0001741830-24-000021 | 10-K | XBRL Viewer

Net Loss Per Share

12 Months Ended

Dec. 31, 2023

The following table summarizes the computation of basic and diluted net loss per share of the Company for the years ended December 31, 2023 and December 31, 2022 (in thousands, except per share data):


	Year Ended December 31,
	2023		2022
Net loss	$	(112,673)	$	(133,204)
Weighted-average common stock outstanding, basic and diluted	57,744		56,201
Net loss per share, basic and diluted	$	(1.95)	$	(2.37)

The Company’s potentially dilutive securities, which include options to purchase shares of the Company's common stock and restricted stock awards subject to future vesting, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share.

The Company excluded the following potential shares of common stock, presented based on amounts outstanding at each stated period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect (in thousands):


	Year Ended December 31,
	2023	2022
Stock options to purchase common stock	8,197	7,151
Early exercised stock options subject to future vesting	56	304
Restricted stock units subject to future vesting	1,635	2,243
Restricted stock awards subject to future vesting	20	54

Total	9,908	9,752

In addition to the potentially dilutive securities noted above, the Company also has the option under its agreement with Tempus to issue common shares upon the achievement of specified milestones. Please refer to Note 8, “Commitment and Contingencies - Amended Tempus Research and Development Agreement” section for

further details. Because the necessary conditions for issuance of the shares had not been met as of December 31, 2023, the Company excluded these shares from the table above.

Significant Accounting Policies and Estimates - Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Restricted cash	$ 2,026	$ 2,026

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Audit Information [Abstract]
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California

Statement of Stockholders’ Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Common stock, beginning balance (in shares) at Dec. 31, 2021		55,703
Beginning balance at Dec. 31, 2021	$ 345,097	$ 56	$ 608,064	$ (39)	$ (262,984)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting and exercise of options and vesting of restricted stock (in shares)		1,003
Issuance of common stock upon vesting and exercise of options and vesting of restricted stock	1,834	$ 1	1,833
Stock-based compensation expense	31,145		31,145
Employee stock purchase plan (in shares)		261
Employee stock purchase plan	380		380
Net unrealized gain (loss) on available-for-sale securities	(753)			(753)
Net loss	$ (133,204)				(133,204)
Common stock, ending balance (in shares) at Dec. 31, 2022	56,967	56,967
Beginning balance at Dec. 31, 2022	$ 244,499	$ 57	641,422	(792)	(396,188)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting and exercise of options and vesting of restricted stock (in shares)		1,553
Issuance of common stock upon vesting and exercise of options and vesting of restricted stock	921	$ 2	919
Stock-based compensation expense	24,982		24,982
Employee stock purchase plan (in shares)		426
Employee stock purchase plan	538		538
Net unrealized gain (loss) on available-for-sale securities	811			811
Net loss	$ (112,673)				(112,673)
Common stock, ending balance (in shares) at Dec. 31, 2023	58,946	58,946
Beginning balance at Dec. 31, 2023	$ 159,078	$ 59	$ 667,861	$ 19	$ (508,861)

Commitments and Contingencies - Schedule of Maturities on Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
2024	$ 5,274
2025	5,921
2026	5,405
2027	4,874
2028	5,020
Thereafter	11,404
Total undiscounted lease payments	37,898
Less: Present value adjustment	(9,626)
Present value of operating lease liabilities	$ 28,272	$ 31,091

Related Parties	12 Months Ended
Related Parties	Dec. 31, 2023
Related Party Transactions [Abstract]
RELATED PARTIES	RELATED PARTIES On December 1, 2017, the Company entered into a services agreement with Two River Consulting, LLC (Two River) to provide various clinical development, operational, managerial, accounting and financial, and administrative services to the Company. Mr. Arie Belldegrun, M.D., FACS, the Chairman of the Board of Directors, is the Chairman of Two River. Mr. Joshua Kazam and Mr. David Tanen, each a director of the Company, are each partners of Two River. The Company incurred expenses of $0.1 million for each of the years ended December 31, 2023 and December 31, 2022 for these services. In 2019, the Company entered into a consulting agreement with Bellco Capital, LLC (Bellco) to provide various executive services to the Company. Mr. Arie Belldegrun, M.D., FACS, the Chairman of the Board of Directors, is the Chairman of Bellco. The Company incurred expense of $25,200 for each of the years ended December 31, 2023 and December 31, 2022 for these services.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

+ Details

Related Parties (Details) - USD ($)	12 Months Ended
Related Parties (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Service Agreement, Charges
Related Party Transaction [Line Items]
Expenses from transaction with related party	$ 100,000	$ 100,000
Consulting Agreement
Related Party Transaction [Line Items]
Expenses from transaction with related party	$ 25,200	$ 25,200

Stockholders’ Equity and Stock-based Compensation - Classified in Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 24,982	$ 31,145
Research and development expenses
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	12,013	14,974
General and administrative expenses
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 12,969	$ 16,171

Significant Accounting Policies and Estimates

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES AND ESTIMATES

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, revenue, the accrual of research and development expenses, the fair value of investments, the fair value of the long-lived assets, income tax uncertainties, the valuation of equity instruments and the incremental borrowing rate for determining the operating lease assets and liabilities. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.

Segment Reporting

Management has determined that it has one business activity and operates as one operating segment as it only reports financial information on an aggregate basis to its Chief Executive Officer, who is the Company’s chief operating decision maker. All long-lived assets are maintained in the United States of America.

Revenue Recognition

The Company recognizes revenue in accordance with the provisions of Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (“ASC 606”). The Company recognizes revenue when the Company’s customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods and services. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance 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 Company will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer.

The Company evaluates the promised goods or services in these agreements to determine which ones represent distinct performance obligations. These agreements may include the following types of promised goods or services: (i) grants of licenses and related transfer of know-how, (ii) performance of research and development services, and (iii) participation on joint research and/or development committees. They also may include options to obtain further research and development services and licenses to the Company’s intellectual property. The payment terms of these agreements may include nonrefundable upfront fees, payments for electing the contractual options, payments based upon the achievement of certain milestones, and royalty payments based on product sales derived from the collaboration.

The Company exercises judgment in assessing those promised goods and services that are distinct and thus representative of performance obligations. To the extent the Company identifies multiple performance obligations in a contract, the Company must develop assumptions that require judgment to determine the estimated standalone selling price for each performance obligation in order to allocate the transaction price among the identified performance obligations. The transaction is allocated on a relative standalone selling price basis.

Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. These estimates are reassessed each reporting period as required.

The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligations when or as the performance obligations are satisfied. For performance obligations satisfied over time, the Company estimates the efforts needed to complete the performance obligations and recognizes revenue by measuring the progress towards complete satisfaction of the performance obligations using an input measure. The estimated period of performance and level of effort, including the value of the Company researchers’ time and third-party costs, are reviewed quarterly and adjusted, as needed, to reflect the Company’s current expectations. The measurement of progress is then used to calculate revenue, including any revenue adjustments as a result of the change in estimate. For arrangements that include sales-based royalties, including commercial milestone payments based on pre-specified level of sales, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligations to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Achievement of these royalties and commercial milestones may solely depend upon the performance of the licensee. Funds received in advance are recorded as deferred revenue and are recognized as the related performance obligations are satisfied.

There are no performance, cancellation, termination, or refund provisions in any of the arrangements that contain material financial consequences to the Company.

Accrued Research and Development Expenses

As part of the process of preparing our financial statements, the Company is required to estimate our accrued research and development and manufacturing expenses. This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on the Company behalf and estimating the level of service performed and the associated costs incurred for the services when the Company has not yet been invoiced or otherwise notified of the actual costs. The majority of service providers invoice the company in arrears for services performed on a pre-determined schedule or when contractual milestones are met; however, some require advanced payments. The Company makes estimates of our accrued expenses as of each balance sheet date in the financial statements based on facts and circumstances known to it at that time. Examples of estimated accrued research and development expenses include fees paid to:

•CROs in connection with performing research activities on the Company behalf and conducting preclinical studies and clinical trials on the Company behalf;

•investigative sites or other service providers in connection with clinical trials;

•vendors in connection with preclinical and clinical development activities; and

•vendors related to product manufacturing and development and distribution of preclinical and clinical supplies.

The Company bases its expenses related to preclinical studies and clinical trials on its estimates of the services received and efforts expended pursuant to quotes and contracts with multiple CROs that conduct and manage preclinical studies and clinical trials on the Company behalf. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the completion of scientific milestones. In accruing fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, the Company adjusts the accrual or amount of prepaid expense accordingly.

The Company accounts for non-refundable advance payments for goods or services that will be used in future R&D activities as expenses when the goods have been received or when the service has been performed rather than when the payment is made.

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents.

Restricted Cash

The Company has deposited cash of $2.0 million as of December 31, 2023 and December 31, 2022 to secure a letter of credit in connection with the lease of the Cambridge facility. Please refer to Note 8, “Commitment and contingencies - Leases” for greater details. The Company has classified the restricted cash as a noncurrent asset on its balance sheets.

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments, which potentially subject the Company to significant concentrations of credit risk, consist primarily of cash and cash equivalents and investments. The primary objectives for the Company’s investment portfolio are the preservation of capital and the maintenance of liquidity. The Company does not enter into any investment transaction for trading or speculative purposes.

The Company’s investment policy limits investments to certain types of instruments such as certificates of deposit, money market instruments, obligations issued by the U.S. government and U.S. government agencies as well as corporate debt securities, and places restrictions on maturities and concentration by type and issuer. The Company maintains cash balances in excess of amounts insured by the FDIC and concentrated within a limited number of financial institutions. As of December 31, 2023 and December 31, 2022, the Company has not experienced any credit losses in such accounts or investments.

The Company is subject to a number of risks common for biopharmaceutical companies, including, but not limited to, dependency on the clinical and commercial success of its product candidates, ability to obtain regulatory approval of its product candidates, the need for substantial additional financing to achieve its goals, uncertainty of broad adoption of its approved products, if any, by physicians and patients, significant competition, and untested manufacturing capabilities.

Investments

Investments are available-for-sale and are carried at estimated fair value. The Company’s valuations of available-for-sale securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets. Management determines the appropriate classification of its investments in debt securities at the time of purchase. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than 12 months from, the balance sheet date are classified as short-term investments.

Unrealized gains and losses are excluded from earnings and are reported as components of comprehensive loss. The Company periodically evaluates whether declines in fair values of its available-for-sale securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the available-for-sale security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or whether it is more likely than not that it will be required to sell any available-for-sale security before recovery of its amortized cost basis. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest income and other expense, net. Interest income on investments is included in interest income and other expense, net on the Company’s statements of operations and comprehensive loss.

Fair Value Measurement

Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3— Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The fair value estimates are made at a discrete point in time based on relevant market information and information about the financial instruments. Fair value estimates are based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of various financial instruments, and

other factors. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and, therefore, cannot be determined with precision. Changes in assumptions could significantly affect the estimates.

