Mirati Therapeutics (MRTX) 10-K 28 Feb 22 2021 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 22, 2022	Jun. 30, 2021
Cover [Abstract]
Entity Central Index Key	0001576263
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	1-15803
Entity Registrant Name	MIRATI THERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-2693615
Entity Address, Address Line One	3545 Cray Court,
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	332-3410
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	MRTX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 7,400,000,000
Entity Common Stock, Shares Outstanding		55,488,261

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2021
Audit Information [Abstract]
Auditor Name	Ernst & Young LLP
Auditor Location	San Diego, California
Auditor Firm ID	42

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 413,083	$ 885,562
Short-term investments	1,078,257	504,544
Other current assets	16,643	13,537
Total current assets	1,507,983	1,403,643
Property and equipment, net	15,824	7,809
Long-term investment	8,218	15,629
Right-of-use asset		39,900
Other long-term assets	19,049	9,157
Total assets	1,588,754	1,476,128
Current liabilities
Accounts payable	35,163	18,117
Accrued liabilities	108,495	53,355
Total current liabilities	143,658	71,472
Lease liability	45,879
Other liabilities	2,179	1,962
Total liabilities	191,716	115,339
Commitments and contingencies (see Note 14)
Shareholders’ equity
Preferred stock, $0.001 par value, 10,000,000 shares authorized; none issued and outstanding at both December 31, 2021 and December 31, 2020	0	0
Common stock, $0.001 par value; 100,000,000 authorized; 55,356,904 and 50,439,069 issued and outstanding at December 31, 2021 and December 31, 2020, respectively	55	50
Additional paid-in capital	3,099,937	2,481,218
Accumulated other comprehensive income	9,068	9,759
Accumulated deficit	(1,712,022)	(1,130,238)
Total shareholders’ equity	1,397,038	1,360,789
Total liabilities and shareholders’ equity	$ 1,588,754	$ 1,476,128

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (USD per share)	$ 0.001	$ 0.001
Preferred stock authorized (shares)	10,000,000	10,000,000
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	100,000,000	100,000,000
Common stock issued (shares)	55,356,904	50,439,069
Common stock outstanding (shares)	55,356,904	50,439,069

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue
Total revenue	$ 72,092	$ 13,398	$ 3,335
Expenses
Research and development	508,594	299,349	182,866
General and administrative	136,679	83,412	42,573
Total operating expenses	645,273	382,761	225,439
Loss from operations	(573,181)	(369,363)	(222,104)
Other (expense) income, net	(5,304)	11,426	8,848
Net loss before tax	(578,485)	(357,937)	(213,256)
Income tax expense	3,299	0	0
Net loss	(581,784)	(357,937)	(213,256)
Unrealized (loss) gain on available-for-sale investments	691	130	(410)
Comprehensive loss	$ (582,475)	$ (358,067)	$ (212,846)
Basic net loss per share (USD per share)	$ (11.21)	$ (7.96)	$ (5.69)
Diluted net loss per share (USD per share)	$ (11.21)	$ (7.96)	$ (5.69)
Weighted average common shares outstanding, basic (shares)	51,882,538	44,987,555	37,467,505
Weighted average common shares outstanding, diluted (shares)	51,882,538	44,987,555	37,467,505

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated other comprehensive income	Accumulated deficit
Balance at beginning of period (shares) at Dec. 31, 2018		32,538,857
Balance at beginning of period at Dec. 31, 2018	$ 201,576	$ 33	$ 751,109	$ 9,479	$ (559,045)
Increase (Decrease) in Stockholders' Equity
Net loss	(213,256)				(213,256)
Issuance of common stock and warrants, net of issuance costs (shares)		4,269,838
Issuance of common stock, net of issuance costs	327,830	$ 4	327,826
Share-based compensation expense	55,537		55,537
Issuance of common stock from ESPP (shares)		14,488
Issuance of common stock from ESPP	675		675
Issuance of common stock under equity incentive plans (shares)		569,146
Issuance of common stock under equity incentive plans	8,473	$ 1	8,472
Proceeds from disgorgement of shareholders’ short-swing profits	1,050
Net exercise of warrants (shares)		2,125,000
Net exercise of warrants	0	$ 2	(2)
Unrealized gain (loss) on investments	410			410
Balance at end of period (shares) at Dec. 31, 2019		39,517,329
Balance at end of period at Dec. 31, 2019	382,295	$ 40	1,144,667	9,889	(772,301)
Increase (Decrease) in Stockholders' Equity
Net loss	(357,937)				(357,937)
Issuance of common stock and warrants, net of issuance costs (shares)		8,124,168
Issuance of common stock, net of issuance costs	1,203,617	$ 8	1,203,609
Share-based compensation expense	85,847		85,847
Issuance of common stock from ESPP (shares)		14,436
Issuance of common stock from ESPP	1,206		1,206
Issuance of common stock under equity incentive plans (shares)		1,319,901
Issuance of common stock under equity incentive plans	$ 45,891	$ 1	45,890
Net exercise of warrants (shares)	1,400,000	1,463,235
Net exercise of warrants	$ 0	$ 1	(1)
Unrealized gain (loss) on investments	$ (130)			(130)
Balance at end of period (shares) at Dec. 31, 2020	50,439,069	50,439,069
Balance at end of period at Dec. 31, 2020	$ 1,360,789	$ 50	2,481,218	9,759	(1,130,238)
Increase (Decrease) in Stockholders' Equity
Net loss	(581,784)				(581,784)
Issuance of common stock and warrants, net of issuance costs (shares)		3,448,275
Issuance of common stock, net of issuance costs	474,697	$ 3	474,694
Share-based compensation expense	113,502		113,502
Issuance of common stock from ESPP (shares)		20,672
Issuance of common stock from ESPP	2,567		2,567
Issuance of common stock under equity incentive plans (shares)		825,074
Issuance of common stock under equity incentive plans	$ 27,958	$ 1	27,957
Net exercise of warrants (shares)	623,814	623,814
Net exercise of warrants	$ 0	$ 1	(1)
Unrealized gain (loss) on investments	$ (691)			(691)
Balance at end of period (shares) at Dec. 31, 2021	55,356,904	55,356,904
Balance at end of period at Dec. 31, 2021	$ 1,397,038	$ 55	$ 3,099,937	$ 9,068	$ (1,712,022)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Operating activities:
Net loss	$ (581,784)	$ (357,937)	$ (213,256)
Non-cash adjustments reconciling net loss to operating cash flows
Non-cash consideration earned from license agreement	0	(11,424)	0
Change in fair value of long-term investment	7,411	(4,205)	0
Depreciation of property and equipment	1,781	641	249
Amortization of premium and accretion of discounts on investments	4,702	(674)	(3,421)
Share-based compensation expense	113,502	85,847	55,537
Changes in operating assets and liabilities:
Other current assets	(3,107)	(4,180)	(5,487)
Other long-term assets	(9,892)	(3,424)	(4,375)
Right-of-use asset	2,210	582	0
Lease liability	5,315	(652)	0
Accounts payable, accrued liabilities, deferred revenue and other liabilities	71,062	23,895	23,027
Cash flows used in operating activities	(388,800)	(271,531)	(147,726)
Investing activities:
Purchases of short-term investments	(1,422,729)	(662,824)	(530,228)
Sales and maturities of short-term investments	843,623	527,334	355,640
Purchases of property and equipment	(9,795)	(4,367)	(1,552)
Cash flows used in investing activities	(588,901)	(139,857)	(176,140)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs	474,697	1,203,617	327,830
Proceeds from issuance of common stock under equity incentive plans	27,958	45,891	8,473
Proceeds from disgorgement of shareholders’ short-swing profits	0	0	1,050
Proceeds from issuances under ESPP	2,567	1,206	675
Cash flows provided by financing activities	505,222	1,250,714	338,028
(Decrease) increase in cash, cash equivalents and restricted cash	(472,479)	839,326	14,162
Cash, cash equivalents and restricted cash, beginning of year	886,182	46,856	32,694
Cash, cash equivalents and restricted cash, end of year	413,703	886,182	46,856
Reconciliation of cash, cash equivalents and restricted cash, end of year:
Cash and cash equivalents	413,083	885,562	46,535
Restricted cash included in other long-term assets	620	620	321
Total cash, cash equivalents and restricted cash	413,703	886,182	46,856
Supplemental disclosures of non-cash investing activities:
Accrued capital expenditures	583	292	0
Allowance utilized for tenant improvements	0	2,015	0
Initial recognition of operating right-of-use asset	0	39,890	0
Initial recognition of operating lease liability	$ 0	$ 41,905	$ 0

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Mirati Therapeutics, Inc. (“Mirati” or the “Company”) is a clinical-stage oncology company developing product candidates to address the genetic and immunological promoters of cancer. The Company was incorporated under the laws of the State of Delaware on April 29, 2013 as Mirati Therapeutics, Inc. and is located in San Diego, California. The Company has a wholly owned subsidiary in Canada, MethylGene, Inc. (“MethylGene”), a wholly owned subsidiary in the Netherlands (“Mirati Therapeutics B.V.”) and operates in the United States. The Company’s common stock has been listed on the Nasdaq Global Select Market since June 5, 2018, and was previously listed on the Nasdaq Capital Market since July 15, 2013, under the ticker symbol “MRTX.”

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Basis of Presentation These consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). These consolidated financial statements include the accounts of the Company and MethylGene and Mirati Therapeutics B.V. All significant inter-company transactions, balances and expenses have been eliminated upon consolidation. Mirati was incorporated under the laws of the State of Delaware on April 29, 2013. On May 8, 2013, the Company’s Board of Directors approved and the Company entered into an arrangement agreement with MethylGene and MethylGene became a wholly-owned subsidiary. On August 3, 2021, Mirati Therapeutics B.V. was formed in Amsterdam, Netherlands, and became a wholly-owned subsidiary. These consolidated financial statements are presented in United States (“U.S.”) Dollars, which is also the functional currency of the Company. Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Reported amounts and note disclosures reflect the overall economic conditions that are most likely to occur and anticipated measures management intends to take. Actual results could differ materially from those estimates. Estimates and assumptions are reviewed quarterly. Any revisions to accounting estimates are recognized in the period in which the estimates are revised and in any future periods affected. Cash, Cash Equivalents and Short-term Investments Cash and cash equivalents consist of cash and highly liquid securities with original maturities at the date of acquisition of ninety days or less. Investments with an original maturity of more than ninety days are considered short-term investments and have been classified by management as available-for-sale. These investments are classified as current assets, even though the stated maturity date may be one year or more beyond the current consolidated balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary. Such investments are carried at fair value, and the unrealized gains and losses are reported as a component of accumulated other comprehensive income in shareholders’ equity until realized. Realized gains and losses from the sale of available-for-sale securities, if any, are determined on a specific identification basis. Concentration of Credit Risk The Company invests its excess cash in accordance with its investment policy. The Company’s investments are comprised primarily of commercial paper and debt instruments of financial institutions, corporations, U.S. government-sponsored agencies and the U.S. Treasury. The Company mitigates credit risk by maintaining a diversified portfolio and limiting the amount of investment exposure as to institution, maturity and investment type. Financial instruments that potentially subject the Company to significant credit risk consist principally of cash equivalents and short-term investments. Revenue Recognition The Company recognizes revenue in connection with certain collaboration and license agreements in accordance with the guidance of Revenue From Contracts With Customers , Accounting Standards Codification (“ASC”) Topic 606 (“Topic 606”). Under Topic 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements the Company determines are within the scope of Topic 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Property and Equipment, Net Property and equipment is stated at historical cost less accumulated depreciation. Historical cost includes expenditures that are directly attributable to the acquisition of the items. All repairs and maintenance are charged to consolidated net loss during the financial period in which they are incurred. Depreciation of property and equipment is calculated using the straight-line method over the estimated useful lives of the assets, as follows: Computer equipment 3 years Office and other equipment 6 years Laboratory equipment 6 years Leasehold improvements The lesser of the lease term or the life of the asset Upon disposal or impairment of property and equipment, the cost and related accumulated depreciation is removed from the consolidated financial statements and the net amount, less any proceeds, is included in consolidated net loss. Impairment of Long-Lived Assets The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If such circumstances are determined to exist, an estimate of undiscounted future cash flows produced by the long-lived asset, including its eventual residual value, is compared to the carrying value to determine whether impairment exists. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written-down to their estimated fair values. Fair value is estimated through discounted cash flow models to project cash flows from the asset. The Company recognized no impairment charges for the years ended December 31, 2021, 2020 and 2019. Share-Based Compensation Expense The Company measures and recognizes compensation expense for share-based payments based on estimated fair value as of the grant date. The fair value of restricted stock units is determined using the intrinsic value method. The fair value of performance stock units, which vest based on the achievement of pre-established performance goals, is determined using the intrinsic value method and the probability that the specified performance criteria will be met. The fair value of stock options is determined using the Black-Scholes option-pricing model. The Black-Scholes option-pricing model requires the use of certain estimates and assumptions that affect the amount of share-based compensation expense recognized in the Company’s consolidated financial statements. These assumptions include the expected volatility of the Company’s stock price, expected term of the options, the risk-free interest rate and expected dividend yields. Share-based compensation expense is recognized using the graded accelerated vesting method. Research and Development Expenses Research and development expenses are charged to consolidated net loss in the period in which they are incurred and are comprised of the following types of costs incurred in performing research and development activities: contract services for clinical trials and related clinical manufacturing costs, salaries and benefits including share-based compensation expense, costs for allocated facilities and depreciation of equipment and license fees paid in connection with the Company’s early discovery efforts. General and Administrative Expenses General and administrative expenses consist primarily of salaries and related benefits, including share-based compensation expense, related to the Company’s executive, finance, legal, commercial and support functions. Other general and administrative expenses include professional fees for auditing, tax, consulting and patent-related services, rent and utilities and insurance. Leases The Company determines if an arrangement is a lease at inception. Lease right-of-use assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent the Company's obligation to make lease payments arising from the lease. For operating leases with an initial term greater than 12 months, the Company recognizes operating lease right-of-use assets and operating lease liabilities based on the present value of lease payments over the lease term at the commencement date. Operating lease right-of-use assets are comprised of the lease liability plus any lease payments made and excludes lease incentives. Lease terms include options to renew or terminate the lease when the Company is reasonably certain that the renewal option will be exercised or when it is reasonably certain that the termination option will not be exercised. For the Company's operating leases, if the interest rate used to determine the present value of future lease payments it not readily determinable, the Company estimates its incremental borrowing rate as the discount rate for the lease. The Company's incremental borrowing rate is estimated to approximate the interest rate on a collateralized basis with similar terms and payments, and in similar economic environments. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Company has elected the practical expedient to not separate lease and non-lease components. Income Taxes Income taxes have been accounted for using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applicable to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in net loss in the period that includes the enactment date. A valuation allowance against deferred tax assets is recorded if, based upon the weight of all available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. For uncertain tax positions that meet “a more likely than not” threshold, the Company recognizes the benefit of uncertain tax positions in the consolidated financial statements. Segment Reporting Operating segments are components of a business where separate discrete financial information is available for evaluation by the chief operating decision-maker for purposes of making decisions regarding resource allocation and assessing performance. To date, the Company and the chief operating decision-maker has viewed its operations and managed its business as one segment operating primarily in the United States. Net Loss per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for common share equivalents as they are anti-dilutive. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and common share equivalents outstanding for the period, as well as certain shares that are contingently issuable. Common share equivalents outstanding, determined using the treasury stock method, are comprised of shares that may be issued under the Company’s stock option and warrant agreements, as well as restricted stock units and performance stock units. The following table presents the weighted average number of common share equivalents, calculated using the treasury stock method, as well as certain shares that are contingently issuable, not included in the calculation of diluted net loss per share due to the anti-dilutive effect of the securities: Year Ended December 31, 2021 2020 2019 Common stock options 2,358,594 2,503,294 2,403,055 Common stock warrants 7,713,576 9,210,824 10,231,006 Unvested restricted stock units and performance stock units 656,158 347,261 — Total 10,728,328 12,061,379 12,634,061 Recently Issued and Recently Adopted Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. The Company has evaluated recently issued accounting pronouncements and does not believe any will have a material impact on the Company’s consolidated financial statements or related financial statement disclosures.

