanced GIST who have received prior treatment with three or more kinase inhibitors, including imatinib. The Company recognizes product revenues, net of variable consideration related to certain allowances and accruals, when the customer takes control of the product, which is typically upon delivery to the customer. Product revenue is recorded at the net sales price, or transaction price. The Company records product revenue reserves, which are classified as a reduction in product revenues, to account for the components of variable consideration. Variable consideration includes the following components: chargebacks, government rebates, trade discounts and allowances, product returns, and other incentives, which are described below. These reserves are based on estimates of the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if the amount is payable to the Company's customer) or a liability (if the amount is payable to a party other than the Company's customer). The Company's estimates of reserves established for variable consideration are calculated based upon a consistent application of the expected value method, which is the sum of probability-weighted amounts in a range of possible consideration amounts. These estimates reflect the Company's historical experience, current contractual and statutory requirements, specific known market events and trends, industry data, forecasted customer buying, and payment patterns. The amount of variable consideration that is included in the transaction price may be subject to constraint and is included in net product revenues only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration received may ultimately differ from the Company's estimates. If actual results vary, the Company adjusts these estimates, which could have an effect on earnings in the period of adjustment. Chargebacks and administrative fees: Chargebacks for discounts represent the Company's estimated obligations resulting from contractual commitments to sell product to qualified healthcare providers and government agencies at prices lower than the list prices charged to the customers who directly purchase the product from the Company. The customers charge the Company for the difference between what the customers pay the Company for the product and the customer's ultimate contractually committed or government required lower selling price to the qualified healthcare providers. As part of the Company's contractual commitments to sell product to qualified healthcare providers, the Company pays fees for administrative services, such as account management and data reporting. Government rebates: Government rebates consist of Medicare, Tricare, and Medicaid rebates. These reserves are recorded in the same period the related revenue is recognized. For Medicare, the Company also estimates the number of patients in the prescription drug coverage gap for whom it will owe a rebate under the Medicare Part D program. Trade discounts and allowances: The Company provides the customers with discounts that are explicitly stated in the contracts and recorded in the period the related product revenue is recognized. In addition, the Company also receives sales order management, inventory management, and data services from the customers in exchange for certain fees. Product returns: The Company estimates the amount of its product sales that may be returned by its customers and records this estimate in the period the related product revenue is recognized. The Company currently estimates product return liabilities based on available industry data and its visibility into the inventory remaining in the distribution channel. Other incentives: Other incentives include co-payment assistance provided to qualified patients, whereby the Company may provide financial assistance to patients with prescription drug co-payments required by the patient's insurance provider. Reserves for co-payment assistance are recorded in the same period the related revenue is recognized. Accounts Receivable Accounts receivable arise from product sales and amounts due from the Company's collaboration partners and have standard payment terms that generally require payment within 30 to 90 days. The amount from product sales represents amounts due from specialty distributors and specialty pharmacies in the U.S., which are recorded net of reserves for customer chargebacks, trade discounts and allowances, and other incentives to the extent such amounts are payable to the customer by the Company. The Company monitors economic conditions to identify facts or circumstances that may indicate that its receivables are at risk of collection. The Company provides reserves against accounts receivable for estimated losses, if any, that may result from a customer's inability to pay based on the composition of its accounts receivable, current economic conditions, and historical credit loss activity. Amounts determined to be uncollectible are charged or written-off against the reserve. During the three and nine months ended September 30, 2020, the Company did not record any expected credit losses related to outstanding accounts receivable. Inventory Inventories are stated at the lower of cost or estimated net realizable value with cost based on the first-in first-out method. Inventory that can be used in either the production of clinical or commercial products is expensed as research and development costs when identified for use in clinical trials. Prior to the regulatory approval of its drug candidates, the Company incurs expenses for the manufacture of drug product supplies to support clinical development that could potentially be available to support the commercial launch of those drugs. Until the date at which regulatory approval has been received or is otherwise considered probable, the Company records all such costs as research and development expenses. The Company performs an assessment of the recoverability of capitalized inventories during each reporting period and writes down any excess and obsolete inventory to its net realizable value in the period in which the impairment is first identified. Such impairment charges, should they occur, are recorded as a component of cost of sales in the Company's consolidated statements of operations and comprehensive loss. The determination of whether inventory costs will be realizable requires the use of estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required. The Company commenced the capitalization of QINLOCK inventory in May 2020 upon receiving FDA approval of QINLOCK. Capitalized inventory consisted of the following: (in thousands) As of September 30, 2020 Raw materials $ 1,352 Work in process 3,160 Finished goods 84 Total inventory $ 4,596 There were no inventory amounts written down as a result of excess, obsolescence, unmarketability, or other reasons charged to cost of sales during the three and nine months ended September 30, 2020. Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed below, the Company does not believe that the adoption of recently issued standards have or may have a material impact on its consolidated financial statements or disclosures. Credit Losses In June 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). The FASB subsequently issued amendments to ASU 2016-13, which have the same effective date and transition date of January 1, 2020. This standard requires entities to estimate an expected lifetime credit loss on financial assets and report credit losses using an expected losses model rather than the incurred losses model that was previously used, and establishes additional disclosures related to credit risks. 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. This standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases. This standard became effective for the Company on January 1, 2020, and adoption of this standard did not have a material impact on the consolidated financial statements and related disclosures.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenues	Revenues Net Product Revenues On May 15, 2020, QINLOCK was approved by the FDA for the treatment of adult patients with advanced GIST who have received prior treatment with three or more kinase inhibitors, including imatinib. As of September 30, 2020, the Company's only source of product revenues were from the sales of QINLOCK. For the three months ended September 30, 2020, product revenues were $15.2 million, which consisted of $14.7 million of revenues in the U.S. and $0.5 million of revenues in the rest of the world. For the nine months ended September 30, 2020, product revenues were $20.0 million, which consisted of $19.5 million of revenues in the U.S. and $0.5 million of revenues in the rest of the world. The Company primarily sells QINLOCK through specialty distributors and specialty pharmacies. The Company recognized revenues from three customers accounting for 56%, 25%, and 12% of gross product revenues for the three months ended September 30, 2020, and 54%, 27%, and 11% of gross product revenues for the nine months ended September 30, 2020. As of September 30, 2020, two customers individually accounted for approximately 59% and 24% of accounts receivable associated with the Company's product sales. Activity in each of the product revenue allowance and reserve categories is summarized as follows: (in thousands) Trade discounts and allowances Chargebacks and administrative fees Government rebates and other incentives Returns Total Balance as of December 31, 2019 $ — $ — $ — $ — $ — Provision related to sales in the current year 302 854 886 662 2,704 Credits and payments made (152) (607) (127) (215) (1,101) Balance as of September 30, 2020 $ 150 $ 247 $ 759 $ 447 $ 1,603 The total reserves described above are summarized as components of the Company's consolidated balance sheets as follows: (in thousands) As of September 30, 2020 Reduction of accounts receivable, net $ 343 Component of accrued expenses and other current liabilities 1,260 Total revenue-related reserves $ 1,603 Collaboration Revenues In June 2019, the Company entered into a License Agreement (the Zai License Agreement) with Zai Lab (Shanghai) Co., Ltd. (Zai), pursuant to which the Company granted Zai exclusive rights to develop and commercialize QINLOCK, including certain follow-on compounds (the Licensed Products), in Greater China (the Territory). The Company retains exclusive rights to, among other things, develop, manufacture, and commercialize the Licensed Products outside the Territory. Pursuant to the terms of the Zai License Agreement, the Company received an upfront cash payment of $20.0 million and became eligible to receive up to $185.0 million in potential development and commercial milestone payments, consisting of up to $50.0 million of development milestones and up to $135.0 million of commercial milestones. In addition, during the term of the Zai License Agreement, Zai will be obligated to pay the Company tiered percentage royalties ranging from low to high teens on potential annual net sales of the Licensed Products in the Territory, subject to adjustments in specified circumstances. Under the Zai License Agreement, the Company recognized revenue of $25.0 million during the second quarter of 2019, which consisted of the $20.0 million upfront payment and a $5.0 million INTRIGUE study-related development milestone payment, which the Company believed to be probable of achievement in the second quarter of 2019 and was achieved in July 2019. Under the Zai License Agreement, the Company recognized revenues of $0.1 million and $2.2 million during the three and nine months ended September 30, 2020, respectively, which, during the three months ended September 30, 2020 consisted of $0.1 million in reimbursable costs, and during the nine months ended September 30, 2020 consisted of the achievement of a $2.0 million development milestone in the second quarter of 2020 and $0.2 million in reimbursable costs. Subject to the terms and conditions of the Zai License Agreement, Zai will be responsible for conducting the development and commercialization activities in the Territory related to the Licensed Products. Please read Note 3, License Agreement , to the consolidated financial statements in the Company's Form 10-K for the year ended December 31, 2019 for further details on the Zai License Agreement. In February 2020, the Company entered into a Supply Agreement (the Zai Supply Agreement) with Zai, as required by terms in the Zai License Agreement, pursuant to which the Company will supply the Licensed Products to Zai for use in the Territory for clinical trials as well as commercial inventory, if QINLOCK obtains regulatory approval in the Territory. Subject to the Zai Supply Agreement, costs incurred by the Company for external manufacturing services are reimbursed by Zai. Under the Zai Supply Agreement, the Company recognized revenues of $0.2 million and $0.4 million for external manufacturing services provided during the three and nine months ended September 30, 2020, respectively.

