0001741830-23-000011 | 10-K | XBRL Viewer

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Investments - Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Due in 1 year or less	$ 174,786	$ 143,014
Due in 1 to 2 years	9,762	0
Total	$ 184,548	$ 143,014

Fair Value Measurements

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTSThe 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, 2022 and 2021 were as follows:


	December 31, 2022
	Level 1		Level 2		Level 3		Fair Value
			(in thousands)
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 securities	—		13,000		—		13,000
U.S. treasury securities	138,734		—		—		138,734
Total financial assets	$	188,227	$	45,324	$	—	$	233,551


	December 31, 2021
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Financial Assets:
Money market funds	$	188,923	$	—	$	—	$	188,923
Corporate bonds	—		63,620		—		63,620
U.S. treasury securities	79,394		—		—		79,394
Total financial assets	$	268,317	$	63,620	$	—	$	331,937

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, 2022 and 2021 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

Commitment and Contingencies - R&D Services Agreement (Details) - Tempus Labs, Inc. - Research And Development Services $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2021 USD ($) service	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Long-term Purchase Commitment [Line Items]
Services contract term	3 years
Number of primary services \| service	3
Annual minimum commitment payment in year one	$ 1.5
Annual minimum commitment payment in year two	2.0
Annual minimum commitment payment in year three	2.5
Payments for purchase obligation		$ 1.1	$ 0.0
Sales milestone payment	$ 22.4
Sales milestone payment in shares of common stock, percent threshold	50.00%

Subsequent Events (Details) - Subsequent Event $ in Millions	Jan. 06, 2023 USD ($) program
Subsequent Event [Line Items]
Number of discovery research programs \| program	2
Genentech, Inc.
Subsequent Event [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.
Subsequent Event [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
Subsequent Event [Line Items]
Expected timing of satisfaction, period	24 months
Genentech, Inc. \| License
Subsequent Event [Line Items]
Upfront payment	$ 20
Maximum aggregate milestone payments	177
Maximum aggregate milestone payments from net sales	$ 100

Cover Page - USD ($) $ in Millions	12 Months Ended
Cover Page - USD ($) $ in Millions	Dec. 31, 2022	Mar. 10, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
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
Entity Shell Company	false
Entity Public Float			$ 204.6
Entity Common Stock, Shares Outstanding		57,630,109
Entity Central Index Key	0001741830
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
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 2023 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 May 1, 2023.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT, NET

Property and equipment, net consisted of the following as of December 31, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Property and equipment:
Lab equipment	$	8,475	$	8,164
Leasehold improvements	9,348		9,335
Furniture and fixtures	619		596
Computer equipment	58		44
Total property and equipment	18,500		18,139
Less: Accumulated depreciation and amortization	(5,515)		(3,259)
Total property and equipment, net	$	12,985	$	14,880

Depreciation and amortization expense was $2.3 million and $2.0 million for the years ended December 31, 2022 and 2021, respectively.

Stock-Based Compensation - Option-pricing Model Assumptions (Details) - Stock options - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock per share (dollars per share)	$ 6.48	$ 25.99
Expected term (in years)	5 years 10 months 28 days	6 years 3 days
Expected volatility	78.21%	85.26%
Risk-free interest rate	2.28%	0.90%
Expected dividend	0.00%	0.00%

Stockholders' Equity (Deficit)	12 Months Ended
Stockholders' Equity (Deficit)	Dec. 31, 2022
Equity [Abstract]
STOCKHOLDERS' EQUITY (DEFICIT)	STOCKHOLDERS’ EQUITY (DEFICIT) 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, of which no shares were issued or outstanding as of December 31, 2022 and 2021. 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. As of December 31, 2022 and 2021, there were 56,967,436 and 55,703,327 shares issued and outstanding, respectively. 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, 2022, no dividends have been declared to date.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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+ Details

Significant Accounting Policies, Estimates and Judgments - Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2022
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

Nature of Operations and Basis of Presentation	12 Months Ended
Nature of Operations and Basis of Presentation	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF OPERATIONS AND BASIS OF PRESENTATION	NATURE OF OPERATIONS AND BASIS OF PRESENTATION 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). Initial Public Offering In October 2020, the Company completed an initial public offering (IPO) of its common stock. In connection with its IPO, the Company issued and sold 15,131,579 shares of its common stock, which included 1,973,684 shares of its common stock issued and sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a price to the public of $19.00 per share. As a result of the IPO, the Company received $263.7 million in net proceeds, after deducting underwriting discounts and commissions of $20.1 million and offering expenses of $3.7 million payable by the Company. At the closing of the IPO, all then outstanding shares of convertible preferred stock were automatically converted into 22,687,625 shares of common stock. Following the IPO, there were no shares of convertible preferred stock outstanding. Need for Additional Capital The Company has incurred net losses since its inception and expects to continue to generate net losses for the foreseeable future. The Company’s ultimate success depends on the outcome of its research and development activities. The Company had cash, cash equivalents and investments of $247.9 million as of December 31, 2022. Since inception through December 31, 2022, the Company has incurred a cumulative net operating loss of $396.2 million. 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 Company expects that its cash and cash equivalents and investments will be sufficient to fund its operations for a period of at least one year from the date the accompanying financial statements are filed with the Securities and Exchange Commission (SEC). 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.

Leases

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

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 and payments. The initial rent payment was paid as of September 30, 2020, with rent payments escalating 3.0% annually after the initial 12 payments. As discussed in Note 2, 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. As of December 31, 2022, $3.7 million in improvement costs incurred by the Company were reimbursed by the lessor are now included within the total lease liability. In connection with the lease, the Company recognized an operating lease right-of-use asset of $21.9 million and an aggregate lease liability of $28.0 million on the December 31, 2022 balance sheet. The remaining lease term is 8.2 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 to move from its current suites, totaling 8,075 square-feet, to a larger suite totaling 17,340 square-feet, and a lease commencement date in the second quarter of 2021. The Company accounted for this change in lease term of the original suites as a modification of the originally amended lease. As a result of the modification, the operating right-of-use asset and lease liability were remeasured as of the modification date.

The new 17,340 square foot suite will be treated as a separate lease for accounting purposes. The initial annual base rent for the new space will be $1.2 million, and such amount will increase by 3% annually on each anniversary of the new premises commencement date. In connection with the larger space leased, the Company has also made an additional one-time cash security deposit in the amount of $59,000. The new lease commenced in April 2021 and the new lease agreement extends the termination date from April 30, 2025 to June 1, 2026. In connection with the lease, the Company recognized an operating lease right-of-use asset of $2.8 million and $3.3 million an aggregate lease liability of $3.7 million and $4.1 million as of December 31, 2022 and December 31, 2021. The remaining lease term is 3.5 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, 2022 and 2021:


Balance Sheet Caption	December 31,
	2022		2021
	(in thousands)
Assets:
Operating lease assets	$	24,707	$	26,904
Liabilities:
Current portion of operating lease liabilities	$	2,347	$	2,109
Noncurrent operating lease liabilities	28,744		31,653
Total operating lease liabilities	$	31,091	$	33,762

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, 2022 and 2021:


Statement of Operations and Comprehensive Loss Caption	Year Ended December 31,
	2022		2021
	(in thousands)
Research and development	$	3,068	$	3,308
General and administrative	2,043		2,015
Total operating lease cost	$	5,111	$	5,323

The Company made cash payments of $5.7 million and $4.4 million under the lease agreements during the years ended December 31, 2022 and 2021, respectively.