Investments

Investments	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Investments	The following tables summarize the Company’s short-term investments (in thousands): As of December 31, 2021 Maturity Amortized cost Gross unrealized gains Gross unrealized losses Estimated fair value Corporate debt securities 2 years or less $ 236,170 $ 36 $ (248) $ 235,958 Commercial paper 1 year or less 621,947 127 (95) 621,979 U.S. Agency bonds 1 years or less 58,092 — — 58,092 U.S. Treasury bills 2 years or less 162,500 — (272) 162,228 $ 1,078,709 $ 163 $ (615) $ 1,078,257 As of December 31, 2020 Maturity Amortized cost Gross unrealized gains Gross unrealized losses Estimated fair value Corporate debt securities 2 years or less $ 130,814 $ 160 $ (4) $ 130,970 Commercial paper 1 year or less 240,725 58 (18) 240,765 U.S. Agency bonds 2 years or less 83,227 37 (1) 83,263 U.S. Treasury bills 2 years or less 49,539 10 (3) 49,546 $ 504,305 $ 265 $ (26) $ 504,544 The Company has classified all of its short-term investments as available-for-sale as the sale of such securities may be required prior to maturity to implement management strategies, and accordingly, carries these investments at fair value. As of December 31, 2021, and December 31, 2020, aggregated gross unrealized losses of available-for-sale investments were not material, and accordingly, no allowance for credit losses was recorded.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	The Company has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. The authoritative guidance for fair value measurements defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or the most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact. The guidance prioritizes the inputs used in measuring fair value into the following hierarchy: • Level 1- Quoted prices (unadjusted) in active markets for identical assets or liabilities; • Level 2- Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable; and • Level 3- Unobservable inputs in which little or no market activity exists, therefore requiring an entity to develop its own assumptions about the assumptions that market participants would use in pricing. The following table summarizes the assets and liabilities measured at fair value on a recurring basis (in thousands): December 31, 2021 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents: Cash $ 19,347 $ 19,347 $ — $ — Money market funds 393,736 393,736 — — Total cash and cash equivalents 413,083 413,083 — — Short-term investments: U.S. Treasury bills 162,228 162,228 — — Corporate debt securities 235,958 — 235,958 — Commercial paper 621,979 — 621,979 — U.S. Agency bonds 58,092 — 58,092 — Total short-term investments 1,078,257 162,228 916,029 — Long-term investment: ORIC Pharmaceuticals, Inc. 8,218 — — 8,218 Total $ 1,499,558 $ 575,311 $ 916,029 $ 8,218 December 31, 2020 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents: Cash $ 20,398 $ 20,398 $ — $ — Money market funds 865,164 865,164 — — Total cash and cash equivalents 885,562 885,562 — — Short-term investments: U.S. Treasury bills 49,546 49,546 — — Corporate debt securities 130,970 — 130,970 — Commercial paper 240,765 — 240,765 — U.S. Agency bonds 83,263 — 83,263 — Total short-term investments 504,544 49,546 454,998 — Long-term investment: ORIC Pharmaceuticals, Inc. 15,629 — — 15,629 Total $ 1,405,735 $ 935,108 $ 454,998 $ 15,629 The Company’s investments in Level 1 assets are valued based on publicly available quoted market prices for identical securities as of December 31, 2021 and 2020. The Company determines the fair value of Level 2 related securities with the aid of valuations provided by third parties using proprietary valuation models and analytical tools. These valuation models and analytical tools use market pricing or prices for similar instruments that are both objective and publicly available, including matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids and/or offers. The Level 3 fair value measurement of the Company’s long-term investment in ORIC Pharmaceuticals, Inc., which was acquired in 2020, utilized a combination of the Asian Protective Put Option and Finnerty Put Option fair value techniques with unobservable inputs of 69% volatility and an expected term of 0.1 years to determine the discount for lack of marketability of 5.0%. See Note 8 for further details on the license agreement with ORIC Pharmaceuticals, Inc. There were no transfers between fair value measurement levels for the years ended December 31, 2021 and 2020. The following table presents the changes in estimated fair value of the Company’s asset measured using significant unobservable inputs (Level 3) (in thousands): December 31, 2021 2020 Balance - beginning of year $ 15,629 $ — Additions — 11,424 Change in fair value (7,411) 4,205 Balance - end of year $ 8,218 $ 15,629

Other Current Assets and Other

Other Current Assets and Other Long-Term Assets	12 Months Ended
	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Current Assets and Other Long-Term Assets	Other current assets consisted of the following (in thousands): December 31, 2021 2020 Prepaid expenses $ 11,895 $ 8,158 Deposits and other receivables 2,235 3,075 Interest receivables 2,513 2,304 $ 16,643 $ 13,537 The other long-term assets balance of $19.0 million as of December 31, 2021 consisted of $18.4 million in deposits paid in connection with the Company’s research and development activities, and $0.6 million for a letter of credit secured by restricted cash in connection with the lease of the Company’s corporate headquarters. The other long-term assets balance of $9.2 million as of December 31, 2020 consisted of $8.6 million in deposits paid in conjunction with the Company’s research

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): December 31, 2021 2020 Laboratory equipment $ 9,733 $ 5,310 Leasehold improvements 6,275 3,639 Office and other equipment 2,131 329 Computer equipment 507 201 Gross property and equipment 18,646 9,479 Less: Accumulated depreciation (2,822) (1,670) Property and equipment, net $ 15,824 $ 7,809

Accrued Liabilities and Other L

Accrued Liabilities and Other Liabilities	12 Months Ended
	Dec. 31, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Accrued Liabilities and Other Liabilities	Accrued liabilities consisted of the following (in thousands): December 31, 2021 2020 Accrued clinical expense $ 29,038 $ 19,221 Accrued manufacturing expense 34,153 13,019 Accrued development expense 10,910 5,439 Accrued compensation and benefits 25,845 13,964 Other accrued expenses 8,549 1,712 $ 108,495 $ 53,355