As of December 31, 2023 and December 31, 2022, the Company recorded financial assets requiring fair value measurement. The financial assets include cash equivalents and investments. There were no financial liabilities requiring fair value measurement as of December 31, 2023 and December 31, 2022.

Leases

The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use (ROU) assets, current portion of operating lease liabilities, and noncurrent operating lease liabilities on the Company’s balance sheet.

ROU 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. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments and initial direct costs incurred, net of lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Company elected to exclude from its balance sheets recognition of leases having a term of 12 months or less (short-term leases) and elected to not separate lease components and non-lease components for its long-term real-estate leases.

Property and Equipment, Net

Property and equipment is stated at cost less accumulated depreciation and amortization. Depreciation is recognized using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are amortized over the lesser of their useful lives or the remaining life of the lease. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is reflected in the statements of operations and comprehensive loss in the period realized. Repairs and maintenance costs are expensed as incurred.

Estimated useful lives in years are generally as follows:


Description						Estimated Useful Life
Lab equipment						3 to 7 years
Leasehold improvements						Shorter of useful life or lease term
Furniture and fixtures						5 to 7 years
Computer equipment						3 years

Valuation of Long-Lived Assets

Long-lived assets, which include property and equipment, right-of-use assets and leasehold improvements, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets might not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset or asset group and its eventual disposition are less than its carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value. The Company recognized a non-cash impairment charge of $2.9 million, including $2.3 million for the right-of-use assets and $0.6 million for the leasehold improvements for the year

ended December 31, 2023. Please see Note 8, “Commitment and Contingencies - Impairment of Operating Lease Right-of-Use Asset and Other Long-Lived Assets” section for greater details.

Long-lived assets are considered held for sale when certain criteria are met, (1) management’s commitment to a plan to sell, (2) availability for immediate sale in its present condition, (3) initiation of an active program to identify a buyer, (4) probability of a completed sale within one year, (5) actively marketed for sale at a reasonable price in relation to its current fair value, and (6) likelihood of significant changes to the plan will be made or that the plan will be withdrawn. If all of the criteria are met as of the balance sheet date, the assets are categorized as held-for-sale at the lower of their carrying amount or fair value less costs to sell. The assets held for sale consist of laboratory equipment based on the above criteria. Losses are recognized for any initial or subsequent write- down to fair value less cost to sell, while gains are recognized for any subsequent increase in fair value less cost to sell, but not in excess of the cumulative loss previously recognized. Any gains or losses not previously recognized that result from the sale of the disposal group shall be recognized at the date of sale. The equipment is not depreciated while classified as held for sale. Assets held for sale were $0.4 million as of December 31, 2023 and zero as of December 31, 2022. Please see Note 5, “Balance Sheet Components - Property and Equipment, net” section for greater details.

Stock-Based Compensation

The Company measures stock-based awards granted to employees and nonemployees based on the fair value on the date of the grant and recognizes stock-based compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. The Company applies the straight-line method of expense recognition to all awards with only service-based vesting conditions. The Company accounts for forfeitures as they occur.

The Company estimates the fair value of each stock option grant on the date of grant using the Black-Scholes option-pricing model. This model requires the use of assumptions to determine the fair value of stock-based awards, including:

•Expected Term—The expected term represents the period that the stock-based awards are expected to be outstanding. The Company uses the simplified method to determine the expected term, which is based on the average of the time-to-vesting and the contractual life of the options.

•Expected Volatility—The Company uses an average historical stock price volatility of comparable public companies within the biotechnology and pharmaceutical industry that were deemed to be representative of future stock price trends, in addition to some consideration to the Company’s own stock price volatility. The Company continues to utilize comparable public companies as part of this process as it does not have sufficient trading history for its common stock. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

•Risk-Free Interest Rate—The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the awards.

•Expected Dividend—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Income Taxes

The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.

The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

Comprehensive Loss

Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2023 and December 31, 2022, other comprehensive loss consisted of unrealized gains and losses from available-for-sale securities.

Net Loss Per Share

Basic net loss per share is computed using the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed using the sum of the weighted-average number of shares of common stock outstanding during the period and the effect of dilutive securities.

In periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive shares of common stock are not assumed to have been issued if their effect on net loss per share is anti-dilutive.

Recent Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board (FASB) issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the disclosures required for income taxes in our annual financial statements. ASU 2023-09 is effective for the Company in its annual reporting for fiscal 2025 on a prospective basis. Early adoption and retrospective reporting are permitted. The Company is currently evaluating the impact of ASU 2023-09 on its Financial Statements.

There have been no other recent accounting pronouncements during fiscal 2023 that are of significance to the Company.

Income Taxes - Components of Net Deferred Tax Asset and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Lease liabilities	$ 5,860	$ 7,948
Stock-based compensation	3,894	4,755
Accrued compensation	928	1,093
Net operating loss carryforwards	68,304	58,628
Tax credit carryforwards	21,462	15,963
Capitalized Research and Development Cost	26,031	18,857
Fixed assets and intangibles	29	0
Other	20	17
Total deferred tax assets	126,528	107,261
Valuation allowance	(122,966)	(100,656)	$ (58,713)
Net deferred tax assets	3,562	6,605
Deferred tax liabilities:
Right-of-use assets	(3,562)	(6,316)
Fixed assets and intangibles	0	(289)
Total deferred tax liabilities	(3,562)	(6,605)
Net deferred tax assets	$ 0	$ 0

Stockholders’ Equity and Stock-based Compensation - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 31, 2020	Dec. 31, 2023	Dec. 31, 2022	Oct. 14, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized (in shares)		10,000,000	10,000,000	10,000,000
Preferred stock, par value (in dollars per share)		$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)		200,000,000	200,000,000	200,000,000
Common stock, par value (in dollars per share)		$ 0.001	$ 0.001	$ 0.001
Weighted-average grant-date fair value, options granted (in dollars per share)		$ 1.41	$ 5.57
Stock options exercised, intrinsic value		$ 29,624	$ 2,000,000
Stock options, unrecognized cost		$ 14,500,000
2020 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
Shares that may be issued, percent increase as total of common stock outstanding	5.00%
Number of shares that may be issued (in shares)		20,417,192
Vesting period	4 years
Number of shares reserved for future issuance (in shares)		5,238,438
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options recognized, weighted average period		1 year 8 months 1 day

Investments - Fair Value and Amortized Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Money market funds, amortized cost	$ 56,110	$ 61,577
Unrealized Gains	74	8
Unrealized Losses	(55)	(800)
Fair Value	130,761
Total cash equivalents and investments, amortized cost	166,751	234,343
Total cash equivalents and investments, fair value	166,770	233,551
Money market funds
Schedule of Held-to-maturity Securities [Line Items]
Money market funds, amortized cost	36,009	49,003
Certificates of deposit
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	735	490
Unrealized Gains	0	0
Unrealized Losses	(2)	0
Fair Value	733	490
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	3,662	30,683
Unrealized Gains	0	3
Unrealized Losses	0	(29)
Fair Value	3,662	30,657
Commercial paper
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		1,667
Unrealized Gains		0
Unrealized Losses		0
Fair Value		1,667
U.S. agency
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		13,024
Unrealized Gains		0
Unrealized Losses		(24)
Fair Value		13,000
U.S. treasury securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	126,345	139,476
Unrealized Gains	74	5
Unrealized Losses	(53)	(747)
Fair Value	$ 126,366	$ 138,734

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Schedule of Assets and Liabilities, Operating Leases, Lessee

The following table summarizes the presentation of the Company’s operating leases in its balance sheets as of December 31, 2023 and December 31, 2022 (in thousands):


Balance Sheet Caption	December 31,
	2023		2022
Assets:
Operating lease assets	$	19,657	$	24,707
Liabilities:
Current portion of operating lease liabilities	$	2,893	$	2,347
Noncurrent operating lease liabilities	25,379		28,744
Total operating lease liabilities	$	28,272	$	31,091

Schedule of Lease Costs

The following table summarizes the effect of operating lease costs in the Company’s statements of operations and comprehensive loss for the years ended December 31, 2023 and December 31, 2022 (in thousands):


Statement of Operations and Comprehensive Loss Caption	Year Ended December 31,
	2023		2022
Research and development	$	3,319	$	3,068
General and administrative	2,133		2,043
Total operating lease cost	$	5,452	$	5,111

Schedule of Maturities on Lease Liabilities

The undiscounted future non-cancellable lease payments under the Company's operating leases as of December 31, 2023 for the next five years and thereafter is expected to be as follows (in thousands):


Period Ending December 31,	Amount
2024	$	5,274
2025	5,921
2026	5,405
2027	4,874
2028	5,020
Thereafter	11,404
Total undiscounted lease payments	37,898
Less: Present value adjustment	(9,626)

Present value of operating lease liabilities	$	28,272

Restructuring - Schedule of Accrued Restructuring Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Restructuring Reserve [Roll Forward]
Balance at December 31, 2022	$ 0
Restructuring costs		$ 0
Balance at December 31, 2023	18,000	0
Severance and Benefits Costs
Restructuring Reserve [Roll Forward]
Balance at December 31, 2022	0
Restructuring costs	1,713,000
Cash payments	(1,695,000)
Balance at December 31, 2023	$ 18,000	$ 0

Investments (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments Classified by Contractual Maturity Date

The fair value and amortized cost of available-for-sale securities by major security type as of December 31, 2023 and December 31, 2022 were as follows (in thousands):


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Money market funds	$	36,009	$	—	$	—	$	36,009
Certificates of deposit	735		—		(2)		733
Corporate bonds	3,662		—		—		3,662
U.S. treasury securities	126,345		74		(53)		126,366
Total cash equivalents and investments	$	166,751	$	74	$	(55)	$	166,770


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Money market funds	$	49,003	$	—	$	—	$	49,003
Certificates of deposit	490		—		—		490
Commercial paper	1,667		—		—		1,667
Corporate bonds	30,683		3		(29)		30,657
U.S. agency	13,024		—		(24)		13,000
U.S. treasury securities	139,476		5		(747)		138,734
Total cash equivalents and investments	$	234,343	$	8	$	(800)	$	233,551

These available-for-sale debt securities were classified on the Company’s balance sheets as of December 31, 2023 and December 31, 2022 as (in thousands):


	Fair Value
	December 31,
	2023		2022
Cash equivalents	$	56,110	$	61,577
Short-term investments	108,671		162,212
Long-term investments	1,989		9,762
Total cash equivalents and investments	$	166,770	$	233,551

The fair values of available-for-sale securities by contractual maturity as of December 31, 2023 were as follows (in thousands):


	December 31, 2023
Due in 1 year or less	$	128,772
Due in 1 to 2 years	1,989
Total	$	130,761

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

The Company follows authoritative accounting guidance, which among other things, defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability.

The Company measures and reports its cash equivalents and investments at fair value.

Money market funds are measured at fair value on a recurring basis using quoted prices and are classified as Level 1. Investments measured at fair value based on inputs other than quoted prices that are derived from observable market data are classified as Level 2.

Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type as of December 31, 2023 and December 31, 2022 were as follows (in thousands):


	December 31, 2023
	Level 1		Level 2		Level 3		Fair Value
Financial Assets:
Money market funds	$	36,009	$	—	$	—	$	36,009

Certificates of deposit	733		—		—		733
Corporate bonds	—		3,662		—		3,662

U.S. treasury securities	126,366		—		—		126,366
Total financial assets	$	163,108	$	3,662	$	—	$	166,770


	December 31, 2022
	Level 1		Level 2		Level 3		Fair Value
Financial Assets:
Money market funds	$	49,003	$	—	$	—	$	49,003
Certificates of deposit	490		—		—		490
Commercial paper	—		1,667				1,667
Corporate bonds	—		30,657		—		30,657
U.S. agency	—		13,000		—		13,000
U.S. treasury securities	138,734		—		—		138,734
Total financial assets	$	188,227	$	45,324	$	—	$	233,551

The carrying amounts of accounts payable and accrued expenses approximate their fair values due to their short-term maturities. The Company’s Level 2 securities are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income- and market-based approaches, for which all significant inputs are observable, either directly or indirectly.

The Company did not have any financial assets or liabilities as of December 31, 2023 and December 31, 2022 that required Level 3 inputs.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation	$ 3,886	$ 4,277
External research and development	5,821	7,694
Accrued outside services	807	945
Accrued taxes	133	40
Accrued restructuring costs	18	0
Other accrued expenses	266	7
Total accrued expenses	$ 10,931	$ 12,963

Income Taxes - Deferred Tax Asset Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred Tax Asset, Valuation Allowance [Roll Forward]
Beginning Balance, January 1	$ 100,656	$ 58,713
Change charged to expense	22,310	41,943
Ending Balance, December 31	$ 122,966	$ 100,656

Commitments and Contingencies - Supplemental Balance Sheet Information - Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Operating lease assets	$ 19,657	$ 24,707
Liabilities:
Current portion of operating lease liabilities	2,893	2,347
Noncurrent operating lease liabilities	25,379	28,744
Total operating lease liabilities	$ 28,272	$ 31,091

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of the year	$ 3,035	$ 246
Additions based on tax positions related to the current year	944	1,993
Additions to tax positions of prior years	388	796
Balance at the end of the year	$ 4,367	$ 3,035

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis


	December 31, 2023
	Level 1		Level 2		Level 3		Fair Value
Financial Assets:
Money market funds	$	36,009	$	—	$	—	$	36,009

Certificates of deposit	733		—		—		733
Corporate bonds	—		3,662		—		3,662

U.S. treasury securities	126,366		—		—		126,366
Total financial assets	$	163,108	$	3,662	$	—	$	166,770


	December 31, 2022
	Level 1		Level 2		Level 3		Fair Value
Financial Assets:
Money market funds	$	49,003	$	—	$	—	$	49,003
Certificates of deposit	490		—		—		490
Commercial paper	—		1,667				1,667
Corporate bonds	—		30,657		—		30,657
U.S. agency	—		13,000		—		13,000
U.S. treasury securities	138,734		—		—		138,734
Total financial assets	$	188,227	$	45,324	$	—	$	233,551

Stockholders’ Equity and Stock-based Compensation - ESPP (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 24,982	$ 31,145
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	12,013	14,974
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 12,969	$ 16,171
The ESPP \| Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend	0.00%	0.00%
Total stock-based compensation expense	$ 568	$ 1,121
The ESPP \| Employee stock purchase plan \| Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	399	845
The ESPP \| Employee stock purchase plan \| General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 169	$ 276
Minimum \| The ESPP \| Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months	5 months 26 days
Expected volatility	70.74%	56.55%
Risk-free interest rate	4.40%	0.22%
Maximum \| The ESPP \| Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	2 years	2 years
Expected volatility	82.61%	87.15%
Risk-free interest rate	5.53%	2.84%

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (112,673)	$ (133,204)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation	2,136	2,266
Net amortization (accretion) on available-for-sale securities	(5,340)	(533)
Change in accrued interest on available-for-sale securities	493	1,025
Stock-based compensation expense	24,982	31,145
Non-cash lease expense	2,780	2,197
Impairment of operating lease right of use asset and leasehold improvements	2,915	0
Loss from write down of held for sale assets	249	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	616	1,605
Other noncurrent assets	590	(1,055)
Accounts payable	(4,148)	4,025
Accrued expenses	(2,032)	4,130
Right-of-use operating assets and liabilities, net	(2,819)	(2,671)
Deferred revenue	13,711	0
Current portion of other liabilities and Other noncurrent liabilities	(42)	144
Net cash used in operating activities	(78,582)	(90,926)
Cash flows from investing activities:
Purchase of property and equipment	(679)	(577)
Purchase of marketable securities	(212,957)	(367,124)
Maturities of marketable securities	280,004	334,979
Proceeds from sale of marketable securities	0	500
Net cash provided by (used in) investing activities	66,368	(32,222)
Cash flows from financing activities:
Proceeds from issuance of common stock upon exercise of stock options	29	471
Proceeds from issuance of common stock under the employee stock purchase plan	538	380
Net cash provided by financing activities	567	851
Net decrease in cash and cash equivalents	(11,647)	(122,297)
Cash, cash equivalents and restricted cash at beginning of period	77,999	200,296
Cash, cash equivalents and restricted cash at end of period	66,352	77,999
Cash and cash equivalents at end of period	64,326	75,973
Restricted cash at end of period	2,026	2,026
Cash, cash equivalents and restricted cash at end of period	66,352	77,999
Supplemental disclosures of non-cash activities:
Property and equipment additions included in accounts payable and accrued expenses	$ 4	$ 20

Commitments and Contingencies - Narrative (Details)	1 Months Ended			3 Months Ended	12 Months Ended
Commitments and Contingencies - Narrative (Details)	Apr. 30, 2023 USD ($) service	Feb. 28, 2021 USD ($) ft²	Mar. 31, 2020 USD ($) ft²	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets					$ 19,657,000	$ 24,707,000
Lease liabilities					28,272,000	31,091,000
Lease payments					5,600,000	5,700,000
Impairment of operating lease right of use asset and leasehold improvements					2,915,000	0
Impairment of long-lived assets, right-of-use asset					2,300,000
Impairment of long-lived assets, related leasehold improvements				$ 600,000	600,000
Impairment of operating lease right of use asset and leasehold improvements						0
Prepaid expenses and other current assets					5,781,000	6,106,000
Tempus Labs, Inc.
Lessee, Lease, Description [Line Items]
Payments for purchase obligation					3,600,000	1,100,000	$ 0
Prepaid expenses and other current assets					700,000	800,000
Purchase Obligation, Quarterly Payment Terms	30 days
Tempus Labs, Inc. \| Research And Development Services
Lessee, Lease, Description [Line Items]
Services contract term	4 years
Number of primary services \| service	3
Annual minimum commitment payment in year one	$ 1,500,000
Annual minimum commitment payment in year two	2,500,000
Annual minimum commitment payment in year three	3,000,000
Annual minimum commitment payment in year four	2,500,000
Sales milestone payment	$ 22,400,000
Sales milestone payment in shares of common stock, percent threshold	50.00%
Research and development expenses
Lessee, Lease, Description [Line Items]
Impairment of operating lease right of use asset and leasehold improvements					1,900,000
General and administrative expenses
Lessee, Lease, Description [Line Items]
Impairment of operating lease right of use asset and leasehold improvements					1,000,000
301 Binney Street, Cambridge, Massachusetts
Lessee, Lease, Description [Line Items]
Lease term			11 years
Facility size \| ft²			40,514
Annual base rent			$ 4,100,000
Escalating rent payments, percent			3.00%
Letter of credit			$ 2,000,000
Tenant improvement allowances			$ 3,700,000
Operating lease right-of-use assets					17,900,000	21,900,000
Lease liabilities					$ 25,600,000	28,000,000
Remaining lease term					7 years 2 months 12 days
Incremental borrowing rate					8.50%
San Mateo, California. February 2021 Lease Agreement
Lessee, Lease, Description [Line Items]
Facility size \| ft²		17,340
Escalating rent payments, percent		3.00%
Operating lease right-of-use assets					$ 1,700,000	2,800,000
Lease liabilities					$ 2,700,000	$ 3,700,000
Remaining lease term					2 years 6 months
Incremental borrowing rate					11.18%
Initial annual base rent		$ 1,200,000
Security deposit		$ 59,000

Stockholders’ Equity and Stock-based Compensation - Stock Based Compensation - Stock Options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 24,982	$ 31,145
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	14,191	18,878
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	12,013	14,974
Research and development expenses \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	6,243	8,464
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	12,969	16,171
General and administrative expenses \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 7,948	$ 10,414

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (c)(2)(ii)
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+ Details

Stockholders’ Equity and Stock-based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Number of Options
Beginning Balance (in shares) \| shares	7,455
Granted (in shares) \| shares	3,234
Forfeited (in shares) \| shares	(2,151)
Exercised (in shares) \| shares	(285)
Ending Balance (in shares) \| shares	8,253
Weighted-Average Exercise Price
Beginning Balance (dollars per share) \| $ / shares	$ 11.83
Granted (dollars per share) \| $ / shares	1.98
Forfeited (dollars per share) \| $ / shares	9.30
Exercised (dollars per share) \| $ / shares	3.23
Ending Balance (dollars per share) \| $ / shares	$ 8.92
Stock Option Activity, Additional Disclosures
Balance, Weighted-Average Remaining Contractual Term	6 years 8 months 26 days
Balance, Aggregate Intrinsic Value \| $	$ 19
Exercisable (in shares) \| shares	4,949
Exercisable (in dollars per share) \| $ / shares	$ 10.66
Exercisable, Weighted-Average Remaining Contractual Term	5 years 6 months 21 days
Exercisable, Aggregate Intrinsic Value \| $	$ 13
Unvested and expected to vest (in shares) \| shares	3,303
Unvested and expected to vest (in dollars per share) \| $ / shares	$ 6.33
Unvested and expected to vest, Weighted-Average Remaining Contractual Term	8 years 7 months 24 days
Unvested and expected to vest, Aggregate Intrinsic Value \| $	$ 6

Investments

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

INVESTMENTS

The fair value and amortized cost of available-for-sale securities by major security type as of December 31, 2023 and December 31, 2022 were as follows (in thousands):


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Money market funds	$	36,009	$	—	$	—	$	36,009
Certificates of deposit	735		—		(2)		733
Corporate bonds	3,662		—		—		3,662
U.S. treasury securities	126,345		74		(53)		126,366
Total cash equivalents and investments	$	166,751	$	74	$	(55)	$	166,770


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Money market funds	$	49,003	$	—	$	—	$	49,003
Certificates of deposit	490		—		—		490
Commercial paper	1,667		—		—		1,667
Corporate bonds	30,683		3		(29)		30,657
U.S. agency	13,024		—		(24)		13,000
U.S. treasury securities	139,476		5		(747)		138,734
Total cash equivalents and investments	$	234,343	$	8	$	(800)	$	233,551

These available-for-sale debt securities were classified on the Company’s balance sheets as of December 31, 2023 and December 31, 2022 as (in thousands):


	Fair Value
	December 31,
	2023		2022
Cash equivalents	$	56,110	$	61,577
Short-term investments	108,671		162,212
Long-term investments	1,989		9,762
Total cash equivalents and investments	$	166,770	$	233,551

The fair values of available-for-sale securities by contractual maturity as of December 31, 2023 were as follows (in thousands):


	December 31, 2023
Due in 1 year or less	$	128,772
Due in 1 to 2 years	1,989
Total	$	130,761

As of December 31, 2023 and December 31, 2022, there have been no significant realized losses on available-for-sale securities for any of the periods presented in the accompanying financial statements. Unrealized losses on available-for-sale securities are not attributed to credit risk for any of the periods presented. The Company believes that it is more likely than not that investments in an unrealized loss position will be held until maturity and all interest and principal will be received. The Company believes that an allowance for credit losses is unnecessary because the unrealized losses on certain of the Company’s available-for-sale securities are due to market factors. To date, the Company has not recorded any impairment charges on available-for-sale securities.

