0000950170-24-053612 | 10-Q | XBRL Viewer | DAY ONE Biopharmaceuticals INC

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Recurring Fair Value Measurement - Schedule of maturities of available-for-sale marketable securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Line Items]
Amortized cost, mature in one year or less	$ 302,522	$ 356,404
Amortized cost, total	302,522	356,404
Fair value, mature in one year or less	302,518	356,413
Fair value, total	$ 302,518	$ 356,413

Commitments and Contingencies

3 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Leases

In April 2022, the Company entered into a lease agreement for approximately 12,000 square feet of general use office space in Brisbane, California. Such agreement was determined to be a lease since the right to control the use of the identified asset was conveyed to the Company for a period of time in exchange for consideration. The term of the lease is 31 months and commenced in May 2022. There is no option to extend the lease term nor is there an option to terminate the lease term prior to its expiration. The Company is obligated to pay monthly rent expense and its pro rata share of the landlord's operating expenses which include utilities, common area maintenance expenses, and property taxes. Such expenses are a non-lease component and a variable consideration and included in the Company's operating expenses as incurred. The Company concluded that this lease is also an operating lease. The total payments for base rent over the term of the lease is approximately $1.1 million. Upon execution of the agreement, the Company paid a security deposit of approximately $40,000 classified as deposits and other long-term assets on the condensed balance sheet.

The Company determined the lease incremental borrowing rate, or IBR, based on the information available at the applicable lease commencement date as the Company’s leases do not provide an implicit rate. The IBR is determined by using the rate of interest that the Company would pay to borrow on a collateralized basis an amount equal to the lease payments for a similar term and in a similar economic environment where the asset is located. As of March 31, 2024, the weighted-average remaining lease term and weighted-average discount rate were 0.7 years and 9.0%, respectively.

The Company’s lease does not require any contingent rental payments, impose financial restrictions, or contain any residual value guarantees.

Lease expense of right-of-use assets is recognized on a straight-line basis over the applicable lease term. Lease expense was $0.1 million for each of the three months ended March 31, 2024 and 2023. Cash paid for amounts included in the measurement of operating lease liabilities was $0.1 million for each of the three months ended March 31, 2024 and 2023. Variable payments expensed during the three months ended March 31, 2024 and 2023 were immaterial.

As of March 31, 2024, the future lease obligations were as follows (in thousands):


	March 31, 2024
Remaining in 2024	$	308
Total future minimum lease payments		308
Less: imputed interest		(8	)
Present value of operating lease liabilities		300
Less: current portion of operating lease liabilities		(300	)
Operating lease liabilities	$	-

Research and Development Agreements

The Company enters into contracts in the normal course of business with clinical research organizations, contract manufacturing organizations, and other third-party vendors for clinical trial, manufacturing, testing, and other research and development activities. These contracts generally provide for termination on notice, with the exception of one vendor where certain costs are non-cancellable after the approval of the project. As of March 31, 2024 and December 31, 2023, there were no amounts accrued related to termination and cancellation charges as these are not probable.

License Agreements

The Company entered into the license agreements, as disclosed in Note 5, pursuant to which the Company is required to pay milestones contingent upon meeting specific events. The first milestone of $2.5 million, related to the MRKDG License Agreement, was achieved and recorded to research and development during the year ended December 31, 2022. The second milestone of $5.0 million, related to the Viracta License Agreement, was achieved and recorded to research and development expense during the year ended December 31, 2023. The Company may be required to pay royalties on sales of products developed under these agreements. All products are in development as of March 31, 2024 and no such royalties were due. Subsequent to March 31, 2024, the U.S. Federal Drug Administration, or the FDA, approved the Company's New Drug Applications, or NDAs, for the tablet formulation and for the powder solution formulation of OJEMDA for the treatment of patients 6 months of age and older with relapsed or refractory pLGG harboring a BRAF fusion or rearrangement, or BRAF

V600 mutation as disclosed in Note 11. Commencing on the first commercial sale of OJEMDA in a country, the Company is obligated to pay tiered royalties ranging in the mid-single-digit percentages on net sales of licensed products under the Viracta License Agreement.

Purchase Commitments

To support product needs for OJEMDA, the Company has entered into a manufacturing and supply agreement with Quotient Sciences - Philadelphia, LLC in July 2023 that requires the Company to meet minimum purchase obligations on an annual basis. The amount of future minimum purchase obligations under the manufacturing and supply agreement over the next five years is approximately $16.7 million, in aggregate, as of March 31, 2024. For the three months ended March 31, 2024, the Company made purchases of $0.5 million under the purchase obligation.