The undiscounted future non-cancellable lease payments under the Company's operating leases as of December 31, 2022 for the next five years and thereafter is expected to be as follows:


Period Ending December 31,	Amount
	(in thousands)
2023	$	5,130
2024	5,749
2025	5,921
2026	5,405
2027 and thereafter	21,298
Total undiscounted lease payments	43,503
Less: Present value adjustment	(12,412)

Present value of operating lease liabilities	$	31,091

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 75,973	$ 198,270
Short-term investments	162,212	141,239
Prepaid expenses and other current assets	6,106	8,045
Total current assets	244,291	347,554
Long-term investments	9,762	0
Property and equipment, net	12,985	14,880
Operating lease right-of-use assets	24,707	26,904
Restricted cash	2,026	2,026
Other noncurrent assets	1,167	112
Total assets	294,938	391,476
Current liabilities:
Accounts payable	5,047	998
Accrued expenses	12,963	9,063
Current portion of operating lease liabilities	2,347	2,109
Current portion of other liabilities	1,129	1,456
Total current liabilities	21,486	13,626
Noncurrent operating lease liabilities	28,744	31,653
Other noncurrent liabilities	209	1,100
Total liabilities	50,439	46,379
Commitments and contingencies
Stockholder's equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 authorized; no shares issued and outstanding
Common stock, $0.001 par value, 200,000,000 shares authorized as of December 31, 2022 and 2021; 56,967,436 and 55,703,327 shares issued and outstanding as of December 31, 2022 and 2021, respectively.	57	56
Additional paid-in capital	641,422	608,064
Accumulated deficit	(396,188)	(262,984)
Accumulated other comprehensive income (loss)	(792)	(39)
Total stockholders' equity (deficit)	244,499	345,097
Total liabilities and stockholders’ equity (deficit)	$ 294,938	$ 391,476

Stock-Based Compensation - ESPP (Details) $ in Thousands			1 Months Ended	12 Months Ended
Stock-Based Compensation - ESPP (Details) $ in Thousands	Jan. 01, 2022 shares	Jan. 01, 2021 shares	Oct. 31, 2020 period shares	Dec. 31, 2022 USD ($) hour shares	Dec. 31, 2021 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 31,145	$ 26,211
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				16,171	13,250
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 14,974	$ 12,961
The ESPP \| Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares that may be issued (in shares) \| shares			688,000
Number of shares that may be issued, increase percentage			1.00%
Number of shares that may be issued, increase (in shares) \| shares	565,798	560,335	1,376,000
Employment eligibility, number of hours employed per week \| hour				20
Employee stock purchase plan (in shares) \| shares				260,765	95,723
Exercise price per share of stock options as percent of fair market value of common stock			85.00%
Number of shares reserved for future issuance (in shares) \| shares				1,553,368
Expected dividend				0.00%
Fixed contribution rate			15.00%
Stock-based compensation expense				$ 1,400	$ 1,100
The ESPP \| Employee stock purchase plan \| General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				300	300
The ESPP \| Employee stock purchase plan \| Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 1,100	$ 800
The ESPP \| Employee stock purchase plan \| Initial Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period				27 months
The ESPP \| 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
Minimum \| The ESPP \| Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)				5 months 26 days	6 months
Expected volatility				56.55%	71.67%
Risk-free interest rate				0.22%	0.05%
Expected dividend					0.00%
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				87.15%	94.85%
Risk-free interest rate				2.84%	0.25%

Significant Accounting Policies, Estimates and Judgments - Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Restricted cash	$ 2,026	$ 2,026

Prepaid Expenses And Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2022

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Schedule of Prepaid Expenses and Other Assets

Prepaid expenses and other current assets consisted of the following as of December 31, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Accrued interest on short-term available-for-sale securities	$	572	$	816
Prepaid equipment service contracts	289		360
Prepaid external research and development and outside services	2,276		3,074
Prepaid software	905		624
Prepaid insurance	1,630		2,644
Other prepaid expenses	434		527
Total prepaid expenses and other current assets	$	6,106	$	8,045

Leases - Schedule of Maturities on Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
2023	$ 5,130
2024	5,749
2025	5,921
2026	5,405
2027 and thereafter	21,298
Total undiscounted lease payments	43,503
Less: Present value adjustment	(12,412)
Present value of operating lease liabilities	$ 31,091	$ 33,762

Net Loss Per Share - Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	9,752,410	7,378,118
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)	7,150,339	5,802,435
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)	304,326	787,965
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)	54,297	88,589
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)	2,243,448	699,129

Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net loss	$ (133,204)	$ (151,078)
Weighted-average shares of common stock, basic (in shares)	56,201,398	54,753,599
Weighted-average shares of common stock, diluted (in shares)	56,201,398	54,753,599
Net loss per share, basic (in dollars per share)	$ (2.37)	$ (2.76)
Net loss per share, diluted (in dollars per share)	$ (2.37)	$ (2.76)

- 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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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Statement of Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Common stock, beginning balance (in shares) at Dec. 31, 2020		54,073,901
Beginning balance at Dec. 31, 2020	$ 465,519	$ 54	$ 577,390	$ (19)	$ (111,906)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting and exercise of options and vesting of restricted stock (in shares)		1,533,703
Issuance of common stock upon vesting and exercise of options and vesting of restricted stock	3,127	$ 2	3,125
Stock-based compensation expense	26,211		26,211
Employee stock purchase plan (in shares)		95,723
Employee stock purchase plan	1,338		1,338
Net unrealized gain (loss) on available-for-sale securities	(20)			(20)
Net loss	(151,078)				(151,078)
Common stock, ending balance (in shares) at Dec. 31, 2021		55,703,327
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)		1,003,344
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)		260,765
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		56,967,436
Beginning balance at Dec. 31, 2022	$ 244,499	$ 57	$ 641,422	$ (792)	$ (396,188)

Income Taxes - Components of Net Deferred Tax Asset and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Lease liabilities	$ 7,948	$ 8,750
Stock-based compensation	4,755	2,777
Accrued compensation	1,093	1,320
Net operating loss carryforwards	58,628	52,052
Tax credit carryforwards	15,963	1,296
Capitalized Research and Development Cost	18,857	0
Other	17	0
Total deferred tax assets	107,261	66,195
Valuation allowance	(100,656)	(58,713)	$ (20,797)
Net deferred tax assets	6,605	7,482
Deferred tax liabilities:
Right-of-use assets	(6,316)	(6,973)
Fixed assets and intangibles	(289)	(509)
Total deferred tax liabilities	(6,605)	(7,482)
Net deferred tax assets	$ 0	$ 0

Stockholders' Equity (Deficit) (Details)	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 $ / shares shares	Oct. 14, 2020 vote $ / shares shares
Equity [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, shares authorized (in shares)	200,000,000		200,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.001	$ 0.001	$ 0.001
Common stock, shares issued (in shares)	56,967,436	55,703,327
Common stock, shares outstanding (in shares)	56,967,436	55,703,327
Common stock, voting rights, number of votes per common share \| vote			1