License and Collaboration Agree

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2021
Research and Development [Abstract]
License and Collaboration Agreements	BeiGene Agreement Terms of Agreement On January 7, 2018, the Company and BeiGene Ltd, (“BeiGene”) entered into a Collaboration and License Agreement (the “BeiGene Agreement”), pursuant to which the Company and BeiGene agreed to collaboratively develop sitravatinib in Asia (excluding Japan and certain other countries), Australia and New Zealand (the “BeiGene Licensed Territory”). Under the BeiGene Agreement, the Company granted BeiGene an exclusive license to develop, manufacture and commercialize sitravatinib in the BeiGene Licensed Territory, with Mirati retaining exclusive rights for the development, manufacture and commercialization of sitravatinib outside the BeiGene Licensed Territory. As consideration for the rights granted to BeiGene under the BeiGene Agreement, BeiGene paid the Company a non-refundable, non-creditable up-front fee of $10.0 million. BeiGene is also required to make milestone payments to the Company of up to an aggregate of $123.0 million upon the first achievement of specified clinical, regulatory and sales milestones. The BeiGene Agreement additionally provides that BeiGene is obligated to pay to the Company royalties at tiered percentage rates ranging from mid-single digits to twenty percent on annual net sales of licensed products in the BeiGene Licensed Territory, subject to reduction under specified circumstances. The BeiGene Agreement also provides that the Company will supply BeiGene with sitravatinib for use in BeiGene’s development activities in the BeiGene Licensed Territory. The BeiGene Agreement will terminate upon the expiration of the last royalty term for the licensed products, which is the latest of (i) the date of expiration of the last valid patent claim related to the licensed products under the BeiGene Agreement, (ii) 10 years after the first commercial sale of a licensed product and (iii) the expiration of any regulatory exclusivity as to a licensed product. BeiGene may terminate the BeiGene Agreement at any time by providing 60 days prior written notice to the Company. Either party may terminate the BeiGene Agreement upon a material breach by the other party that remains uncured following 60 days after the date of written notice of such breach or upon certain bankruptcy events. In addition, the Company may terminate the BeiGene Agreement upon written notice to BeiGene under specified circumstances if BeiGene challenges the licensed patent rights. Revenue Recognition The Company evaluated the BeiGene Agreement under Topic 606. In determining the appropriate amount of revenue to be recognized as the Company fulfills its obligations under the BeiGene Agreement, the Company performed the following steps: (i) identified the promised goods or services in the contract; (ii) determined whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measured the transaction price, including any constraints on variable consideration; (iv) allocated the transaction price to the performance obligations; and (v) recognized revenue when (or as) the Company satisfied each performance obligation. The Company determined the transaction price was equal to the up-front fee of $10.0 million. The transaction price 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. As such, of the up-front fee, the Company allocated $9.5 million to the license of the Company’s intellectual property, bundled with the associated know-how, and $0.5 million to the initial obligation to supply sitravatinib for clinical development in the BeiGene Licensed Territory. Licenses of Intellectual Property. The license to the Company’s intellectual property, bundled with the associated know-how, represents a distinct performance obligation. The license and associated know-how was transferred to BeiGene during the three months ended March 31, 2018, therefore the Company recognized the full revenue related to this performance obligation in the amount of $9.5 million during the year ended December 31, 2018 as license and collaboration revenues in its consolidated statements of operations and comprehensive loss. Manufacturing Supply Services. The Company’s initial obligation to supply sitravatinib for clinical development in the BeiGene Licensed Territory represents a distinct performance obligation. The Company recognizes revenue when BeiGene obtains control of the goods, upon delivery, over the period of the obligation, which began in late 2018 and continued into 2021. The Company recognized $0.4 million as license and collaboration revenues for this performance obligation for the year ended December 31, 2021. The Company recognized $2.0 million for this performance obligation during the year ended December 31, 2020, of which $1.8 million relates to cost-sharing payments due from BeiGene, and $0.2 million relates to recognition from the deferred revenue balance. The Company recognized $3.3 million for this performance obligation during the year ended December 31, 2019, of which $3.0 million relates to cost-sharing payments due from BeiGene, and $0.3 million relates to recognition from the deferred revenue balance. The Company recorded a cost-sharing receivable from BeiGene within other current assets on the consolidated balance sheets of $0.3 million and $1.3 million as of December 31, 2021 and 2020, respectively. Milestone Payments. The Company is entitled to development milestones under the agreement. The Company recognized $5.0 million milestone payment related to the initiation of the first pivotal clinical trial in the BeiGene Licensed Territory during the year ended December 31, 2021, and did not recognize revenue associated with development milestones during the years ended December 31, 2020 or 2019. The Company is also entitled to certain regulatory milestone payments which are paid upon receipt of regulatory approvals within the BeiGene Licensed Territory. The Company determined that as of December 31, 2021, the remaining potential milestone payments are probable of significant revenue reversal as their achievement is highly dependent on factors outside the Company’s control. Therefore, these payments have been fully constrained and are therefore not recognized as revenue. At the end of each subsequent reporting period, the Company will re-evaluate the probability of achievement of each milestone and any related constraint, and if necessary, adjust its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect the reported amount of license and collaboration revenues in the period of adjustment. Royalties. As the license is deemed to be the predominant item to which sales-based royalties relate, the Company will recognize revenue when the related sales occur. No royalty revenue was recognized during the years ended December 31, 2021, 2020, or 2019. Pfizer Agreement In October 2014, the Company entered into a drug discovery collaboration and option agreement with Array BioPharma, Inc. (“Array,” acquired by Pfizer Inc. (“Pfizer”) during 2019) whereby Array provided services to facilitate the discovery, optimization and development of small molecule compounds that bind and specifically inhibit KRAS G12C. In June 2017, the two parties entered into a second, separate discovery collaboration and option agreement whereby Array provided services to facilitate the discovery, optimization and development of small molecule compounds that bind and specifically inhibit KRAS G12D. Both agreements established an option mechanism which enabled the Company to elect an exclusive worldwide license under the technology for the development and commercialization of certain products based on such compounds. Under the agreements, following the joint discovery periods which have concluded, the Company executed its options to retain exclusive worldwide licenses to develop, manufacture and commercialize inhibitors of KRAS G12C and KRAS G12D, including but not limited to, MRTX849 (adagrasib is the provisionally filed name for MRTX849) and MRTX1133. Under each agreement, Pfizer is entitled to potential development milestone payments of up to $9.3 million, and tiered sales milestone payments of up to $337.0 million based upon worldwide net sales, and tiered royalties in the high single digits to mid-teens on worldwide net sales of products arising from the collaborations. Under the agreements, the Company has incurred $9.5 million in development milestone payments from inception through December 31, 2021. The royalty term for each agreement shall be payable on a country-by-country and product-by-product basis, and separately will terminate at the later of (i) the date of expiration of the last valid patent claim within the collaboration patent rights or the Pfizer background technology covering such product in the country in which such product is sold at the time of such sale, or (ii) 10 years after the first commercial sale of such product in such country. The Company may terminate each agreement at any time by providing 60 days prior written notice to Pfizer. Either party may terminate each agreement upon a material breach by the other party that remains uncured following 60 days after the date of written notice of such breach or upon certain bankruptcy events. For the year ended December 31, 2021, the Company incurred expenses under these agreements with Pfizer of $5.0 million related to initiation of the first Phase 3 trial for adagrasib. For the year ended December 31, 2020, the Company incurred expenses of $4.8 million, consisting of a $3.0 million milestone payment for initiation of the first Phase 2 trial for adagrasib, a $0.3 million milestone payment for initiation of the first regulatory toxicology study for MRTX1133, and $1.5 million in research and development services. For the year ended December 31, 2019, the Company incurred expense of $7.0 million, consisting of a $1.0 million milestone payment for initiation of the first Phase 1 trial for adagrasib, and $6.0 million in research and development services. ORIC Pharmaceuticals Agreement Terms of Agreement On August 3, 2020, the Company entered into a license agreement with ORIC Pharmaceuticals, Inc. (“ORIC”) pursuant to which the Company granted to ORIC an exclusive, worldwide license to develop and commercialize the Company’s allosteric polycomb repressive complex 2 (“PRC2”) inhibitors for all indications (the “ORIC License Agreement”). In accordance with the terms of the ORIC License Agreement, in exchange for such license, ORIC issued 588,235 shares of its common stock (the “Shares”) to the Company on August 3, 2020. The Shares were issued under a stock issuance agreement entered into between ORIC and the Company, dated August 3, 2020. During the eighteen-month period following the date of the stock issuance agreement, the Company is subject to certain transfer restrictions. ORIC is not obligated to pay the Company milestone payments or royalty payments under the ORIC License Agreement. Unless terminated earlier, the ORIC License Agreement will continue in effect on a country-by-country and licensed product-by-licensed product basis until the later (a) the expiration of the last valid claim of a licensed patent covering such licensed product in such country or (b) 10 years after the first commercial sale of such licensed product in such country. Following the expiration of the ORIC License Agreement, ORIC will retain its licenses under the intellectual property the Company licensed to ORIC on a royalty-free basis. The Company and ORIC may each terminate the ORIC License Agreement if the other party materially breaches the terms of such agreement, subject to specified notice and cure provisions, or enters into bankruptcy or insolvency proceedings. The Company may terminate the agreement if ORIC challenges any of the patent rights licensed to ORIC by the Company or if ORIC discontinues development of licensed products for a specified period of time. ORIC also has the right to terminate the ORIC License Agreement without cause by providing prior written notice to the Company. Revenue Recognition The Company accounted for the ORIC License Agreement under Topic 606 and identified the granting of an exclusive, worldwide license to develop and commercialize the Company’s allosteric PRC2 inhibitors for all indications as a distinct performance obligation since ORIC can benefit from the license on its own by developing and commercializing the underlying product using its own resources. In determining the transaction price, the Company received the Shares as non-cash consideration. The Company allocated the entire transaction price to the distinct performance obligation described above, and the license and related know-how was transferred to ORIC during the third quarter of 2020. Therefore, the Company recognized the entire transaction price of $11.4 million as license and collaboration revenues in its consolidated statements of operations and comprehensive loss during the year ended December 31, 2020 . The Shares are carried at fair value and are recorded on the consolidated balance sheet as a long-term investment. Any change in fair value is recorded within other (expense) income, net on the consolidated statements of operations and comprehensive loss. The value of the long-term investment is determined by utilizing a Level 3 fair value measurement as further described in Note 4. Zai Agreement Terms of Agreement On May 28, 2021, the Company and Zai Lab Ltd. (“Zai”) entered into a Collaboration and License Agreement (the “Zai Agreement”), pursuant to which the Company and Zai agreed to collaboratively develop adagrasib in China, Hong Kong, Macau and Taiwan (collectively, the “Zai Licensed Territory”). Under the Zai Agreement, the Company granted Zai the rights to research, develop, manufacture and exclusively commercialize adagrasib in all indications in the Zai Licensed Territory, with the Company retaining exclusive rights for the development, manufacture and commercialization of adagrasib outside the Zai Licensed Territory and certain co-commercialization, manufacture, and development rights in the Zai Licensed Territory. Zai is obligated to participate in selected global, registration-enabling clinical trials and enroll patients in the Zai Licensed Territory at Zai’s expense. As consideration for the rights granted to Zai under the Zai Agreement, Zai agreed to pay the Company a non-refundable, non-creditable up-front fee of $65.0 million. Under the Zai Agreement, the Company is entitled to potential development and regulatory-based milestone payments of up to $93.0 million, and tiered sales milestone payments of up to $180.0 million based on net sales in the Zai Licensed Territory. The Zai Agreement additionally provides that Zai is obligated to pay to the Company royalties at tiered percentage rates ranging from the high-teens to the low-twenties on annual net sales of licensed products in the Zai Licensed Territory, subject to reduction under specified circumstances. The Zai Agreement also provides that the Company will supply Zai with adagrasib for use in Zai’s development activities in the Zai Licensed Territory at Zai’s expense. The Zai Agreement will terminate on a licensed product-by-licensed product basis and on a region-by-region basis in the Zai Licensed Territory, upon the later to occur of (i) the date of expiration of the last valid claim covering such licensed product in such region, (ii) the date that is ten years after the date of the first commercial sale in such region and (iii) the expiration date of any regulatory exclusivity for such licensed product in such region, or for a co-commercialized product on the date the parties agree to terminate such co-commercialization, or in its entirety upon the expiration of all payment obligations under the Zai Agreement. Zai may terminate the Zai Agreement at any time by providing 12 months’ notice to the Company. Either party may terminate the Zai Agreement upon a material breach by the other party that remains uncured or upon certain bankruptcy events. In addition, the Company may terminate the Zai Agreement if Zai challenges the licensed patent rights. Revenue Recognition The Company evaluated the Zai Agreement under Topic 606. The Company determined that two performance obligations existed: (1) the license to intellectual property, bundled with the associated know-how and (2) the Company’s initial obligation to supply adagrasib for clinical development in the Zai Licensed Territory. At the time it entered into the Zai Agreement, the Company determined the transaction price was equal to $66.6 million, which includes the up-front fee and other incidental amounts. 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, forecasted costs for manufacturing clinical supplies and cost savings related to Zai’s participation in selected trials. The Company allocated the full transaction price to the license to the Company’s intellectual property, bundled with the associated know-how. The Company concluded the variable payments related to the Company’s initial obligation to supply adagrasib for clinical development in the Zai Licensed Territory relate specifically to the Company’s efforts to satisfy this performance obligation and the obligation to provide the initial clinical supply approximates the stand-alone selling price. Payments under the Zai Agreement are subject to foreign tax withholdings. Licenses of Intellectual Property. The license to the Company’s intellectual property, bundled with the associated know-how, represents a distinct performance obligation. The license and associated know-how was transferred to Zai during the year ended December 31, 2021, therefore, the Company recognized revenue of $66.6 million as license and collaboration revenues and $3.3 million as income tax expense in its consolidated statements of operations and comprehensive loss during the year ended December 31, 2021. Manufacturing Supply Services. The Company’s initial obligation to supply adagrasib for clinical development in the Zai Licensed Territory represents a distinct performance obligation. As such, the Company will recognize revenue when Zai obtains control of the goods. No revenue related to this performance obligation was recognized for the year ended December 31, 2021. The Company may also become responsible for manufacturing adagrasib for commercial supply and will receive reimbursement that approximates stand-alone selling prices. Milestone Payments. The Company is entitled to development milestone payments and certain regulatory and sales milestone payments which are paid upon achievement of the development milestones, upon receipt of regulatory approvals and annual net sales thresholds within the Zai Licensed Territory under the Zai Agreement. The Company evaluated whether or not the milestones are considered probable of being reached and determined that their achievement is highly dependent on factors outside of the Company’s control. These payments have been fully constrained and therefore are not included in the transaction price. At the end of each subsequent reporting period, the Company will re-evaluate the probability of achievement of each milestone and any related constraint and, if necessary, adjust its estimate of the overall transaction price. Any such adjustments will be recorded on a cumulative catch-up basis, which would affect the reported amount of license and collaboration revenues in the period of adjustment. Royalties. As the license is deemed to be the predominant item to which sales-based royalties relate, the Company will recognize revenue when the related sales occur. No royalty revenue was recognized during the year ended December 31, 2021.