Turning Point Therapeutics (TPTX) 10-Q 9 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Aug. 02, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Trading Symbol	TPTX
Entity Registrant Name	Turning Point Therapeutics, Inc.
Entity Central Index Key	0001595893
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		49,407,966
Entity File Number	001-38871
Entity Tax Identification Number	46-3826166
Entity Address, Address Line One	10628 Science Center Drive
Entity Address, Address Line Two	Ste. 200
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	926-5251
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 426,047	$ 554,101
Marketable securities	651,759	568,407
Prepaid and other current assets	13,614	8,171
Total current assets	1,091,420	1,130,679
Property and equipment, net	3,210	2,604
Right-of-use lease assets	6,269	3,357
Other assets	2,021	73
Total assets	1,102,920	1,136,713
Current liabilities:
Accounts payable	7,088	5,225
Accrued expenses and other current liabilities	16,096	9,183
Accrued compensation	5,727	8,588
Current portion of operating lease liabilities	2,984	1,396
Total current liabilities	31,895	24,392
Operating lease liabilities, long-term	3,518	2,423
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized at June 30, 2021 and December 31, 2020, zero shares outstanding at June 30, 2021 and December 31, 2020
Common stock, $0.0001 par value; 200,000,000 shares authorized at June 30, 2021 and December 31, 2020; 49,391,738 and 48,678,540 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	5	5
Additional paid-in capital	1,439,453	1,389,860
Accumulated other comprehensive income	2	209
Accumulated deficit	(371,953)	(280,176)
Total stockholders' equity	1,067,507	1,109,898
Total liabilities and stockholders’ equity	$ 1,102,920	$ 1,136,713

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	49,391,738	48,678,540
Common stock, shares outstanding	49,391,738	48,678,540

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenue	$ 5,164		$ 30,369
Operating expenses:
Research and development	44,650	$ 24,154	85,913	$ 46,923
General and administrative	17,171	8,578	37,162	48,435
Total operating expenses	61,821	32,732	123,075	95,358
Loss from operations	(56,657)	(32,732)	(92,706)	(95,358)
Other income, net	384	1,239	929	3,147
Net loss	(56,273)	(31,493)	(91,777)	(92,211)
Unrealized gain / (loss) on marketable securities, net of tax	(22)	1,063	(208)	747
Comprehensive loss	$ (56,295)	$ (30,430)	$ (91,985)	$ (91,464)
Net loss per share, basic and diluted	$ (1.14)	$ (0.82)	$ (1.87)	$ (2.47)
Weighted-average common shares outstanding, basic and diluted	49,204,425	38,603,236	49,063,298	37,261,296

Condensed Statements of Stockho

Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2019	$ 404,351	$ 4	$ 526,960	$ 271	$ (122,884)
Balance, Shares at Dec. 31, 2019		35,915,119
Option exercises	25		25
Option exercises, Shares		7,129
Stock-based compensation expense	38,365		38,365
Net loss	(60,718)				(60,718)
Other comprehensive (loss) income	(316)			(316)
Balance at Mar. 31, 2020	381,707	$ 4	565,350	(45)	(183,602)
Balance, Shares at Mar. 31, 2020		35,922,248
Balance at Dec. 31, 2019	404,351	$ 4	526,960	271	(122,884)
Balance, Shares at Dec. 31, 2019		35,915,119
Net loss	(92,211)
Balance at Jun. 30, 2020	710,827	$ 5	924,899	1,018	(215,095)
Balance, Shares at Jun. 30, 2020		42,168,889
Balance at Mar. 31, 2020	381,707	$ 4	565,350	(45)	(183,602)
Balance, Shares at Mar. 31, 2020		35,922,248
Option exercises	31		31
Option exercises, Shares		3,049
Shares issued under employee stock purchase plan	504		504
Shares issued under employee stock purchase plan, Shares		14,425
Issuance of common stock in connection with a public offering, net of underwriting discounts, commissions, and offering costs	351,611	$ 1	351,610
Issuance of common stock in connection with a public offering, net of underwriting discounts, commissions, and offering costs, Shares		6,229,167
Stock-based compensation expense	7,404		7,404
Net loss	(31,493)				(31,493)
Other comprehensive (loss) income	1,063			1,063
Balance at Jun. 30, 2020	710,827	$ 5	924,899	1,018	(215,095)
Balance, Shares at Jun. 30, 2020		42,168,889
Balance at Dec. 31, 2020	$ 1,109,898	$ 5	1,389,860	209	(280,176)
Balance, Shares at Dec. 31, 2020	48,678,540	48,678,540
Option exercises	$ 9,679		9,679
Option exercises, Shares		438,500
Stock-based compensation expense	17,278		17,278
Net loss	(35,504)				(35,504)
Other comprehensive (loss) income	(186)			(186)
Balance at Mar. 31, 2021	1,101,165	$ 5	1,416,817	23	(315,680)
Balance, Shares at Mar. 31, 2021		49,117,040
Balance at Dec. 31, 2020	$ 1,109,898	$ 5	1,389,860	209	(280,176)
Balance, Shares at Dec. 31, 2020	48,678,540	48,678,540
Option exercises, Shares	691,537
Net loss	$ (91,777)
Balance at Jun. 30, 2021	$ 1,067,507	$ 5	1,439,453	2	(371,953)
Balance, Shares at Jun. 30, 2021	49,391,738	49,391,738
Balance at Mar. 31, 2021	$ 1,101,165	$ 5	1,416,817	23	(315,680)
Balance, Shares at Mar. 31, 2021		49,117,040
Option exercises	8,398		8,398
Option exercises, Shares		253,037
Shares issued under employee stock purchase plan	943		943
Shares issued under employee stock purchase plan, Shares		21,661
Stock-based compensation expense	13,295		13,295
Net loss	(56,273)				(56,273)
Other comprehensive (loss) income	(21)			(21)
Balance at Jun. 30, 2021	$ 1,067,507	$ 5	$ 1,439,453	$ 2	$ (371,953)
Balance, Shares at Jun. 30, 2021	49,391,738	49,391,738

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net loss	$ (91,777)	$ (92,211)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	30,573	45,769
Depreciation	518	423
Accretion of discount (premium) on marketable securities	2,771	(236)
Amortization of right-of-use operating lease asset	965	759
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(5,589)	(2,650)
Accounts payable	1,612	(378)
Accrued expenses and other current liabilities	5,719	204
Accrued compensation	(2,861)	(2,842)
Net cash used in operating activities	(58,069)	(51,162)
Investing activities
Purchases of marketable securities	(255,763)	(118,687)
Sales and maturities of marketable securities	169,434	240,717
Purchases of property and equipment	(874)	(713)
Net cash (used in) provided by investing activities	(87,203)	121,317
Financing activities
Proceeds from issuance of common stock in public offering, net		351,611
Proceeds from issuance of common stock under equity incentive plans	19,020	560
Net cash provided by financing activities	19,020	352,171
Net (decrease) increase in cash, cash equivalents and restricted cash	(126,252)	422,326
Cash, cash equivalents and restricted cash at the beginning of period	554,174	48,261
Cash, cash equivalents and restricted at the end of period	427,922	470,587
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1	$ 1
Supplemental disclosure of non-cash investing and financing information:
Purchases of property and equipment in accounts payable	250
Operating lease liabilities arising from obtaining right-of-use assets	$ 3,544