Marketable Securities and Fair

Marketable Securities and Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Investments, All Other Investments [Abstract]
Marketable Securities and Fair Value Measurements	Marketable Securities and Fair Value Measurements The following tables present marketable securities by contractual maturity and security type: As of September 30, 2020 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Due within one year: U.S. government securities 434,134 42 (5) 434,171 Due after one year through five years: U.S. government securities 38,987 4 (2) 38,989 Total $ 473,121 $ 46 $ (7) $ 473,160 As of December 31, 2019 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Due within one year: Commercial paper $ 314,292 $ 74 $ (23) $ 314,343 U.S. government securities 78,612 48 (3) 78,657 Certificates of deposit 66,241 17 (2) 66,256 Total $ 459,145 $ 139 $ (28) $ 459,256 The following tables present information about the Company's financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: As of September 30, 2020 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ — $ 41,204 $ — $ 41,204 U.S. government securities — 27,497 — 27,497 Marketable securities: U.S. government securities — 473,160 — 473,160 Total $ — $ 541,861 $ — $ 541,861 As of December 31, 2019 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ — $ 28,192 $ — $ 28,192 Certificates of deposit — 20,500 — 20,500 Marketable securities: Commercial paper — 314,343 — 314,343 U.S. government securities — 78,657 — 78,657 Certificates of deposit — 66,256 — 66,256 Total $ — $ 507,948 $ — $ 507,948 The table above excludes certificates of deposit totaling $2.1 million and $1.5 million as of September 30, 2020 and December 31, 2019, respectively, that the Company held to secure a letter of credit associated with its leases and to secure a credit card account. The Company increased its credit card limit and corresponding certificate of deposit in the first quarter of 2020. The certificates of deposit are Level 2 instruments and are measured at carrying value in the consolidated balance sheets in long-term investments—restricted and approximate fair value. For additional information on the letter of credit associated with the Company's leases, please read Note 4, Leases , to these consolidated financial statements. The fair value of Level 2 instruments classified as cash equivalents and marketable securities were determined through third-party pricing services. The pricing services use many observable market inputs to determine value, including reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, current spot rates, and other industry and economic events.