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Shareholders' Equity	Common Stock The following shares were reserved for future issuance: December 31, 2021 Common stock options outstanding 4,532,252 Restricted stock units outstanding 1,002,178 Warrants to purchase common stock 7,605,811 Employee Stock Purchase Plan 107,764 Shares available for grant 2,743,693 Total 15,991,698 Sale of Common Stock In November 2021, the Company sold 3,448,275 shares of its common stock at a public offering price of $145.00 per share. After deducting underwriter discounts, commissions and estimated offering expenses, the Company received net proceeds from the transaction of $474.7 million. In October 2020, the Company sold 4,585,706 shares of its common stock at a public offering price of $202.00 per share. After deducting underwriter discounts, commissions and estimated offering expenses, the Company received net proceeds from the transaction of approximately $879.6 million. In January 2020, the Company sold 3,538,462 shares of its common stock at a public offering price of $97.50 per share. After deducting underwriter discounts, commissions and offering expenses, the Company received net proceeds from the transaction of $324.0 million. In June 2019, the Company sold 2,415,000 shares of its common stock at a public offering price of $97.00 per share. After deducting underwriter discounts, commissions and offering expenses, the Company received net cash proceeds from the transaction of $219.9 million. In January 2019, the Company sold 1,854,838 shares of its common stock at a public offering price of $62.00 per share. After deducting underwriter discounts, commissions and offering expenses, the Company received net cash proceeds from the transaction of $107.9 million. At-the-Market Facility On July 2, 2020, the Company entered into a sales agreement pursuant to which the Company may, from time to time, sell shares of the Company’s common stock, par value $0.001 per share, having an aggregate offering price of up to $200.0 million. On July 2, 2021, the Company entered into an amended and restated sales agreement pursuant to which the Company may, from time to time, sell shares of the Company’s common stock, par value $0.001 per share, having an aggregate offering price of up to $500.0 million. As of December 31, 2021, the Company has not offered or sold any shares of common stock pursuant to this sales agreement. Disgorgement Proceeds In January 2019, the Company received a payment of $1.1 million representing a disgorgement of short-swing profits from the sale of common stock by a beneficial owner pursuant to Section 16(b) of the Securities Exchange Act of 1934, as amended. The Company recognized these proceeds as a capital contribution from shareholders and reflected a corresponding increase to additional paid-in capital. Warrants As of December 31, 2021, the following warrants for common stock were issued and outstanding: Issue Date Expiration Date Exercise Price Number of Warrants Outstanding January 11, 2017 None $ 0.001 3,578,036 November 20, 2017 None $ 0.001 3,669,360 June 11, 2018 None $ 0.001 358,415 7,605,811 During the year ended December 31, 2021, warrants for 623,821 shares of the Company’s common stock were exercised via cashless exercises, resulting in the issuance of 623,814 shares of common stock. During the year ended December 31, 2020, warrants for 1,400,012 shares of the Company’s common stock were exercised via cashless exercise, resulting in the issuance of 1,400,000 shares of common stock, and warrants for 63,235 shares of the common stock were exercised for cash, generating immaterial net proceeds. During the year ended December 31, 2019, warrants for 2,125,033 shares of the Company’s common stock were exercised via cashless exercises, resulting in the issuance of 2,125,000 shares of common stock.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	Equity Incentive Plan The Company has a stock option plan (the “Stock Option Plan”) for the benefit of employees, directors, officers and consultants of the Company. In May 2013 the Company’s Board of Directors adopted the 2013 Equity Incentive Plan (the “2013 Plan”). The 2013 Plan was approved by the Company’s shareholders in connection with the Arrangement. The Company’s Board of Directors and shareholders approved an amendment to the 2013 Plan in 2021 to, among other things, increase the aggregate number of shares of common stock authorized for issuance under the 2013 Plan by 2.5 million shares. The 2013 Plan is a continuation of and successor to the Stock Option Plan and no further grants will be made under the Stock Option Plan. As of December 31, 2021, there were approximately 2.6 million shares available to be granted from the 2013 Plan. In December 2019, the Company’s Board of Directors adopted the Inducement Plan, reserving 417,343 shares of the Company’s common stock for issuance of stock options and other equity-based awards to new employees who satisfy the standards for inducement grants in accordance with the Nasdaq Stock Market LLC listing rules. As of December 31, 2021, there were 121,574 shares available to be issued from the Inducement Plan. As of December 31, 2021, share-based compensation awards under both the Stock Option Plan and the 2013 Plan consist of incentive and non-qualified stock options, and restricted stock units. Stock options granted under each of the plans must have an exercise price equal to at least 100% of the fair market value of the Company’s common stock on the date of grant and generally vest over four years. Stock options granted under the Stock Option Plan had a contractual term of seven years and stock options granted under the 2013 Plan have a contractual term of ten years. Stock Options The following table summarizes the Company’s stock option activity and related information for the year ended December 31, 2021: Number of Weighted Weighted-Average Remaining Contractual Term (years) Aggregate Intrinsic Value (millions) Balance outstanding as of December 31, 2020 4,429,489 $ 58.82 Granted 1,012,211 $ 177.84 Exercised (673,095) $ 41.54 Forfeited and expired (236,353) $ 108.53 Balance outstanding as of December 31, 2021 4,532,252 $ 85.38 6.9 $ 311.7 Options exercisable at December 31, 2021 2,685,192 $ 50.44 5.7 $ 261.2 The total intrinsic value of stock options exercised was $91.1 million, $121.5 million and $38.6 million for the years ended December 31, 2021, 2020, and 2019, respectively. The Company received total cash of $28.0 million, $45.9 million and $8.5 million for the exercise of options for the years ended December 31, 2021, 2020 and 2019, respectively. The total fair value of options vested during the years ended December 31, 2021, 2020 and 2019 was $58.3 million, $52.1 million and $20.4 million, respectively. Upon option exercise, the Company issues new shares of its common stock. The fair value of options granted is estimated at the date of grant using the Black-Scholes option pricing model. Forfeitures are accounted for as incurred as a reversal of any share-based compensation expense related to options that will not vest. The assumptions used for the specified reporting periods and the resulting estimates of weighted-average estimated fair value per share of options granted during those periods are as follows: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.8% 1.1% 2.2% Dividend yield —% —% —% Volatility factor 76.9% 81.5% 82.1% Expected term (in years) 5.1 5.6 5.6 Weighted average estimated fair value per share $110.43 $77.92 $52.03 Risk-Free Interest Rate - The risk-free interest rate is the rate for periods equal to the expected term of the stock option based on U.S. Treasury zero-coupon bonds. Dividend Yield - The dividend yield is based on the Company’s history and expectation of dividend payouts. The Company has not paid, and does not intend to pay dividends. Volatility Factor - The expected volatility assumption was determined by examining the historical volatility of the Company’s stock. Expected Term - The expected term represents the weighted average period the stock options are expected to be outstanding. The total compensation cost not yet recognized as of December 31, 2021 related to non-vested option awards was $88.8 million which will be recognized over a weighted-average period of 1.3 years. Restricted Stock Units (“RSUs”) The Company began issuing RSUs during 2020. The RSUs generally vest annually over four years and are subject to continued service. A summary of the Company’s RSU activity for the year ended December 31, 2021 is as follows: Number of Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (millions) Balance outstanding as of December 31, 2020 450,260 $ 114.58 Granted 484,409 $ 182.35 Releases (148,551) $ 117.35 Canceled/forfeited (65,551) $ 147.70 Balance outstanding as of December 31, 2021 720,567 $ 156.55 $ 105.7 The total vest date fair value of RSUs that vested during the year ended December 31, 2021 was $17.4 million. The total compensation cost not yet recognized as of December 31, 2021 related to non-vested RSUs was $67.6 million, which will be recognized over a weighted-average period of 2.0 years. Performance Stock Units (“PSUs”) The Company began issuing PSUs during 2020. The PSUs generally vest upon achieving certain performance goals and are subject to continued service. A summary of the Company’s PSU activity for the year ended December 31, 2021 is as follows: Number of Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (millions) Balance outstanding as of December 31, 2020 15,000 $ 101.00 Granted 323,337 $ 158.96 Releases (3,428) $ 212.93 Canceled/forfeited (53,298) $ 146.48 Balance outstanding as of December 31, 2021 281,611 $ 157.58 $ 41.3 The total vest date fair value of PSUs that vested during the year ended December 31, 2021 was $0.7 million. The total compensation cost not yet recognized as of December 31, 2021 related to non-vested PSUs was $5.4 million, which will be recognized over a weighted-average period of 3.1 years. Total share-based compensation expense by consolidated statement of operations and comprehensive loss classification is presented below (in thousands): Year ended December 31, 2021 2020 2019 Research and development expense $ 68,496 $ 48,044 $ 31,024 General and administrative expense 45,006 37,803 24,513 $ 113,502 $ 85,847 $ 55,537 For the years ended December 31, 2021, 2020 and 2019, no share-based compensation expense was capitalized and there were no recognized tax benefits associated with the share-based compensation charge. 2013 Employee Stock Purchase Plan In May 2013, the Company’s Board of Directors adopted the 2013 Employee Stock Purchase Plan (the “ESPP”). The ESPP was approved by the Company’s shareholders in connection with the Arrangement. In December 2014, the ESPP became effective and the first purchase period began. The ESPP permits eligible employees to make payroll deductions to purchase up to $25,000 of the Company’s common stock on regularly scheduled purchase dates at a discount. Offering periods under the ESPP are not more than six months in duration and shares are purchased at 85% of the lower of the closing price for the Company’s common stock on the first day of the offering period or the date of purchase. The ESPP initially authorized the issuance of 300,000 shares of the Company’s common stock pursuant to rights granted to employees for their payroll deductions. As of December 31, 2021, 192,236 shares have been issued out of the plan.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Employee Benefit Plan	The Company has a defined contribution 401(k) plan (the “Plan”) for all employees. Employees are eligible to participate in the Plan if they are at least 21 years of age or older. Under the terms of the Plan, employees may make voluntary contributions as a percentage of compensation. During the years ended December 31, 2021 and 2020, the Company matched up to 5% of an employee’s earnings, subject to Internal Revenue Service limitations. In 2019, the Company matched up to 4% of an employee’s contributions, subject to a limit of $2,500. Expense associated with the Company’s matching contribution totaled $2.5 million, $1.3 million, and $0.2 million for the years ended December 31, 2021, 2020, and 2019 respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	The income tax expense recorded during the year ended December 31, 2021, of $3.3 million was related to foreign withholding taxes on the up-front fee in connection with the Zai Agreement. The Company had no federal income tax expense and immaterial state tax expense for the years ended December 31, 2020 and 2019. The differences between the effective income tax rate and the statutory tax rates during the years ended 2021, 2020 and 2019 are as follows (in thousands): Year Ended December 31, 2021 2020 2019 Net loss before tax $ (578,485) $ (357,937) $ (213,256) Statutory U.S. federal tax rate 21.00 % 21.00 % 21.00 % Tax computed at federal statutory rate (121,482) (75,167) (44,784) State income taxes, net of federal benefit (4,657) (13,490) — Increase (decrease) in taxes recoverable resulting from: Effect of change in valuation allowance 150,487 110,985 52,719 Non-deductible share-based compensation 4,783 2,724 1,810 Tax deductions for share-based compensation (17,243) (17,991) (6,917) Tax credits (30,289) (15,672) (8,621) Foreign withholding taxes 3,299 — — Change in tax rate 2,972 — — Unrecognized tax benefits 7,573 3,857 2,143 Non-deductible officers’ compensation 8,318 4,697 3,527 Other differences (462) 57 123 Income tax expense $ 3,299 $ — $ — Deferred Tax The following table summarizes the significant components of the Company’s deferred tax assets (in thousands): December 31, 2021 2020 Deferred tax assets: Tangible and intangible depreciable assets $ 29,576 $ 32,180 Stock compensation 26,738 19,183 Provisions 5,740 2,510 Lease liability 9,916 8,800 Non-current investment 673 — Net operating loss carryforward 299,204 182,536 Capital loss carryforward 89 114 Canada scientific research and experimental development expenditures 5,471 5,471 U.S. research and development tax credits 51,550 28,834 Total gross deferred tax assets 428,957 279,628 Less valuation allowance (421,044) (270,368) Net deferred tax assets $ 7,913 $ 9,260 Deferred tax liabilities: Right-of-use asset $ (7,913) $ (8,377) Non-current investment — (883) Net deferred income taxes $ — $ — The total valuation allowance increased by $150.7 million for the year ended December 31, 2021. The Company has established a full valuation allowance against its net deferred tax assets as of December 31, 2021 due to the uncertainty surrounding the realization of such assets as evidenced by the cumulative losses from operations through December 31, 2021. For Canadian federal income tax purposes, the Company’s Canadian federal scientific research and experimental development expenditures amounted to $19.9 million at December 31, 2021, 2020 and 2019 and for provincial income tax purposes amounted to $21.6 million at December 31, 2021, 2020 and 2019. As operations in Canada ceased during 2014, no expenditures were incurred for the years ended December 31, 2021, 2020 and 2019. These expenditures are available to reduce future taxable income and have an unlimited carry forward period. Scientific research and development expenditures are subject to verification by the taxation authorities, and accordingly, these amounts may vary by a material amount. In addition, the Company has research and development tax credit carryforwards for U.S. federal and state income tax purposes as of December 31, 2021 of $48.5 million and $16.8 million, respectively. The federal credits will begin to expire in 2033 unless utilized and the state credits have an indefinite life. Further, the Company has orphan drug tax credit carryforwards for U.S. federal income tax purposes as of December 31, 2021 of $7.2 million. The credits will begin to expire in 2041 unless previously utilized. At December 31, 2021, the Company’s net operating loss carry forwards (“NOLs”) for U.S. federal and state income taxes were $1.3 billion and $296.4 million, respectively, and the Company’s NOLs for Canadian federal and provincial income tax purposes were $79.5 million and $78.9 million, respectively. The NOLs expire as follows (in thousands): US Canada Federal State Federal Provincial Expires in: 2030 $ 4,830 $ 4,907 2031 7,059 7,066 2032 13,308 12,433 2033 2,225 2,232 18,623 19,385 2034 7,276 22,162 32,401 31,809 2035 53,359 52,950 1,084 1,084 2036 23,379 — 777 777 2037 65,509 — 697 697 2038 — 3,741 — — 2039 — — 242 242 2040 — 190,783 273 273 2041 — 24,569 251 251 Does not expire 1,099,025 — — — $ 1,250,773 $ 296,437 $ 79,545 $ 78,924 The future utilization of the U.S. federal and state NOL and credit carryforwards to offset future taxable income and tax, respectively, may be subject to an annual limitation as a result of ownership changes that may have occurred previously or may occur in the future. The Tax Reform Act of 1986 (the “Act”) limits a company’s ability to utilize certain tax credit carryforwards and net operating loss carryforwards in the event of a cumulative change in ownership in excess of 50% (by value) as defined in the Act. During 2017, the Company completed a study to assess whether an ownership change, as defined by Section 382 of the Act, had occurred from the Company’s formation through December 31, 2017. The results of the study have been extended through December 31, 2021. Based upon the study, the Company determined an ownership change had occurred during 2017, causing the annual utilization of the NOL and credit carryforwards to be limited. The Company does not believe any of the NOL and credit carryforwards generated through December 31, 2021 would expire solely as a result of annual limitations on the utilization of those attributes. The Canadian Federal and Provincial Tax Acts maintain similar rules in the case of acquisition of control, which may limit the utilization of tax attributes. The Company files income tax returns in the U.S. (federal and state) and Canada (federal and provincial). The Company’s U.S. operations have not been audited for any open taxation years. The Company has experienced losses for U.S. tax purposes and therefore, the taxation authorities may review any loss year, if and when the losses are utilized. For Canadian tax purposes, the Company remains subject to federal and provincial audit for the December 31, 2016 and subsequent taxable years. Where tax years remain open, the Company considers it reasonably possible that issues may be raised or tax positions agreed to with the taxation authorities, which may result in increases or decreases of the balance of non-refundable investment tax credits (“ITCs”) and NOLs. However, an estimate of such increases and decreases cannot be currently made. A reconciliation of the beginning and ending amounts of unrecognized tax positions are as follows (in thousands): Federal Provincial/State December 31, December 31, 2021 2020 2019 2021 2020 2019 Unrecognized tax positions, beginning of year $ 7,394 $ 4,268 $ 2,617 $ 9,652 $ 8,648 $ 8,010 Gross increase — current period tax positions 6,482 3,126 1,651 1,367 1,004 638 Gross decrease — prior period tax positions — — — (78) — — Gross increase — prior period tax positions — — — — — — Expiration of statute of limitations — — — — — — Unrecognized tax positions, end of year $ 13,876 $ 7,394 $ 4,268 $ 10,941 $ 9,652 $ 8,648 If recognized, none of the unrecognized tax positions would impact the Company’s income tax benefit or effective tax rate as long as the Company’s net deferred tax assets remain subject to a full valuation allowance. The Company does not expect any significant increases or decreases to the Company’s unrecognized tax positions within the next 12 months. The Company recognizes interest and penalties related to unrecognized tax benefits in income tax expense. The Company had no accrual for interest or penalties on tax matters as of December 31, 2021, 2020 and 2019. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was enacted in response to the COVID-19 pandemic. The CARES Act, among other things, permits NOL carryovers and carrybacks to offset 100% of taxable income for taxable years beginning before 2021. In addition, the CARES Act allows NOLs incurred in 2018, 2019 and 2020 to be carried back to each of the five preceding taxable years to generate a refund of previously paid income taxes. Due to the Company’s history of net operating losses, the CARES Act did not have a material impact on the Company’s consolidated financial statements.