Formation and Business of the C

Formation and Business of the Company; Basis of Presentation	6 Months Ended
	Jun. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Formation and Business of the Company; Basis of Presentation	1. Formation and Business of the Company; Basis of Presentation Organization Turning Point Therapeutics, Inc. (the Company) was organized in 2013 and commenced operations in 2014. The Company is a clinical-stage precision oncology biopharmaceutical company designing and developing novel small molecule, targeted oncology therapies. The Company’s principal operations are in the United States and the Company operates in one segment, with its headquarters in San Diego, California. The Company’s primary activities since inception have been to build infrastructure, conduct research and development, including clinical trials, perform business and financial planning, and raise capital. Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (SEC). Accordingly, since they are interim statements, the accompanying condensed financial statements do not include all of the information and notes required by GAAP for complete financial statements. The unaudited interim financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The condensed balance sheet at December 31, 2020 has been derived from the audited financial statements at that date, but does not include all information and footnotes required by GAAP for complete financial statements. The operating results presented in these unaudited condensed financial statements are not necessarily indicative of the results that may be expected for any future periods. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 filed with the SEC. In the opinion of management, the unaudited condensed financial statements and notes thereto include all adjustments that are of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position and of the results of operations and cash flows for the periods presented. Liquidity Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year from the financial statement issuance date. The Company determined that there are no conditions or events that raise substantial doubt about its ability to continue as a going concern within one year after the date that the unaudited condensed financial statements for the quarter ended June 30, 2021 are issued. The COVID-19 pandemic continues to rapidly evolve and has already resulted in a significant disruption of global financial markets. The Company’s ability to raise additional capital may be adversely impacted by potential worsening global economic conditions and further disruptions to, and volatility in, the credit and financial markets in the United States and worldwide resulting from the pandemic. If such further disruption occurs, the Company could experience an inability to access additional capital.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2 of the Notes to Financial Statements included in its Annual Report on Form 10‑K for the year ended December 31, 2020. Revenue The Company recognizes revenue in accordance with Accounting Standards Codification (ASC) Topic 606, Revenue From Contracts With Customers The Company assesses the goods or services promised within each contract and determines those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). In assessing whether a promised good or service is distinct, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, an entity is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (SSP) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations requires significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment. If an arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. For arrangements with licenses of intellectual property that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty has been allocated has been satisfied. In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied, either at a point in time or over time, and if over time, recognition is based on the use of an output or input method. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent liabilities in the Company’s financial statements and accompanying notes. The most significant estimates in the Company’s financial statements relate to determining the SSP of performance obligations associated with license arrangements , preclinical and clinical trial costs and accruals and stock-based compensation costs . Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Alth ough the impact of the COVID-19 pandemic to the Company’s business and operating results presents additional uncertainty, the Company continues to use the best information available to update its critical accounting estimates . Cash, Cash Equivalents and Restricted Cash The following table presents a reconciliation of cash, cash equivalents and restricted cash to amounts shown in the unaudited condensed statement of cash flows (in thousands): June 30, 2021 June 30, 2020 Cash and cash equivalents $ 426,047 $ 470,514 Restricted Cash, as part of other assets 1,875 73 Total cash, cash equivalents and restricted cash $ 427,922 $ 470,587 Concentration of Credit Risk Substantially all of the Company’s cash, cash equivalents, and marketable securities are held at two financial institutions. Due to the financial strength of the depository institutions, the Company believes these financial institutions represent minimal credit risk. Cash amounts held at financial institutions are insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000. At June 30, 2021, cash and cash equivalents and marketable securities totaling $1,077.6 million are either not subject to FDIC insurance, or exceed the FDIC insured limit. The Company’s cash and cash equivalents and marketable securities are invested in short term, high credit quality securities, and as a result, the Company believes represent a minimal credit risk. Clinical Trial Costs and Accruals A significant portion of the Company’s clinical trial costs relate to contracts with contract research organizations (CROs). The financial terms of the Company’s CRO contracts may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate clinical trial expenses in the Company’s financial statements by matching those expenses with the period in which services and efforts are expended. As part of the process of preparing the Company’s financial statements, the Company evaluates cost information provided by the Company’s CROs concerning estimated monthly expenses for services rendered and unbilled obligations as the sponsor of the Company’s clinical trials. Accordingly, the Company’s clinical trial accrual is dependent upon the timely and accurate reporting of CROs and other third-party vendors, and the Company’s ability to accurately estimate any unbilled obligations. If the contracted amounts are modified, for instance, as a result of changes in the clinical trial protocol or scope of work to be performed, the Company modifies its accruals accordingly on a prospective basis. Revisions in the scope of a contract are charged to research and development expense in the period in which the facts that give rise to the revision become reasonably certain. Research and Development Expenses Research and development costs are expensed as incurred. These costs consist primarily of salaries and other personnel-related expenses, including stock-based compensation; facility-related expenses; depreciation of facilities and equipment; laboratory consumables; and services performed by clinical research organizations, research institutions, and other outside service providers. The Company recorded the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and include these costs in accrued expenses and other current liabilities accrued expenses and other current liabilities Net Loss Per Share The Company computes basic loss per share by dividing the net loss available to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss assumes the conversion, exercise or issuance of all potential common stock equivalents, unless the effect of inclusion would be anti-dilutive. For purposes of this calculation, common stock equivalents include the Company’s stock options, restricted stock units (RSUs) and contingently issuable shares. The Company excluded stock options to purchase common stock, RSUs and contingently issuable shares from the number of shares used to calculate diluted shares outstanding because the inclusion of these potentially dilutive securities would have been antidilutive. Historical outstanding anti-dilutive securities not included in the diluted net loss per share calculation include the following: Six Months Ended June 30, 2021 2020 Options to purchase common stock 5,406,931 6,445,367 RSUs 192,281 - Total 5,599,212 6,445,367