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	4. Leases The Company leases real estate, including office and laboratory space. In May 2018, the Company entered into a lease for office space (the Initial Space) at 200 Smith Street in Waltham, Massachusetts (the Premises). In October 2019, the lease for the Initial Space commenced under Accounting Standards Codification (ASC) Topic 842, Leases (ASC 842), and resulted in the addition of an operating lease asset of $21.2 million and a corresponding lease liability of $17.0 million in the fourth quarter of 2019. The Premises became the Company's new headquarters in October 2019. For additional information on the Initial Space, please read Note 6, Leases , to the consolidated financial statements in the Company's Form 10-K for the year ended December 31, 2019. In April 2019, the Company amended its lease for office space at the Premises to add an additional 38,003 square feet (the Additional Space) for a total of 82,346 square feet of space. The initial term of the lease for the Additional Space will expire in November 2029 unless terminated earlier in accordance with the terms of the lease and the Company is entitled to two five-year options to extend the lease. The initial annual base rent for the Additional Space is approximately $1.9 million and will increase annually for a total of $18.2 million over the lease term. In July 2020, the lease for the Additional Space commenced under ASC 842 and resulted in the addition of an operating lease asset of $16.5 million and a corresponding lease liability of $13.5 million in the third quarter of 2020. The Company is required to maintain a letter of credit associated with its leases at the Premises. The balances of the Company's certificate of deposit associated with the letter of credit for its leases at the Premises of $1.1 million as of September 30, 2020 and December 31, 2019 were classified as long-term investment—restricted in the consolidated balance sheets. The Company expects to increase the letter of credit and associated certificate of deposit by $0.9 million for the Additional Space in the fourth quarter of 2020. In August 2020, the Company amended and restated its real estate leases primarily for office and laboratory space in Lawrence, Kansas (the 2020 Lawrence Lease Agreements). The initial term of the 2020 Lawrence Lease Agreements will expire on December 31, 2030 unless terminated earlier in accordance with the terms of the lease and the Company is entitled to two five-year options to extend the leases. The 2020 Lawrence Lease Agreements modified a previously existing operating lease which resulted in an additional operating lease asset of $1.4 million and a corresponding lease liability of $1.4 million during the third quarter of 2020. Additionally, as a result of the 2020 Lawrence Lease Agreements, some previously existing operating leases will terminate as of December 31, 2020. The Company expects that additional new operating leases associated with the 2020 Lawrence Lease Agreements will commence in 2021 under ASC 842. The Company's leases contain options to extend the lease terms; however, these extensions were not included in the operating lease assets and lease liabilities recorded on the consolidated balance sheets as they were not reasonably certain of being exercised. During the three and nine months ended September 30, 2020 and 2019, the Company was subject to certain lease agreements to accommodate short-term or temporary needs. The expenses related to the Company's short-term or temporary lease agreements are included in short-term lease costs for the three and nine months ended September 30, 2020 and 2019, as applicable. The Company's leases require the Company to pay for its share of certain operating expenses, taxes, and other expenses based on actual costs incurred and therefore, as the amounts are variable in nature, are expensed in the period incurred and included in variable lease costs for the three and nine months ended September 30, 2020 and 2019. Payment escalations specified in the leases are recognized on a straight-line basis over the lease terms. All of the Company's leases qualify as operating leases. The following table summarizes the presentation of the Company's operating leases in the consolidated balance sheet: (in thousands) As of September 30, 2020 As of December 31, 2019 Operating lease assets $ 37,171 $ 21,158 Current operating lease liabilities $ 2,010 $ 1,747 Operating lease liabilities, net of current portion 29,394 15,904 Total operating lease liabilities $ 31,404 $ 17,651 The components of lease expense were as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2020 2019 2020 2019 Operating lease cost $ 1,321 $ 104 $ 2,843 $ 462 Short-term lease cost 18 82 336 270 Variable lease cost 144 128 343 337 Total lease expense $ 1,483 $ 314 $ 3,522 $ 1,069 Future annual minimum lease payments under operating leases were as follows: (in thousands) As of September 30, 2020 Remainder of 2020 (three months) $ 622 2021 4,143 2022 4,225 2023 4,308 2024 4,390 2025 4,472 Thereafter 18,519 Total future minimum lease payments 40,679 Less: imputed interest (9,275) Total operating lease liabilities $ 31,404 The weighted-average remaining lease term and weighted-average discount rate of the Company's operating leases are as follows: As of September 30, 2020 As of December 31, 2019 Weighted-average remaining lease term in years 9.21 9.63 Weighted-average discount rate 5.60 % 5.36 % Supplemental disclosure of cash flow information related to the Company's operating leases included in cash flows used in operating activities in the consolidated statement of cash flows is as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2020 2019 2020 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 618 $ 104 $ 2,024 $ 424 Operating lease liabilities arising from obtaining operating lease assets $ 14,883 $ 142 $ 14,883 $ 142

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2020
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: (in thousands) As of September 30, 2020 As of December 31, 2019 External research and development expenses $ 31,354 $ 20,462 Payroll and related expenses 13,450 12,902 Professional fees 2,514 3,810 Revenue-related reserves 1,260 — Other 363 1,542 Total accrued expenses and other current liabilities $ 48,941 $ 38,716