Investment Tax Credits

Investment Tax Credits	12 Months Ended
	Dec. 31, 2021
INVESTMENT TAX CREDITS
Investment Tax Credits	In prior years, the Company was entitled to claim Canadian federal and provincial ITCs for eligible scientific research and development expenditures. The Company recorded ITCs based on management’s best estimates of the amount to be recovered and ITCs claimed are subject to audit by the taxation authorities and accordingly, may vary by a material amount. The Company has not recorded federal or provincial ITCs since the year ended December 31, 2013, as the primary operations of the Company were moved from Canada to San Diego, California in early 2014. The Company’s non-refundable Canadian federal ITCs as of December 31, 2021 are $3.9 million and relate to scientific research and development expenditures, which may be utilized to reduce Canadian federal income taxes payable in future years. The benefits of the non-refundable Canadian federal ITCs have not been recognized in the financial statements and will be recorded as a reduction of tax expense when realized. The non-refundable investment tax credits expire as follows (in thousands): Federal ITC Expires in: 2030 $ 764 2031 1,000 2032 1,125 2033 1,031 $ 3,920

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	On June 30, 2020, the Company entered into an amended and restated lease agreement (the “Amended and Restated Lease”) for office and laboratory space located in San Diego, California, for the Company’s new corporate headquarters. The Amended and Restated Lease supersedes in its entirety the original lease agreement for the Company’s future corporate headquarters dated as of August 22, 2019. The Amended and Restated Lease has a lease term of approximately 12 years (“Lease Term”), unless terminated earlier. The Lease Term has an initial abatement period, and the initial base rent payable will be approximately $0.6 million per month following the abatement period, which amount will increase by 3% per year over the Lease Term. The Company has also received incentives from the landlord for tenant improvements. During 2020, the underlying asset was available for use by the Company to construct tenant improvements and therefore, the Lease Term is considered to have commenced. The Amended and Restated Lease is considered to be an operating lease, and the Amended and Restated Lease indicates the interest rate applicable to the lease is 12%, therefore the Company used a discount rate of 12% to calculate the present value of its lease payments over the Lease Term. As of December 31, 2021, the consolidated balance sheet includes an operating right-of-use asset of $37.7 million and an operating lease liability of $47.2 million, of which $1.3 million is a current lease liability and included in other accrued expenses, and $45.9 million is included in non-current lease liability. For the year ended December 31, 2021, the Company recorded $7.7 million in operating lease expense. As of December 31, 2020, the consolidated balance sheet includes an operating right-of-use asset of $39.9 million and an operating lease liability of $41.9 million. For the year ended December 31, 2020, the Company recorded $0.3 million in operating lease cost. As of December 31, 2021, the approximate future minimum lease payments under the Amended and Restated Lease are as follows (in thousands): Operating Lease 2022 $ 1,681 2023 7,844 2024 8,080 2025 8,322 2026 8,572 Thereafter 59,685 Total operating lease payments (†) 94,184 Less: Amount representing interest (46,964) Total lease liability $ 47,220 ____________________ † The Company has an early termination right 7 years into the lease term, in which the total contractual obligation would be reduced by $41.1 million. On June 24, 2014, the Company entered into a lease agreement for completed office and laboratory space located in San Diego, California. The office space under the lease is the Company’s corporate headquarters. The lease commenced in two phases (in July 2014 and March 2015) at a combined total initial monthly rent of $24,100 per month. The leased property is subject to a 3% annual rent increase following availability. In addition to such base monthly rent, the Company is obligated to pay certain customary amounts for its share of operating expenses and facility amenities. The original lease provided for expiration on January 31, 2018, and the Company entered into subsequent amendments to the original lease to extend the lease term to July 2021 and expand the size of the existing space. All other terms and covenants from the original lease agreement remain unchanged.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	The following is a summary of the quarterly results of the Company for the years ended December 31, 2021 and 2020 (unaudited, in thousands, except per share data): Three Months Ended 3/31/2021 6/30/2021 9/30/2021 12/31/2021 License and collaboration revenues $ — $ — $ 71,793 $ 299 Loss from operations (132,421) (164,186) (79,499) (197,075) Net loss (135,680) (166,430) (80,054) (199,620) Basic and diluted net loss per share $ (2.67) $ (3.23) $ (1.55) $ (3.72) Three Months Ended 3/31/2020 6/30/2020 9/30/2020 12/31/2020 License and collaboration revenues $ 267 $ — $ 11,424 $ 1,707 Loss from operations (89,487) (84,862) (88,678) (106,336) Net loss (86,655) (82,859) (87,336) (101,087) Basic and diluted net loss per share $ (2.02) $ (1.89) $ (1.96) $ (2.08) Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). These consolidated financial statements include the accounts of the Company and MethylGene and Mirati Therapeutics B.V. All significant inter-company transactions, balances and expenses have been eliminated upon consolidation. Mirati was incorporated under the laws of the State of Delaware on April 29, 2013. On May 8, 2013, the Company’s Board of Directors approved and the Company entered into an arrangement agreement with MethylGene and MethylGene became a wholly-owned subsidiary. On August 3, 2021, Mirati Therapeutics B.V. was formed in Amsterdam, Netherlands, and became a wholly-owned subsidiary. These consolidated financial statements are presented in United States (“U.S.”) Dollars, which is also the functional currency of the Company.
Use of Estimates	Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Reported amounts and note disclosures reflect the overall economic conditions that are most likely to occur and anticipated measures management intends to take. Actual results could differ materially from those estimates. Estimates and assumptions are reviewed quarterly. Any revisions to accounting estimates are recognized in the period in which the estimates are revised and in any future periods affected.
Cash, Cash Equivalents, and Short-term Investments	Cash, Cash Equivalents and Short-term InvestmentsCash and cash equivalents consist of cash and highly liquid securities with original maturities at the date of acquisition of ninety days or less. Investments with an original maturity of more than ninety days are considered short-term investments and have been classified by management as available-for-sale. These investments are classified as current assets, even though the stated maturity date may be one year or more beyond the current consolidated balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary. Such investments are carried at fair value, and the unrealized gains and losses are reported as a component of accumulated other comprehensive income in shareholders’ equity until realized. Realized gains and losses from the sale of available-for-sale securities, if any, are determined on a specific identification basis.
Concentration of Credit Risk	Concentration of Credit Risk The Company invests its excess cash in accordance with its investment policy. The Company’s investments are comprised primarily of commercial paper and debt instruments of financial institutions, corporations, U.S. government-sponsored agencies and the U.S. Treasury. The Company mitigates credit risk by maintaining a diversified portfolio and
Revenue Recognition	Revenue Recognition The Company recognizes revenue in connection with certain collaboration and license agreements in accordance with the guidance of Revenue From Contracts With Customers , Accounting Standards Codification (“ASC”) Topic 606 (“Topic 606”). Under Topic 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements the Company determines are within the scope of Topic 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.
Property and Equipment, Net	Property and Equipment, Net Property and equipment is stated at historical cost less accumulated depreciation. Historical cost includes expenditures that are directly attributable to the acquisition of the items. All repairs and maintenance are charged to consolidated net loss during the financial period in which they are incurred. Depreciation of property and equipment is calculated using the straight-line method over the estimated useful lives of the assets, as follows: Computer equipment 3 years Office and other equipment 6 years Laboratory equipment 6 years Leasehold improvements The lesser of the lease term or the life of the asset Upon disposal or impairment of property and equipment, the cost and related accumulated depreciation is removed from the consolidated financial statements and the net amount, less any proceeds, is included in consolidated net loss.
Impairment of Long-Lived Assets	Impairment of Long-Lived AssetsThe Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If such circumstances are determined to exist, an estimate of undiscounted future cash flows produced by the long-lived asset, including its eventual residual value, is compared to the carrying value to determine whether impairment exists. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written-down to their estimated fair values. Fair value is estimated through discounted cash flow models to project cash flows from the asset.
Share-Based Compensation Expense	Share-Based Compensation Expense The Company measures and recognizes compensation expense for share-based payments based on estimated fair value as of the grant date. The fair value of restricted stock units is determined using the intrinsic value method. The fair value of performance stock units, which vest based on the achievement of pre-established performance goals, is determined using the intrinsic value method and the probability that the specified performance criteria will be met. The fair value of stock options is determined using the Black-Scholes option-pricing model. The Black-Scholes option-pricing model requires the use of certain estimates and assumptions that affect the amount of share-based compensation expense recognized in the Company’s consolidated financial statements. These assumptions include the expected volatility of the Company’s stock price, expected term of the options, the risk-free interest rate and expected dividend yields. Share-based compensation expense is recognized using the graded accelerated vesting method.
Research and Development Expenses	Research and Development ExpensesResearch and development expenses are charged to consolidated net loss in the period in which they are incurred and are comprised of the following types of costs incurred in performing research and development activities: contract services for clinical trials and related clinical manufacturing costs, salaries and benefits including share-based compensation expense, costs for allocated facilities and depreciation of equipment and license fees paid in connection with the Company’s early discovery efforts
General and Administrative Expenses	General and Administrative ExpensesGeneral and administrative expenses consist primarily of salaries and related benefits, including share-based compensation expense, related to the Company’s executive, finance, legal, commercial and support functions. Other general and administrative expenses include professional fees for auditing, tax, consulting and patent-related services, rent and utilities and insurance.
Leases	Leases The Company determines if an arrangement is a lease at inception. Lease right-of-use assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent the Company's obligation to make lease payments arising from the lease. For operating leases with an initial term greater than 12 months, the Company recognizes operating lease right-of-use assets and operating lease liabilities based on the present value of lease payments over the lease term at the commencement date. Operating lease right-of-use assets are comprised of the lease liability plus any lease payments made and excludes lease incentives. Lease terms include options to renew or terminate the lease when the Company is reasonably certain that the renewal option will be exercised or when it is reasonably certain that the termination option will not be exercised. For the Company's operating leases, if the interest rate used to determine the present value of future lease payments it not readily determinable, the Company estimates its incremental borrowing rate as the discount rate for the lease. The Company's incremental borrowing rate is estimated to approximate the interest rate on a collateralized basis with similar terms and payments, and in similar economic environments. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Company has elected the practical expedient to not separate lease and non-lease components.
Income Taxes	Income Taxes Income taxes have been accounted for using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applicable to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in net loss in the period that includes the enactment date. A valuation allowance against deferred tax assets is recorded if, based upon the weight of all available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. For uncertain tax positions that meet “a more likely than not” threshold, the Company recognizes the benefit of uncertain tax positions in the consolidated financial statements.
Segment Reporting	Segment Reporting Operating segments are components of a business where separate discrete financial information is available for evaluation by the chief operating decision-maker for purposes of making decisions regarding resource allocation and assessing performance. To date, the Company and the chief operating decision-maker has viewed its operations and managed its business as one segment operating primarily in the United States.
Net Loss per Share	Net Loss per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for common share equivalents as they are anti-dilutive. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and common share equivalents outstanding for the period, as well as certain shares that are contingently issuable. Common share equivalents outstanding, determined using the treasury stock method, are comprised of shares that may be issued under the Company’s stock option and warrant agreements, as well as restricted stock units and performance stock units.
Recently Adopted Accounting Pronouncements	Recently Issued and Recently Adopted Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. The Company has evaluated recently issued accounting pronouncements and does not believe any will have a material impact on the Company’s consolidated financial statements or related financial statement disclosures.
Fair Value Measurements	The authoritative guidance for fair value measurements defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or the most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact. The guidance prioritizes the inputs used in measuring fair value into the following hierarchy: • Level 1- Quoted prices (unadjusted) in active markets for identical assets or liabilities; • Level 2- Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable; and • Level 3- Unobservable inputs in which little or no market activity exists, therefore requiring an entity to develop its own assumptions about the assumptions that market participants would use in pricing.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Schedule of Estimated Useful Lives of Assets	Depreciation of property and equipment is calculated using the straight-line method over the estimated useful lives of the assets, as follows: Computer equipment 3 years Office and other equipment 6 years Laboratory equipment 6 years Leasehold improvements The lesser of the lease term or the life of the asset
Schedule of Potentially Dilutive Securities Excluded from Earnings Per Share Calculation	The following table presents the weighted average number of common share equivalents, calculated using the treasury stock method, as well as certain shares that are contingently issuable, not included in the calculation of diluted net loss per share due to the anti-dilutive effect of the securities: Year Ended December 31, 2021 2020 2019 Common stock options 2,358,594 2,503,294 2,403,055 Common stock warrants 7,713,576 9,210,824 10,231,006 Unvested restricted stock units and performance stock units 656,158 347,261 — Total 10,728,328 12,061,379 12,634,061