Marketable Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2021
Investments Debt And Equity Securities [Abstract]
Marketable Securities	3. Marketable Securities T he Company invests its excess cash in marketable securities, including debt instruments of financial institutions, corporations with investment grade credit ratings, commercial paper and government agencies. At June 30, 2021, marketable securities consisted of the following (in thousands): Unrealized Maturity in Years Amortized Cost Gains Losses Fair Value U.S. Treasuries 2 years or less 195,076 27 (54 ) 195,049 U.S. Government agency securities 2 years or less 179,648 77 (45 ) 179,680 Non-U.S. Government agency securities 2 years or less 24,012 - (13 ) 23,999 Corporate debt securities 2 years or less 115,783 31 (21 ) 115,793 Commercial paper Less than 1 137,238 - - 137,238 Total marketable securities $ 651,757 $ 135 $ (133 ) $ 651,759 At December 31, 2020, marketable securities consisted of the following (in thousands): Unrealized Maturity in Years Amortized Cost Gains Losses Fair Value U.S. Treasuries 2 years or less $ 113,662 $ 19 $ (1 ) $ 113,680 U.S. Government agency securities 2 years or less 173,583 100 - 173,683 Corporate debt securities 2 years or less 169,189 103 (27 ) 169,265 Commercial paper Less than 1 111,779 - - 111,779 Total marketable securities $ 568,213 $ 222 $ (28 ) $ 568,407 The Company segments its portfolio based on the underlying risk profiles of their current securities being held. The Company regularly reviews the securities in an unrealized loss position and evaluates the current expected credit loss by considering factors such as historical experience, market data, issuer-specific factors, current and expected future economic conditions. As of June 30, 2021, the Company did not record an allowance for credit loss related to its investment portfolio.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Fair value should maximize the use of observable inputs and minimize the use of unobservable inputs. The Company determines the fair value of financial assets and liabilities using three levels of inputs as follows: Level 1—Inputs which include quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Inputs (other than quoted market prices included in Level 1) that are either directly or indirectly observable, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life. Level 3—Unobservable inputs for assets or liabilities and include little or no market activity. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s financial assets subject to fair value measurements on a recurring basis and the level of inputs used for such measurements were as follows (in thousands): Fair Value Measurements at June 30, 2021 Using: Level 1 Level 2 Level 3 Total Money market funds $ 143,203 $ - $ - $ 143,203 U.S. Treasuries 195,049 - - 195,049 U.S. Government agency securities - 179,680 - 179,680 Non-U.S. Government securities - 23,999 - 23,999 Corporate debt securities - 115,793 - 115,793 Commercial paper - 419,636 - 419,636 Total cash equivalents and marketable securities $ 338,252 $ 739,108 $ - $ 1,077,360 Fair Value Measurements at December 31, 2020 Using: Level 1 Level 2 Level 3 Total Money market funds $ 299,571 $ - $ - $ 299,571 U.S. Treasuries 113,680 - - 113,680 U.S. Government agency securities - 173,683 - 173,683 Corporate debt securities - 180,718 - 180,718 Commercial paper - 354,223 - 354,223 Total cash equivalents and marketable securities $ 413,251 $ 708,624 $ - $ 1,121,875

Property and Equipment, Net

Property and Equipment, Net	6 Months Ended
	Jun. 30, 2021
Property Plant And Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands) June 30, December 31, 2021 2020 Laboratory equipment $ 2,240 $ 1,629 Computer equipment and software 1,275 956 Tenant improvements 1,302 1,108 Furniture and fixtures 357 357 Property and equipment 5,174 4,050 Less: accumulated depreciation (1,964 ) (1,446 ) Property and equipment, net $ 3,210 $ 2,604 Depreciation expense for the three months ended June 30, 2021 and 2020 was $0.3 million and $0.2 million, respectively. Depreciation expense for the six months ended June 30, 2021 and 2020 was $0.5 million and $0.4 million, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	6 Months Ended
	Jun. 30, 2021
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands) June 30, December 31, 2021 2020 Accrued research and development expenses $ 15,194 $ 8,457 Accrued general and administrative expenses 818 682 Other current liabilities 84 44 Total $ 16,096 $ 9,183