Stock-Based Awards

Stock-Based Awards	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Awards	Stock-Based Awards The Company grants stock-based awards under its 2017 Stock Option and Incentive Plan (the 2017 Plan) and is authorized to issue common stock under its 2017 Employee Stock Purchase Plan (ESPP). The Company also has outstanding stock options under its 2015 Equity Incentive Plan but is no longer granting awards under this plan. As of September 30, 2020, 1,748,489 shares of common stock were available for issuance under the 2017 Plan. As of September 30, 2020, 1,409,433 shares of common stock were available for issuance to participating employees under the ESPP. The purchase price of common stock under the Company's 2017 ESPP, is equal to 85% of the lesser of (i) the fair market value per share of the common stock on the first business day of an offering period and (ii) the fair market value per share of the common stock on the purchase date. The fair value of the discounted purchases made under the Company's 2017 ESPP is calculated using the Black-Scholes valuation model. The fair value of the look-back provision plus the 15% discount is recognized as stock-based compensation expense in the consolidated statements of operations and comprehensive loss over the 6-month purchase period. Employees began participating in the ESPP program during the second quarter of 2020. Stock-based compensation expense was classified in the consolidated statements of operations and comprehensive loss as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2020 2019 2020 2019 Research and development expenses $ 4,518 $ 1,992 $ 13,082 $ 5,474 Selling, general, and administrative expenses 5,310 2,737 14,349 9,591 Total stock-based compensation $ 9,828 $ 4,729 $ 27,431 $ 15,065 As of September 30, 2020, total unrecognized compensation cost related to the unvested share-based awards was $92.6 million, which is expected to be recognized over a weighted average of 2.7 years. During the nine months ended September 30, 2019, the Company recorded $2.4 million of stock-based compensation expense related to the modification of stock options pursuant to the transition agreement with its former President and Chief Executive Officer. These expenses were classified as selling, general, and administrative expenses within the consolidated statements of operations and comprehensive loss. During the three and nine months ended September 30, 2020, the Company recorded $0.4 million and $1.7 million, respectively, of stock-based compensation expense related to vesting events associated with performance-based restricted stock units that became probable and were achieved during the second quarter of 2020. These expenses were classified as research and development expenses within the consolidated statements of operations and comprehensive loss.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies KBA Grants Prior to 2014, the Company received funding from two research and development grants from the Kansas Bioscience Authority (KBA), totaling $2.0 million and no further amounts will be received under these grants. Pursuant to Kansas law, the Company may be required to repay some or all of the financial assistance received from the KBA, subject to the discretion of the KBA, if the Company relocates the operations in which the KBA invested outside of the State of Kansas, if the Company initiates procedures to dissolve and wind up or cease operations within ten years after receiving such financial assistance or upon certain significant changes to ownership of the Company. The Company will only account for the repayment of the grants if it becomes probable that the Company will be required to repay any funds previously received. Purchase Commitments Associated with Commercial Supply Agreements The Company has entered into commercial supply agreements related to the supply of QINLOCK that require the Company to make binding forecasts for a certain amount of purchases. The related cancellation clauses would as a general matter require the Company to pay the full amount of these binding forecasts. As of September 30, 2020, the Company's contractual commitments for such obligations were $7.9 million, which are primarily expected to be paid within one year. Legal Proceedings The Company is not currently a party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses the costs related to its legal proceedings as they are incurred. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and senior management that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims under indemnification arrangements, and it has not accrued any liabilities related to such obligations in its consolidated financial statements as of September 30, 2020 or December 31, 2019.