Commitment and Contingencies	12 Months Ended
Commitment and Contingencies	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES R&D Services Agreement In October 2021, the Company entered into an agreement for research and development services (Tempus Agreement) with Tempus Labs, Inc. (Tempus), pursuant to which Tempus agreed to provide the Company with research and development services for a period of three years. The three primary services are analytical services, data licensing, and organoid services. The Company intends to utilize the services contemplated under the Tempus Agreement to advance the development of KB-0742 and lanraplenib. 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, $2.0 million in year two, and $2.5 million in year three. Payments are made in quarterly installments. As of December 31, 2022, the Company has paid $1.1 million under the Tempus Agreement. As of December 31, 2021, the Company had not made any payments under the Tempus Agreement. In addition, the Company is required to make milestone payments upon successful achievement of certain regulatory milestones for KB-0742, lanraplenib, 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. Asset Purchase Agreement In July 2020, the Company entered into the Gilead Asset Purchase Agreement with Gilead Sciences, Inc. (Gilead), pursuant to which the Company acquired certain assets from and assumed certain liabilities of Gilead related to lanraplenib or entospletinib, and patents and other intellectual property covering or related to the development, manufacture and commercialization of lanraplenib or entospletinib. In consideration for such assets, on the date of the Gilead Asset Purchase Agreement, the Company made a $3.0 million upfront cash payment and issued a $3.0 million principal amount convertible promissory note, which was settled in exchange for 188,567 shares of common stock in connection with the closing of the Company's IPO at a settlement price of $16.15 per share. The Company also made a $0.7 million payment to reimburse Gilead for certain liabilities assumed by the Company pursuant to the Gilead Asset Purchase Agreement. In addition, 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 the Company as a back-up to entospletinib or lanraplenib (Other Compounds). Upon initiation of the Company’s registrational Phase 3 clinical trial of entospletinib in combination with induction chemotherapy in acute myeloid leukemia patients with NPM1 mutations in December 2021, the Company paid a milestone payment to Gilead of $29.0 million. Upon successful completion of certain other regulatory milestones in the United States, European Union and United Kingdom for lanraplenib, entospletinib and any Other Compounds, across up to two distinct indications, the Company will be required to pay to Gilead an aggregate total of $51.3 million. Upon achieving certain thresholds for the aggregate annual net sales of lanraplenib, entospletinib and any Other Compounds combined, the Company would owe to Gilead potential milestone payments totaling $115.0 million. Gilead is also eligible to receive (i) tiered marginal royalties ranging from high-single digits to the mid-teens on annual worldwide net sales of lanraplenib, (ii) tiered marginal royalties ranging from the very low-teens to high-teens on annual worldwide net sales of entospletinib, and (iii) tiered marginal royalties ranging from low single digits to mid-single digits on annual worldwide net sales of any Other Compounds. The royalties in the foregoing clauses are subject to reduction, on a country-by-country basis, for products not covered by certain claims within the assigned patents, for generic entry and, in the case of lanraplenib and entospletinib, for any royalties paid for future licenses of third party intellectual property required to develop or commercialize lanraplenib or entospletinib. The Company’s royalty obligation with respect to a given product in a given country begins upon the first commercial sale of such product in such country and ends on the latest of (i) expiration of the last claim of a defined set of the assigned patent rights covering such product in such country; (ii) loss of exclusive data or marketing rights to such product in such country; or (iii) 10 years from the first commercial sale of such product in such country. Under the Gilead Asset Purchase Agreement, the Company is required to use commercially reasonable efforts to develop, obtain regulatory approval for and commercialize either lanraplenib or entospletinib. Purchase Commitments In the normal course of business, the Company enters into contracts with CROs for preclinical and clinical studies and other vendors for other 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.

Fair Value Measurements (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 233,551	$ 331,937
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	49,003	188,923
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	490
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,667
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	30,657	63,620
U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	13,000
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	138,734	79,394
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	188,227	268,317
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	49,003	188,923
Level 1 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	490
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0
Level 1 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0
Level 1 \| U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0
Level 1 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	138,734	79,394
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	45,324	63,620
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]
Investments, fair value	0
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,667
Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	30,657	63,620
Level 2 \| U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	13,000
Level 2 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0
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]
Investments, fair value	0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value
Level 3 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0
Level 3 \| U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0
Level 3 \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	$ 0	$ 0

Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	$ (27,973,000)	$ (31,726,000)
State taxes	(5,017,000)	(7,138,000)
Research tax credits	(15,012,000)	(597,000)
Change in valuation allowance	42,664,000	38,846,000
Stock based compensation	5,181,000	1,212,000
Other	157,000	(597,000)
Expense/(Benefit) for income taxes	$ 0	$ 0	$ 0

- Definition

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

+ References + Details

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (133,204)	$ (151,078)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	2,266	1,977
Net amortization/accretion on available-for-sale securities	(533)	3,997
Change in accrued interest on available-for-sale securities	1,025	485
Stock-based compensation expense	31,145	26,211
Noncash lease expense	2,197	2,104
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,605	(975)
Other long-term assets	(1,055)	54
Accounts payable	4,025	(3,195)
Accrued expenses	4,130	4,786
Right-of-use operating assets and liabilities, net	(2,671)	19
Other liabilities	144	(2,309)
Net cash provided by (used in) operating activities	(90,926)	(117,924)
Cash flows from investing activities:
Purchase of property and equipment	(577)	(4,260)
Purchase of marketable securities	(367,124)	(177,734)
Maturities of marketable securities	334,979	226,245
Sale of marketable securities	500	19,473
Net cash provided by (used in) investing activities	(32,222)	63,724
Cash flows from financing activities:
Principal payments on finance lease	0	(5)
Proceeds from issuance of common stock upon exercise of stock options	471	3,127
Proceeds from issuance of common stock under the employee stock purchase plan	380	1,338
Net cash provided by (used in) financing activities	851	4,460
Net increase (decrease) in cash and cash equivalents	(122,297)	(49,740)
Cash, cash equivalents and restricted cash at beginning of period	200,296	250,036
Cash, cash equivalents and restricted cash at end of period	77,999	200,296
Supplemental disclosures of non-cash activities:
Property and equipment additions included in accounts payable and accrued expenses	20	226
Reduction of right-of-use asset due to modification	0	(1,741)
Right-of-use asset obtained in exchange for operating lease liability	0	3,764
Cash and cash equivalents at end of period	75,973	198,270
Restricted cash at end of period	2,026	2,026
Cash, cash equivalents and restricted cash at end of period	$ 77,999	$ 200,296

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021	Oct. 14, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	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	$ 0.001
Common stock, shares authorized (in shares)	200,000,000		200,000,000
Common stock, shares issued (in shares)	56,967,436	55,703,327
Common stock, shares outstanding (in shares)	56,967,436	55,703,327

Significant Accounting Policies, Estimates and Judgments

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES, ESTIMATES AND JUDGMENTS

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, the accrual of research and development expenses, the fair value of investments, 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.

Research and Development Expenses

Research and development (R&D) expenses consist primarily of personnel costs, including salaries, benefits and stock-based compensation, discovery and development research performed by contract research organizations (CROs), investigator grants, materials and supplies, licenses and fees and overhead allocations consisting of various support and facility-related costs. The Company expenses R&D costs as the services are performed or the goods are received.

CRO costs are a significant component of R&D expenses. The Company monitors levels of performance under each significant contract through communications with its CROs. The Company accrues costs for discovery research and development performed by CROs over the service periods specified in the contracts and adjusts its estimates, if required, based upon its ongoing review of the level of effort and costs actually incurred by the CROs. All of the Company’s material CRO contracts are terminable by the Company upon written notice and it is generally only liable for actual services completed by the CRO and certain non-cancellable expenses incurred at any point of termination.

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, 2022 and 2021 to secure a letter of credit in connection with the lease of the Cambridge facility (see Note 13). 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. The accounts are monitored by management and management believes that the financial institutions are financially sound, and, accordingly, minimal credit risk exists with respect to these financial institutions. As of December 31, 2022 and 2021, 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 and other income, net. Interest income on investments is included in interest and other income, 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, 2022 and 2021, 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, 2022 and 2021.

Property and Equipment, Net

Property and equipment is stated at cost less accumulated depreciation and amortization. Depreciation and amortization are 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 and amortization 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

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.

Impairment of Long-Lived Assets

Long-lived assets, including property and equipment, are reviewed for impairment whenever facts or circumstances either internally or externally may suggest that the carrying value of an asset or asset group may not be recoverable. Should there be an indication of impairment, the Company tests for recoverability by comparing the estimated undiscounted future cash flows expected to result from the use of the asset or asset group and its eventual disposition to the carrying amount of the asset or asset group. Any excess of the carrying value of the asset or asset group over its estimated fair value is recognized as an impairment loss.

Stock-Based Compensation

The Company has an equity incentive plan under which various types of equity-based awards are granted, including stock options, restricted stock awards (RSAs), and restricted stock units (RSUs). 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 calculates the fair value measurement of stock options using the Black-Scholes option-pricing model. Forfeitures are accounted for as

they occur. The fair value of the RSA and RSUs is equal to the fair value of the Company’s common stock on the grant date of the award.

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 (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2022 and 2021, 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 May 2021, the FASB issued ASU No. 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options (a consensus of the FASB Emerging Issues Task Force), which clarifies and reduces diversity in accounting for modifications or exchanges of freestanding equity-classified written call options (for example, warrants) that remain equity classified after modification or exchange. This guidance was effective for the Company in the first quarter of 2022. The effect on the Company’s financial statements and related disclosures was not material.