Zai License Agreements

Zai License Agreements	6 Months Ended
	Jun. 30, 2021
Research And Development [Abstract]
Zai License Agreements	7. Zai License Agreements Zai Repotrectinib Agreement In J uly 2020 , the Company entered into a l icense a greement (the Zai Repotrectinib Agreement) with Zai Lab (Shanghai) Co., Ltd. ( Zai ), pursuant to which the Company grant ed Zai exclusive rights to develop and commercialize products containing the Company’s drug candidate, repotrectinib (the Repotrectinib Products), in Mainland China, Hong Kong, Macau and Taiwan (collectively, the Zai Territory or Greater China ). The Company retains exclusive rights to, among other things, develop, manufacture and commercialize the Repotrectinib Products outside the Zai Territory. The Company will supply or have supplied to Zai the Repotrectinib Products for use in the Zai Territory pursuant to a supply agreement for agreed upon consideration, except that Zai has the right, at its election, to package and label the Repotrectinib Products in or outside the Zai Territory for use in the Zai Territory . Pursuant to the terms of the Zai Repotrectinib Agreement, the Company has received an upfront cash payment of $25.0 million and is eligible to receive up to $151.0 million in development and sales milestone payments, consisting of up to $46.0 million of development milestones and up to $105.0 million of sales milestones. In addition, during the term of the Zai Repotrectinib Agreement, Zai is obligated to pay the Company tiered percentage royalties ranging from teens on annual net sales of the Repotrectinib Products in the Zai Territory, subject to adjustments in specified circumstances Zai is responsible for conducting the development and commercialization activities in the Zai Territory related to the Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib The Zai Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Repotrectinib Revenue Recognition The Company determined that two performance obligations existed: (1) the exclusive license, bundled with the associated know-how and (2) the Company's initial obligation to supply repotrectinib for clinical development in the Zai Territory. The total transaction price of $25.7 million was allocated to the performance obligations on the basis of the relative stand-alone selling price estimated for each performance obligation. In estimating the stand-alone selling price for each performance obligation, the Company developed assumptions that require judgment and included forecasted revenues, expected development timelines, discount rates, probabilities of technical and regulatory success and costs for manufacturing clinical supplies. The Company delivered the license and technical know-how to Zai in the third quarter of 2020 to satisfy this performance obligation, and accordingly the Company recognized license revenue of $25.0 million in the third quarter of 2020. The $0.7 million in consideration allocable to the clinical supply performance obligation will be recognized when clinical trial material has been shipped by the Company and Zai obtains control of the goods, upon delivery, over the period of the obligation. For the three and six months ended June 30, 2021, the Company recognized $0.2 million and $0.4 million, respectively in revenue associated with the clinical supply performance obligation. The Company assessed the Zai Repotrectinib Agreement to determine whether a financing component exists and concluded that a significant financing component does not exist. The development milestones were subject to foreign tax withholdings. The Company recorded this tax expense to general and administrative expense in the condensed statements of operations and comprehensive loss. Zai TPX-0022 Agreement On January 10, 2021, the Company entered into a license agreement with Zai, which was amended on March 31, 2021 (the Zai TPX-0022 Agreement), pursuant to which the Company granted Zai exclusive rights to develop and commercialize products containing the Company’s drug candidate, TPX-0022 (the TPX-0022 Products), in the Zai Territory. The Company retains exclusive rights to, among other things, develop, manufacture and commercialize the TPX-0022 Products outside the Zai Territory. Pursuant to the terms of the Zai TPX-0022 Agreement, the Company has received an upfront cash payment of $25.0 million and is eligible to receive up to $336.0 million in development and sales milestone payments, consisting of up to $121.0 million of development milestones and up to $215.0 million of sales milestones. In addition, during the term of the Zai TPX-0022 Agreement, Zai is obligated to pay the Company tiered percentage royalties ranging from mid-teens to low twenties on annual net sales of the TPX-0022 Products in the Zai Territory, subject to adjustments in specified circumstances Zai is responsible for conducting the development and commercialization activities in the Zai Territory related to the TPX-0022 Products at Zai’s own expense, subject to limited exceptions pursuant to which the Company may be responsible for the cost. The Company is responsible for global clinical studies of the TPX-0022 TPX-0022 TPX-0022 TPX-0022 The Zai TPX-0022 Agreement will continue in effect until expiration of the last royalty term for a TPX-0022 TPX-0022 TPX-0022 TPX-0022 TPX-0022 TPX-0022 TPX-0022 TPX-0022 TPX-0022 TPX-0022 TPX-0022 Revenue Recognition The Company determined that two performance obligations existed: (1) the exclusive license, bundled with the associated know-how and (2) the Company’s initial obligation to supply TPX-0022 for clinical development in the Zai Territory. The total transaction price of $25.9 million was allocated to the performance obligations on the basis of the relative stand-alone selling price estimated for each performance obligation. In estimating the stand-alone selling price for each performance obligation, the Company developed assumptions that require judgment and included forecasted revenues, expected development timelines, discount rates, probabilities of technical and regulatory success and costs for manufacturing clinical supplies. The Company delivered the license and technical know-how to Zai in the first quarter of 2021 to satisfy this performance obligation, and accordingly the Company recognized license revenue of $25.0 million in the first quarter of 2021. The $0.9 million in consideration allocable to the clinical supply performance obligation will be recognized when clinical trial material has been shipped by the Company and Zai obtains control of the goods, upon delivery, over the period of the obligation. As of June 30, 2021, the Company has not recognized any revenue associated with the clinical supply performance obligation under the Zai TPX-0022 Agreement. The Company assessed the Zai TPX-0022 Agreement to determine whether a financing component exists and concluded that a significant financing component does not exist. The upfront payment received by the was subject to foreign tax withholdings. The Company recorded this tax expense to general and administrative expense in the condensed statements of operations and comprehensive loss.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Operating Leases The Company has an operating lease In February 2021, the Company entered into a lease agreement for additional office and laboratory space, which commenced on April 20, 2021, with an initial expiration date of December 31, 2021. In May 2021, the lease was amended to extend the expiration date to June 30, 2023. The Company recorded an operating lease liability and corresponding right-of-use asset of approximately $1.2 million as of the lease commencement date. In April 2021, the Company entered into a lease agreement for additional office space, which commenced on May 24, 2021 which expires June 30, 2023 with no options to extend. In June 2021, the lease terms were amended to add additional office space which is expected to commence in the third quarter of 2021. The Company recorded an operating lease liability of approximately $2.4 million and a right-of-use asset of $2.5 million, which includes lease incentives. In May 2021, the Company entered into a lease agreement with HCP Callan Road, LLC (Landlord) for the lease of approximately 185,000 square feet of office and laboratory space, delivered in two phases, for the Company’s future principal executive offices and laboratory space. The term of the lease is approximately 11 years and nine months and is expected to commence in March 2023 Future minimum payments under the leases as of June 30, 2021 are as follows (in thousands) Year Ending December 31, 2021 (remaining) 1,577 2022 3,589 2023 1,831 Total future minimum lease payments 6,997 Less: amounts representing interest (495 ) Total lease liability $ 6,502 Remaining lease term 2 years Amounts presented in the table above exclude non-cancelable future minimum lease payments for operating leases that have not commenced Rent expense was $0.6 million and $0.4 million for the three months ended June 30, 2021 and 2020, respectively. The Company paid $0.6 million and $0.4 million of cash payments related to its operating lease agreements for each of the three months ended June 30, 2021 and 2020, respectively. Rent expense was $1.0 million and $0.8 million for the six months ended June 30, 2021 and 2020, respectively. The Company paid $1.0 million and $0.8 million of cash payments related to its operating lease agreement for the six months ended June 30, 2021 and 2020, respectively. The Company’s operating leases had a weighted average remaining lease term of 2 years as of June 30, 2021 and 2.6 years as of December 31, 2020, and a weighted average discount rate of 7.1% as of June 30, 2021 and 8.5% as of December 31, 2020.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity At the Market Offering In August 2020, the Company entered into an Open Market Sale Agreement SM Equity Compensation Plans T In addition, the number of shares of common stock available for issuance under the Plan will be automatically increased on the first day of each calendar year through January 1, 2029, by an amount equal to 4% of the outstanding number of shares of the Company’s common stock on December 31 of the preceding calendar year or such lesser amount as determined by the Company’s board of directors. On January 1, 2021, the Company added 1,947,141 shares to the Plan. At June 30, 2021, the Plan had 3,574,211 total shares available for issuance Stock Options Options expire within a period of not more than ten years from the date of grant. Initial option grants to employees typically vest 25% after one year and monthly thereafter over a three-year The following summarizes option activity under the Plan for the periods presented: Outstanding Options Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in thousands) Balance as of December 31, 2020 5,790,713 $ 34.97 8.4 $ 503,114 Options granted 820,286 $ 113.61 Options exercised (691,537 ) $ 26.14 Options forfeited or cancelled (512,531 ) $ 56.05 Balance as of June 30, 2021 5,406,931 $ 46.02 7.9 $ 208,216 Options vested and exercisable as of June 30, 2021 2,100,703 $ 22.24 6.8 $ 119,126 The fair values of the employee stock options granted during the three and six months ended June 30, 2021 and 2020 were estimated at the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Risk-free interest rate 1.05 % 1.01 % 0.80 % 1.49 % Volatility 79.9 % 79.0 % 80.4 % 79.0 % Expected term (in years) 5.98 5.84 6.04 6.06 Dividend yield - - - - The weighted-average grant-date fair value of options granted to employees was $48.45 and $38.41 for the three months ended June 30, 2021 and 2020 , respectively and was $77.86 and $41.20 for the six months ended June 30, 2021 and 2020, respectively. As of June 30, 2021, there was $130.9 million in total unrecognized compensation expense expected to be recognized over a weighted average period of 2.49 years. Restricted Stock Units The summary of the Company’s restricted stock unit activity for the periods presented is as follows: Restricted Stock Units Outstanding Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (in thousands) Balance as of December 31, 2020 21,500 $ 59.94 $ 2,620 Granted 187,507 $ 121.57 Vested - $ - Forfeited (16,726 ) $ 129.87 Outstanding as of June 30, 2021 192,281 $ 113.96 $ 15,002 No Performance Stock Units The Company has granted performance stock units (PSUs) which vest based on the achievement of certain predefined Company-specific performance criteria and expire as of December 31, 2023. The fair value of PSUs is estimated based on the closing sale price of the Company’s common stock on the date of grant. The Company will recognize expense in proportion to the number of PSUs that are deemed probable of vesting, based on the Company’s evaluation of the respective performance-based criteria, at each reporting date. The summary of the Company’s PSU activity for the periods presented is as follows: Performance Stock Units Outstanding Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (in thousands) Balance as of December 31, 2020 - $ - $ - Granted 210,949 $ 130.97 Vested - $ - Forfeited (22,431 ) $ 136.85 Outstanding as of June 30, 2021 188,518 $ 130.27 $ 14,708 As of June 30, 2021 2019 Employee Stock Purchase Plan In April 2019, the Company’s board of directors and stockholders approved and adopted the 2019 Employee Stock Purchase Plan (the ESPP). The ESPP became effective immediately prior to the date of the underwriting agreement related to the Company’s initial public offering. The ESPP permits eligible employees who elect to participate in an offering under the ESPP to have up to 15% of their eligible earnings withheld, subject to certain limitations, to purchase shares of common stock pursuant to the ESPP. The price of common stock purchased under the ESPP is equal to 85 percent of the lower of the fair market value of the common stock at the commencement date of each offering period or the relevant date of purchase. Each offering period is 24 months, with new offering periods commencing every six months on the dates of June 11 and December 11 of each year. Each offering period consists of four six month purchase periods (each a Purchase Period) during which payroll deductions of the participants are accumulated under the ESPP. The last business day of each Purchase Period is referred to as the “Purchase .” Purchase Dates are every six months on the dates of June 10 and December 10 of each year. As of June 30, 2021, The assumptions used for the six months ended June 30, 2021 and 2020 and the resulting estimates of weighted-average fair value per share for stock purchased under the ESPP during such periods were as follows Six Months Ended June 30, 2021 2020 Risk-free interest rate 0.04 - 0.16% 0.17 - 2.13% Volatility 69.9 - 79.8% 70.6 - 91.6% Expected term (in years) 0.50 - 2.00 0.50 - 2.00 Dividend yield - - Modifications to Outstanding Equity Awards On March 30, 2021, Sheila Gujrathi, M.D. and Jacob M. Chacko, M.D. resigned from the Board of Directors (the Board) of the Company, effective immediately, to focus on other endeavors. Dr. Gujrathi also resigned from her position as Chair of the Board and Dr. Chacko resigned from each committee of the Board for which he was a member. In connection with the foregoing, the Board approved an amendment to the option awards held by Drs. Gujrathi and Chacko to provide that (i) all shares subject to such option awards are fully vested and exercisable as of the resignation date and (ii) the post-resignation exercise period shall be extended to September 30, 2022. The Company determined that the modification to extend the term of vested stock options was a Type I modification pursuant to ASC 718, Compensation – Stock Compensation (ASC 718). The acceleration of the vesting of the unvested stock options was deemed a Type III modification pursuant to ASC 718, because without Board approval, these stock options would have been forfeited on the date of resignation. As a result of these modifications the Company recognized $5.6 million in stock-based compensation expense in the first quarter of 2021 in general and administrative expenses in the condensed statements of operations and comprehensive loss. On January 9, 2020, the Company entered into a Transition Separation and Consulting Agreement (the Transition Agreement) with the Company’s former Chief Scientific Officer (CSO), Dr. Jingrong Jean Cui. In connection with this Transition Agreement, Dr. Cui resigned from her position as CSO effective January 31, 2020 and thereafter agreed to serve as a consultant to the Company on an as needed basis until June 30, 2020. In accordance with the terms of the The Company determined that the modification to extend the term of vested stock options was a Type I modification pursuant to ASC 718. The acceleration of the vesting of the unvested stock options was deemed a Type III modification pursuant to ASC 718, because pursuant to Dr. Cui’s existing employment agreement as of her resignation date, these stock options would have been forfeited on the date of termination. As a result of these modifications the Company recognized $31.4 million in stock-based compensation expense in the first quarter of 2020. Because the services performed during the consulting period were considered nonsubstantive, the Company recognized the full $31.4 million in stock-based compensation expense on the date of the modification and presented this amount in general and administrative expenses in the statement of operations and comprehensive loss. Stock-Based Compensation Expense Stock-based compensation expense for awards granted under the Company’s equity plans totaled the following (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Research and development $ 6,980 $ 3,523 $ 12,982 $ 6,888 General and administrative 6,315 3,881 17,591 38,881 Total stock-based compensation expense $ 13,295 $ 7,404 $ 30,573 $ 45,769 Common Stock Reserved for Future Issuance Common stock reserved for future issuance consisted of the following: June 30, 2021 Options to purchase common stock 5,406,931 PSUs outstanding 188,518 RSUs outstanding 192,281 Options to purchase common stock available for issuance under the Plan 3,574,211 Shares available for purchase under ESPP 228,156 Total 9,590,097