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Schedule of Short-Term Investments	The following tables summarize the Company’s short-term investments (in thousands): As of December 31, 2021 Maturity Amortized cost Gross unrealized gains Gross unrealized losses Estimated fair value Corporate debt securities 2 years or less $ 236,170 $ 36 $ (248) $ 235,958 Commercial paper 1 year or less 621,947 127 (95) 621,979 U.S. Agency bonds 1 years or less 58,092 — — 58,092 U.S. Treasury bills 2 years or less 162,500 — (272) 162,228 $ 1,078,709 $ 163 $ (615) $ 1,078,257 As of December 31, 2020 Maturity Amortized cost Gross unrealized gains Gross unrealized losses Estimated fair value Corporate debt securities 2 years or less $ 130,814 $ 160 $ (4) $ 130,970 Commercial paper 1 year or less 240,725 58 (18) 240,765 U.S. Agency bonds 2 years or less 83,227 37 (1) 83,263 U.S. Treasury bills 2 years or less 49,539 10 (3) 49,546 $ 504,305 $ 265 $ (26) $ 504,544

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table summarizes the assets and liabilities measured at fair value on a recurring basis (in thousands): December 31, 2021 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents: Cash $ 19,347 $ 19,347 $ — $ — Money market funds 393,736 393,736 — — Total cash and cash equivalents 413,083 413,083 — — Short-term investments: U.S. Treasury bills 162,228 162,228 — — Corporate debt securities 235,958 — 235,958 — Commercial paper 621,979 — 621,979 — U.S. Agency bonds 58,092 — 58,092 — Total short-term investments 1,078,257 162,228 916,029 — Long-term investment: ORIC Pharmaceuticals, Inc. 8,218 — — 8,218 Total $ 1,499,558 $ 575,311 $ 916,029 $ 8,218 December 31, 2020 Total Level 1 Level 2 Level 3 Assets Cash and cash equivalents: Cash $ 20,398 $ 20,398 $ — $ — Money market funds 865,164 865,164 — — Total cash and cash equivalents 885,562 885,562 — — Short-term investments: U.S. Treasury bills 49,546 49,546 — — Corporate debt securities 130,970 — 130,970 — Commercial paper 240,765 — 240,765 — U.S. Agency bonds 83,263 — 83,263 — Total short-term investments 504,544 49,546 454,998 — Long-term investment: ORIC Pharmaceuticals, Inc. 15,629 — — 15,629 Total $ 1,405,735 $ 935,108 $ 454,998 $ 15,629
Schedule of Changes in Estimated Fair Value of Assets with Unobservable Inputs	The following table presents the changes in estimated fair value of the Company’s asset measured using significant unobservable inputs (Level 3) (in thousands): December 31, 2021 2020 Balance - beginning of year $ 15,629 $ — Additions — 11,424 Change in fair value (7,411) 4,205 Balance - end of year $ 8,218 $ 15,629

Other Current Assets and Othe_2

Other Current Assets and Other Long-Term Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Current Assets	Other current assets consisted of the following (in thousands): December 31, 2021 2020 Prepaid expenses $ 11,895 $ 8,158 Deposits and other receivables 2,235 3,075 Interest receivables 2,513 2,304 $ 16,643 $ 13,537

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment, net consisted of the following (in thousands): December 31, 2021 2020 Laboratory equipment $ 9,733 $ 5,310 Leasehold improvements 6,275 3,639 Office and other equipment 2,131 329 Computer equipment 507 201 Gross property and equipment 18,646 9,479 Less: Accumulated depreciation (2,822) (1,670) Property and equipment, net $ 15,824 $ 7,809

Accrued Liabilities and Other_2

Accrued Liabilities and Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Schedule of Accrued Liabilities and Other Liabilities	Accrued liabilities consisted of the following (in thousands): December 31, 2021 2020 Accrued clinical expense $ 29,038 $ 19,221 Accrued manufacturing expense 34,153 13,019 Accrued development expense 10,910 5,439 Accrued compensation and benefits 25,845 13,964 Other accrued expenses 8,549 1,712 $ 108,495 $ 53,355

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Schedule of Shares Reserved for Future Issuance	The following shares were reserved for future issuance: December 31, 2021 Common stock options outstanding 4,532,252 Restricted stock units outstanding 1,002,178 Warrants to purchase common stock 7,605,811 Employee Stock Purchase Plan 107,764 Shares available for grant 2,743,693 Total 15,991,698
Schedule of Warrants Issued and Outstanding	As of December 31, 2021, the following warrants for common stock were issued and outstanding: Issue Date Expiration Date Exercise Price Number of Warrants Outstanding January 11, 2017 None $ 0.001 3,578,036 November 20, 2017 None $ 0.001 3,669,360 June 11, 2018 None $ 0.001 358,415 7,605,811

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Stock Option Activity	The following table summarizes the Company’s stock option activity and related information for the year ended December 31, 2021: Number of Weighted Weighted-Average Remaining Contractual Term (years) Aggregate Intrinsic Value (millions) Balance outstanding as of December 31, 2020 4,429,489 $ 58.82 Granted 1,012,211 $ 177.84 Exercised (673,095) $ 41.54 Forfeited and expired (236,353) $ 108.53 Balance outstanding as of December 31, 2021 4,532,252 $ 85.38 6.9 $ 311.7 Options exercisable at December 31, 2021 2,685,192 $ 50.44 5.7 $ 261.2
Schedule of Assumptions Used in Fair Value Estimates	The assumptions used for the specified reporting periods and the resulting estimates of weighted-average estimated fair value per share of options granted during those periods are as follows: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.8% 1.1% 2.2% Dividend yield —% —% —% Volatility factor 76.9% 81.5% 82.1% Expected term (in years) 5.1 5.6 5.6 Weighted average estimated fair value per share $110.43 $77.92 $52.03
Schedule of Restricted Stock Units Activity and Performance Stock Units Activity	A summary of the Company’s RSU activity for the year ended December 31, 2021 is as follows: Number of Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (millions) Balance outstanding as of December 31, 2020 450,260 $ 114.58 Granted 484,409 $ 182.35 Releases (148,551) $ 117.35 Canceled/forfeited (65,551) $ 147.70 Balance outstanding as of December 31, 2021 720,567 $ 156.55 $ 105.7 Number of Weighted Average Grant Date Fair Value Aggregate Intrinsic Value (millions) Balance outstanding as of December 31, 2020 15,000 $ 101.00 Granted 323,337 $ 158.96 Releases (3,428) $ 212.93 Canceled/forfeited (53,298) $ 146.48 Balance outstanding as of December 31, 2021 281,611 $ 157.58 $ 41.3
Schedule of Share-based Compensation Expense	Total share-based compensation expense by consolidated statement of operations and comprehensive loss classification is presented below (in thousands): Year ended December 31, 2021 2020 2019 Research and development expense $ 68,496 $ 48,044 $ 31,024 General and administrative expense 45,006 37,803 24,513 $ 113,502 $ 85,847 $ 55,537

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Reconciliation	The differences between the effective income tax rate and the statutory tax rates during the years ended 2021, 2020 and 2019 are as follows (in thousands): Year Ended December 31, 2021 2020 2019 Net loss before tax $ (578,485) $ (357,937) $ (213,256) Statutory U.S. federal tax rate 21.00 % 21.00 % 21.00 % Tax computed at federal statutory rate (121,482) (75,167) (44,784) State income taxes, net of federal benefit (4,657) (13,490) — Increase (decrease) in taxes recoverable resulting from: Effect of change in valuation allowance 150,487 110,985 52,719 Non-deductible share-based compensation 4,783 2,724 1,810 Tax deductions for share-based compensation (17,243) (17,991) (6,917) Tax credits (30,289) (15,672) (8,621) Foreign withholding taxes 3,299 — — Change in tax rate 2,972 — — Unrecognized tax benefits 7,573 3,857 2,143 Non-deductible officers’ compensation 8,318 4,697 3,527 Other differences (462) 57 123 Income tax expense $ 3,299 $ — $ —
Schedule of Deferred Tax	The following table summarizes the significant components of the Company’s deferred tax assets (in thousands): December 31, 2021 2020 Deferred tax assets: Tangible and intangible depreciable assets $ 29,576 $ 32,180 Stock compensation 26,738 19,183 Provisions 5,740 2,510 Lease liability 9,916 8,800 Non-current investment 673 — Net operating loss carryforward 299,204 182,536 Capital loss carryforward 89 114 Canada scientific research and experimental development expenditures 5,471 5,471 U.S. research and development tax credits 51,550 28,834 Total gross deferred tax assets 428,957 279,628 Less valuation allowance (421,044) (270,368) Net deferred tax assets $ 7,913 $ 9,260 Deferred tax liabilities: Right-of-use asset $ (7,913) $ (8,377) Non-current investment — (883) Net deferred income taxes $ — $ —
Schedule of Expiration of NOLs	The NOLs expire as follows (in thousands): US Canada Federal State Federal Provincial Expires in: 2030 $ 4,830 $ 4,907 2031 7,059 7,066 2032 13,308 12,433 2033 2,225 2,232 18,623 19,385 2034 7,276 22,162 32,401 31,809 2035 53,359 52,950 1,084 1,084 2036 23,379 — 777 777 2037 65,509 — 697 697 2038 — 3,741 — — 2039 — — 242 242 2040 — 190,783 273 273 2041 — 24,569 251 251 Does not expire 1,099,025 — — — $ 1,250,773 $ 296,437 $ 79,545 $ 78,924
Schedule of Unrecognized Tax Positions	A reconciliation of the beginning and ending amounts of unrecognized tax positions are as follows (in thousands): Federal Provincial/State December 31, December 31, 2021 2020 2019 2021 2020 2019 Unrecognized tax positions, beginning of year $ 7,394 $ 4,268 $ 2,617 $ 9,652 $ 8,648 $ 8,010 Gross increase — current period tax positions 6,482 3,126 1,651 1,367 1,004 638 Gross decrease — prior period tax positions — — — (78) — — Gross increase — prior period tax positions — — — — — — Expiration of statute of limitations — — — — — — Unrecognized tax positions, end of year $ 13,876 $ 7,394 $ 4,268 $ 10,941 $ 9,652 $ 8,648

Investment Tax Credits (Tables)

Investment Tax Credits (Tables)	12 Months Ended
	Dec. 31, 2021
INVESTMENT TAX CREDITS
Schedule of Non-Refundable Investment Tax Credits	The non-refundable investment tax credits expire as follows (in thousands): Federal ITC Expires in: 2030 $ 764 2031 1,000 2032 1,125 2033 1,031 $ 3,920

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	As of December 31, 2021, the approximate future minimum lease payments under the Amended and Restated Lease are as follows (in thousands): Operating Lease 2022 $ 1,681 2023 7,844 2024 8,080 2025 8,322 2026 8,572 Thereafter 59,685 Total operating lease payments (†) 94,184 Less: Amount representing interest (46,964) Total lease liability $ 47,220 ____________________ † The Company has an early termination right 7 years into the lease term, in which the total contractual obligation would be reduced by $41.1 million.