The Company continues to monitor new accounting pronouncements issued by the FASB and does not believe any accounting pronouncements issued through the date of this report will have a material impact on the Company's consolidated financial statements.

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2022
Audit Information [Abstract]
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California
Auditor Firm ID	42

Significant Accounting Policies, Estimates and Judgments (Policies)

12 Months Ended

Dec. 31, 2022

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

Research and Development Expenses

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.

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

Deferred Offering Costs

Leases

Impairment of Long-Lived Assets

Stock-Based Compensation

they occur. The fair value of the RSA and RSUs is equal to the fair value of the Company’s common stock on the grant date of the award.

Income Taxes

Comprehensive Loss

Net Loss Per Share

Recently Adopted Accounting Pronouncements Not Yet Adopted

Recent Accounting Pronouncements

Leases - Supplemental Balance Sheet Information - Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets:
Operating lease assets	$ 24,707	$ 26,904
Liabilities:
Current portion of operating lease liabilities	2,347	2,109
Noncurrent operating lease liabilities	28,744	31,653
Total operating lease liabilities	$ 31,091	$ 33,762

Significant Accounting Policies, Estimates and Judgments (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

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, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Property and equipment:
Lab equipment	$	8,475	$	8,164
Leasehold improvements	9,348		9,335
Furniture and fixtures	619		596
Computer equipment	58		44
Total property and equipment	18,500		18,139
Less: Accumulated depreciation and amortization	(5,515)		(3,259)
Total property and equipment, net	$	12,985	$	14,880

Leases - Summary of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 5,111	$ 5,323
Research and development
Lessee, Lease, Description [Line Items]
Operating lease cost	3,068	3,308
General and administrative expenses
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 2,043	$ 2,015

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

INCOME TAXES

The Company recorded a small amount of income tax expense related to state minimum taxes for the year ended December 31, 2022 and did not record any income tax expense for the years ended December 31, 2021. 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.

Reconciliation of the income tax expense calculated at the statutory rate to our zero expense for income taxes for the years ended December 31, 2022 and 2021 were as follows:


	Year Ended December 31,
	2022		2021
	(in thousands)
Tax benefit at federal statutory rate	$	(27,973)	$	(31,726)
State taxes	(5,017)		(7,138)
Research tax credits	(15,012)		(597)
Change in valuation allowance	42,664		38,846
Stock based compensation	5,181		1,212
Other	157		(597)
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, 2022 and 2021. Significant components of the Company’s deferred tax assets and liabilities are as follows:


	Year Ended December 31,
	2022		2021
	(in thousands)
Deferred tax assets:
Lease liabilities	$	7,948	$	8,750
Stock-based compensation	4,755		2,777
Accrued compensation	1,093		1,320
Net operating loss carryforwards	58,628		52,052
Tax credit carryforwards	15,963		1,296
Capitalized Research and Development Cost	18,857		—
Other	17		—
Total deferred tax assets	107,261		66,195
Valuation allowance	(100,656)		(58,713)
Net deferred tax assets	6,605		7,482
Deferred tax liabilities:
Right-of-use assets	(6,316)		(6,973)
Fixed assets and intangibles	(289)		(509)
Total deferred tax liabilities	(6,605)		(7,482)
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 $100.7 million and $58.7 million for the years ended December 31, 2022 and 2021, respectively. The change in valuation allowance of $41.9 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, 2022:


	Amount		Expiration
	(in thousands)
Net operating losses, federal	$	229,617	Indefinite
Net operating losses, federal	$	601	2037
Net operating losses, state	$	162,694	2037-2042
Tax credits, federal	$	13,775	2037-2042
Tax credits, state	6,358		2037

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.

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:


	Year Ended December 31,
	2022		2021
	(in thousands)
Balance at beginning of the year	$	246	$	141
Additions based on tax positions related to the current year	1,993		105
Additions to tax positions of prior years	796		—
Balance at the end of the year	$	3,035	$	246

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, 2022 and 2021. 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.

Beginning January 1, 2022, the Tax Cuts and Jobs Act enacted in 2017, eliminates the option to deduct research and development expenditures in the current year and requires taxpayers to capitalize and amortize pursuant to IRC Section 174. As a result, we recognized an increase in our deferred tax assets due to the capitalization of $73.8 million. Given such amount was offset by our valuation allowance there were no material impacts to the financial statements outside of the deferred tax table.

During August 2022, the CHIPS and Science Act (“CHIPS Act”) and Inflation Reduction Act (“IRA”) were enacted, neither of which are expected to have a material impact to our financial statements.

The American Rescue Plan Act (“ARA”) was signed into law on March 11, 2021. We do not expect the ARA to have a material impact on our financial statements but given potential changes to IRC Section 162(m) will take place in 2027, we will continue to monitor and assess.

The following table shows the change in the deferred tax valuation as follows:


	Year Ended December 31,
	2022		2021
	(in thousands)
Beginning Balance, January 1	$	58,713	$	20,797
Change charged to expense/(income)	$	41,943	$	37,916
Ending Balance, December 31	$	100,656	$	58,713

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Accrued Expenses And Current Portion Of Other Liabilities - Current Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Current portion of unvested early exercised share liability	$ 891	$ 1,364
ESPP withholdings	238	92
Total current portion of other liabilities	$ 1,129	$ 1,456

Stock-Based Compensation - Restricted Stock Awards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 31,145,000	$ 26,211,000
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	14,974,000	12,961,000
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 16,171,000	13,250,000
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards issued (in shares)	2,061,081
Unrecognized stock based compensation	$ 200,000
Awards weighted average recognition period	1 year 6 months 29 days
Total grant date fair value for awards vested	$ 100,000	200,000
Vested (in shares)	329,345
Restricted stock \| Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0	5,000
Restricted stock \| General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	100,000	100,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	11,000,000	$ 8,500,000
Unrecognized stock based compensation	$ 15,700,000
Awards weighted average recognition period	1 year 3 months 25 days
Vested (in shares)	295,053	188,470
Restricted Stock Units (RSUs) \| Executive Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards issued (in shares)	2,061,081	347,267
Vesting period	3 years
Restricted Stock Units (RSUs) \| Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 5,700,000	$ 4,100,000
Restricted Stock Units (RSUs) \| General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 5,300,000	$ 4,400,000

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0	$ 0
Valuation allowance	(100,656,000)	(58,713,000)	$ (20,797,000)
Valuation allowance increase	41,943,000	37,916,000
Accrued interest or penalties related to uncertain tax positions	0	$ 0
Deferred Expense, Capitalized Research And Development Costs	$ 73,800,000

- Definition

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

+ References + Details

Related Parties	12 Months Ended
Related Parties	Dec. 31, 2022
Related Party Transactions [Abstract]
RELATED PARTIES	RELATED PARTIESOn 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. On December 31, 2021, the Company amended the agreement to limit the scope to accounting and managerial consulting services. Arie Belldegrun, M.D., FACS, the Chair of the Board of Directors, is the Chair of Two River. Mr. Joshua Kazam and Mr. David Tanen, each a director of the Company, are each partners of Two River. Mr. Christopher Wilfong, a strategic advisor to the Company, is an Operating Partner of Two River and Mr. Sean Algeo, serving as a financial consultant to the Company, is the Chief Financial Officer of Two River. During the years ended December 31, 2022 and 2021, the Company incurred expenses of $0.1 million and $0.3 million, respectively, 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. Arie Belldegrun, M.D., FACS, the Chair of the Board of Directors, is the Chairman of Bellco. Rebecka Belldegrun, M.D., who served as a director of the Company through January 25, 2021, is the President and Chief Executive Officer of Bellco. During the years ended December 31, 2022 and 2021, the Company incurred expenses of $25,200 and $129,000, respectively, for these services.