Legal Proceedings

The Company, from time to time, may be party to litigation, claims and assessments arising in the ordinary course of business. The Company accrues liabilities for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. The Company is not subject to any material legal proceedings, and to the best of its knowledge, no material legal proceedings are currently pending or threatened.

Indemnification Agreements

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for indemnification for certain liabilities. The exposure under these agreements is unknown because it involves claims that may be made against it in the future but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. The Company also has indemnification obligations to its directors and executive officers for specified events or occurrences, subject to some limits, while they are serving at its request in such capacities. There have been no claims to date, and the Company believes the fair value of these indemnification agreements is minimal. Accordingly, the Company had not recorded any liabilities for these agreements as of March 31, 2024 and December 31, 2023.

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 30, 2022 USD ($) ft²	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease term	31 months
Amortization of operating right-of-use assets		$ 93,000	$ 83,000
Operating lease payments	$ 1,100,000
Research and development		$ 40,210,000	27,828,000
Weighted average remaining lease term		8 months 12 days
Weighted average discount rate percent		9.00%
Research And Development Agreements
Lessee, Lease, Description [Line Items]
Termination and cancellation charges payable		$ 0		$ 0
Viracta License Agreement
Lessee, Lease, Description [Line Items]
Research and development				5,000,000
Royalty fee payable		0
MRKDG License Agreement
Lessee, Lease, Description [Line Items]
Research and development					$ 2,500,000
Indemnification Agreement
Lessee, Lease, Description [Line Items]
Termination and cancellation charges payable		0		$ 0
Purchase Commitments
Lessee, Lease, Description [Line Items]
Aggregate amount of future minimum purchase obligations		16,700,000
Purchases under the purchase obligation		500,000
Brisbane, California
Lessee, Lease, Description [Line Items]
Sublease agreement area \| ft²	12,000
Security deposit	$ 40,000
Lease For Corporate Office Facility
Lessee, Lease, Description [Line Items]
Amortization of operating right-of-use assets		100,000	100,000
Operating lease payments		$ 100,000	$ 100,000

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or U.S. GAAP, for interim financial information and Article 10 of Regulation S-X of the Securities and Exchange Commission, or SEC, and should be read in conjunction with the Company's consolidated financial statements and notes thereto contained in the Company's Annual Report on Form 10-K for the year ended December 31, 2023, filed with the SEC on February 26, 2024. The condensed financial statements presented in this Quarterly Report on Form 10-Q are unaudited; however, in the opinion of management, such financial statements reflect all adjustments, consisting solely of normal recurring adjustments, necessary for a fair presentation of the results for the interim periods presented. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in Accounting Standards Codification, or ASC, and Accounting Standards Updates, or ASU, of the Financial Accounting Standards Board, or FASB.
Use of Estimates	Use of Estimates The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosure of contingent assets and liabilities at the date of the condensed financial statements, and the reported amounts of expenses during the reporting period. Estimates and assumptions made in the accompanying condensed financial statements include, but are not limited to, the valuation of share-based awards, the valuation of deferred tax assets and income tax uncertainties, and accruals for research and development activities. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable. Actual results may differ from those estimates or assumptions.
Segments	Segments The Company has determined that its chief executive officer is the chief operating decision maker, or CODM. The Company operates and manages the business as one reporting and one operating segment, which is the business of identifying and advancing targeted therapies for people of all ages with genomically-defined cancers. The Company’s CODM reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s assets are located in the United States.
Concentration of credit risk and other risks and uncertainties	Concentration of credit risk and other risks and uncertainties Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term investments. Amounts on deposit may at times exceed federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash, cash equivalents and short-term investments that are recorded on its balance sheet. Per policy, the Company mitigates its risk by investing in high-grade instruments and limiting the concentration in any one issuer, which limits its exposure. The Company has not experienced any losses on its cash, cash equivalents and short-term investments. The Company is subject to certain risks and uncertainties and believes that changes in any of the following areas could have a material adverse effect on the Company's future financial position or results of its operations: ability to obtain future financing; regulatory requirements for approval and market acceptance of, and reimbursement for, product candidates; performance of third-party clinical research organizations and manufacturers upon which the Company relies; development of sales channels; protection of the Company’s intellectual property; litigation or claims against the Company based on intellectual property, patent, product, regulatory or other factors; changes to the market landscape; and the Company’s ability to attract and retain employees necessary to support its growth. The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs.
Recently Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures, which requires incremental disclosure of segment information on an interim and annual basis. This ASU is effective for public entities for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Retrospective application to all prior periods presented in the financial statements is required for public entities. The Company is currently evaluating the effect of this update on its financial statement disclosures. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) – Improvements to Income Tax Disclosures, which enhances the transparency and decision usefulness of income tax disclosures by requiring disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. The ASU is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. The Company is currently evaluating the effect of this update on its financial statement disclosures.