Significant Accounting Policies and Estimates - Long-Lived Assets (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Impairment of operating lease right of use asset and leasehold improvements		$ 2,915,000	$ 0
Impairment of long-lived assets, right-of-use asset		2,300,000
Impairment of long-lived assets, related leasehold improvements	$ 600,000	600,000
Assets held for sale		$ 400,000	$ 0

Nature of Operations and Basis of Presentation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments \| segment	1
Accumulated deficit \| $	$ 508,861	$ 396,188

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Commitments and Contingencies - Schedule of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 5,452	$ 5,111
Research and development
Lessee, Lease, Description [Line Items]
Operating lease cost	3,319	3,068
General and administrative
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 2,133	$ 2,043

Significant Accounting Policies and Estimates - Property, Plant and Equipment (Details)	Dec. 31, 2023
Lab equipment \| Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Lab equipment \| Maximum
Property, Plant and Equipment [Line Items]
Useful life	7 years
Furniture and fixtures \| Minimum
Property, Plant and Equipment [Line Items]
Useful life	5 years
Furniture and fixtures \| Maximum
Property, Plant and Equipment [Line Items]
Useful life	7 years
Computer equipment
Property, Plant and Equipment [Line Items]
Useful life	3 years

Stockholders’ Equity and Stock-based Compensation

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

STOCKHOLDERS’ EQUITY AND STOCK-BASED COMPENSATION

Preferred Stock

Pursuant to the Amended and Restated Certificate of Incorporation filed on October 14, 2020, as amended, the Company is authorized to issue a total of 10,000,000 shares of undesignated preferred stock, par value $0.001.

Common Stock

Pursuant to the Company’s amended and restated certificate of incorporation filed on October 14, 2020, as amended, the Company is authorized to issue a total of 200,000,000 shares of its common stock, par value $0.001.

Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company's stockholders. Subject to the rights of the Preferred Stock, holders of the Company’s common stock are entitled to receive dividends, as may be declared by the Board of Directors. As of December 31, 2023, no dividends have been declared to date.

2020 Equity Incentive Plan

In October 2020, the Company adopted its 2020 Equity Incentive Plan (the 2020 Plan) which replaced the 2017 Equity Incentive Plan (Prior Plan) upon completion of the IPO. The 2020 Plan provides for the grant of incentive stock options or nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards and other forms of awards to employees, directors, and consultants of the Company. The number of shares of common stock reserved for issuance under the 2020 Plan will automatically increase each year for a period of 10 years, beginning in 2021 and continuing through 2030, in an amount equal to (1) 5.0% of the total numbers of shares of the Company’s common stock outstanding on December 31st of the immediately preceding year, or (2) a lesser number of shares determined by the Board of Directors no later than December 31st of the immediately preceding year. As of December 31, 2023, the maximum number of shares of common stock that may be issued was 20,417,192 shares.

Under the 2020 Plan options shall not have an exercise price less than 100% of the fair market value of the Company’s common stock on the grant date. Vesting periods are determined at the discretion of the Board of Directors. The maximum contractual term is 10 years. Stock options typically vest over four years.

As of December 31, 2023, there were 5,238,438 shares reserved by the Company under the 2020 Plan for the future issuance of equity awards.

Stock Options

Stock option activity under the 2020 Plan as of December 31, 2023 is summarized as follows:


	Number of Options	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
	(in thousands)			(in years)	(in thousands)
Outstanding at December 31, 2022	7,455	$	11.83
Granted	3,234	$	1.98
Forfeited	(2,151)	$	9.30
Exercised	(285)	$	3.23
Outstanding at December 31, 2023	8,253	$	8.92	6.74	$	19
Exercisable at December 31, 2023	4,949	$	10.66	5.56	$	13
Unvested and expected to vest at December 31, 2023	3,303	$	6.33	8.65	$	6

The aggregate intrinsic values of options outstanding, exercisable, vested and expected to vest were calculated as the difference between the exercise price of the options and the closing price of the Company’s common stock on the Nasdaq Global Select Market on December 31, 2023.

The weighted-average grant-date fair value per share of stock options granted, using the assumptions listed above, was $1.41 and $5.57, during the years ended December 31, 2023 and December 31, 2022, respectively.

The intrinsic value of options exercised for the years ended December 31, 2023 and December 31, 2022 was $29,624 and $2.0 million, respectively, determined as of the applicable date of exercise. There was no future tax benefit related to options exercised, as the Company had accumulated net operating losses as of December 31, 2023.

The Black-Scholes option-pricing model assumptions that the Company used to determine the grant-date fair value of stock options for the years ended December 31, 2023 and December 31, 2022 were as follows, presented on a weighted-average basis:


	Year Ended December 31,
	2023	2022
Expected term (in years)	5.99	5.91
Expected volatility	79.92%	78.21%
Risk-free interest rate	3.96%	2.28%
Expected dividend	—%	—%

For the years ended December 31, 2023 and December 31, 2022 total stock-based compensation related to stock options was classified in the Company’s statements of operations and comprehensive loss as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development expenses	$	6,243	$	8,464
General and administrative expenses	7,948		10,414
Total stock-based compensation expense	$	14,191	$	18,878

As of December 31, 2023, $14.5 million of unrecognized compensation costs related to unvested stock options is expected to be recognized over a weighted average period of 1.67 years.

Early Exercised Options

The Company allows certain of its employees and its consultants to exercise options granted under the Prior Plan prior to vesting. The shares related to early exercised stock options are subject to the Company’s lapsing repurchase right upon termination of employment or service on the Board of Directors at the lesser of the original purchase price or fair market value at the time of repurchase. In order to vest, the holders are required to provide continued service to the Company. The early exercise by an employee or consultant of a stock option is not considered to be a substantive exercise for accounting purposes, and therefore the payment received by the employer for the exercise price is recognized as a liability. For accounting purposes, unvested early exercised shares are not considered issued and outstanding and therefore not reflected as issued and outstanding in the accompanying balance sheets or the accompanying statements of stockholders' equity until the awards vest.

The deposits received are initially recorded in current portion of other liabilities and other noncurrent liabilities for the noncurrent portion. The liabilities are reclassified to common stock and paid-in capital as the repurchase right lapses. During the years ended December 31, 2023 and December 31, 2022, there have been no early exercised options.

At December 31, 2023 and December 31, 2022, there was $0.2 million and $0.9 million recorded in “current portion of other liabilities”, respectively, related to shares held by employees and nonemployees that were subject to repurchase.

At December 31, 2023 and December 31, 2022, there was zero and $0.2 million recorded in “other noncurrent liabilities”, respectively, related to shares held by employees and nonemployees that were subject to repurchase.

Restricted Stock

Restricted stock units and awards as of December 31, 2023 are summarized as follows:


	Number of Restricted Stock	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Vesting Life
	(in thousands)			(in years)
Outstanding at December 31, 2022	2,298	$	9.18
Granted - restricted stock units	1,634	$	1.98
Vested and converted to shares	(1,268)	$	10.56
Forfeited	(1,007)	$	4.67
Unvested outstanding at December 31, 2023	1,657	$	3.76	1.92

Restricted Stock Units

Pursuant to the 2020 Plan, the RSUs granted have a three-year vest period and in order to vest, the holder is required to provide service to the Company.

For the years ended December 31, 2023 and December 31, 2022 total stock-based compensation related to RSUs was classified in the Company’s statements of operations and comprehensive loss as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development expenses	$	5,371	$	5,665
General and administrative expenses	4,710		5,339
Total stock-based compensation expense	$	10,081	$	11,004

As of December 31, 2023, there was $3.3 million of unrecognized stock-based compensation related to RSUs, which is expected to be recognized over a weighted average period of 1.69 years.

For the year ended December 31, 2023 and December 31, 2022, 1,234,192 RSUs and 295,053 RSUs have vested, respectively.

Restricted Stock Awards (RSAs)

For the years ended December 31, 2023 and December 31, 2022 total stock-based compensation related to RSAs was classified in the Company’s statements of operations and comprehensive loss as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development expenses	$	—	$	—
General and administrative expenses	142		142
Total stock-based compensation expense	$	142	$	142

As of December 31, 2023, there was $0.1 million of unrecognized stock-based compensation related to RSAs, which is expected to be recognized over a weighted average period of 0.58 years.

The total grant date fair value for RSAs vested during the years ended December 31, 2023 and December 31, 2022 was $0.1 million and $0.1 million, respectively.

2020 Employee Stock Purchase Plan

In October 2020, the Company adopted its 2020 Employee Stock Purchase Plan (ESPP), which initially reserved 688,000 shares of the Company’s common stock for employee purchase under terms and provisions established by the Board of Directors. The number of shares of our common stock reserved for issuance under the ESPP automatically increases in 2021 and continuing through 2030, by the lesser of (i) 1.0% of the total number of shares of common stock outstanding on December 31st of the immediately preceding year, and (ii) 1,376,000 shares, except before the date of any increase, the Board of Directors may determine that such increase will be less than the amount set forth in clauses (i) and (ii). Effective January 1, 2023 and 2022, the number of shares authorized under the ESPP for employee purchases increased by 569,674 and 565,798 shares, respectively. The ESPP is intended to qualify as an ‘employee stock purchase plan’ under Section 423 of the Internal Revenue Code. Under the current offering adopted pursuant the ESPP, each offering period shall not exceed 27 months, with shorter duration purchase periods within each offering. Employees are eligible to participate if they are employed by the Company for at least 20 hours per week and more than five months of the year. As of December 31, 2023, 1,601,194 shares of common stock were available and reserved for future issuance under the ESPP.