Related Party Disclosures (Details) - Affiliated Entity - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Two River Consulting, LLC
Related Party Transaction [Line Items]
Expenses from transaction with related party	$ 100,000	$ 300,000
Bellco Capital, LLC
Related Party Transaction [Line Items]
Expenses from transaction with related party	$ 25,200	$ 129,000

Investments - Fair Value and Amortized Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Money market funds, amortized cost	$ 61,577	$ 190,698
Fair Value	184,548	143,014
Total cash equivalents and investments, amortized cost	234,344	331,976
Total cash equivalents and investments, unrealized gains	7	2
Total cash equivalents and investments, unrealized losses	(800)	(41)
Total cash equivalents and investments, fair value	233,551	331,937
Money market funds
Schedule of Held-to-maturity Securities [Line Items]
Money market funds, amortized cost	49,003	188,923
Certificates of deposit
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	490
Unrealized Gains	0
Unrealized Losses	0
Fair Value	490
Commercial paper
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,667
Unrealized Gains	0
Unrealized Losses	0
Fair Value	1,667
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	30,683	63,647
Unrealized Gains	3	2
Unrealized Losses	(29)	(29)
Fair Value	30,657	63,620
U.S. agency securities
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	139,477	79,406
Unrealized Gains	4	0
Unrealized Losses	(747)	(12)
Fair Value	$ 138,734	$ 79,394

Stock-Based Compensation - Restricted Stock Awards Activity (Details) - Restricted stock $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares
Number of Restricted Stock
Unvested Beginning Balance (in shares) \| shares	787,719
Granted - restricted stock awards and units (in shares) \| shares	2,061,081
Vested and converted to shares (in shares) \| shares	(329,345)
Forfeited (in shares) \| shares	(221,710)
Unvested Ending Balance (in shares) \| shares	2,297,745
Weighted-Average Grant Date Fair Value
Unvested Beginning Balance (in dollars per share) \| $ / shares	$ 26.88
Granted - restricted stock awards and units (in dollars per share) \| $ / shares	5.50
Vested and converted to shares (in dollars per share) \| $ / shares	27.51
Forfeited (in dollars per share) \| $ / shares	11.50
Unvested Ending Balance (in dollars per share) \| $ / shares	$ 9.18
Restricted Stock, Additional Disclosures
Unvested, Weighted Average Remaining Vesting Life	1 year 6 months 29 days
Unvested, Aggregate Intrinsic Value \| $	$ 3,722
Vested and expected to vest, Outstanding (in shares) \| shares	2,297,745
Vested and expected to vest, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares	$ 9.18
Vested and expected to vest, Weighted Average Remaining Vesting Life	1 year 6 months 29 days
Vested and expected to vest, Aggregate Intrinsic Value \| $	$ 3,722

Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION

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. Under the 2020 Plan, the maximum number of shares of common stock that may be issued increased to 11,938,152 shares. The number of shares of common stock reserved for issuance under the 2020 Plan will automatically increase each year for a period of ten 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 a result of the automatic annual increases, the maximum number of shares of common stock that may be issued under the 2020 Plan as of December 31, 2022 was 17,568,821 shares.

Under the 2020 Plan, the exercise prices, vesting, and other restrictions are determined at the discretion of the Board of Directors, or a designated committee thereof, except that the exercise price per share of stock options may not be less than 100% of the fair market value of the common stock on the date of grant and the term of stock option may not be greater than 10 years. The Company recognizes the impact of forfeitures on stock-based compensation expense as forfeitures occur. The Company applies the straight-line method of expense recognition to all awards with only service-based vesting conditions. Vesting periods are determined at the discretion of the Board of Directors. Stock options typically vest over four years. The maximum contractual term is 10 years.

As of December 31, 2022 and 2021, there were 4,098,939 and 4,647,580 shares, respectively, reserved by the Company under the 2020 Plan for the future issuance of equity awards.

Stock Option Valuation

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:

•Fair Value of Common Stock—For grants before the completion of the IPO in October 2020 when the Company was a privately held company with no public market for its common stock, the fair value of its common stock underlying share-based awards was estimated on each grant date by its Board of Directors. In order to determine the fair value of our common stock underlying option grants, the Company’s Board of Directors considered, among other things, valuations of its common stock prepared by an unrelated third-party valuation firm in accordance with the guidance provided by the American Institute of Certified Public Accounts Practice Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. For all grants subsequent to our IPO in October 2020, the fair value of common stock was determined by taking the closing price per share of common stock as reported on the Nasdaq Stock Market.

•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 expected volatility for the years ended December 31, 2022 and 2021 is estimated based on the average historical volatilities of common stock of comparable publicly traded entities over a period equal to the expected term of the stock option grants. The comparable companies are chosen based on their size, stage in the product development cycle or area of specialty. 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.

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, 2022 and 2021 were as follows, presented on a weighted-average basis:


	Year Ended December 31,
	2022		2021
Fair value of common stock per share	$	6.48	$	25.99
Expected term (in years)	5.91		6.01
Expected volatility	78.21%		85.26%
Risk-free interest rate	2.28%		0.90%
Expected dividend	—%		—%

The weighted-average grant-date fair value per share of stock options granted, using the assumptions listed above, was $5.57 and $18.52, during the years ended December 31, 2022 and 2021, respectively.

Stock Options

Stock option activity under the 2020 Plan as of December 31, 2022 is summarized as follows:


	Number of Options	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
				(in years)	(in thousands)
Balance at December 31, 2021	6,590,400	$	14.33
Granted	2,730,338	6.48
Forfeited	(1,192,074)	18.54
Exercised	(673,999)	2.72
Balance at December 31, 2022	7,454,665	$	11.83	7.69	$	54
Exercisable at December 31, 2022	3,394,398	$	11.94	7.38	$	53
Unvested and expected to vest at December 31, 2022	4,060,267	$	11.75	7.94	$	1

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, 2022. The intrinsic value of options exercised for the years ended December 31, 2022 and 2021 was $2.0 million and $23.8 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, 2022 and December 31, 2021.

For the years ended December 31, 2022 and 2021 total stock-based compensation related to stock options was classified in the Company’s statements of operations and comprehensive loss as follows:


	Year Ended December 31,
	2022		2021
	(in thousands)
Research and development expenses	$	8,464	$	7,753
General and administrative expenses	10,414		8,406
Total stock-based compensation expense	$	18,878	$	16,159

As of December 31, 2022 and 2021, there was $35.4 million and $49.9 million of unrecognized stock-based compensation related to stock options, respectively, which is expected to be recognized over a weighted average period of 2.25 and 2.93 years, 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, 2022 and 2021, the number of shares authorized under the ESPP for employee purchases increased by 565,798 and 560,335 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. The Company issued and sold 260,765 and 95,723 shares of common stock under the ESPP during the years ended December 31, 2022 and 2021. The Company has 1,553,368 shares reserved for future issuance under the ESPP as of December 31, 2022.

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,
	2022	2021
Expected term (in years)	0.49 - 2.00	0.50 - 2.00
Expected volatility	56.55% - 87.15%	71.67% - 94.85%
Risk-free interest rate	0.22% - 2.84%	0.05% - 0.25%
Dividend yield	—%	—%

For the years ended December 31, 2022 and 2021, total stock-based compensation related to the ESPP was $1.1 million and $1.4 million, respectively, with $0.3 million and $0.3 million, respectively, recorded in general and administrative expenses and $0.8 million and $1.1 million, respectively, recorded in research and development expenses in the statements of operations and comprehensive loss.

Restricted Stock

Restricted stock awards and units as of December 31, 2022 are summarized as follows:


	Number of Restricted Stock	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Vesting Life	Aggregate Intrinsic Value
				(in years)	(in thousands)
Unvested at December 31, 2021	787,719	$	26.88
Granted - restricted stock units	2,061,081	5.50
Vested and converted to shares	(329,345)	27.51
Forfeited	(221,710)	11.50
Unvested at December 31, 2022	2,297,745	$	9.18	1.58	$	3,722
Vested and expected to vest at December 31, 2022	2,297,745	$	9.18	1.58	$	3,722

The Company recorded stock-based compensation expense for the RSAs of $0.1 million and $0.1 million in general and administrative expenses and zero and $5,000 in research and development expenses in the statements of operations and comprehensive loss for the years ended December 31, 2022 and 2021, respectively. As of December 31, 2022, there was $0.2 million of unrecognized stock-based compensation related to RSAs, which is expected to be recognized over a weighted average period of 1.58 years.