Nature of the Business and Su_2

Nature of the Business and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets, and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has incurred recurring losses including net losses of $203.7 million and $192.3 million for the nine months ended September 30, 2020 and the year ended December 31, 2019, respectively. As of September 30, 2020, the Company had an accumulated deficit of $691.7 million. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash, cash equivalents, and marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements through at least 12 months from the issuance date of these consolidated financial statements. The future viability of the Company is dependent on its ability to raise additional capital to fund its operations. The Company will need to obtain substantial additional funding in connection with continuing operations. If the Company is unable to raise capital when needed, or on attractive terms, it could be forced to delay, reduce, or eliminate its research or drug development programs or certain commercialization efforts. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. These consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated.
Unaudited Interim Financial Information	Unaudited Interim Financial Information These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (GAAP). The consolidated balance sheet as of December 31, 2019 was derived from audited financial statements, but does not include all disclosures required by GAAP. The accompanying unaudited consolidated financial statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (SEC) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. These consolidated financial statements should be read in conjunction with the Company's audited financial statements and the notes thereto for the year ended December 31, 2019 included in the Company's Annual Report on Form 10-K (Form 10-K) on file with the SEC. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company's consolidated financial position as of September 30, 2020 and consolidated results of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019 and consolidated cash flows for the nine months ended September 30, 2020 and 2019 have been made. The consolidated results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2020. Certain prior year amounts have been reclassified to conform to current year presentation. The significant accounting policies used in preparation of these consolidated financial statements for the three and nine months ended September 30, 2020 are consistent with those discussed in Note 2, Summary of Significant Accounting Policies, to
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, the accrual for research and development expenses, and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts, and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.
Net Loss per Share	Net Loss per Share Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted average number of common shares outstanding for the period. Diluted net income (loss) per share is computed by dividing the diluted net income (loss) by the weighted average number of common shares, including potential dilutive common shares assuming the dilutive effect as determined using the treasury stock method. For periods in which the Company has reported net losses, diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported a net loss for the three and nine months ended September 30, 2020 and 2019. The following potential dilutive securities, presented based on amounts outstanding at the end of each reporting period, have been excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive impact: As of September 30, 2020 2019 Options to purchase common stock 6,351,397 6,891,125 Unvested time-based restricted common stock units 419,235 67,000 Unvested performance-based restricted common stock units 55,200 — Unvested employee stock purchase plan shares 39,600 — Total 6,865,432 6,958,125
Product Revenues	Product Revenues In May 2020, the Company began generating product revenue from sales of QINLOCK to specialty distributors and specialty pharmacies in the U.S. following the approval of QINLOCK by the FDA on May 15, 2020 for the treatment of adult patients with advanced GIST who have received prior treatment with three or more kinase inhibitors, including imatinib. The Company recognizes product revenues, net of variable consideration related to certain allowances and accruals, when the customer takes control of the product, which is typically upon delivery to the customer. Product revenue is recorded at the net sales price, or transaction price. The Company records product revenue reserves, which are classified as a reduction in product revenues, to account for the components of variable consideration. Variable consideration includes the following components: chargebacks, government rebates, trade discounts and allowances, product returns, and other incentives, which are described below. These reserves are based on estimates of the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if the amount is payable to the Company's customer) or a liability (if the amount is payable to a party other than the Company's customer). The Company's estimates of reserves established for variable consideration are calculated based upon a consistent application of the expected value method, which is the sum of probability-weighted amounts in a range of possible consideration amounts. These estimates reflect the Company's historical experience, current contractual and statutory requirements, specific known market events and trends, industry data, forecasted customer buying, and payment patterns. The amount of variable consideration that is included in the transaction price may be subject to constraint and is included in net product revenues only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration received may ultimately differ from the Company's estimates. If actual results vary, the Company adjusts these estimates, which could have an effect on earnings in the period of adjustment. Chargebacks and administrative fees: Chargebacks for discounts represent the Company's estimated obligations resulting from contractual commitments to sell product to qualified healthcare providers and government agencies at prices lower than the list prices charged to the customers who directly purchase the product from the Company. The customers charge the Company for the difference between what the customers pay the Company for the product and the customer's ultimate contractually committed or government required lower selling price to the qualified healthcare providers. As part of the Company's contractual commitments to sell product to qualified healthcare providers, the Company pays fees for administrative services, such as account management and data reporting. Government rebates: Government rebates consist of Medicare, Tricare, and Medicaid rebates. These reserves are recorded in the same period the related revenue is recognized. For Medicare, the Company also estimates the number of patients in the prescription drug coverage gap for whom it will owe a rebate under the Medicare Part D program. Trade discounts and allowances: The Company provides the customers with discounts that are explicitly stated in the contracts and recorded in the period the related product revenue is recognized. In addition, the Company also receives sales order management, inventory management, and data services from the customers in exchange for certain fees. Product returns: The Company estimates the amount of its product sales that may be returned by its customers and records this estimate in the period the related product revenue is recognized. The Company currently estimates product return liabilities based on available industry data and its visibility into the inventory remaining in the distribution channel. Other incentives: Other incentives include co-payment assistance provided to qualified patients, whereby the Company may provide financial assistance to patients with prescription drug co-payments required by the patient's insurance provider. Reserves for co-payment assistance are recorded in the same period the related revenue is recognized.
Accounts Receivable	Accounts Receivable Accounts receivable arise from product sales and amounts due from the Company's collaboration partners and have standard payment terms that generally require payment within 30 to 90 days. The amount from product sales represents amounts due from specialty distributors and specialty pharmacies in the U.S., which are recorded net of reserves for customer chargebacks, trade discounts and allowances, and other incentives to the extent such amounts are payable to the customer by the Company. The Company monitors economic conditions to identify facts or circumstances that may indicate that its receivables are at risk of collection. The Company provides reserves against accounts receivable for estimated losses, if any, that may result from a customer's inability to pay based on the composition of its accounts receivable, current economic conditions, and historical credit loss activity. Amounts determined to be uncollectible are charged or written-off against the reserve. During the three and nine months ended September 30, 2020, the Company did not record any expected credit losses related to outstanding accounts receivable.
Inventory	Inventory Inventories are stated at the lower of cost or estimated net realizable value with cost based on the first-in first-out method. Inventory that can be used in either the production of clinical or commercial products is expensed as research and development costs when identified for use in clinical trials. Prior to the regulatory approval of its drug candidates, the Company incurs expenses for the manufacture of drug product supplies to support clinical development that could potentially be available to support the commercial launch of those drugs. Until the date at which regulatory approval has been received or is otherwise considered probable, the Company records all such costs as research and development expenses. The Company performs an assessment of the recoverability of capitalized inventories during each reporting period and writes down any excess and obsolete inventory to its net realizable value in the period in which the impairment is first identified. Such impairment charges, should they occur, are recorded as a component of cost of sales in the Company's consolidated statements of operations and comprehensive loss. The determination of whether inventory costs will be realizable requires the use of estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required. The Company commenced the capitalization of QINLOCK inventory in May 2020 upon receiving FDA approval of QINLOCK. Capitalized inventory consisted of the following: (in thousands) As of September 30, 2020 Raw materials $ 1,352 Work in process 3,160 Finished goods 84 Total inventory $ 4,596 There were no inventory amounts written down as a result of excess, obsolescence, unmarketability, or other reasons charged to cost of sales during the three and nine months ended September 30, 2020.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed below, the Company does not believe that the adoption of recently issued standards have or may have a material impact on its consolidated financial statements or disclosures. Credit Losses In June 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13). The FASB subsequently issued amendments to ASU 2016-13, which have the same effective date and transition date of January 1, 2020. This standard requires entities to estimate an expected lifetime credit loss on financial assets and report credit losses using an expected losses model rather than the incurred losses model that was previously used, and establishes additional disclosures related to credit risks. 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. This standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases. This standard became effective for the Company on January 1, 2020, and adoption of this standard did not have a material impact on the consolidated financial statements and related disclosures.

Nature of the Business and Su_3

Nature of the Business and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Potential Dilutive Securities	The following potential dilutive securities, presented based on amounts outstanding at the end of each reporting period, have been excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive impact: As of September 30, 2020 2019 Options to purchase common stock 6,351,397 6,891,125 Unvested time-based restricted common stock units 419,235 67,000 Unvested performance-based restricted common stock units 55,200 — Unvested employee stock purchase plan shares 39,600 — Total 6,865,432 6,958,125
Schedule of Inventory	The Company commenced the capitalization of QINLOCK inventory in May 2020 upon receiving FDA approval of QINLOCK. Capitalized inventory consisted of the following: (in thousands) As of September 30, 2020 Raw materials $ 1,352 Work in process 3,160 Finished goods 84 Total inventory $ 4,596

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Analysis Of Amount Of And Change In Product Revenue Reserves.	Activity in each of the product revenue allowance and reserve categories is summarized as follows: (in thousands) Trade discounts and allowances Chargebacks and administrative fees Government rebates and other incentives Returns Total Balance as of December 31, 2019 $ — $ — $ — $ — $ — Provision related to sales in the current year 302 854 886 662 2,704 Credits and payments made (152) (607) (127) (215) (1,101) Balance as of September 30, 2020 $ 150 $ 247 $ 759 $ 447 $ 1,603
Summary Of Total Product Revenue Reserves Included In The Consolidated Balance Sheets	The total reserves described above are summarized as components of the Company's consolidated balance sheets as follows: (in thousands) As of September 30, 2020 Reduction of accounts receivable, net $ 343 Component of accrued expenses and other current liabilities 1,260 Total revenue-related reserves $ 1,603