Under the ESPP, employees may purchase common stock through payroll deductions at a price equal to 85% of the lower of the fair market value of common stock on the first trading day of each offering period or on the purchase date. The initial offering period commenced on October 8, 2020, the date of the underwriting agreement related to the Company’s IPO. A new offering (Subsequent Offering) automatically began in 2021, and a new offering will begin every six months thereafter over the term of the ESPP. Each Subsequent Offering will be approximately 24 months long and will consist of four purchase periods (with the purchase dates occurring on June 30 and December 31 each year during the term of the Subsequent Offering). Contributions under the ESPP are limited to a maximum of 15% of an employee’s eligible compensation.

The fair values of the rights granted under the ESPP were calculated using the following assumptions:


	Year Ended December 31,
	2023	2022
Expected term (in years)	0.50 - 2.00	0.49 - 2.00
Expected volatility	70.74% - 82.61%	56.55% - 87.15%
Risk-free interest rate	4.40% - 5.53%	0.22% - 2.84%
Dividend yield	—%	—%

For the years ended December 31, 2023 and December 31, 2022 total stock-based compensation related to ESPP was classified in the Company’s statements of operations and comprehensive loss as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development expenses	$	399	$	845
General and administrative expenses	169		276
Total stock-based compensation expense	$	568	$	1,121

Stock-Based Compensation Summary

Total stock-based compensation expense was classified in the Company’s statements of operations and comprehensive loss for the years ended December 31, 2023 and December 31, 2022 as follows for stock options, RSUs, RSAs and ESPP (in thousands):


	Year Ended December 31,
	2023		2022
Research and development expenses	$	12,013	$	14,974
General and administrative expenses	12,969		16,171
Total stock-based compensation expense	$	24,982	$	31,145

Stockholders’ Equity and Stock-based Compensation - Restricted Stock Awards Activity (Details) - Restricted Stock And Restricted Stock Units	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Number of Restricted Stock
Unvested Beginning Balance (in shares) \| shares	2,298
Granted - restricted stock awards and units (in shares) \| shares	1,634
Vested and converted to shares (in shares) \| shares	(1,268)
Forfeited (in shares) \| shares	(1,007)
Unvested Ending Balance (in shares) \| shares	1,657
Weighted-Average Grant Date Fair Value
Unvested Beginning Balance (in dollars per share) \| $ / shares	$ 9.18
Granted - restricted stock awards and units (in dollars per share) \| $ / shares	1.98
Vested and converted to shares (in dollars per share) \| $ / shares	10.56
Forfeited (in dollars per share) \| $ / shares	4.67
Unvested Ending Balance (in dollars per share) \| $ / shares	$ 3.76
Restricted Stock Awards, Additional Disclosures
Weighted-Average Remaining Vesting Life	1 year 11 months 1 day

Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Revenue	$ 6,288	$ 0
Operating expenses:
Research and development	86,379	93,715
General and administrative	41,739	43,400
Total operating expenses	128,118	137,115
Loss from operations	(121,830)	(137,115)
Other income (expense), net:
Interest income and other expense, net	9,157	3,911
Total other income (expense), net	9,157	3,911
Net loss	(112,673)	(133,204)
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale securities	811	(753)
Net comprehensive loss	$ (111,862)	$ (133,957)
Net loss per share, basic (in dollars per share)	$ (1.95)	$ (2.37)
Net loss per share, diluted (in dollars per share)	$ (1.95)	$ (2.37)
Weighted-average number of shares used to compute net loss per share, basic (in shares)	57,744	56,201
Weighted-average number of shares used to compute net loss per share, diluted (in shares)	57,744	56,201

Stockholders’ Equity and Stock-based Compensation - Early Exercised Options (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Early exercised stock options (in shares)	0	0
Current liabilities related to shares that were subject to repurchase	$ 209,000	$ 891,000
Current portion of other liabilities
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Current liabilities related to shares that were subject to repurchase	200,000	900,000
Other noncurrent liabilities
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-current liabilities related to shares that were subject to repurchase	$ 0	$ 200,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Restructuring - Narrative (Details) - USD ($)	12 Months Ended
Restructuring - Narrative (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Oct. 31, 2023
Restructuring Cost and Reserve [Line Items]
Reduction of workforce (as a percent)			19.00%
Restructuring costs		$ 0
General and administrative expenses
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1,700,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted


	Year Ended December 31,
	2023		2022
Net loss	$	(112,673)	$	(133,204)
Weighted-average common stock outstanding, basic and diluted	57,744		56,201
Net loss per share, basic and diluted	$	(1.95)	$	(2.37)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share


	Year Ended December 31,
	2023	2022
Stock options to purchase common stock	8,197	7,151
Early exercised stock options subject to future vesting	56	304
Restricted stock units subject to future vesting	1,635	2,243
Restricted stock awards subject to future vesting	20	54

Total	9,908	9,752

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

Reconciliation of the income tax expense calculated at the statutory rate to our zero expense for income taxes for the years ended December 31, 2023 and December 31, 2022 were as follows (in thousands):


	Year Ended December 31,
	2023		2022
Tax benefit at federal statutory rate	$	(23,603)	$	(27,973)
State taxes	(4,425)		(5,017)
Research tax credits	(5,454)		(15,012)
Change in valuation allowance	22,310		42,664
Stock based compensation	4,950		5,181
Change in rate	6,165		—
Other	57		157
Expense/(Benefit) for income taxes	$	—	$	—

Schedule of Deferred Taxes

Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands):


	Year Ended December 31,
	2023		2022
Deferred tax assets:
Lease liabilities	$	5,860	$	7,948
Stock-based compensation	3,894		4,755
Accrued compensation	928		1,093
Net operating loss carryforwards	68,304		58,628
Tax credit carryforwards	21,462		15,963
Capitalized Research and Development Cost	26,031		18,857
Fixed assets and intangibles	29		—
Other	20		17
Total deferred tax assets	126,528		107,261
Valuation allowance	(122,966)		(100,656)
Net deferred tax assets	3,562		6,605
Deferred tax liabilities:
Right-of-use assets	(3,562)		(6,316)
Fixed assets and intangibles	—		(289)
Total deferred tax liabilities	(3,562)		(6,605)
Net deferred tax assets	$	—	$	—

Schedule of Net Operating Loss and Research Credit Carryforwards

The following table sets forth the Company’s federal and state net operating loss and research credit carryforwards as of December 31, 2023 (in thousands)


	Amount		Expiration
Net operating losses, federal	$	268,618	Indefinite
Net operating losses, federal	$	601	2037
Net operating losses, state	$	186,045	2037-2043
Tax credits, federal	$	18,958	2037-2043
Tax credits, state	$	8,322	2038-2043

Schedule of Unrecognized Tax Benefits Roll Forward

The Company applies the provisions of ASC Topic 740 to account for uncertain income tax positions. A reconciliation of the beginning and ending amount of unrecognized tax benefits were as follows (in thousands):


	Year Ended December 31,
	2023		2022
Balance at beginning of the year	$	3,035	$	246
Additions based on tax positions related to the current year	944		1,993
Additions to tax positions of prior years	388		796
Balance at the end of the year	$	4,367	$	3,035

Schedule of Valuation Allowance

The following table shows the change in the deferred tax valuation allowance as follows (in thousands):


	Year Ended December 31,
	2023		2022
Beginning Balance, January 1	$	100,656	$	58,713
Change charged to expense	22,310		41,943
Ending Balance, December 31	$	122,966	$	100,656

Nature of Operations and Basis of Presentation	12 Months Ended
Nature of Operations and Basis of Presentation	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF OPERATIONS AND BASIS OF PRESENTATION	NATURE OF OPERATIONS AND BASIS OF PRESENTATION Operations Kronos Bio, Inc. (Kronos or the Company), a Delaware corporation, was incorporated on June 2, 2017. The Company is an integrated discovery through clinical development biopharmaceutical company, with a focus on developing therapeutics that target the dysregulated transcription that causes cancer and other serious diseases. The Company operates in one business segment, the development of biopharmaceutical products. Basis of Presentation The accompanying financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC) and accounting principles generally accepted in the United States of America (GAAP). Need for Additional Capital Since inception through December 31, 2023, the Company has incurred a cumulative net operating loss of $508.9 million. The Company expects that its cash, cash equivalents and investments as of December 31, 2023 will be sufficient to fund its operations for a period of at least one year from the date of issuance of these financial statements. Management expects to incur additional losses in the future to fund its operations and conduct product research and development and recognizes the need to raise additional capital. The Company intends to raise additional capital through the issuance of equity securities, debt financings or other sources in order to continue its operations. However, if such financing is not available when needed and at adequate levels, the Company will need to reevaluate its operating plan and may be required to delay the development of its product candidates. The future viability of the Company is dependent on its ability to generate cash from operating activities or to raise additional capital to finance its operations. The Company’s failure to raise capital as and when needed could have a material adverse effect on its financial condition and ability to pursue business strategies. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into collaboration arrangements or obtain government grants. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce, or eliminate its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects. In the event that the Company requires additional funding, there can be no assurance that it will be successful in obtaining sufficient funding on terms acceptable to the Company to fund its continuing operations, if at all.

Stockholders’ Equity and Stock-based Compensation - Restricted Stock Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 24,982	$ 31,145
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	12,013	14,974
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 12,969	16,171
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Total stock-based compensation expense	$ 10,081	$ 11,004
Unrecognized stock based compensation	$ 3,300
Awards weighted average recognition period	1 year 8 months 8 days
Vested (in shares)	1,234,192	295,053
Restricted Stock Units (RSUs) \| Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 5,371	$ 5,665
Restricted Stock Units (RSUs) \| General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	4,710	5,339
Restricted Stock And Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	142	142
Unrecognized stock based compensation	$ 100
Awards weighted average recognition period	6 months 29 days
Total grant date fair value for awards vested	$ 100	100
Restricted Stock And Restricted Stock Units \| Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	0	0
Restricted Stock And Restricted Stock Units \| General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 142	$ 142

Stockholders’ Equity and Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Schedule of Stock Option Activity

Stock option activity under the 2020 Plan as of December 31, 2023 is summarized as follows:


	Number of Options	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
	(in thousands)			(in years)	(in thousands)
Outstanding at December 31, 2022	7,455	$	11.83
Granted	3,234	$	1.98
Forfeited	(2,151)	$	9.30
Exercised	(285)	$	3.23
Outstanding at December 31, 2023	8,253	$	8.92	6.74	$	19
Exercisable at December 31, 2023	4,949	$	10.66	5.56	$	13
Unvested and expected to vest at December 31, 2023	3,303	$	6.33	8.65	$	6

Schedule of Option-pricing Model Assumptions


	Year Ended December 31,
	2023	2022
Expected term (in years)	5.99	5.91
Expected volatility	79.92%	78.21%
Risk-free interest rate	3.96%	2.28%
Expected dividend	—%	—%

Schedule of Stock-based Compensation, Classified in Statements of Operations


	Year Ended December 31,
	2023		2022
Research and development expenses	$	6,243	$	8,464
General and administrative expenses	7,948		10,414
Total stock-based compensation expense	$	14,191	$	18,878


	Year Ended December 31,
	2023		2022
Research and development expenses	$	5,371	$	5,665
General and administrative expenses	4,710		5,339
Total stock-based compensation expense	$	10,081	$	11,004


	Year Ended December 31,
	2023		2022
Research and development expenses	$	—	$	—
General and administrative expenses	142		142
Total stock-based compensation expense	$	142	$	142


	Year Ended December 31,
	2023		2022
Research and development expenses	$	399	$	845
General and administrative expenses	169		276
Total stock-based compensation expense	$	568	$	1,121


	Year Ended December 31,
	2023		2022
Research and development expenses	$	12,013	$	14,974
General and administrative expenses	12,969		16,171
Total stock-based compensation expense	$	24,982	$	31,145

Schedule of Nonvested Share Activity

Restricted stock units and awards as of December 31, 2023 are summarized as follows:


	Number of Restricted Stock	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Vesting Life
	(in thousands)			(in years)
Outstanding at December 31, 2022	2,298	$	9.18
Granted - restricted stock units	1,634	$	1.98
Vested and converted to shares	(1,268)	$	10.56
Forfeited	(1,007)	$	4.67
Unvested outstanding at December 31, 2023	1,657	$	3.76	1.92

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The fair values of the rights granted under the ESPP were calculated using the following assumptions:


	Year Ended December 31,
	2023	2022
Expected term (in years)	0.50 - 2.00	0.49 - 2.00
Expected volatility	70.74% - 82.61%	56.55% - 87.15%
Risk-free interest rate	4.40% - 5.53%	0.22% - 2.84%
Dividend yield	—%	—%

Significant Accounting Policies and Estimates (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Presentation

The accompanying financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC) and accounting principles generally accepted in the United States of America (GAAP).