The total grant date fair value for RSAs vested during the years ended December 31, 2022 and 2021 was $0.1 million and $0.2 million, respectively.

For the years ended December 31, 2022 and 2021, the Company issued 2,061,081 and 347,267, restricted stock units (RSUs), respectively, to executive officers and non-executive employees pursuant to the 2020 Plan. These RSUs have a three year vest period and in order to vest, the holder is required to provide service to the Company.

The Company recognized $11.0 million of stock-based compensation expense related to the RSUs for the year ended December 31, 2022, of which $5.7 million and $5.3 million are recorded in research and development and general and administrative expenses, respectively, in the current year statement of operations and comprehensive loss. The Company recognized $8.5 million of stock-based compensation expense related to the RSUs for the year ended December 31, 2021, of which $4.1 million and $4.4 million are recorded in research and development and general and administrative expenses, respectively, in the current year statement of operations and comprehensive loss.

As of December 31, 2022, there was $15.7 million of unrecognized stock-based compensation related to RSUs, which is expected to be recognized over a weighted average period of 1.32 years. As of December 31, 2022 and 2021, 295,053 and 188,470 RSUs have vested, respectively.

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, 2022 and 2021 as follows for stock options, RSAs, RSUs, and ESPP:


	Year Ended December 31,
	2022		2021
	(in thousands)
Research and development expenses	$	14,974	$	12,961
General and administrative expenses	16,171		13,250
Total stock-based compensation expense	$	31,145	$	26,211

Early Exercised Options

The terms of certain stock options granted under the Prior Plan allow the holder to exercise options 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 are not reflected as issued and outstanding in the accompanying statements of convertible preferred stock and stockholders' equity (deficit) 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, 2022 and 2021, there have been no early exercised options. At December 31, 2022 and 2021, there was $0.9 million and $1.4 million recorded in current portion of other liabilities, and $0.2 million and $1.1 million recorded in other noncurrent liabilities, respectively, related to shares held by employees and nonemployees that were subject to repurchase.

Accrued Expenses and Current Portion of Other Liabilities

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

ACCRUED EXPENSES AND CURRENT PORTION OF OTHER LIABILITIES

Accrued expenses consisted of the following as of December 31, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Accrued compensation	$	4,277	$	4,570
External research and development	7,694		2,655
Accrued outside services	945		1,598
Accrued taxes	40		—
Other accrued expenses	7		240
Total accrued expenses	$	12,963	$	9,063

Current portion of other liabilities consist of the following as of December 31, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Current portion of unvested early exercised share liability	891		1,364
ESPP withholdings	238		92
Total current portion of other liabilities	$	1,129	$	1,456

Investments (Tables)

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

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, 2022 and 2021 were as follows:


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
			(in thousands)
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 securities	13,024		—		(24)		13,000
U.S. treasury securities	139,477		4		(747)		138,734
Total cash equivalents and investments	$	234,344	$	7	$	(800)	$	233,551


	December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	188,923	$	—	$	—	$	188,923
Corporate bonds	63,647		2		(29)		63,620
U.S. treasury securities	79,406		—		(12)		79,394
Total cash equivalents and investments	$	331,976	$	2	$	(41)	$	331,937

Marketable securities that had been in unrealized loss positions as of December 31, 2022 and 2021 were in an unrealized loss position for less than twelve months.

These available-for-sale debt securities were classified on the Company’s balance sheets as of December 31, 2022 and 2021 as:


	Fair Value
	December 31,
	2022		2021
	(in thousands)
Cash equivalents	$	61,577	$	190,698
Short-term investments	162,212		141,239
Long-term investments	9,762		—
Total cash equivalents and investments	$	233,551	$	331,937

The fair values of available-for-sale securities by contractual maturity as of December 31, 2022 and 2021 were as follows:


	December 31,
	2022		2021
	(in thousands)
Due in 1 year or less	$	174,786	$	143,014
Due in 1 to 2 years	9,762		—
Total	$	184,548	$	143,014

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

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, 2022 and 2021 were as follows:


	Year Ended December 31,
	2022		2021
	(in thousands)
Tax benefit at federal statutory rate	$	(27,973)	$	(31,726)
State taxes	(5,017)		(7,138)
Research tax credits	(15,012)		(597)
Change in valuation allowance	42,664		38,846
Stock based compensation	5,181		1,212
Other	157		(597)
Expense/(Benefit) for income taxes	$	—	$	—

Schedule of Deferred Taxes

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


	Year Ended December 31,
	2022		2021
	(in thousands)
Deferred tax assets:
Lease liabilities	$	7,948	$	8,750
Stock-based compensation	4,755		2,777
Accrued compensation	1,093		1,320
Net operating loss carryforwards	58,628		52,052
Tax credit carryforwards	15,963		1,296
Capitalized Research and Development Cost	18,857		—
Other	17		—
Total deferred tax assets	107,261		66,195
Valuation allowance	(100,656)		(58,713)
Net deferred tax assets	6,605		7,482
Deferred tax liabilities:
Right-of-use assets	(6,316)		(6,973)
Fixed assets and intangibles	(289)		(509)
Total deferred tax liabilities	(6,605)		(7,482)
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, 2022:


	Amount		Expiration
	(in thousands)
Net operating losses, federal	$	229,617	Indefinite
Net operating losses, federal	$	601	2037
Net operating losses, state	$	162,694	2037-2042
Tax credits, federal	$	13,775	2037-2042
Tax credits, state	6,358		2037

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:


	Year Ended December 31,
	2022		2021
	(in thousands)
Balance at beginning of the year	$	246	$	141
Additions based on tax positions related to the current year	1,993		105
Additions to tax positions of prior years	796		—
Balance at the end of the year	$	3,035	$	246

Summary of Valuation Allowance

The following table shows the change in the deferred tax valuation as follows:


	Year Ended December 31,
	2022		2021
	(in thousands)
Beginning Balance, January 1	$	58,713	$	20,797
Change charged to expense/(income)	$	41,943	$	37,916
Ending Balance, December 31	$	100,656	$	58,713

Nature of Operations and Basis of Presentation (Details) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)
Subsidiary, Sale of Stock [Line Items]
Number of operating segments \| segment		1
Cash, cash equivalents, and short-term investments		$ 247,900
Cumulative net operating losses		$ (396,188)	$ (262,984)
IPO
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares) \| shares	15,131,579
Shares issued, price per share (in dollars per share) \| $ / shares	$ 19.00
Net proceeds from stock offering	$ 263,700
Payments of underwriting discounts and commissions	20,100
Payments of offering costs	$ 3,700
Convertible preferred stock, shares outstanding (in shares) \| shares	0
IPO \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares issued upon conversion of convertible notes (in shares) \| shares	22,687,625
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares) \| shares	1,973,684

Prepaid Expenses And Other Current Assets

12 Months Ended

Dec. 31, 2022

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consisted of the following as of December 31, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Accrued interest on short-term available-for-sale securities	$	572	$	816
Prepaid equipment service contracts	289		360
Prepaid external research and development and outside services	2,276		3,074
Prepaid software	905		624
Prepaid insurance	1,630		2,644
Other prepaid expenses	434		527
Total prepaid expenses and other current assets	$	6,106	$	8,045

Investments - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Cash equivalents	$ 61,577	$ 190,698
Short-term investments	162,212	141,239
Long-term investments	9,762	0
Total cash equivalents and investments	$ 233,551	$ 331,937

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of the year	$ 246	$ 141
Additions based on tax positions related to the current year	1,993	105
Additions to tax positions of prior years	796	0
Balance at the end of the year	$ 3,035	$ 246

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2022
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On January 6, 2023 (the “Effective Date”), the Company entered into a Collaboration and License Agreement (the “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 will primarily consist 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 will lead discovery and research activities under the discovery research programs and will use 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 will be 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.