Marketable Securities and Fai_2

Marketable Securities and Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Investments, All Other Investments [Abstract]
Schedule of Marketable Securities	The following tables present marketable securities by contractual maturity and security type: As of September 30, 2020 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Due within one year: U.S. government securities 434,134 42 (5) 434,171 Due after one year through five years: U.S. government securities 38,987 4 (2) 38,989 Total $ 473,121 $ 46 $ (7) $ 473,160 As of December 31, 2019 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Due within one year: Commercial paper $ 314,292 $ 74 $ (23) $ 314,343 U.S. government securities 78,612 48 (3) 78,657 Certificates of deposit 66,241 17 (2) 66,256 Total $ 459,145 $ 139 $ (28) $ 459,256
Schedule of Financial Assets Measured at Fair Value on a Recurring Basis	The following tables present information about the Company's financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: As of September 30, 2020 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ — $ 41,204 $ — $ 41,204 U.S. government securities — 27,497 — 27,497 Marketable securities: U.S. government securities — 473,160 — 473,160 Total $ — $ 541,861 $ — $ 541,861 As of December 31, 2019 (in thousands) Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ — $ 28,192 $ — $ 28,192 Certificates of deposit — 20,500 — 20,500 Marketable securities: Commercial paper — 314,343 — 314,343 U.S. government securities — 78,657 — 78,657 Certificates of deposit — 66,256 — 66,256 Total $ — $ 507,948 $ — $ 507,948

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Operating Leases in the Consolidated Balance Sheet	All of the Company's leases qualify as operating leases. The following table summarizes the presentation of the Company's operating leases in the consolidated balance sheet: (in thousands) As of September 30, 2020 As of December 31, 2019 Operating lease assets $ 37,171 $ 21,158 Current operating lease liabilities $ 2,010 $ 1,747 Operating lease liabilities, net of current portion 29,394 15,904 Total operating lease liabilities $ 31,404 $ 17,651
Components of Lease Expense	The components of lease expense were as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2020 2019 2020 2019 Operating lease cost $ 1,321 $ 104 $ 2,843 $ 462 Short-term lease cost 18 82 336 270 Variable lease cost 144 128 343 337 Total lease expense $ 1,483 $ 314 $ 3,522 $ 1,069
Future Annual Minimum Lease Payments Under Operating Leases	Future annual minimum lease payments under operating leases were as follows: (in thousands) As of September 30, 2020 Remainder of 2020 (three months) $ 622 2021 4,143 2022 4,225 2023 4,308 2024 4,390 2025 4,472 Thereafter 18,519 Total future minimum lease payments 40,679 Less: imputed interest (9,275) Total operating lease liabilities $ 31,404
Weighted-Average Remaining Lease Term and Discount Rate	The weighted-average remaining lease term and weighted-average discount rate of the Company's operating leases are as follows: As of September 30, 2020 As of December 31, 2019 Weighted-average remaining lease term in years 9.21 9.63 Weighted-average discount rate 5.60 % 5.36 %
Supplemental Cash Flow Information	Supplemental disclosure of cash flow information related to the Company's operating leases included in cash flows used in operating activities in the consolidated statement of cash flows is as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2020 2019 2020 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 618 $ 104 $ 2,024 $ 424 Operating lease liabilities arising from obtaining operating lease assets $ 14,883 $ 142 $ 14,883 $ 142

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: (in thousands) As of September 30, 2020 As of December 31, 2019 External research and development expenses $ 31,354 $ 20,462 Payroll and related expenses 13,450 12,902 Professional fees 2,514 3,810 Revenue-related reserves 1,260 — Other 363 1,542 Total accrued expenses and other current liabilities $ 48,941 $ 38,716

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Classification of Stock-Based Compensation Expense	Stock-based compensation expense was classified in the consolidated statements of operations and comprehensive loss as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2020 2019 2020 2019 Research and development expenses $ 4,518 $ 1,992 $ 13,082 $ 5,474 Selling, general, and administrative expenses 5,310 2,737 14,349 9,591 Total stock-based compensation $ 9,828 $ 4,729 $ 27,431 $ 15,065

Nature of the Business and Su_4

Nature of the Business and Summary of Significant Accounting Policies - Summary of Potential Dilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share (in shares)	6,865,432	6,958,125
Unvested time-based restricted common stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share (in shares)	419,235	67,000
Unvested performance-based restricted common stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share (in shares)	55,200	0
Unvested employee stock purchase plan shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share (in shares)	39,600	0
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share (in shares)	6,351,397	6,891,125

Nature of the Business and Su_5

Nature of the Business and Summary of Significant Accounting Policies - Inventory (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 1,352,000	$ 1,352,000
Work in process	3,160,000	3,160,000
Finished goods	84,000	84,000
Inventory	4,596,000	4,596,000	$ 0
Inventory written down	$ 0	$ 0

Nature of the Business and Su_6

Nature of the Business and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2020	Feb. 29, 2020	Jun. 30, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Nature Of Business And Basis Of Presentation [Line Items]
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs					$ 431,780,000	$ 188,385,000	$ 431,780,000
Net loss				$ (63,701,000)	$ (56,196,000)	(203,749,000)	$ (125,040,000)	$ (192,300,000)
Accumulated deficit				(691,728,000)		(691,728,000)		$ (487,979,000)
Accounts Receivable, Credit Loss Expense (Reversal)				0		$ 0
Common Stock
Nature Of Business And Basis Of Presentation [Line Items]
Number of shares issued and sold (in shares)					12,432,431	3,659,090	12,432,431
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs					$ 124,000	$ 37,000	$ 124,000
Follow on Offering | Common Stock
Nature Of Business And Basis Of Presentation [Line Items]
Number of shares issued and sold (in shares)		3,659,090	4,945,000		12,432,431
Additional offering price of common stock (in dollars per share)		$ 55	$ 40		$ 37		$ 37
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs		$ 188,400,000	$ 185,300,000		$ 431,800,000
Open Market Sale Agreement
Nature Of Business And Basis Of Presentation [Line Items]
Offering proceeds	$ 200,000,000
Sale on agreement				$ 0		$ 0

