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

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

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.