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (SEC). Accordingly, since they are interim statements, the accompanying condensed financial statements do not include all of the information and notes required by GAAP for complete financial statements. The unaudited interim financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The condensed balance sheet at December 31, 2020 has been derived from the audited financial statements at that date, but does not include all information and footnotes required by GAAP for complete financial statements. The operating results presented in these unaudited condensed financial statements are not necessarily indicative of the results that may be expected for any future periods. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 filed with the SEC. In the opinion of management, the unaudited condensed financial statements and notes thereto include all adjustments that are of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position and of the results of operations and cash flows for the periods presented.
Revenue	Revenue The Company recognizes revenue in accordance with Accounting Standards Codification (ASC) Topic 606, Revenue From Contracts With Customers The Company assesses the goods or services promised within each contract and determines those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). In assessing whether a promised good or service is distinct, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, an entity is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (SSP) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations requires significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment. If an arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. For arrangements with licenses of intellectual property that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty has been allocated has been satisfied. In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied, either at a point in time or over time, and if over time, recognition is based on the use of an output or input method.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent liabilities in the Company’s financial statements and accompanying notes. The most significant estimates in the Company’s financial statements relate to determining the SSP of performance obligations associated with license arrangements , preclinical and clinical trial costs and accruals and stock-based compensation costs . Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Alth ough the impact of the COVID-19 pandemic to the Company’s business and operating results presents additional uncertainty, the Company continues to use the best information available to update its critical accounting estimates .
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The following table presents a reconciliation of cash, cash equivalents and restricted cash to amounts shown in the unaudited condensed statement of cash flows (in thousands): June 30, 2021 June 30, 2020 Cash and cash equivalents $ 426,047 $ 470,514 Restricted Cash, as part of other assets 1,875 73 Total cash, cash equivalents and restricted cash $ 427,922 $ 470,587
Concentration of Credit Risk	Concentration of Credit Risk Substantially all of the Company’s cash, cash equivalents, and marketable securities are held at two financial institutions. Due to the financial strength of the depository institutions, the Company believes these financial institutions represent minimal credit risk. Cash amounts held at financial institutions are insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000. At June 30, 2021, cash and cash equivalents and marketable securities totaling $1,077.6 million are either not subject to FDIC insurance, or exceed the FDIC insured limit. The Company’s cash and cash equivalents and marketable securities are invested in short term, high credit quality securities, and as a result, the Company believes represent a minimal credit risk.
Clinical Trial Costs and Accruals	Clinical Trial Costs and Accruals A significant portion of the Company’s clinical trial costs relate to contracts with contract research organizations (CROs). The financial terms of the Company’s CRO contracts may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate clinical trial expenses in the Company’s financial statements by matching those expenses with the period in which services and efforts are expended. As part of the process of preparing the Company’s financial statements, the Company evaluates cost information provided by the Company’s CROs concerning estimated monthly expenses for services rendered and unbilled obligations as the sponsor of the Company’s clinical trials. Accordingly, the Company’s clinical trial accrual is dependent upon the timely and accurate reporting of CROs and other third-party vendors, and the Company’s ability to accurately estimate any unbilled obligations. If the contracted amounts are modified, for instance, as a result of changes in the clinical trial protocol or scope of work to be performed, the Company modifies its accruals accordingly on a prospective basis. Revisions in the scope of a contract are charged to research and development expense in the period in which the facts that give rise to the revision become reasonably certain.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. These costs consist primarily of salaries and other personnel-related expenses, including stock-based compensation; facility-related expenses; depreciation of facilities and equipment; laboratory consumables; and services performed by clinical research organizations, research institutions, and other outside service providers. The Company recorded the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and include these costs in accrued expenses and other current liabilities accrued expenses and other current liabilities
Net Loss Per Share	Net Loss Per Share The Company computes basic loss per share by dividing the net loss available to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss assumes the conversion, exercise or issuance of all potential common stock equivalents, unless the effect of inclusion would be anti-dilutive. For purposes of this calculation, common stock equivalents include the Company’s stock options, restricted stock units (RSUs) and contingently issuable shares. The Company excluded stock options to purchase common stock, RSUs and contingently issuable shares from the number of shares used to calculate diluted shares outstanding because the inclusion of these potentially dilutive securities would have been antidilutive. Historical outstanding anti-dilutive securities not included in the diluted net loss per share calculation include the following: Six Months Ended June 30, 2021 2020 Options to purchase common stock 5,406,931 6,445,367 RSUs 192,281 - Total 5,599,212 6,445,367