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2020	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value, options granted (in dollars per share)		$ 5.57	$ 18.52
Stock options exercised, intrinsic value		$ 2.0	$ 23.8
Stock options, unrecognized cost		$ 35.4	$ 49.9
2020 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares that may be issued (in shares)	11,938,152	17,568,821
Expiration period	10 years	10 years
Shares that may be issued, percent increase as total of common stock outstanding	5.00%
Number of shares reserved for future issuance (in shares)		4,098,939	4,647,580
Exercise price per share of stock options as percent of fair market value of common stock	100.00%
2020 Equity Incentive Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
2020 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		10 years
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend		0.00%	0.00%
Stock options recognized, weighted average period		2 years 3 months	2 years 11 months 4 days

Income Taxes - Schedule of Deferred Tax Asset Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Deferred Tax Asset, Valuation Allowance [Roll Forward]
Beginning Balance, January 1	$ 58,713	$ 20,797
Change charged to expense/(income)	41,943	37,916
Ending Balance, December 31	$ 100,656	$ 58,713

Leases - Additional Information (Details) $ in Thousands	1 Months Ended		12 Months Ended
Leases - Additional Information (Details) $ in Thousands	Feb. 28, 2021 USD ($) ft²	Mar. 31, 2020 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jul. 01, 2020 ft²
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets			$ 24,707	$ 26,904
Lease liabilities			31,091	33,762
Lease payments			5,700	4,400
301 Binney Street, Cambridge, Massachusetts
Lessee, Lease, Description [Line Items]
Lease term		11 years
Facility size \| ft²		40,514
Annual base rent		$ 4,100
Escalating rent payments, percent		3.00%
Letter of credit			2,000
Tenant improvement allowances		$ 3,700
Improvement costs incurred, reimbursed by lessor			3,700
Operating lease right-of-use assets			21,900
Lease liabilities			$ 28,000
Remaining lease term			8 years 2 months 12 days
Incremental borrowing rate			8.50%
San Mateo, California. Original Lease
Lessee, Lease, Description [Line Items]
Facility size \| ft²					8,075
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			$ 2,800	3,300
Lease liabilities			$ 3,700	$ 4,100
Remaining lease term			3 years 6 months
Incremental borrowing rate			11.18%
Initial annual base rent	$ 1,200
Security deposit	$ 59

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following table summarizes the computation of basic and diluted net loss per share of the Company for the years ended December 31, 2022 and 2021:


	Year Ended December 31,
	2022		2021
	(in thousands, except share and per share amounts)
Net loss	$	(133,204)	$	(151,078)
Weighted-average common stock outstanding, basic and diluted	56,201,398		54,753,599
Net loss per share, basic and diluted	$	(2.37)	$	(2.76)

Schedule of Antidilutive Securities Excluded from Computation of Earnings 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:


	Year Ended December 31,
	2022	2021
Stock options to purchase common stock	7,150,339	5,802,435
Early exercised stock options subject to future vesting	304,326	787,965
Restricted stock awards subject to future vesting	54,297	88,589
Restricted stock units subject to future vesting	2,243,448	699,129

Total	9,752,410	7,378,118

Investments

12 Months Ended

Dec. 31, 2022

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, 2022 and 2021 were as follows:


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
			(in thousands)
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 securities	13,024		—		(24)		13,000
U.S. treasury securities	139,477		4		(747)		138,734
Total cash equivalents and investments	$	234,344	$	7	$	(800)	$	233,551


	December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(in thousands)
Money market funds	$	188,923	$	—	$	—	$	188,923
Corporate bonds	63,647		2		(29)		63,620
U.S. treasury securities	79,406		—		(12)		79,394
Total cash equivalents and investments	$	331,976	$	2	$	(41)	$	331,937

Marketable securities that had been in unrealized loss positions as of December 31, 2022 and 2021 were in an unrealized loss position for less than twelve months.

These available-for-sale debt securities were classified on the Company’s balance sheets as of December 31, 2022 and 2021 as:


	Fair Value
	December 31,
	2022		2021
	(in thousands)
Cash equivalents	$	61,577	$	190,698
Short-term investments	162,212		141,239
Long-term investments	9,762		—
Total cash equivalents and investments	$	233,551	$	331,937

The fair values of available-for-sale securities by contractual maturity as of December 31, 2022 and 2021 were as follows:


	December 31,
	2022		2021
	(in thousands)
Due in 1 year or less	$	174,786	$	143,014
Due in 1 to 2 years	9,762		—
Total	$	184,548	$	143,014

As of December 31, 2022 and 2021, the remaining contractual maturities of available-for-sale securities were less than two years, respectively. There have been no significant realized losses on available-for-sale securities for any of the periods presented in the accompanying financial statements. As of December 31, 2022 and 2021, unrealized losses on available-for-sale securities are not attributed to credit risk. 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.

Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

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, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Property and equipment:
Lab equipment	$	8,475	$	8,164
Leasehold improvements	9,348		9,335
Furniture and fixtures	619		596
Computer equipment	58		44
Total property and equipment	18,500		18,139
Less: Accumulated depreciation and amortization	(5,515)		(3,259)
Total property and equipment, net	$	12,985	$	14,880

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Option-pricing Model Assumptions


	Year Ended December 31,
	2022		2021
Fair value of common stock per share	$	6.48	$	25.99
Expected term (in years)	5.91		6.01
Expected volatility	78.21%		85.26%
Risk-free interest rate	2.28%		0.90%
Expected dividend	—%		—%

Stock Option Activity

Stock option activity under the 2020 Plan as of December 31, 2022 is summarized as follows:


	Number of Options	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
				(in years)	(in thousands)
Balance at December 31, 2021	6,590,400	$	14.33
Granted	2,730,338	6.48
Forfeited	(1,192,074)	18.54
Exercised	(673,999)	2.72
Balance at December 31, 2022	7,454,665	$	11.83	7.69	$	54
Exercisable at December 31, 2022	3,394,398	$	11.94	7.38	$	53
Unvested and expected to vest at December 31, 2022	4,060,267	$	11.75	7.94	$	1

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,
	2022	2021
Expected term (in years)	0.49 - 2.00	0.50 - 2.00
Expected volatility	56.55% - 87.15%	71.67% - 94.85%
Risk-free interest rate	0.22% - 2.84%	0.05% - 0.25%
Dividend yield	—%	—%

Schedule of Nonvested Share Activity

Restricted stock awards and units as of December 31, 2022 are summarized as follows:


	Number of Restricted Stock	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Vesting Life	Aggregate Intrinsic Value
				(in years)	(in thousands)
Unvested at December 31, 2021	787,719	$	26.88
Granted - restricted stock units	2,061,081	5.50
Vested and converted to shares	(329,345)	27.51
Forfeited	(221,710)	11.50
Unvested at December 31, 2022	2,297,745	$	9.18	1.58	$	3,722
Vested and expected to vest at December 31, 2022	2,297,745	$	9.18	1.58	$	3,722

Stock-based Compensation, Classified in Statements of Operations

For the years ended December 31, 2022 and 2021 total stock-based compensation related to stock options was classified in the Company’s statements of operations and comprehensive loss as follows:


	Year Ended December 31,
	2022		2021
	(in thousands)
Research and development expenses	$	8,464	$	7,753
General and administrative expenses	10,414		8,406
Total stock-based compensation expense	$	18,878	$	16,159


	Year Ended December 31,
	2022		2021
	(in thousands)
Research and development expenses	$	14,974	$	12,961
General and administrative expenses	16,171		13,250
Total stock-based compensation expense	$	31,145	$	26,211

Net Loss Per Share

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

NET LOSS PER SHARE

The following table summarizes the computation of basic and diluted net loss per share of the Company for the years ended December 31, 2022 and 2021:


	Year Ended December 31,
	2022		2021
	(in thousands, except share and per share amounts)
Net loss	$	(133,204)	$	(151,078)
Weighted-average common stock outstanding, basic and diluted	56,201,398		54,753,599
Net loss per share, basic and diluted	$	(2.37)	$	(2.76)

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. Therefore, the weighted-average number of shares of common stock outstanding used to calculate both basic and diluted net loss per share is the same. 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:


	Year Ended December 31,
	2022	2021
Stock options to purchase common stock	7,150,339	5,802,435
Early exercised stock options subject to future vesting	304,326	787,965
Restricted stock awards subject to future vesting	54,297	88,589
Restricted stock units subject to future vesting	2,243,448	699,129

Total	9,752,410	7,378,118

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 (see Note 12). Because the necessary conditions for issuance of the shares had not been met as of December 31, 2022, the Company excluded these shares from the table above and from the calculation of diluted net loss per share for the year ended December 31, 2022.