Use of Estimates

Segment Reporting

Revenue Recognition

There are no performance, cancellation, termination, or refund provisions in any of the arrangements that contain material financial consequences to the Company.

Research and Development Expenses

Accrued Research and Development Expenses

•CROs in connection with performing research activities on the Company behalf and conducting preclinical studies and clinical trials on the Company behalf;

•investigative sites or other service providers in connection with clinical trials;

•vendors in connection with preclinical and clinical development activities; and

•vendors related to product manufacturing and development and distribution of preclinical and clinical supplies.

Cash and Cash Equivalents and Restricted Cash

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents.

Restricted Cash

Concentration of Credit Risk and Other Risks and Uncertainties

Investments

Fair Value Measurement

Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 3— Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Leases

Property and Equipment, Net

Estimated useful lives in years are generally as follows:


Description						Estimated Useful Life
Lab equipment						3 to 7 years
Leasehold improvements						Shorter of useful life or lease term
Furniture and fixtures						5 to 7 years
Computer equipment						3 years

Valuation of Long-Lived Assets

ended December 31, 2023. Please see Note 8, “Commitment and Contingencies - Impairment of Operating Lease Right-of-Use Asset and Other Long-Lived Assets” section for greater details.

Stock-Based Compensation

•Expected Dividend—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Income Taxes

Comprehensive Loss

Net Loss Per Share

Recent Accounting Pronouncements

There have been no other recent accounting pronouncements during fiscal 2023 that are of significance to the Company.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS Restructuring On January 24, 2024, the Company and three executive officers, Jorge DiMartino, M.D., Ph.D., the Company’s Chief Medical Officer and Executive Vice President, Clinical Development, Barbara Kosacz, J.D., the Company’s Chief Operating Officer and General Counsel, and Christopher Dinsmore, Ph.D., Chief Scientific Officer ("the Officers") mutually agreed to the termination of employment effective February 16, 2024 (“the Separation Date”). The separation agreements signed with the Officers outlined the terms of severance and contemplate the engagement of each as a consultant through December 31, 2024 to the Company following the Separation Date. In connection with the separation agreements with the Officers, the Company expects to incur charges of approximately $1.1 million associated with cash severance payments that were made in February 2024. On March 5, 2024, the Company approved an approximate 21% reduction in its workforce as part of a strategic resource allocation and cost containment plan. The workforce reduction was completed on March 7, 2024. In connection with the reduction in workforce, the Company expects to incur charges of approximately $0.6 million associated with cash severance and COBRA benefit payments primarily in the first half of 2024.

Subsequent Events (Details) $ in Thousands	Mar. 05, 2024 USD ($)	Jan. 24, 2024 USD ($) officer	Oct. 31, 2023
Subsequent Event [Line Items]
Reduction of workforce (as a percent)			19.00%
Subsequent Event
Subsequent Event [Line Items]
Number of executive officers, terminated \| officer		3
Reduction of workforce (as a percent)	21.00%
Subsequent Event \| Severance and Benefits Costs
Subsequent Event [Line Items]
Expected cost		$ 1,100
Subsequent Event \| Employee COBRA Insurance
Subsequent Event [Line Items]
Expected cost	$ 600

Cover Page - USD ($) $ in Millions	12 Months Ended
Cover Page - USD ($) $ in Millions	Dec. 31, 2023	Mar. 14, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-39592
Entity Registrant Name	Kronos Bio, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-1895605
Entity Address, Address Line One	1300 So. El Camino Real
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	San Mateo
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94402
City Area Code	650
Local Phone Number	781-5200
Title of 12(b) Security	Common stock, $0.001 par value per share
Trading Symbol	KRON
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 48.3
Entity Common Stock, Shares Outstanding		60,095,013
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement to be filed with the Securities and Exchange Commission (SEC) subsequent to the date hereof pursuant to Regulation 14A in connection with the registrant's 2024 Annual Meeting of Stockholders, are incorporated by reference into Part III of this Annual Report on Form 10-K. Such proxy statement will be filed with the SEC not later than April 29, 2024.
Entity Central Index Key	0001741830
Document Fiscal Year End	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheet Components - Property, Plant and Equipment (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Property and equipment:
Property, plant and equipment, gross		$ 17,542,000	$ 18,500,000
Less: Accumulated depreciation		(7,290,000)	(5,515,000)
Total property and equipment, net		10,252,000	12,985,000
Depreciation		2,136,000	2,266,000
Impairment of long-lived assets, related leasehold improvements	$ 600,000	600,000
Remeasurement, loss on asset		200,000
Assets held for sale		400,000	0
Lab equipment
Property and equipment:
Property, plant and equipment, gross		8,055,000	8,475,000
Leasehold improvements
Property and equipment:
Property, plant and equipment, gross		8,703,000	9,348,000
Furniture, fixtures and computer equipment
Property and equipment:
Property, plant and equipment, gross		$ 784,000	$ 677,000

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 64,326	$ 75,973
Short-term investments	108,671	162,212
Prepaid expenses and other current assets	5,781	6,106
Total current assets	178,778	244,291
Long-term investments	1,989	9,762
Property and equipment, net	10,252	12,985
Operating lease right-of-use assets	19,657	24,707
Restricted cash	2,026	2,026
Other noncurrent assets	577	1,167
Total assets	213,279	294,938
Current liabilities
Accounts payable	883	5,047
Accrued expenses	10,931	12,963
Current portion of operating lease liabilities	2,893	2,347
Current portion of deferred revenue	9,584	0
Current portion of other liabilities	404	1,129
Total current liabilities	24,695	21,486
Noncurrent operating lease liabilities	25,379	28,744
Deferred revenue, net of current portion	4,127	0
Other noncurrent liabilities	0	209
Total liabilities	54,201	50,439
Commitments and contingencies (Note 8)
Stockholder's equity
Preferred stock, $0.001 par value; 10,000 authorized; no shares issued and outstanding
Common stock, $0.001 par value, 200,000 shares authorized as of December 31, 2023 and December 31, 2022; 58,946 and 56,967 shares issued and outstanding as of December 31, 2023 and 2022, respectively.	59	57
Additional paid-in capital	667,861	641,422
Accumulated deficit	(508,861)	(396,188)
Accumulated other comprehensive income (loss)	19	(792)
Total stockholders' equity	159,078	244,499
Total liabilities and stockholders’ equity	$ 213,279	$ 294,938
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000

Collaboration and License Agreement (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 06, 2023	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue		$ 6,288	$ 0
Genentech, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration and license agreement, termination notice period, prior written notice	60 days
Collaboration and license agreement, termination notice period, uncured material breach	90 days
Collaboration and license agreement, termination notice period, uncured material breach, nonpayment	45 days
Genentech, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expected timing of satisfaction, extension period	6 months
Genentech, Inc. \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-07
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expected timing of satisfaction, period	24 months
Genentech, Inc. \| License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment	$ 20,000	$ 13,700
Maximum aggregate milestone payments	177,000
Maximum aggregate milestone payments from net sales	$ 100,000

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	58,946,000	56,967,000
Common stock, shares outstanding (in shares)	58,946,000	56,967,000

Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	$ (23,603,000)	$ (27,973,000)
State taxes	(4,425,000)	(5,017,000)
Research tax credits	(5,454,000)	(15,012,000)
Change in valuation allowance	22,310,000	42,664,000
Stock based compensation	4,950,000	5,181,000
Change in rate	6,165,000	0
Other	57,000	157,000
Expense/(Benefit) for income taxes	$ 0	$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

BALANCE SHEET COMPONENTS

Property and Equipment, net

Property and equipment, net consisted of the following as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31,
	2023		2022
Lab equipment	$	8,055	$	8,475
Leasehold improvements	8,703		9,348
Furniture, fixtures and computer equipment	784		677
Total property and equipment	17,542		18,500
Less: Accumulated depreciation	(7,290)		(5,515)
Total property and equipment, net	$	10,252	$	12,985

Depreciation expense was $2.1 million and $2.3 million for the years ended December 31, 2023 and December 31, 2022, respectively.

During the second quarter of 2023, the Company recognized a non-cash impairment charge of $0.6 million related to Leasehold improvements. Please refer to Note 8, “Commitment and contingencies - Leases” for further details.

During the year ended December 31, 2023, we committed to a plan to sell a few pieces of lab equipment no longer in service. The Company recognized a loss of $0.2 million on remeasurement of assets held for sale in the “Interest income and other expense, net” in the Statements of Operations and Comprehensive Loss. The assets held for sale of $0.4 million have been classified within the “Prepaid Expenses and Other Current Assets” in the Balance Sheet.

Accrued Expenses

Accrued expenses consisted of the following as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31,
	2023		2022
Accrued compensation	$	3,886	$	4,277
External research and development	5,821		7,694
Accrued outside services	807		945
Accrued taxes	133		40
Accrued restructuring costs	18		—
Other accrued expenses	266		7
Total accrued expenses	$	10,931	$	12,963

Current Portion of Other Liabilities

Current portion of other liabilities consist of the following as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31,
	2023		2022
Current portion of unvested early exercised share liability	$	209	$	891
ESPP withholdings	195		238
Total current portion of other liabilities	$	404	$	1,129

Income Taxes - Net Operating Loss and Research Credit Carryforwards (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Federal \| Expiring Indefinitely
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 268,618
Federal \| Expiring In 2037
Operating Loss Carryforwards [Line Items]
Net operating losses	601
Federal \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credits	18,958
State
Operating Loss Carryforwards [Line Items]
Net operating losses	186,045
State \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credits	$ 8,322

Net Loss Per Share - Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	9,908	9,752
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	8,197	7,151
Early exercised stock options subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	56	304
Restricted stock units subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	1,635	2,243
Restricted stock awards subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	20	54

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

INCOME TAXES

The Company did not record any income tax expense for the year ended December 31, 2023 and recorded a small amount of income tax expense related to state minimum taxes for the year ended December 31, 2022. The Company has incurred net operating losses for all the periods presented and has not reflected any benefit of such net operating loss carryforwards in the accompanying financial statements. The Company has recorded a full valuation allowance against all of its deferred tax assets as it is not more likely than not that such assets will be realized in the near future.