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	The following is a summary of the quarterly results of the Company for the years ended December 31, 2021 and 2020 (unaudited, in thousands, except per share data): Three Months Ended 3/31/2021 6/30/2021 9/30/2021 12/31/2021 License and collaboration revenues $ — $ — $ 71,793 $ 299 Loss from operations (132,421) (164,186) (79,499) (197,075) Net loss (135,680) (166,430) (80,054) (199,620) Basic and diluted net loss per share $ (2.67) $ (3.23) $ (1.55) $ (3.72) Three Months Ended 3/31/2020 6/30/2020 9/30/2020 12/31/2020 License and collaboration revenues $ 267 $ — $ 11,424 $ 1,707 Loss from operations (89,487) (84,862) (88,678) (106,336) Net loss (86,655) (82,859) (87,336) (101,087) Basic and diluted net loss per share $ (2.02) $ (1.89) $ (1.96) $ (2.08)

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2021
Computer equipment
Property and equipment
Estimated useful lives	3 years
Office and other equipment
Property and equipment
Estimated useful lives	6 years
Laboratory equipment
Property and equipment
Estimated useful lives	6 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Asset impairment charges	$ 0	$ 0	$ 0

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Potentially Dilutive Shares (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share (shares)	10,728,328	12,061,379	12,634,061
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share (shares)	2,358,594	2,503,294	2,403,055
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share (shares)	7,713,576	9,210,824	10,231,006
Restricted Stock Units and Performance Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share (shares)	656,158	347,261	0

Investments - Summary (Details)

Investments - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 1,078,709	$ 504,305
Gross unrealized gains	163	265
Gross unrealized losses	(615)	(26)
Estimated fair value	1,078,257	504,544
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	236,170	130,814
Gross unrealized gains	36	160
Gross unrealized losses	(248)	(4)
Estimated fair value	$ 235,958	$ 130,970
Corporate debt securities | Maximum
Debt Securities, Available-for-sale [Line Items]
Maturity	2 years	2 years
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 621,947	$ 240,725
Gross unrealized gains	127	58
Gross unrealized losses	(95)	(18)
Estimated fair value	$ 621,979	$ 240,765
Commercial paper | Maximum
Debt Securities, Available-for-sale [Line Items]
Maturity	1 year	1 year
U.S. Agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 58,092	$ 83,227
Gross unrealized gains	0	37
Gross unrealized losses	0	(1)
Estimated fair value	$ 58,092	$ 83,263
U.S. Agency bonds | Maximum
Debt Securities, Available-for-sale [Line Items]
Maturity	1 year	2 years
U.S. Treasury bills
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 162,500	$ 49,539
Gross unrealized gains	0	10
Gross unrealized losses	(272)	(3)
Estimated fair value	$ 162,228	$ 49,546
U.S. Treasury bills | Maximum
Debt Securities, Available-for-sale [Line Items]
Maturity	2 years	2 years

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments [Line Items]
Allowance for credit losses on available-for-sale investments	$ 0	$ 0
ORIC
Schedule of Investments [Line Items]
Stock held in investment (shares)	588,235

Fair Value Measurements - Summa

Fair Value Measurements - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	$ 413,083	$ 885,562
Investments	1,078,257	504,544
Total	1,499,558	1,405,735
U.S. Treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	162,228	49,546
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	235,958	130,970
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	621,979	240,765
U.S. Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	58,092	83,263
Long-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	8,218	15,629
Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	19,347	20,398
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	393,736	865,164
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	413,083	885,562
Investments	162,228	49,546
Total	575,311	935,108
Level 1 | U.S. Treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	162,228	49,546
Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 1 | U.S. Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 1 | Long-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 1 | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	19,347	20,398
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	393,736	865,164
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	0	0
Investments	916,029	454,998
Total	916,029	454,998
Level 2 | U.S. Treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	235,958	130,970
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	621,979	240,765
Level 2 | U.S. Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	58,092	83,263
Level 2 | Long-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 2 | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents		0
Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents		0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	0	0
Investments	0	0
Total	8,218	15,629
Level 3 | U.S. Treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 3 | U.S. Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Level 3 | Long-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	8,218	15,629
Level 3 | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	0	0
Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details)	Dec. 31, 2021
Volatility
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Measurement input of investment	0.69
Expected Term
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Measurement input of investment	0.1
Discount for Lack of Marketability
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Measurement input of investment	0.050

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Estimated Fair Value of Assets with Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 15,629
Balance at end of period	8,218	$ 15,629
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	15,629	0
Additions	0	11,424
Change in fair value	$ (7,411)	4,205
Balance at end of period		$ 15,629

Other Current Assets and Othe_3

Other Current Assets and Other Long-Term Assets - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 11,895	$ 8,158
Deposits and other receivables	2,235	3,075
Interest receivables	2,513	2,304
Other current assets	$ 16,643	$ 13,537

Other Current Assets and Othe_4

Other Current Assets and Other Long-Term Assets - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other long-term assets	$ 19,049	$ 9,157
Deposits paid for research and development	18,400	8,600
Letter of credit secured by restricted cash	$ 600	$ 600

Property and Equipment, Net - S

Property and Equipment, Net - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property and equipment
Gross property and equipment	$ 18,646	$ 9,479
Less: Accumulated depreciation	(2,822)	(1,670)
Property and equipment, net	15,824	7,809
Laboratory equipment
Property and equipment
Gross property and equipment	9,733	5,310
Leasehold improvements
Property and equipment
Gross property and equipment	6,275	3,639
Office and other equipment
Property and equipment
Gross property and equipment	2,131	329
Computer equipment
Property and equipment
Gross property and equipment	$ 507	$ 201

Property and Equipment, Net - N

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation	$ 1,781	$ 641	$ 249

Accrued Liabilities and Other_3

Accrued Liabilities and Other Liabilities - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Accrued clinical expense	$ 29,038	$ 19,221
Accrued manufacturing expense	34,153	13,019
Accrued development expense	10,910	5,439
Accrued compensation and benefits	25,845	13,964
Other accrued expenses	8,549	1,712
Total accounts payable and accrued liabilities	$ 108,495	$ 53,355

Accrued Liabilities and Other_4

Accrued Liabilities and Other Liabilities - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Long-term liabilities	$ 2,179	$ 1,962

License and Collaboration Agr_2

License and Collaboration Agreements - Narrative (Details) - USD ($)	May 28, 2021	Aug. 03, 2020	Jan. 07, 2018	Oct. 31, 2014	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to collaboration agreement					$ 508,594,000	$ 299,349,000	$ 182,866,000
Income tax expense					3,299,000	0	0
Milestone Payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to collaboration agreement						4,800,000
BeiGene Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Up-front fee received			$ 10,000,000
Revenue from performance obligation expected to be earned			$ 123,000,000
Termination of contract, period after first commercial sale of product			10 years
Period required for notice of termination of contract			60 days
Revenue from performance obligation earned							500,000
BeiGene Agreement | Licenses of Intellectual Property
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from performance obligation earned								$ 9,500,000
BeiGene Agreement | Manufacturing Supply Services
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from performance obligation earned						1,800,000	300,000
Revenue recognized							(3,300,000)
Cost sharing receivable					300,000	1,300,000
Revenue from Contract with Customer, Including Assessed Tax					400,000	2,000,000
Contract with Customer, Liability, Revenue Recognized						200,000	3,000,000
BeiGene Agreement | Milestone Payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognized						0	0
Contract with Customer, Milestone Payments Receivable					5,000,000
BeiGene Agreement | Royalties
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue					0	0	0
Pfizer Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Termination of contract, period after first commercial sale of product				10 years
Period required for notice of termination of contract				60 days
Expenses related to collaboration agreement							7,000,000
Pfizer Agreement | adagrasib
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to collaboration agreement					5,000,000
Pfizer Agreement | Research and Development Services
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to collaboration agreement							$ 6,000,000
Pfizer Agreement | Milestone Payments | adagrasib
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to collaboration agreement						3,000,000
Pfizer Agreement | Milestone Payments | MRTX1133
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to collaboration agreement						300,000
Pfizer Agreement | Research and Development Services
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to collaboration agreement						$ 1,500,000
ORIC Pharmaceuticals Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock received as part of stock issuance and license agreements (shares)		588,235
License agreement, period of transfer restrictions		18 months
License agreement, period of agreement after first commercial sale		10 years
ORIC Pharmaceuticals Agreement | Level 3
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License agreement, transaction price		$ 11,400,000
Zai Collaboration and License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration Arrangement, Research and Development Arrangement, Up-Front Fee Received	$ 65,000,000
Collaborative Arrangement, Research and Development Arrangement, Discovery and Collaboration Agreement, Termination of Contract, Period after First Commercial Sale of Product	10 years
Collaboration Arrangement, Research and Development Arrangement, Contract to Perform for Others, Period Required for Notice of Termination of Contract	12 months
Collaboration Arrangement, Research and Development Arrangement, Transaction Price	$ 66,600,000
Zai Collaboration and License Agreement | Licenses of Intellectual Property
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from Contract with Customer, Including Assessed Tax					66,600,000
Income tax expense					3,300,000
Zai Collaboration and License Agreement | Manufacturing Supply Services
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from Contract with Customer, Including Assessed Tax					0
Zai Collaboration and License Agreement | Sales Milestone Payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration Arrangement, Research and Development Arrangement, Contract to Perform for Others, Compensation Expected to be Earned	180,000,000
Zai Collaboration and License Agreement | Royalties
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue					$ 0
Zai Collaboration and License Agreement | Development and Regulatory-Based Milestone Payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration Arrangement, Research and Development Arrangement, Contract to Perform for Others, Compensation Expected to be Earned	$ 93,000,000

Shareholders' Equity - Stock Re

Shareholders' Equity - Stock Reserved for Future Issuance (Details)	Dec. 31, 2021shares
Class of Stock [Line Items]
Common stock reserved for future issuance (shares)	15,991,698
Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock reserved for future issuance (shares)	107,764
Warrant
Class of Stock [Line Items]
Common stock reserved for future issuance (shares)	7,605,811
Common stock options
Class of Stock [Line Items]
Common stock reserved for future issuance (shares)	4,532,252
Restricted stock units
Class of Stock [Line Items]
Common stock reserved for future issuance (shares)	1,002,178
Shares available for grant
Class of Stock [Line Items]
Common stock reserved for future issuance (shares)	2,743,693

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Nov. 30, 2021	Oct. 31, 2020	Jan. 31, 2020	Jun. 30, 2019	Jan. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 02, 2021	Jul. 02, 2020	Jun. 30, 2020
Equity [Abstract]
Stock issued in transaction (shares)	3,448,275	4,585,706	3,538,462	2,415,000	1,854,838
Sale price of common stock (USD per share)	$ 145	$ 202	$ 97.50		$ 62						$ 97
Proceeds from sale of common stock	$ 474,700	$ 879,600	$ 324,000	$ 219,900	$ 107,900
Common stock, par value (USD per share)						$ 0.001	$ 0.001		$ 0.001	$ 0.001
Aggregate offering price									$ 500,000	$ 200,000
Proceeds from disgorgement of shareholders’ short-swing profits					$ 1,100	$ 0	$ 0	$ 1,050
Number of warrants exercised via cashless exercises (shares)						623,821	1,400,012	2,125,033
Net exercise of warrants (shares)						623,814	1,400,000
Exercise of warrants for cash (shares)							63,235	2,125,000

Shareholders' Equity - Warrants

Shareholders' Equity - Warrants Issued and Outstanding (Details) - $ / shares	Dec. 31, 2021	Jun. 11, 2018	Nov. 20, 2017	Jan. 11, 2017
Class of Stock [Line Items]
Number of warrants (shares)	7,605,811
Private Placement | January 11, 2017 Warrants
Class of Stock [Line Items]
Exercise price of warrants (USD per share)				$ 0.001
Number of warrants (shares)	3,578,036
Private Placement | November 20, 2017 Warrants
Class of Stock [Line Items]
Exercise price of warrants (USD per share)			$ 0.001
Number of warrants (shares)	3,669,360
Private Placement | June 11, 2018 Warrants
Class of Stock [Line Items]
Exercise price of warrants (USD per share)		$ 0.001
Number of warrants (shares)	358,415

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	May 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price required percentage of fair market value	100.00%
Award vesting period	4 years
Intrinsic value of options exercised	$ 91,100,000	$ 121,500,000	$ 38,600,000
Cash received from exercise of stock options	28,000,000	45,900,000	8,500,000
Fair value of options vested	58,300,000	52,100,000	20,400,000
Compensation cost not yet recognized	$ 88,800,000
Compensation cost not yet recognized, period for recognition	1 year 3 months 18 days
Capitalized costs	$ 0	0	0
Tax benefit from compensation expense	$ 0	$ 0	$ 0
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Fair value of options vested	$ 17,400,000
Compensation cost not yet recognized	$ 67,600,000
Compensation cost not yet recognized, period for recognition	2 years
Performance Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of options vested	$ 700,000
Compensation cost not yet recognized	$ 5,400,000
Compensation cost not yet recognized, period for recognition	3 years 1 month 6 days
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized (shares)	2,500,000
Authorized amount for issuance (shares)	2,600,000
Stock option contractual terms	10 years
Stock authorized for purchase				$ 25,000
Purchase discount (as a percent)				85.00%
Stock reserved for future issuance (shares)				300,000
Issuance of common stock from ESPP (shares)	192,236
Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized amount for issuance (shares)	0
Stock option contractual terms	7 years
Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding	121,574		417,343