Accrued Expenses And Current Portion Of Other Liabilities (Tables)

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued expenses consisted of the following as of December 31, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Accrued compensation	$	4,277	$	4,570
External research and development	7,694		2,655
Accrued outside services	945		1,598
Accrued taxes	40		—
Other accrued expenses	7		240
Total accrued expenses	$	12,963	$	9,063

Other Current Liabilities

Current portion of other liabilities consist of the following as of December 31, 2022 and 2021:


	December 31,
	2022		2021
	(in thousands)
Current portion of unvested early exercised share liability	891		1,364
ESPP withholdings	238		92
Total current portion of other liabilities	$	1,129	$	1,456

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Research and development	$ 93,715	$ 112,903
General and administrative	43,400	38,495
Total operating expenses	137,115	151,398
Loss from operations	(137,115)	(151,398)
Other income (expense), net:
Interest and other income, net	3,911	320
Total other income (expense), net	3,911	320
Net loss	(133,204)	(151,078)
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale securities	(753)	(20)
Net comprehensive loss	$ (133,957)	$ (151,098)
Net loss per share, basic (in dollars per share)	$ (2.37)	$ (2.76)
Net loss per share, diluted (in dollars per share)	$ (2.37)	$ (2.76)
Weighted-average shares of common stock, basic (in shares)	56,201,398	54,753,599
Weighted-average shares of common stock, diluted (in shares)	56,201,398	54,753,599

Commitment and Contingencies - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Oct. 31, 2020	Jul. 31, 2020
Schedule Of Asset Acquisition [Line Items]
Royalty obligation, termination, period from first commercial sale		10 years
Common Stock \| IPO
Schedule Of Asset Acquisition [Line Items]
Shares issued upon conversion of convertible notes (in shares)	22,687,625
2020 Gilead Notes \| Common Stock \| IPO
Schedule Of Asset Acquisition [Line Items]
Shares issued upon conversion of convertible notes (in shares)	188,567
Settlement price per share (in dollars per share)	$ 16.15
Asset Purchase Agreement
Schedule Of Asset Acquisition [Line Items]
Sales milestone payment		$ 29.0
Regulatory milestone payment		51.3
Aggregate sales milestone payment		115.0
Gilead Asset Purchase
Schedule Of Asset Acquisition [Line Items]
Upfront cash payment		3.0
Convertible promissory note issued		3.0
Payments for reimbursements		$ 0.7

Stock-Based Compensation - Stock Based Compensation - Stock Options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 31,145	$ 26,211
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	18,878	16,159
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	14,974	12,961
Research and development expenses \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	8,464	7,753
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	16,171	13,250
General and administrative expenses \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 10,414	$ 8,406

Prepaid Expenses And Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Accrued interest on short-term available-for-sale securities	$ 572	$ 816
Prepaid equipment service contracts	289	360
Prepaid external research and development and outside services	2,276	3,074
Prepaid software	905	624
Prepaid insurance	1,630	2,644
Other prepaid expenses	434	527
Prepaid expenses and other current assets	$ 6,106	$ 8,045

Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

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, 2022 and 2021:


Balance Sheet Caption	December 31,
	2022		2021
	(in thousands)
Assets:
Operating lease assets	$	24,707	$	26,904
Liabilities:
Current portion of operating lease liabilities	$	2,347	$	2,109
Noncurrent operating lease liabilities	28,744		31,653
Total operating lease liabilities	$	31,091	$	33,762

Summary 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, 2022 and 2021:


Statement of Operations and Comprehensive Loss Caption	Year Ended December 31,
	2022		2021
	(in thousands)
Research and development	$	3,068	$	3,308
General and administrative	2,043		2,015
Total operating lease cost	$	5,111	$	5,323

Schedule of Maturities on Lease Liabilities

The undiscounted future non-cancellable lease payments under the Company's operating leases as of December 31, 2022 for the next five years and thereafter is expected to be as follows:


Period Ending December 31,	Amount
	(in thousands)
2023	$	5,130
2024	5,749
2025	5,921
2026	5,405
2027 and thereafter	21,298
Total undiscounted lease payments	43,503
Less: Present value adjustment	(12,412)

Present value of operating lease liabilities	$	31,091

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

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


	December 31, 2022
	Level 1		Level 2		Level 3		Fair Value
			(in thousands)
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 securities	—		13,000		—		13,000
U.S. treasury securities	138,734		—		—		138,734
Total financial assets	$	188,227	$	45,324	$	—	$	233,551


	December 31, 2021
	Level 1		Level 2		Level 3		Fair Value
	(in thousands)
Financial Assets:
Money market funds	$	188,923	$	—	$	—	$	188,923
Corporate bonds	—		63,620		—		63,620
U.S. treasury securities	79,394		—		—		79,394
Total financial assets	$	268,317	$	63,620	$	—	$	331,937

Stock-Based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares
Number of Options
Beginning Balance (in shares) \| shares	6,590,400
Granted (in shares) \| shares	2,730,338
Forfeited (in shares) \| shares	(1,192,074)
Exercised (in shares) \| shares	(673,999)
Ending Balance (in shares) \| shares	7,454,665
Weighted-Average Exercise Price
Beginning Balance (dollars per share) \| $ / shares	$ 14.33
Granted (dollars per share) \| $ / shares	6.48
Forfeited (dollars per share) \| $ / shares	18.54
Exercised (dollars per share) \| $ / shares	2.72
Ending Balance (dollars per share) \| $ / shares	$ 11.83
Stock Option Activity, Additional Disclosures [Abstract]
Balance, Weighted-Average Remaining Contractual Term	7 years 8 months 8 days
Balance, Aggregate Intrinsic Value \| $	$ 54
Exercisable (in shares) \| shares	3,394,398
Exercisable (in dollars per share) \| $ / shares	$ 11.94
Exercisable, Weighted-Average Remaining Contractual Term	7 years 4 months 17 days
Exercisable, Aggregate Intrinsic Value \| $	$ 53
Unvested and expected to vest (in shares) \| shares	4,060,267
Unvested and expected to vest (in dollars per share) \| $ / shares	$ 11.75
Unvested and expected to vest, Weighted-Average Remaining Contractual Term	7 years 11 months 8 days
Unvested and expected to vest, Aggregate Intrinsic Value \| $	$ 1

Income Taxes - Net Operating Loss and Research Credit Carryforwards (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Federal \| Expiring Indefinitely
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 229,617
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	13,775
State
Operating Loss Carryforwards [Line Items]
Net operating losses	162,694
State \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credits	$ 6,358

Stock-Based Compensation - Early Exercised Options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
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	$ 891	$ 1,364
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	900	1,400
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	$ 200	$ 1,100

Accrued Expenses And Current Portion Of Other Liabilities - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued compensation	$ 4,277	$ 4,570
External research and development	7,694	2,655
Accrued outside services	945	1,598
Accrued taxes	40	0
Other accrued expenses	7	240
Total accrued expenses	$ 12,963	$ 9,063

Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 18,500	$ 18,139
Less: Accumulated depreciation and amortization	(5,515)	(3,259)
Total property and equipment, net	12,985	14,880
Depreciation and amortization	2,266	1,977
Lab equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	8,475	8,164
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,348	9,335
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	619	596
Computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 58	$ 44