- Definition

Disclosure of accounting policy for segment reporting.

+ References + Details

Recurring Fair Value Measurement - Schedule of cash equivalents, marketable securities, and unrealized gains and losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Line Items]
Cash equivalents, amortized cost	$ 270,391	$ 230,784
Marketable securities
Cash and Cash Equivalents [Line Items]
Debt securities, available-for-sale, amortized cost	47,557	135,554
Debt securities, available-for-sale, unrealized gain	0	9
Debt securities, available-for-sale, unrealized loss	(4)	0
Debt securities, available-for-sale, estimated fair value	47,553	135,563
Cash equivalents
Cash and Cash Equivalents [Line Items]
Cash equivalents, amortized cost	254,965	220,850
Cash equivalents, unrealized gains	0	0
Cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value disclosure	254,965	220,850
Money market funds
Cash and Cash Equivalents [Line Items]
Cash equivalents, amortized cost	71,447	47,003
Cash equivalents, unrealized gains	0	0
Cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value disclosure	71,447	47,003
U.S. government agency securities
Cash and Cash Equivalents [Line Items]
Cash equivalents, amortized cost	81,216	63,202
Cash equivalents, unrealized gains	0	0
Cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value disclosure	81,216	63,202
U.S. treasury securities
Cash and Cash Equivalents [Line Items]
Cash equivalents, amortized cost	102,302	110,645
Cash equivalents, unrealized gains	0	0
Cash equivalents, unrealized losses	0	0
Cash and cash equivalents, fair value disclosure	102,302	110,645
Debt securities, available-for-sale, amortized cost	47,557	135,554
Debt securities, available-for-sale, unrealized gain	0	9
Debt securities, available-for-sale, unrealized loss	(4)	0
Debt securities, available-for-sale, estimated fair value	$ 47,553	$ 135,563

Share-based Compensation - Summary of Stock Option Activity (Detail) - 2021 Equity Incentive Plan $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares, Beginning Balance \| shares	10,211,758
Granted \| shares	2,277,282
Exercised \| shares	(4,862)
Forfeiture \| shares	(80,088)
Ending Balance Outstanding at March 31, 2024 \| shares	12,404,090
Vested and expected to vest at March 31, 2024 \| shares	12,338,890
Exercisable at March 31, 2024 \| shares	5,485,361
Weighted Average Exercise Price Per Share, Beginning Balance \| $ / shares	$ 17.1
Granted \| $ / shares	14.42
Exercised \| $ / shares	9.9
Forfeiture \| $ / shares	17.85
Weighted Average Exercise Price Per Share, Ending Balance \| $ / shares	16.61
Weighted Average Exercise Price Per Share, Vested and expected to vest at March 31, 2024 \| $ / shares	16.62
Exercisable at March 31, 2024 \| $ / shares	$ 16.81
Weighted-Average Remaining Contractual Term, Outstanding at March 31, 2024	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest at March 31, 2024	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Exercisable at March 31, 2024	7 years 8 months 12 days
Exercised \| $	$ 31
Outstanding at March 31, 2024 Aggregate Intrinsic Value \| $	16,445
Vested and expected to vest at March 31, 2024, Aggregate Intrinsic Value \| $	16,362
Exercisable at March 31, 2024 \| $	$ 5,330

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Common Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Shares Issued	87,377,163	87,227,132
Common Stock, Shares Outstanding	87,377,163	87,227,132

Share-based Compensation (Tables)

3 Months Ended

Mar. 31, 2024

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Restricted Stock Units Activity

The following table provides a summary of restricted stock units activity during the three months ended March 31, 2024:


	Number of Shares			Weighted Average Grant Date Fair Value Per Share
Unvested restricted stock units at December 31, 2023		1,031,545		$	18.27
Granted		1,390,330		$	14.45
Vested		(157,724	)	$	17.17
Forfeiture		(20,153	)	$	17.55
Unvested restricted stock units at March 31, 2024		2,243,998		$	15.99

Summary of Share/Stock-based Compensation Expense Recorded in The Accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss

Share-based compensation expense recorded in the accompanying condensed statements of operations is as follows (in thousands):


	Three Months Ended March 31,
	2024		2023
Research and development expense	$	4,653	$	3,380
General and administrative expense		7,991		6,067
Total share-based compensation expense	$	12,644	$	9,447

Summary of The Unvested Common Stock

The following table provides a summary of the unvested common stock awards activity during the three months ended March 31, 2024.