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash to Amounts	The following table presents a reconciliation of cash, cash equivalents and restricted cash to amounts shown in the unaudited condensed statement of cash flows (in thousands): June 30, 2021 June 30, 2020 Cash and cash equivalents $ 426,047 $ 470,514 Restricted Cash, as part of other assets 1,875 73 Total cash, cash equivalents and restricted cash $ 427,922 $ 470,587
Schedule of Outstanding Anti-Dilutive Securities not Included in Diluted Net Loss Per Share Calculation	Historical outstanding anti-dilutive securities not included in the diluted net loss per share calculation include the following: Six Months Ended June 30, 2021 2020 Options to purchase common stock 5,406,931 6,445,367 RSUs 192,281 - Total 5,599,212 6,445,367

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2021
Investments Debt And Equity Securities [Abstract]
Summary of Marketable Securities	At June 30, 2021, marketable securities consisted of the following (in thousands): Unrealized Maturity in Years Amortized Cost Gains Losses Fair Value U.S. Treasuries 2 years or less 195,076 27 (54 ) 195,049 U.S. Government agency securities 2 years or less 179,648 77 (45 ) 179,680 Non-U.S. Government agency securities 2 years or less 24,012 - (13 ) 23,999 Corporate debt securities 2 years or less 115,783 31 (21 ) 115,793 Commercial paper Less than 1 137,238 - - 137,238 Total marketable securities $ 651,757 $ 135 $ (133 ) $ 651,759 At December 31, 2020, marketable securities consisted of the following (in thousands): Unrealized Maturity in Years Amortized Cost Gains Losses Fair Value U.S. Treasuries 2 years or less $ 113,662 $ 19 $ (1 ) $ 113,680 U.S. Government agency securities 2 years or less 173,583 100 - 173,683 Corporate debt securities 2 years or less 169,189 103 (27 ) 169,265 Commercial paper Less than 1 111,779 - - 111,779 Total marketable securities $ 568,213 $ 222 $ (28 ) $ 568,407

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Subject to Fair Value Measurements on a Recurring Basis and the Level of Inputs	The Company’s financial assets subject to fair value measurements on a recurring basis and the level of inputs used for such measurements were as follows (in thousands): Fair Value Measurements at June 30, 2021 Using: Level 1 Level 2 Level 3 Total Money market funds $ 143,203 $ - $ - $ 143,203 U.S. Treasuries 195,049 - - 195,049 U.S. Government agency securities - 179,680 - 179,680 Non-U.S. Government securities - 23,999 - 23,999 Corporate debt securities - 115,793 - 115,793 Commercial paper - 419,636 - 419,636 Total cash equivalents and marketable securities $ 338,252 $ 739,108 $ - $ 1,077,360 Fair Value Measurements at December 31, 2020 Using: Level 1 Level 2 Level 3 Total Money market funds $ 299,571 $ - $ - $ 299,571 U.S. Treasuries 113,680 - - 113,680 U.S. Government agency securities - 173,683 - 173,683 Corporate debt securities - 180,718 - 180,718 Commercial paper - 354,223 - 354,223 Total cash equivalents and marketable securities $ 413,251 $ 708,624 $ - $ 1,121,875

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	6 Months Ended
	Jun. 30, 2021
Property Plant And Equipment [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands) June 30, December 31, 2021 2020 Laboratory equipment $ 2,240 $ 1,629 Computer equipment and software 1,275 956 Tenant improvements 1,302 1,108 Furniture and fixtures 357 357 Property and equipment 5,174 4,050 Less: accumulated depreciation (1,964 ) (1,446 ) Property and equipment, net $ 3,210 $ 2,604

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	6 Months Ended
	Jun. 30, 2021
Payables And Accruals [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands) June 30, December 31, 2021 2020 Accrued research and development expenses $ 15,194 $ 8,457 Accrued general and administrative expenses 818 682 Other current liabilities 84 44 Total $ 16,096 $ 9,183

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Summary of Operating Leases Future Minimum Payments	Future minimum payments under the leases as of June 30, 2021 are as follows (in thousands) Year Ending December 31, 2021 (remaining) 1,577 2022 3,589 2023 1,831 Total future minimum lease payments 6,997 Less: amounts representing interest (495 ) Total lease liability $ 6,502 Remaining lease term 2 years

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Schedule of Option Activity	The following summarizes option activity under the Plan for the periods presented: Outstanding Options Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in thousands) Balance as of December 31, 2020 5,790,713 $ 34.97 8.4 $ 503,114 Options granted 820,286 $ 113.61 Options exercised (691,537 ) $ 26.14 Options forfeited or cancelled (512,531 ) $ 56.05 Balance as of June 30, 2021 5,406,931 $ 46.02 7.9 $ 208,216 Options vested and exercisable as of June 30, 2021 2,100,703 $ 22.24 6.8 $ 119,126
Schedule of Fair Values of Employee Stock Options Granted	The fair values of the employee stock options granted during the three and six months ended June 30, 2021 and 2020 were estimated at the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Risk-free interest rate 1.05 % 1.01 % 0.80 % 1.49 % Volatility 79.9 % 79.0 % 80.4 % 79.0 % Expected term (in years) 5.98 5.84 6.04 6.06 Dividend yield - - - - The assumptions used for the six months ended June 30, 2021 and 2020 and the resulting estimates of weighted-average fair value per share for stock purchased under the ESPP during such periods were as follows Six Months Ended June 30, 2021 2020 Risk-free interest rate 0.04 - 0.16% 0.17 - 2.13% Volatility 69.9 - 79.8% 70.6 - 91.6% Expected term (in years) 0.50 - 2.00 0.50 - 2.00 Dividend yield - -
Summary of Restricted Stock Unit Activity	The summary of the Company’s restricted stock unit activity for the periods presented is as follows: Restricted Stock Units Outstanding Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (in thousands) Balance as of December 31, 2020 21,500 $ 59.94 $ 2,620 Granted 187,507 $ 121.57 Vested - $ - Forfeited (16,726 ) $ 129.87 Outstanding as of June 30, 2021 192,281 $ 113.96 $ 15,002
Summary of PSU Activity	The summary of the Company’s PSU activity for the periods presented is as follows: Performance Stock Units Outstanding Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (in thousands) Balance as of December 31, 2020 - $ - $ - Granted 210,949 $ 130.97 Vested - $ - Forfeited (22,431 ) $ 136.85 Outstanding as of June 30, 2021 188,518 $ 130.27 $ 14,708
Schedule of Stock Based Compensation Expense	Stock-based compensation expense for awards granted under the Company’s equity plans totaled the following (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Research and development $ 6,980 $ 3,523 $ 12,982 $ 6,888 General and administrative 6,315 3,881 17,591 38,881 Total stock-based compensation expense $ 13,295 $ 7,404 $ 30,573 $ 45,769
Schedule of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consisted of the following: June 30, 2021 Options to purchase common stock 5,406,931 PSUs outstanding 188,518 RSUs outstanding 192,281 Options to purchase common stock available for issuance under the Plan 3,574,211 Shares available for purchase under ESPP 228,156 Total 9,590,097