	Year Ended December 31,
	2023		2022
Tax benefit at federal statutory rate	$	(23,603)	$	(27,973)
State taxes	(4,425)		(5,017)
Research tax credits	(5,454)		(15,012)
Change in valuation allowance	22,310		42,664
Stock based compensation	4,950		5,181
Change in rate	6,165		—
Other	57		157
Expense/(Benefit) for income taxes	$	—	$	—

The Company’s deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets or liabilities for financial reporting purposes and the amounts used for income tax purposes as of December 31, 2023 and December 31, 2022. Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands):


	Year Ended December 31,
	2023		2022
Deferred tax assets:
Lease liabilities	$	5,860	$	7,948
Stock-based compensation	3,894		4,755
Accrued compensation	928		1,093
Net operating loss carryforwards	68,304		58,628
Tax credit carryforwards	21,462		15,963
Capitalized Research and Development Cost	26,031		18,857
Fixed assets and intangibles	29		—
Other	20		17
Total deferred tax assets	126,528		107,261
Valuation allowance	(122,966)		(100,656)
Net deferred tax assets	3,562		6,605
Deferred tax liabilities:
Right-of-use assets	(3,562)		(6,316)
Fixed assets and intangibles	—		(289)
Total deferred tax liabilities	(3,562)		(6,605)
Net deferred tax assets	$	—	$	—

The Company records a valuation allowance for certain temporary differences for which it is more likely than not that it will not receive future tax benefits. The Company assesses its past earnings history, income tax planning and projections of future net income when determining whether it is more likely than not future tax benefits will be realized. Based on the Company’s history of losses, the Company has maintained a full valuation allowance of approximately $123.0 million and $100.7 million for the years ended December 31, 2023 and December 31, 2022, respectively. The change in valuation allowance of $22.3 million is due to increases in net operating losses and other deferred tax assets due to current year activity.

The following table sets forth the Company’s federal and state net operating loss and research credit carryforwards as of December 31, 2023 (in thousands)


	Amount		Expiration
Net operating losses, federal	$	268,618	Indefinite
Net operating losses, federal	$	601	2037
Net operating losses, state	$	186,045	2037-2043
Tax credits, federal	$	18,958	2037-2043
Tax credits, state	$	8,322	2038-2043

Current federal and state tax laws include substantial restrictions on the utilization of net operating loss and tax credit carryforwards in the event of an ownership change as defined under Section 382 of the Internal Revenue Code of 1986, as amended. Accordingly, the Company’s ability to use these carryforward attributes may be limited as a result of such ownership change.


	Year Ended December 31,
	2023		2022
Balance at beginning of the year	$	3,035	$	246
Additions based on tax positions related to the current year	944		1,993
Additions to tax positions of prior years	388		796
Balance at the end of the year	$	4,367	$	3,035

It is the Company’s policy to record penalties and interest related to income taxes as a component of income tax expense. The Company has not recorded any interest or penalties related to income taxes during the years ended December 31, 2023 and December 31, 2022. Unrecognized tax benefits are not expected to change during the next 12 months. The reversal of the unrecognized tax benefits would not affect the effective tax rate. The Company is subject to examination by U.S. federal and state tax authorities for all years since its inception.

The following table shows the change in the deferred tax valuation allowance as follows (in thousands):


	Year Ended December 31,
	2023		2022
Beginning Balance, January 1	$	100,656	$	58,713
Change charged to expense	22,310		41,943
Ending Balance, December 31	$	122,966	$	100,656

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

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-Paragraph 13
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+ Details

Stockholders’ Equity and Stock-based Compensation - Option-pricing Model Assumptions (Details) - Stock options	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 11 months 26 days	5 years 10 months 28 days
Expected volatility	79.92%	78.21%
Risk-free interest rate	3.96%	2.28%
Expected dividend	0.00%	0.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Stockholders’ Equity and Stock-based Compensation - 2020 Employee Stock Purchase Plan (Details) - The ESPP			1 Months Ended	12 Months Ended
	Jan. 01, 2023 shares	Jan. 01, 2022 shares	Oct. 31, 2020 period shares	Dec. 31, 2023 hour shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)				1,601,194
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares that may be issued (in shares)			688,000
Number of shares that may be issued, increase percentage			1.00%
Number of shares that may be issued, increase (in shares)	569,674	565,798	1,376,000
Employment eligibility, number of hours employed per week \| hour				20
Exercise price per share of stock options as percent of fair market value of common stock			85.00%
Fixed contribution rate			15.00%
Employee stock purchase plan \| Initial Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period				27 months
Employee stock purchase plan \| Subsequent Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period			24 months
Number of offering periods \| period			4

Restructuring (Tables)

12 Months Ended

Dec. 31, 2023

Restructuring and Related Activities [Abstract]

Schedule of Accrued Restructuring Costs

The following table is a summary of accrued restructuring costs included within the “Accrued Expenses” line on the Company’s Balance Sheet as of December 31, 2023 (in thousands):


	Severance and Benefits Costs
Balance at December 31, 2022	$	—
Restructuring costs	1,713
Cash payments	(1,695)
Balance at December 31, 2023	$	18

Investments - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Cash equivalents	$ 56,110	$ 61,577
Short-term investments	108,671	162,212
Long-term investments	1,989	9,762
Total cash equivalents and investments	$ 166,770	$ 233,551

Restructuring

12 Months Ended

Dec. 31, 2023

Restructuring and Related Activities [Abstract]

RESTRUCTURING

In October 2023 the Board of Directors of the Company approved an approximate 19% reduction of our workforce as part of a strategic resource allocation and restructuring. For the November 2023 restructuring, costs of $1.7 million were recorded in “General and Administration” expense for the year ended December 31, 2023 and zero for the year ended December 31, 2022. The workforce reduction was completed on November 2, 2023.

The following table is a summary of accrued restructuring costs included within the “Accrued Expenses” line on the Company’s Balance Sheet as of December 31, 2023 (in thousands):


	Severance and Benefits Costs
Balance at December 31, 2022	$	—
Restructuring costs	1,713
Cash payments	(1,695)
Balance at December 31, 2023	$	18

Collaboration and License Agreement	12 Months Ended
Collaboration and License Agreement	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
COLLABORATION AND LICENSE AGREEMENT	COLLABORATION AND LICENSE AGREEMENT On January 6, 2023, the Company entered into a Collaboration and License Agreement with Genentech, Inc., a member of the Roche Group (“Genentech”). Pursuant to the agreement, the parties have agreed to initially collaborate on two discovery research programs in oncology, each focused on a designated transcription factor, to discover small-molecule GLP-Tox-ready candidates that modulate transcription factor targets selected by Genentech. Each discovery research program primarily consists of (i) a mapping phase with the goal of identifying the transcription regulatory network for such designated transcription factor, and (ii) a screening phase having the goal of identifying and characterizing multiple screening hits suitable for nomination as a preclinical development program. The Company leads discovery and research activities under the discovery research programs and uses its proprietary drug discovery platform, including the small molecule microarray (SMM), for hit finding. Following the completion of initial discovery and research activities, Genentech will have the exclusive right to pursue further preclinical and clinical development and commercialization of compounds identified in the discovery research programs and designated by Genentech (each, a “Hit Program”). Pursuant to the agreement, the Company received an upfront payment of $20.0 million from Genentech. In addition, the Company is eligible for additional milestone payments upon achievement of certain preclinical, clinical and regulatory (including first-sale) milestones, totaling up to $177 million for the first development candidate per Hit Program, and is eligible to receive net sales milestones of up to $100 million for the first licensed product per Hit Program. The Company is also eligible to receive tiered royalties in the low- to high-single digits on any products that are commercialized by Genentech as a result of the collaboration. The term of the discovery research programs under the agreement is up to 24 months, which may be extended by six months at the Company’s option subject to satisfying certain conditions. Unless earlier terminated, the agreement will remain in effect for each product licensed under the agreement until expiration of the royalty term for such licensed product. Genentech has the right to terminate this agreement in its entirety, or with respect to a particular discovery research program or Hit Program, in its sole discretion, at any time by providing 60 days’ advance written notice to the Company. Each party may also terminate the agreement upon the other party’s material breach that remains uncured for 90 days (or 45 days in the event of nonpayment), or in the event of certain insolvency events involving the other party. The Company evaluated the agreement and determined it was within the scope of ASC 606. The Company determined there were performance obligations to perform research and development services. Each consists of various exclusive and non-exclusive licenses to use the Company’s intellectual property and know-how, initial discovery activities, and substitution of the designated transcription factor. The Company also identified customer options contained within the contract to perform further research and development services and the renewal of the licenses that were deemed a material right as these involved a discount to Genentech that they would not have otherwise received. As a result, the material rights for various options were recognized as separate performance obligations and the transaction price was allocated to the material rights based on the relative standalone selling price, the identified discount and the probability that the customer will exercise the option or the option is cancelled. Amounts allocated to a material right are not recognized as revenue until the option is exercised. The transaction price was determined to consist of the upfront payment of $20.0 million. Potential development and regulatory milestones have been fully constrained. The Company is expected to perform research and development services for each selected target up until a defined point at which time Genentech will decide whether or not to exercise an option to nominate a development candidate and take over future development and commercialization. The Company concluded this is not a material right. Any consideration related to sales-based milestones (including royalties) will be recognized when the related sales occur as these amounts have been determined to relate predominantly to the license granted to Genentech. The Company determined that the performance obligations to perform research and development services are satisfied over time, and therefore, the related revenue will be recognized as services are provided. The Company recognized $6.3 million in revenue during the year ended December 31, 2023, using the cost-based input model related to the research and development activities associated with the identified performance obligations. The remaining $13.7 million of the upfront payment is included in short and long-term deferred revenue as of December 31, 2023 and will be recognized as the performance obligations are satisfied.