Revenues - Product Revenue Allo

Revenues - Product Revenue Allowance and Reserve Categories (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 0
Provision related to sales in the current year	2,704
Credits and payments made	1,101
Ending balance	1,603
Trade discounts and allowances
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	0
Provision related to sales in the current year	302
Credits and payments made	152
Ending balance	150
Chargebacks and administrative fees
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	0
Provision related to sales in the current year	854
Credits and payments made	607
Ending balance	247
Government rebates and other incentives
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	0
Provision related to sales in the current year	886
Credits and payments made	127
Ending balance	759
Returns
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	0
Provision related to sales in the current year	662
Credits and payments made	215
Ending balance	$ 447

Revenues - Total Reserves Summa

Revenues - Total Reserves Summarized (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue-related reserves	$ 1,603	$ 0
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Revenue-related reserves	1,603	0
Accounts Receivable
Revenue from Contract with Customer [Abstract]
Revenue-related reserves	343
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Revenue-related reserves	343
Accrued Expenses And Other Current Liabilities
Revenue from Contract with Customer [Abstract]
Revenue-related reserves	1,260	0
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Revenue-related reserves	$ 1,260	$ 0

Revenues - Additional Informati

Revenues - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended			9 Months Ended
	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from External Customer [Line Items]
Total revenues		$ 15,449,000	$ 0		$ 22,601,000	$ 25,000,000
Revenue from Contract with Customer [Member] | Customer Concentration Risk | Customer One [Member]
Revenue from External Customer [Line Items]
Major customer percentage of gross product revenues		56.00%			54.00%
Revenue from Contract with Customer [Member] | Customer Concentration Risk | Customer Two [Member]
Revenue from External Customer [Line Items]
Major customer percentage of gross product revenues		25.00%			27.00%
Revenue from Contract with Customer [Member] | Customer Concentration Risk | Customer Three [Member]
Revenue from External Customer [Line Items]
Major customer percentage of gross product revenues		12.00%			11.00%
Accounts Receivable | Customer Concentration Risk | Customer One [Member]
Revenue from External Customer [Line Items]
Percentage of accounts receivable		59.00%			59.00%
Accounts Receivable | Customer Concentration Risk | Customer Two [Member]
Revenue from External Customer [Line Items]
Percentage of accounts receivable		24.00%			24.00%
Product revenues, net
Revenue from External Customer [Line Items]
Total revenues		$ 15,164,000	0		$ 19,989,000	0
Product revenues, net | UNITED STATES
Revenue from External Customer [Line Items]
Total revenues		14,700,000			19,500,000
Product revenues, net | Non-US [Member]
Revenue from External Customer [Line Items]
Total revenues		500,000			500,000
Collaboration revenues
Revenue from External Customer [Line Items]
Total revenues		285,000	$ 0		2,612,000	$ 25,000,000
Zai License Agreement
Revenue from External Customer [Line Items]
Upfront cash payment receivable	$ 20,000,000			$ 20,000,000
Upfront payment recognized revenue				20,000,000
Revenues		100,000			200,000
Zai License Agreement | Collaboration revenues
Revenue from External Customer [Line Items]
Revenues		100,000		25,000,000	2,200,000
Zai License Agreement | Development And Commercial Milestone | Maximum
Revenue from External Customer [Line Items]
License agreement milestone	185,000,000
Zai License Agreement | Development Milestone | INTRIGUE Study Related Milestone
Revenue from External Customer [Line Items]
License agreement milestone				$ 5,000,000
Zai License Agreement | Development Milestone | Maximum
Revenue from External Customer [Line Items]
License agreement milestone	50,000,000
Zai License Agreement | Commercial Milestone | Maximum
Revenue from External Customer [Line Items]
License agreement milestone	$ 135,000,000
Zai License Agreement | Regulatory related development milestone
Revenue from External Customer [Line Items]
Revenues					2,000,000
Zai Supply Agreement | Collaboration revenues
Revenue from External Customer [Line Items]
Revenues		$ 200,000			$ 400,000

Marketable Securities and Fai_3

Marketable Securities and Fair Value Measurements - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Amortized Cost	$ 473,121	$ 459,145
Gross Unrealized Gains	46	139
Gross Unrealized Losses	(7)	(28)
Estimated Fair Value	473,160	459,256
U.S. government securities
Marketable Securities [Line Items]
Amortized Cost, due within one year	434,134	78,612
Amortized Cost, due after on year through five years	38,987
Gross Unrealized Gains, due within one year	42	48
Gross Unrealized Gains, due after one year through five years	4
Gross Unrealized Losses, due within one year	(5)	(3)
Gross Unrealized Losses, due after one year through five years	(2)
Estimated Fair Value, due within one year	434,171	78,657
Estimated Fair Value, due after on year through five years	38,989
Estimated Fair Value	$ 473,160	78,657
Commercial paper
Marketable Securities [Line Items]
Amortized Cost, due within one year		314,292
Gross Unrealized Gains, due within one year		74
Gross Unrealized Losses, due within one year		(23)
Estimated Fair Value, due within one year		314,343
Certificates of deposit
Marketable Securities [Line Items]
Amortized Cost, due within one year		66,241
Gross Unrealized Gains, due within one year		17
Gross Unrealized Losses, due within one year		(2)
Estimated Fair Value, due within one year		$ 66,256