Formation and Business of the_2

Formation and Business of the Company; Basis of Presentation - Additional Information (Details)	Oct. 08, 2013Segment
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of operating segments	1

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash to Amounts (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 426,047	$ 554,101	$ 470,514
Restricted Cash, as part of other assets	1,875		73
Total cash, cash equivalents and restricted cash	$ 427,922	$ 554,174	$ 470,587	$ 48,261

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional Information (Details)	6 Months Ended
	Jun. 30, 2021USD ($)
Significant Accounting Policies [Line Items]
Exceed of federal deposits insurance limit	$ 1,077,600,000
Maximum
Significant Accounting Policies [Line Items]
Cash FDIC insured amount	$ 250,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Outstanding Anti-Dilutive Securities not Included in Diluted Net Loss Per Share Calculation (Details) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share	5,599,212	6,445,367
Options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share	5,406,931	6,445,367
RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the diluted net loss per share	192,281

Marketable Securities - Summary

Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Amortized Cost	$ 651,757	$ 568,213
Unrealized Gains	135	222
Unrealized Losses	(133)	(28)
Fair Value	$ 651,759	$ 568,407
U.S. Treasuries
Marketable Securities [Line Items]
Maturity in Years	2 years or less	2 years or less
Amortized Cost	$ 195,076	$ 113,662
Unrealized Gains	27	19
Unrealized Losses	(54)	(1)
Fair Value	$ 195,049	$ 113,680
U.S. Government Agency Securities
Marketable Securities [Line Items]
Maturity in Years	2 years or less	2 years or less
Amortized Cost	$ 179,648	$ 173,583
Unrealized Gains	77	100
Unrealized Losses	(45)
Fair Value	$ 179,680	$ 173,683
Non-U.S. Government Agency Securities
Marketable Securities [Line Items]
Maturity in Years	2 years or less
Amortized Cost	$ 24,012
Unrealized Losses	(13)
Fair Value	$ 23,999
Corporate Debt Securities
Marketable Securities [Line Items]
Maturity in Years	2 years or less	2 years or less
Amortized Cost	$ 115,783	$ 169,189
Unrealized Gains	31	103
Unrealized Losses	(21)	(27)
Fair Value	$ 115,793	$ 169,265
Commercial Paper
Marketable Securities [Line Items]
Maturity in Years	Less than 1	Less than 1
Amortized Cost	$ 137,238	$ 111,779
Fair Value	$ 137,238	$ 111,779

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Subject to Fair Value Measurements on a Recurring Basis and the Level of Inputs (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	$ 1,077,360	$ 1,121,875
Money Market Funds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	143,203	299,571
U.S. Treasuries
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	195,049	113,680
U.S Government Agency Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	179,680	173,683
Non U S Government Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	23,999
Corporate Debt Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	115,793	180,718
Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	419,636	354,223
Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	338,252	413,251
Level 1 | Money Market Funds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	143,203	299,571
Level 1 | U.S. Treasuries
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	195,049	113,680
Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	739,108	708,624
Level 2 | U.S Government Agency Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	179,680	173,683
Level 2 | Non U S Government Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	23,999
Level 2 | Corporate Debt Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	115,793	180,718
Level 2 | Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and market securities	$ 419,636	$ 354,223

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 5,174	$ 4,050
Less: accumulated depreciation	(1,964)	(1,446)
Property and equipment, net	3,210	2,604
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,240	1,629
Computer Equipment And Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,275	956
Tenant Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,302	1,108
Furniture And Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 357	$ 357

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Property Plant And Equipment [Abstract]
Depreciation	$ 300	$ 200	$ 518	$ 423

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued research and development expenses	$ 15,194	$ 8,457
Accrued general and administrative expenses	818	682
Other current liabilities	84	44
Total	$ 16,096	$ 9,183

Zai License Agreements - Additi

Zai License Agreements - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Jan. 10, 2021	Jul. 31, 2020
Zai Repotrectinib Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront cash payment received					$ 25,000,000
Total transaction price allocated to performance obligation	$ 25,700,000		$ 25,700,000
Zai Repotrectinib Agreement | License
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue recognized		$ 25,000,000
Zai Repotrectinib Agreement | Clinical Supply
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total transaction price allocated to performance obligation	700,000		700,000
Revenue recognized	200,000		400,000
Zai Repotrectinib Agreement | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payments eligible to receive					151,000,000
Zai Repotrectinib Agreement | Development Milestones | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payments eligible to receive					46,000,000
Zai Repotrectinib Agreement | Sales Milestones | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payments eligible to receive					$ 105,000,000
Zai TPX-0022 Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront cash payment received				$ 25,000,000
Total transaction price allocated to performance obligation	25,900,000		25,900,000
Zai TPX-0022 Agreement | License
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue recognized			25,000,000
Zai TPX-0022 Agreement | Clinical Supply
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total transaction price allocated to performance obligation	900,000		900,000
Revenue recognized			0
Zai TPX-0022 Agreement | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payments eligible to receive				336,000,000
Zai TPX-0022 Agreement | Development Milestones
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue recognized	$ 5,000,000		5,000,000
Zai TPX-0022 Agreement | Development Milestones | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payments eligible to receive				121,000,000
Zai TPX-0022 Agreement | Sales Milestones
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue recognized			$ 0
Zai TPX-0022 Agreement | Sales Milestones | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payments eligible to receive				$ 215,000,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	Jul. 01, 2019USD ($)	May 31, 2021USD ($)ft²	Apr. 30, 2021USD ($)	Feb. 28, 2021USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Apr. 20, 2021USD ($)	Dec. 31, 2020USD ($)
Commitment And Contingencies [Line Items]
Right-of-use lease assets	$ 3,700,000		$ 2,500,000	$ 1,200,000	$ 6,269,000		$ 6,269,000		$ 1,200,000	$ 3,357,000
Operating lease right-to-use liability	$ 4,000,000		$ 2,400,000	$ 1,200,000	6,502,000		6,502,000		$ 1,200,000
Operating lease expiration date	Jun. 30, 2023	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2021
Deferred gain	$ 300,000
Operating lease commencement date			May 24, 2021	Apr. 20, 2021
Lessee, Operating Lease, Existence of Option to Extend [true false]			false
Rent expense					600,000	$ 400,000	1,000,000	$ 800,000
Operating lease, cash payments					$ 600,000	$ 400,000	$ 1,000,000	$ 800,000
Operating lease, remaining lease term					2 years		2 years			2 years 7 months 6 days
Operating lease, discount rate					7.10%		7.10%			8.50%
HCP Callan Road, LLC
Commitment And Contingencies [Line Items]
Operating lease commencement date		Mar. 31, 2023
Rentable area | ft²		185,000
Operating lease, lease term		11 years 9 months
Lessee operating lease option to extend lease term		5 years
Base rent		$ 1,000,000
Tenant improvement allowance per square foot		220
Other Assets
Commitment And Contingencies [Line Items]
Letter of credit, secured deposit	$ 100,000
Other Assets | HCP Callan Road, LLC
Commitment And Contingencies [Line Items]
Letter of credit, secured deposit		$ 1,800,000