Share-Based Compensation - Stoc

Share-Based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance at beginning of year (shares) | shares	4,429,489
Granted (shares) | shares	1,012,211
Exercised (shares) | shares	(673,095)
Canceled (shares) | shares	(236,353)
Balance at end of year (shares) | shares	4,532,252
Options exercisable at end of year (shares) | shares	2,685,192
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Balance at beginning of year (USD per share) | $ / shares	$ 58.82
Granted (USD per share) | $ / shares	177.84
Exercised (USD per share) | $ / shares	41.54
Canceled (USD per share) | $ / shares	108.53
Balance at end of year (USD per share) | $ / shares	85.38
Options exercisable at end of year (USD per share) | $ / shares	$ 50.44
Options outstanding, Weighted-Average Remaining Contractual Term (years)	6 years 10 months 24 days
Options exercisable, Weighted-Average Remaining Contractual Term (years)	5 years 8 months 12 days
Options outstanding, Aggregate Intrinsic Value | $	$ 311.7
Options exercisable, Aggregate Intrinsic Value | $	$ 261.2

Share-Based Compensation - RSU

Share-Based Compensation - RSU and PSU Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)$ / sharesshares
Restricted stock units
Number of RSUs
Balance outstanding at beginning of period (shares) | shares	450,260
Granted (shares) | shares	484,409
Releases (shares) | shares	(148,551)
Canceled/forfeited (shares) | shares	(65,551)
Balance outstanding at end of period (shares) | shares	720,567
Weighted Average Grant Date Fair Value
Balance outstanding at beginning of period (USD per share) | $ / shares	$ 114.58
Granted (USD per share) | $ / shares	182.35
Releases (USD per share) | $ / shares	117.35
Canceled/Forfeited (USD per share) | $ / shares	147.70
Balance outstanding at end of period (USD per share) | $ / shares	$ 156.55
Aggregate Intrinsic Value (millions) | $	$ 105.7
Performance Share Units (PSUs)
Number of RSUs
Balance outstanding at beginning of period (shares) | shares	15,000
Granted (shares) | shares	323,337
Releases (shares) | shares	(3,428)
Canceled/forfeited (shares) | shares	(53,298)
Balance outstanding at end of period (shares) | shares	281,611
Weighted Average Grant Date Fair Value
Balance outstanding at beginning of period (USD per share) | $ / shares	$ 101
Granted (USD per share) | $ / shares	158.96
Releases (USD per share) | $ / shares	212.93
Canceled/Forfeited (USD per share) | $ / shares	146.48
Balance outstanding at end of period (USD per share) | $ / shares	$ 157.58
Aggregate Intrinsic Value (millions) | $	$ 41.3

Share-Based Compensation - Assu

Share-Based Compensation - Assumptions Used in Fair Value Estimates (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Risk-free interest rate (as a percent)	0.80%	1.10%	2.20%
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Volatility factor (as a percent)	76.90%	81.50%	82.10%
Expected term (in years)	5 years 1 month 6 days	5 years 7 months 6 days	5 years 7 months 6 days
Weighted average estimated fair value per share (USD per share)	$ 110.43	$ 77.92	$ 52.03

Share-Based Compensation - Shar

Share-Based Compensation - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 113,502	$ 85,847	$ 55,537
Research and development expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	68,496	48,044	31,024
General and administrative expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 45,006	$ 37,803	$ 24,513

Employee Benefit Plan - Narrati

Employee Benefit Plan - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Proportion of employee contributions matched (as a percent)	5.00%	5.00%	4.00%
Maximum employer contribution per employee			$ 2,500
Matching contribution amount	$ 2,500,000	$ 1,300,000	$ 200,000

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax [Line Items]
Income tax expense	$ 3,299,000	$ 0	$ 0
Amount of increase in valuation allowance	(150,700,000)
Accrual for interest or penalties on tax matters	0	0	0
Foreign Tax Authority
Income Tax [Line Items]
Income tax expense	3,300,000
Canadian Federal
Income Tax [Line Items]
Scientific research and experimental development expenses deductible for income tax purposes	19,900,000	19,900,000	19,900,000
Net operating loss carry forwards (NOLs)	79,545,000
Canadian Provincial
Income Tax [Line Items]
Scientific research and experimental development expenses deductible for income tax purposes	21,600,000	21,600,000	21,600,000
Net operating loss carry forwards (NOLs)	78,924,000
US Federal
Income Tax [Line Items]
Income tax expense		$ 0	$ 0
Net operating loss carry forwards (NOLs)	1,250,773,000
US Federal | Research Tax Credit Carryforward
Income Tax [Line Items]
Tax credit carryforward	48,500,000
US Federal | Orphan Drug Tax Credit Carryforward
Income Tax [Line Items]
Tax credit carryforward	7,200,000
US State
Income Tax [Line Items]
Net operating loss carry forwards (NOLs)	296,437,000
US State | Research Tax Credit Carryforward
Income Tax [Line Items]
Tax credit carryforward	$ 16,800,000

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Net loss before tax	$ (578,485)	$ (357,937)	$ (213,256)
Statutory combined U.S. federal and state tax rate (as a percent)	21.00%	21.00%	21.00%
Tax computed at federal statutory rate	$ (121,482)	$ (75,167)	$ (44,784)
State income taxes, net of federal benefit	(4,657)	(13,490)	0
Effect of change in valuation allowance	150,487	110,985	52,719
Non-deductible share-based compensation	4,783	2,724	1,810
Tax deductions for share-based compensation	(17,243)	(17,991)	(6,917)
Tax credits	(30,289)	(15,672)	(8,621)
Foreign withholding taxes	3,299	0	0
Change in tax rate	2,972	0	0
Unrecognized tax benefits	7,573	3,857	2,143
Non-deductible officers’ compensation	8,318	4,697	3,527
Other differences	(462)	57	123
Income tax expense	$ 3,299	$ 0	$ 0

Income Taxes - Net Deferred Inc

Income Taxes - Net Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Tangible and intangible depreciable assets	$ 29,576	$ 32,180
Stock compensation	26,738	19,183
Provisions	5,740	2,510
Lease liability	9,916	8,800
Non-current investment	673	0
Net operating loss carryforward	299,204	182,536
Capital loss carryforward	89	114
Canada scientific research and experimental development expenditures	5,471	5,471
U.S. research and development tax credits	51,550	28,834
Total gross deferred tax assets	428,957	279,628
Less valuation allowance	(421,044)	(270,368)
Net deferred tax assets	7,913	9,260
Deferred tax liabilities:
Right-of-use asset	(7,913)	(8,377)
Non-current investment	0	(883)
Net deferred income taxes	$ 0	$ 0

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss Expirations (Details) $ in Thousands	Dec. 31, 2021USD ($)
US Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	$ 1,250,773
US Federal | 2030
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)
US Federal | 2031
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)
US Federal | 2032
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)
US Federal | 2033
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	2,225
US Federal | 2034
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	7,276
US Federal | 2035
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	53,359
US Federal | 2036
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	23,379
US Federal | 2037
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	65,509
US Federal | 2038
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
US Federal | 2039
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
US Federal | 2040
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
US Federal | 2041
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
US Federal | Does not expire
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	1,099,025
US State
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	296,437
US State | 2030
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)
US State | 2031
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)
US State | 2032
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)
US State | 2033
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	2,232
US State | 2034
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	22,162
US State | 2035
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	52,950
US State | 2036
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
US State | 2037
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
US State | 2038
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	3,741
US State | 2039
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
US State | 2040
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	190,783
US State | 2041
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	24,569
US State | Does not expire
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
Canadian Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	79,545
Canadian Federal | 2030
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	4,830
Canadian Federal | 2031
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	7,059
Canadian Federal | 2032
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	13,308
Canadian Federal | 2033
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	18,623
Canadian Federal | 2034
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	32,401
Canadian Federal | 2035
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	1,084
Canadian Federal | 2036
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	777
Canadian Federal | 2037
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	697
Canadian Federal | 2038
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
Canadian Federal | 2039
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	242
Canadian Federal | 2040
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	273
Canadian Federal | 2041
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	251
Canadian Federal | Does not expire
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
Canadian Provincial
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	78,924
Canadian Provincial | 2030
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	4,907
Canadian Provincial | 2031
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	7,066
Canadian Provincial | 2032
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	12,433
Canadian Provincial | 2033
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	19,385
Canadian Provincial | 2034
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	31,809
Canadian Provincial | 2035
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	1,084
Canadian Provincial | 2036
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	777
Canadian Provincial | 2037
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	697
Canadian Provincial | 2038
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	0
Canadian Provincial | 2039
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	242
Canadian Provincial | 2040
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	273
Canadian Provincial | 2041
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	251
Canadian Provincial | Does not expire
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards (NOLs)	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Canadian Federal
Reconciliation of the beginning and ending gross amounts of unrecognized tax positions
Unrecognized tax positions, beginning of year	$ 7,394	$ 4,268	$ 2,617
Gross increase — current period tax positions	6,482	3,126	1,651
Gross decrease — prior period tax positions	0	0	0
Gross increase — prior period tax positions	0	0	0
Expiration of statute of limitations	0	0	0
Unrecognized tax positions, end of year	13,876	7,394	4,268
Canadian Provincial
Reconciliation of the beginning and ending gross amounts of unrecognized tax positions
Unrecognized tax positions, beginning of year	9,652	8,648	8,010
Gross increase — current period tax positions	1,367	1,004	638
Gross decrease — prior period tax positions	(78)	0	0
Gross increase — prior period tax positions	0	0	0
Expiration of statute of limitations	0	0	0
Unrecognized tax positions, end of year	$ 10,941	$ 9,652	$ 8,648

Investment Tax Credits - Summar

Investment Tax Credits - Summary (Details) - Canadian Federal $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
INVESTMENT TAX CREDITS
Non-refundable ITCs related to scientific research and development expenditures	$ 3,920
2030
INVESTMENT TAX CREDITS
Non-refundable ITCs related to scientific research and development expenditures	764
2031
INVESTMENT TAX CREDITS
Non-refundable ITCs related to scientific research and development expenditures	1,000
2032
INVESTMENT TAX CREDITS
Non-refundable ITCs related to scientific research and development expenditures	1,125
2033
INVESTMENT TAX CREDITS
Non-refundable ITCs related to scientific research and development expenditures	$ 1,031

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating right-of-use asset		$ 39,900,000
Total lease liability		41,900,000
Lease liability	$ 45,879,000
Current Headquarters
Lessee, Lease, Description [Line Items]
Discount rate (as a percent)	12.00%
Operating right-of-use asset	$ 37,680,000	39,890,000
Total lease liability	47,220,000
Operating lease expense	7,700,000
Operating lease liability current	1,300,000
Operating lease cost		300,000
Lease liability	$ 45,900,000	$ 41,905,000
Building | Future Headquarters
Lessee, Lease, Description [Line Items]
Lease term	12 years
Future monthly rent expense	$ 600,000
Annual rent increase (as a percent)	3.00%
Building | Current Headquarters
Lessee, Lease, Description [Line Items]
Annual rent increase (as a percent)	3.00%
Monthly rent expense	$ 24,100

Commitments and Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Total lease liability		$ 41,900
Current Headquarters
Lessee, Lease, Description [Line Items]
2022	$ 1,681
2023	7,844
2024	8,080
2025	8,322
2026	8,572
Thereafter	59,685
Total operating lease payments	94,184
Less: Amount representing interest	(46,964)
Total lease liability	47,220
Operating Lease, Lease Termination, Reduction of Lease Liability, Amount	$ 41,100

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) - Summary (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
License and collaboration revenues	$ 299	$ 71,793	$ 0	$ 0	$ 1,707	$ 11,424	$ 0	$ 267	$ 72,092	$ 13,398	$ 3,335
Loss from operations	(197,075)	(79,499)	(164,186)	(132,421)	(106,336)	(88,678)	(84,862)	(89,487)	(573,181)	(369,363)	(222,104)
Net loss	$ (199,620)	$ (80,054)	$ (166,430)	$ (135,680)	$ (101,087)	$ (87,336)	$ (82,859)	$ (86,655)	$ (581,784)	$ (357,937)	$ (213,256)
Basic and diluted net loss per share (USD per share)	$ (3.72)	$ (1.55)	$ (3.23)	$ (2.67)	$ (2.08)	$ (1.96)	$ (1.89)	$ (2.02)

Uncategorized Items - mrtx-2021

Label	Element	Value
Pfizer Discovery and Collaboration Agreement [Member] | Milestone Payments - Initiation of First Phase 1 Trial for MRTX849 [Member]
Research and Development Expense	us-gaap_ResearchAndDevelopmentExpense	$ 1,000,000
Pfizer Discovery and Collaboration Agreement [Member] | Development Milestone Payments [Member]
Research and Development Arrangement, Discovery and Collaboration Agreement, Milestone Payments Paid	mrtx_ResearchandDevelopmentArrangementDiscoveryandCollaborationAgreementMilestonePaymentsPaid	9,500,000
Research and Development Arrangement, Discovery and Collaboration Agreement, Compensation Expected to be Paid	mrtx_ResearchandDevelopmentArrangementDiscoveryandCollaborationAgreementCompensationExpectedtobePaid	9,300,000
Pfizer Discovery and Collaboration Agreement [Member] | Sales Milestone Payments [Member]
Research and Development Arrangement, Discovery and Collaboration Agreement, Compensation Expected to be Paid	mrtx_ResearchandDevelopmentArrangementDiscoveryandCollaborationAgreementCompensationExpectedtobePaid	$ 337,000,000