Marketable Securities and Fai_4

Marketable Securities and Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Marketable securities:
Total Marketable securities	$ 473,160	$ 459,256
Total	541,861	507,948
U.S. government securities
Cash equivalents:
Total Cash equivalents	27,497
Marketable securities:
Total Marketable securities	473,160	78,657
Commercial paper
Marketable securities:
Total Marketable securities		314,343
Money market funds
Cash equivalents:
Total Cash equivalents	41,204	28,192
Certificates of deposit
Cash equivalents:
Total Cash equivalents		20,500
Marketable securities:
Total Marketable securities		66,256
Level 1
Marketable securities:
Total	0	0
Level 1 | U.S. government securities
Cash equivalents:
Total Cash equivalents	0
Marketable securities:
Total Marketable securities	0	0
Level 1 | Commercial paper
Marketable securities:
Total Marketable securities		0
Level 1 | Money market funds
Cash equivalents:
Total Cash equivalents	0	0
Level 1 | Certificates of deposit
Cash equivalents:
Total Cash equivalents		0
Marketable securities:
Total Marketable securities		0
Level 2
Marketable securities:
Total	541,861	507,948
Level 2 | U.S. government securities
Cash equivalents:
Total Cash equivalents	27,497
Marketable securities:
Total Marketable securities	473,160	78,657
Level 2 | Commercial paper
Marketable securities:
Total Marketable securities		314,343
Level 2 | Money market funds
Cash equivalents:
Total Cash equivalents	41,204	28,192
Level 2 | Certificates of deposit
Cash equivalents:
Total Cash equivalents		20,500
Marketable securities:
Total Marketable securities		66,256
Level 3
Marketable securities:
Total	0	0
Level 3 | U.S. government securities
Cash equivalents:
Total Cash equivalents	0
Marketable securities:
Total Marketable securities	0	0
Level 3 | Commercial paper
Marketable securities:
Total Marketable securities		0
Level 3 | Money market funds
Cash equivalents:
Total Cash equivalents	$ 0	0
Level 3 | Certificates of deposit
Cash equivalents:
Total Cash equivalents		0
Marketable securities:
Total Marketable securities		$ 0

Marketable Securities and Fai_5

Marketable Securities and Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities	$ 473,160	$ 459,256
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Marketable securities		66,256
Certificates of deposit | Letter of Credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certificate of deposit held to secure letter of credit associated with lease and credit card	$ 2,100	$ 1,500

Leases - Operating Leases in th

Leases - Operating Leases in the Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease assets	$ 37,171	$ 21,158
Current operating lease liabilities	2,010	1,747
Operating lease liabilities, net of current portion	29,394	15,904
Total operating lease liabilities	$ 31,404	$ 17,651

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 1,321	$ 104	$ 2,843	$ 462
Short-term lease cost	18	82	336	270
Variable lease cost	144	128	343	337
Total lease cost	$ 1,483	$ 314	$ 3,522	$ 1,069
Weighted-average remaining lease term in years	9 years 2 months 15 days		9 years 2 months 15 days		9 years 7 months 17 days
Weighted-average discount rate	5.60%		5.60%		5.36%

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Lease Payments under Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Operating Leases, After Adoption
Remainder of 2020 (three months)	$ 622
2021	4,143
2022	4,225
2023	4,308
2024	4,390
2025	4,472
Thereafter	18,519
Total future minimum lease payments	40,679
Less: imputed interest	(9,275)
Total operating lease liabilities	$ 31,404	$ 17,651

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 618	$ 104	$ 2,024	$ 424
Operating lease liabilities arising from obtaining operating lease assets	$ 14,883	$ 142	$ 14,883	$ 142

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Apr. 30, 2019USD ($)ft²	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)renewal_option	Jul. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Oct. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease assets			$ 37,171		$ 21,158
Operating lease liability			$ 31,404		17,651
The Initial Space [Member]
Lessee, Lease, Description [Line Items]
Operating lease assets						$ 21,200
Operating lease liability						$ 17,000
The Additional Space [Member]
Lessee, Lease, Description [Line Items]
Operating lease assets				$ 16,500
Operating lease liability				$ 13,500
Additional area of lease space | ft²	38,003
Number of options to extend | renewal_option			2
Options to extend terms of the lease			5 years
Initial annual base rent expense	$ 1,900
Rent expense	$ 18,200
The Premises [Member]
Lessee, Lease, Description [Line Items]
Total lease area | ft²	82,346
Certificates of deposit | Letter of Credit
Lessee, Lease, Description [Line Items]
Certificate of deposit to secure letter of credit associated with lease			$ 2,100		1,500
Certificates of deposit | Letter of Credit | The Premises [Member]
Lessee, Lease, Description [Line Items]
Certificate of deposit to secure letter of credit associated with lease			1,100		$ 1,100
Certificates of deposit | Letter of Credit | Subsequent Event [Member] | The Additional Space [Member]
Lessee, Lease, Description [Line Items]
Increase (Decrease) in Deposit Assets		$ 900
Kansas
Lessee, Lease, Description [Line Items]
Operating lease assets			1,400
Operating lease liability			$ 1,400
Number of options to extend | renewal_option			2
Options to extend terms of the lease			5 years

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Accrued Expenses and Other Current Liabilities
External research and development expenses	$ 31,354	$ 20,462
Payroll and related expenses	13,450	12,902
Professional fees	2,514	3,810
Revenue-related reserves	1,603	0
Other	363	1,542
Total accrued expenses and other current liabilities	48,941	38,716
Accrued Expenses And Other Current Liabilities
Schedule of Accrued Expenses and Other Current Liabilities
Revenue-related reserves	$ 1,260	$ 0

Stock-Based Awards - Classifica

Stock-Based Awards - Classification of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 9,828	$ 4,729	$ 27,431	$ 15,065
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	4,518	1,992	13,082	5,474
Selling, general, and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 5,310	$ 2,737	$ 14,349	$ 9,591

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested share-based awards	$ 92,600,000		$ 92,600,000
Unrecognized compensation cost related to unvested share-based awards, period for recognition			2 years 8 months 12 days
Share-based compensation expense	9,828,000	$ 4,729,000	$ 27,431,000	$ 15,065,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 400,000		$ 1,700,000
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent			85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date			15.00%
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period			6 months
President And Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense related to modification				$ 2,400,000
2017 Stock Option and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	1,748,489		1,748,489
Employee Stock Purchase Plan (ESPP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	1,409,433		1,409,433

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	Dec. 31, 2013USD ($)award	Dec. 31, 2013	Sep. 30, 2020USD ($)
Other Commitments [Line Items]
Supply commitment amount			$ 7.9
KBA Grants
Other Commitments [Line Items]
Number of awards grants | award	2
Amount of grants awarded	$ 2
Repayment of Grant Term, Period from Grant Date		10 years