Significant Accounting Policies and Estimates (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Property, Plant and Equipment

Estimated useful lives in years are generally as follows:


Description						Estimated Useful Life
Lab equipment						3 to 7 years
Leasehold improvements						Shorter of useful life or lease term
Furniture and fixtures						5 to 7 years
Computer equipment						3 years

Property and equipment, net consisted of the following as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31,
	2023		2022
Lab equipment	$	8,055	$	8,475
Leasehold improvements	8,703		9,348
Furniture, fixtures and computer equipment	784		677
Total property and equipment	17,542		18,500
Less: Accumulated depreciation	(7,290)		(5,515)
Total property and equipment, net	$	10,252	$	12,985

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0
Valuation allowance	122,966,000	100,656,000	$ 58,713,000
Valuation allowance increase	22,310,000	41,943,000
Accrued interest or penalties related to uncertain tax positions	$ 0	$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net loss	$ (112,673)	$ (133,204)
Weighted-average common stock outstanding, basic (in shares)	57,744	56,201
Weighted-average common stock outstanding, diluted (in shares)	57,744	56,201
Net loss per share, basic (in dollars per share)	$ (1.95)	$ (2.37)
Net loss per share, diluted (in dollars per share)	$ (1.95)	$ (2.37)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Property, Plant and Equipment

Estimated useful lives in years are generally as follows:


Description						Estimated Useful Life
Lab equipment						3 to 7 years
Leasehold improvements						Shorter of useful life or lease term
Furniture and fixtures						5 to 7 years
Computer equipment						3 years

Property and equipment, net consisted of the following as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31,
	2023		2022
Lab equipment	$	8,055	$	8,475
Leasehold improvements	8,703		9,348
Furniture, fixtures and computer equipment	784		677
Total property and equipment	17,542		18,500
Less: Accumulated depreciation	(7,290)		(5,515)
Total property and equipment, net	$	10,252	$	12,985

Schedule of Accrued Expenses

Accrued expenses consisted of the following as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31,
	2023		2022
Accrued compensation	$	3,886	$	4,277
External research and development	5,821		7,694
Accrued outside services	807		945
Accrued taxes	133		40
Accrued restructuring costs	18		—
Other accrued expenses	266		7
Total accrued expenses	$	10,931	$	12,963

Schedule of Other Current Liabilities

Current portion of other liabilities consist of the following as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31,
	2023		2022
Current portion of unvested early exercised share liability	$	209	$	891
ESPP withholdings	195		238
Total current portion of other liabilities	$	404	$	1,129

Balance Sheet Components - Current Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Current portion of unvested early exercised share liability	$ 209	$ 891
ESPP withholdings	195	238
Total current portion of other liabilities	$ 404	$ 1,129

Fair Value Measurements (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 166,770	$ 233,551
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	36,009	49,003
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	733	490
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3,662	30,657
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	126,366	138,734
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		1,667
U.S. agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		13,000
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	163,108	188,227
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	36,009	49,003
Level 1 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	733	490
Level 1 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Level 1 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	126,366	138,734
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		0
Level 1 \| U.S. agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	3,662	45,324
Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Level 2 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3,662	30,657
Level 2 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		1,667
Level 2 \| U.S. agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		13,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Level 3 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Level 3 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Level 3 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 0	0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value
Level 3 \| U.S. agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		$ 0

Investments - Contractual Maturity (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Investments, Debt and Equity Securities [Abstract]
Due in 1 year or less	$ 128,772
Due in 1 to 2 years	1,989
Total	$ 130,761

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Leases

In March 2020, the Company entered into an 11-year lease agreement to move its research and development operations from 21 Erie Street, Cambridge, Massachusetts, to a 40,514 square-feet facility at 301 Binney Street, Cambridge, Massachusetts (Cambridge facility). The lease commenced on February 28, 2020 with an initial annual base rent of $4.1 million with rent escalations of 3.0% annually. The Company executed a letter of credit for $2.0 million in connection with the lease. The lease includes $3.7 million in certain tenant improvement allowances, which the Company included in its calculation of the right-of-use asset in the lease at commencement and all costs incurred by the Company were reimbursed by the lessor and were included within the total lease liability. In connection with the lease, the Company recognized an operating lease right-of-use asset of $17.9 million and $21.9 million as of December 31, 2023 and December 31, 2022, respectively. The Company recognized an aggregate lease liability of $25.6 million and $28.0 million as of December 31, 2023 and December 31, 2022, respectively. The remaining lease term is 7.2 years, and the estimated incremental borrowing rate is 8.50%.

In February 2021, the Company entered into a new lease agreement for its office space in San Mateo, California totaling 17,340 square feet, The initial annual base rent for the new space will be $1.2 million, and such amount increases by 3% annually on each anniversary of the new premises commencement date. In connection with the larger space leased, the Company made a one-time cash security deposit in the amount of $59,000. The

lease commenced in April 2021 and terminates August 31, 2026. In connection with the lease, the Company recognized an operating lease right-of-use asset of $1.7 million and $2.8 million as of December 31, 2023 and December 31, 2022, respectively. The Company recognized an aggregate lease liability of $2.7 million and $3.7 million as of December 31, 2023 and December 31, 2022, respectively. The remaining lease term is 2.5 years, and the estimated incremental borrowing rate is 11.18%.

The following table summarizes the presentation of the Company’s operating leases in its balance sheets as of December 31, 2023 and December 31, 2022 (in thousands):


Balance Sheet Caption	December 31,
	2023		2022
Assets:
Operating lease assets	$	19,657	$	24,707
Liabilities:
Current portion of operating lease liabilities	$	2,893	$	2,347
Noncurrent operating lease liabilities	25,379		28,744
Total operating lease liabilities	$	28,272	$	31,091


Statement of Operations and Comprehensive Loss Caption	Year Ended December 31,
	2023		2022
Research and development	$	3,319	$	3,068
General and administrative	2,133		2,043
Total operating lease cost	$	5,452	$	5,111

The Company made cash payments of $5.6 million and $5.7 million under the lease agreements during the years ended December 31, 2023 and December 31, 2022, respectively.

The undiscounted future non-cancellable lease payments under the Company's operating leases as of December 31, 2023 for the next five years and thereafter is expected to be as follows (in thousands):


Period Ending December 31,	Amount
2024	$	5,274
2025	5,921
2026	5,405
2027	4,874
2028	5,020
Thereafter	11,404
Total undiscounted lease payments	37,898
Less: Present value adjustment	(9,626)

Present value of operating lease liabilities	$	28,272

Impairment of Operating Lease Right-of-Use Asset and Other Long-Lived Assets

As a result of the continued and sustained decline in the Company’s stock price, the Company determined an impairment indicator was present. The Company determined all of its long-lived assets represent a single asset group for the purpose of the long-lived asset impairment assessment. The Company concluded that the carrying value of the single asset group was not recoverable as it exceeded the future net undiscounted cash flows that are expected to be generated from the use and eventual disposition of the assets within the asset group. To allocate and recognize the impairment loss, the Company, with the assistance of a third-party valuation firm,

determined the fair value of the Company using the adjusted net asset method under the cost approach. The implied allocated impairment loss to any individual asset within the long-lived asset group shall not reduce the carrying amount of that asset below its fair value. To determine the fair value of the individual assets within the asset group, the Company utilized the discounted cash flow method of the income approach and the indirect cost approach.

Based on this analysis, during the year ended December 31, 2023, the Company recognized a non-cash impairment charge of $2.9 million, including $2.3 million for the right-of-use assets and $0.6 million for the leasehold improvements. The Company recorded $1.9 million in “Research and Development” expense and $1.0 million in “General and Administration” expense, based on the relative allocation of the operating lease costs and depreciation and amortization expense. No impairment charge was recorded for the year ended December 31, 2022.

These represent a Level 3 nonrecurring fair value measurement. Calculating the fair value of the assets involves significant estimates and assumptions. These estimates and assumptions include, among others, projected future cash flows, risk-adjusted discount rates and market conditions. Changes in the factors and assumptions used could materially affect the amount of impairment loss recognized in the period the asset was considered impaired.

Amended Tempus Research and Development Agreement

In October 2021, as subsequently amended in April 2023, the Company entered into an agreement for research and development services (the Amended Tempus Agreement) with Tempus AI, Inc. (formerly known as Tempus Labs, Inc., and referred to herein as Tempus), pursuant to which Tempus agreed to provide the Company with research and development services for a period of four years. The three primary services are analytical services, data licensing, and organoid services. The Company intends to utilize the services contemplated under the Amended Tempus Agreement to advance the development of KB-0742.

In consideration for the access to the services throughout the term of the Tempus Agreement, the Company has agreed to pay an annual minimum commitment of $1.5 million in year one, $2.5 million in year two, $3.0 million in year three and $2.5 million in year four. Payments are made in quarterly installments. The Company has paid $3.6 million and $1.1 million for the years ended December 31, 2023 and December 31, 2022, respectively, under the Tempus Agreement. The Company did not make any payments for the year ended December 31, 2021 under the Tempus Agreement. The annual minimum commitment is nonrefundable and is invoiced quarterly in advance due within 30 days. Nonrefundable advance payments for services that will be rendered for future research and development activities are recorded and recognized as an expense as the related services are performed. Tempus provides detailed reporting monthly which serves as the unit of account for calculating expense for actual services utilized for the analytical services, data licensing, and organoid services. As of December 31, 2023 and December 31, 2022, the prepaid expenses relating to the Tempus advance payments were $0.7 million and $0.8 million, respectively.

The Company is required to make milestone payments upon successful achievement of certain regulatory milestones for KB-0742 and other discovery pipeline compounds up to a combined maximum of $22.4 million. For each milestone payment that becomes due, the Company has the right to pay up to 50% of such milestone payment amount in shares of its common stock as long as certain regulatory requirements are met. As of December 31, 2023 and December 31, 2022, the Company determined that achievement of the milestones is not probable and therefore no corresponding liability was recorded in either period.

Gilead Asset Purchase Agreement

In July 2020, the Company entered into an asset purchase agreement (Gilead Asset Purchase Agreement) with Gilead Sciences, Inc. (Gilead), pursuant to which the Company acquired certain assets from Gilead related to entospletinib and lanraplenib, and patents and other intellectual property covering or related to the development, manufacture and commercialization of entospletinib and lanraplenib. Under the agreement, the Company is required to make milestone payments upon successful achievement of certain regulatory and sales milestones for lanraplenib, entospletinib and other SYK inhibitor compounds covered by the patent rights acquired pursuant to

the Gilead Asset Purchase Agreement and developed by us as a back-up to entospletinib or lanraplenib. The Company is also committed to pay royalties ranging from high-single digits to the mid-teens on annual worldwide net sales of any SYK inhibitor compounds. The Company is currently unable to estimate the timing or likelihood of achieving remaining milestones or generating future product sales.

Purchase Commitments

In the normal course of business, the Company enters into contracts with contract research organizations (CROs) for preclinical and clinical studies and other vendors for services and products. These agreements generally provide for termination or cancellation, other than for costs already incurred and certain wind down costs that may be associated with the termination of a contract or clinical trial program.

Contingencies

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown, because it involves claims that may be made against the Company in the future, but have not yet been made. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated.

Indemnification

In accordance with the Company’s amended and restated certificate of incorporation and amended and restated bylaws, the Company has indemnification obligations to its officers and directors for certain events or occurrences, subject to certain limits, while they are serving in such capacity. There have been no claims to date, and the Company has a directors and officers liability insurance policy that may enable it to recover a portion of any amounts paid for future claims.