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Operating Leases Future Minimum Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Apr. 30, 2021	Apr. 20, 2021	Feb. 28, 2021	Dec. 31, 2020	Jul. 01, 2019
Commitments And Contingencies Disclosure [Abstract]
2021 (remaining)	$ 1,577
2022	3,589
2023	1,831
Total future minimum lease payments	6,997
Less: amounts representing interest	(495)
Total lease liability	$ 6,502	$ 2,400	$ 1,200	$ 1,200		$ 4,000
Remaining lease term	2 years				2 years 7 months 6 days

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2021	Aug. 01, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for issuance			3,574,211			3,574,211
Weighted-average grant-date fair value of options granted to employees			$ 48.45	$ 38.41		$ 77.86	$ 41.20
Unrecognized compensation expense related to unvested options			$ 130,900			$ 130,900
Unrecognized compensation expense, weighted-average period for recognition						2 years 5 months 26 days
Common stock available for purchase			9,590,097			9,590,097
Stock-based compensation expense			$ 13,295	$ 7,404		$ 30,573	$ 45,769
Resignation of Board of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options exercise period extended date						Sep. 30, 2022
General and Administrative Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense			6,315	$ 3,881		$ 17,591	$ 38,881
General and Administrative Expenses | Resignation of Board of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense						$ 5,600
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense, weighted-average period for recognition						3 years 6 months 29 days
Number of awards vested						0
Unrecognized compensation expense related to unvested awards			$ 19,800			$ 19,800
Performance Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Plan expiration date						Dec. 31, 2023
Number of awards vested						0
Chief Scientific Officer | Transition Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period							18 months
Cash severance expense					$ 1,200
Chief Scientific Officer | General and Administrative Expenses | Transition Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense					$ 31,400
Chief Scientific Officer | Maximum | Transition Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Extended options vesting period							12 months
Chief Scientific Officer | Minimum | Transition Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Extended options vesting period							90 days
2019 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, description						The Company’s 2019 Equity Incentive Plan (the Plan) provides for the grant of stock options, restricted stock and other equity awards of the Company’s common stock to employees, officers, consultants, and directors. In addition, the number of shares of common stock available for issuance under the Plan will be automatically increased on the first day of each calendar year through January 1, 2029, by an amount equal to 4% of the outstanding number of shares of the Company’s common stock on December 31 of the preceding calendar year or such lesser amount as determined by the Company’s board of directors.  On January 1, 2021, the Company added 1,947,141 shares to the Plan. At June 30, 2021, the Plan had 3,574,211 total shares available for issuance
Plan expiration date						Jan. 1, 2029
Percentage of outstanding common stock added to plan each year						4.00%
Number of shares added to plan	1,947,141
Number of shares available for issuance			3,574,211			3,574,211
2019 Equity Incentive Plan | After 2nd year
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options expiration period						3 months
2019 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options expiration period						10 years
2019 Equity Incentive Plan | Employees | After one year
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights						Initial option grants to employees typically vest 25% after one year and monthly thereafter over a three-year period and expire three months after employee termination.
Exercise price of options as percentage						25.00%
2019 Equity Incentive Plan | Employees | After 2nd year
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period						3 years
2019 Equity Incentive Plan | Employees and non - employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights						Subsequent option grants to employees and grants to non-employees typically vest monthly over a four-year period. The majority of options outstanding at June 30, 2021 had vesting periods of four years.
Options vesting period						4 years
2019 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of eligible earnings withholding			15.00%			15.00%
Percentage of price of common stock purchased under ESPP						85.00%
Common stock available for purchase			228,156			228,156
ATM Facility
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock authorized for issuance yet to issue		$ 250,000

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Option Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Outstanding Options
Balance as of December 31, 2020 | shares	5,790,713
Options granted | shares	820,286
Options exercised | shares	(691,537)
Options forfeited or cancelled | shares	(512,531)
Balance as of June 30, 2021 | shares	5,406,931	5,790,713
Options vested and exercisable as of June 30, 2021 | shares	2,100,703
Weighted Average Exercise Price Per Share
Balance as of December 31, 2020 | $ / shares	$ 34.97
Options granted | $ / shares	113.61
Options exercised | $ / shares	26.14
Options forfeited or cancelled | $ / shares	56.05
Balance as of June 30, 2021 | $ / shares	46.02	$ 34.97
Options vested and exercisable as of June 30, 2021 | $ / shares	$ 22.24
Weighted average remaining contractual term
Weighted average remaining contractual term	7 years 10 months 24 days	8 years 4 months 24 days
Options vested and exercisable as of June 30, 2021	6 years 9 months 18 days
Aggregate Intrinsic Value
Balance | $	$ 208,216	$ 503,114
Options vested and exercisable as of June 30, 2021 | $	$ 119,126

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Fair Values of Employee Stock Options Granted (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	1.05%	1.01%	0.80%	1.49%
Volatility	79.90%	79.00%	80.40%	79.00%
Expected term (in years)	5 years 11 months 23 days	5 years 10 months 2 days	6 years 14 days	6 years 21 days
2019 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate. minimum			0.04%	0.17%
Risk-free interest rate. maximum			0.16%	2.13%
Volatility, minimum			69.90%	70.60%
Volatility, maximum			79.80%	91.60%
Minimum | 2019 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)			6 months	6 months
Maximum | 2019 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)			2 years	2 years

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Stock Units Outstanding
Balance as of December 31, 2020	21,500
Granted	187,507
Vested	0
Forfeited	(16,726)
Outstanding as of June 30, 2021	192,281
Weighted Average Grant Date Fair Value
Balance as of December 31, 2020	$ 59.94
Granted	121.57
Forfeited	129.87
Outstanding as of June 30, 2021	$ 113.96
Aggregate Intrinsic Value
Outstanding	$ 15,002	$ 2,620

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of PSU Activity (Details) - PSUs $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Stock Units Outstanding
Granted	210,949
Vested	0
Forfeited	(22,431)
Outstanding as of June 30, 2021	188,518
Weighted Average Grant Date Fair Value
Granted | $ / shares	$ 130.97
Forfeited | $ / shares	136.85
Outstanding as of June 30, 2021 | $ / shares	$ 130.27
Aggregate Intrinsic Value
Outstanding | $	$ 14,708

Stockholders' Equity - Schedu_3

Stockholders' Equity - Schedule of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 13,295	$ 7,404	$ 30,573	$ 45,769
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	6,980	3,523	12,982	6,888
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 6,315	$ 3,881	$ 17,591	$ 38,881

Stockholders' Equity - Schedu_4

Stockholders' Equity - Schedule of Common Stock Reserved for Future Issuance (Details) - shares	Jun. 30, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options to purchase common stock	5,406,931	5,790,713
Options to purchase common stock available for issuance under the Plan	3,574,211
Shares available for purchase under ESPP	228,156
Total	9,590,097
PSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards outstanding	188,518
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards outstanding	192,281	21,500