	Number of Shares			Weighted Average Grant Date Fair Value Per Share
Unvested common stock as of December 31, 2023		747,679		$	16.00
Vested		(191,885	)	$	16.00
Forfeiture		(12,555	)	$	16.00
Unvested common stock as of March 31, 2024		543,239		$	16.00

Summary of The Black-Scholes Option Pricing Model to Estimate The Fair Value of Stock Option Granted

The Company used the Black-Scholes option pricing model to estimate the fair value of stock option awards granted with the following assumptions:


	Three Months Ended March 31,
	2024	2023
Expected term (in years)	5.77 - 6.74	5.86 - 6.25
Expected volatility	68.27% - 70.57%	80.79% - 81.98%
Risk-free interest rate	3.90% - 4.31%	3.55% - 4.08%
Expected dividend yield	—	—

2021 Equity Incentive Plan

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Stock Option Activity

The following table provides a summary of stock option activity during the three months ended March 31, 2024.


	Options			Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2023		10,211,758		$	17.10
Granted		2,277,282		$	14.42
Exercised		(4,862	)	$	9.90			$	31
Forfeiture		(80,088	)	$	17.85
Outstanding at March 31, 2024		12,404,090		$	16.61		8.3	$	16,445
Vested and expected to vest at March 31, 2024		12,338,890		$	16.62		8.3	$	16,362
Exercisable at March 31, 2024		5,485,361		$	16.81		7.7	$	5,330

- Definition

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

+ References

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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Balance Sheet Items

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Items

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	March 31, 2024		December 31, 2023
Prepaid research and development expenses	$	4,577	$	5,657
Prepaid insurance		384		918
Other prepaid expenses and other assets		3,129		2,352
Total prepaid expenses and other current assets	$	8,090	$	8,927

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	March 31, 2024		December 31, 2023
Accrued research and development expenses	$	16,273	$	12,643
Accrued payroll related expenses		4,087		9,165
Accrued professional service expenses		3,525		3,675
Other		874		1,041
Total accrued expenses and other current liabilities	$	24,759	$	26,524

Balance Sheet Items (Tables)

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	March 31, 2024		December 31, 2023
Prepaid research and development expenses	$	4,577	$	5,657
Prepaid insurance		384		918
Other prepaid expenses and other assets		3,129		2,352
Total prepaid expenses and other current assets	$	8,090	$	8,927

Schedule of Accrued expenses and other current liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	March 31, 2024		December 31, 2023
Accrued research and development expenses	$	16,273	$	12,643
Accrued payroll related expenses		4,087		9,165
Accrued professional service expenses		3,525		3,675
Other		874		1,041
Total accrued expenses and other current liabilities	$	24,759	$	26,524

Recurring Fair Value Measurement - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, measurement recurring basis, asset, transfers, net	$ 0	$ 0
Unrealized losses twelve months or greater	$ 0	$ 0

Summary Of Significant Accounting Policies	3 Months Ended
Summary Of Significant Accounting Policies	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The Company’s unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States, or U.S. GAAP, for interim financial information and Article 10 of Regulation S-X of the Securities and Exchange Commission, or SEC, and should be read in conjunction with the Company's consolidated financial statements and notes thereto contained in the Company's Annual Report on Form 10-K for the year ended December 31, 2023, filed with the SEC on February 26, 2024. The condensed financial statements presented in this Quarterly Report on Form 10-Q are unaudited; however, in the opinion of management, such financial statements reflect all adjustments, consisting solely of normal recurring adjustments, necessary for a fair presentation of the results for the interim periods presented. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in Accounting Standards Codification, or ASC, and Accounting Standards Updates, or ASU, of the Financial Accounting Standards Board, or FASB. Use of Estimates The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosure of contingent assets and liabilities at the date of the condensed financial statements, and the reported amounts of expenses during the reporting period. Estimates and assumptions made in the accompanying condensed financial statements include, but are not limited to, the valuation of share-based awards, the valuation of deferred tax assets and income tax uncertainties, and accruals for research and development activities. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable. Actual results may differ from those estimates or assumptions. Segments The Company has determined that its chief executive officer is the chief operating decision maker, or CODM. The Company operates and manages the business as one reporting and one operating segment, which is the business of identifying and advancing targeted therapies for people of all ages with genomically-defined cancers. The Company’s CODM reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s assets are located in the United States. Concentration of credit risk and other risks and uncertainties Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term investments. Amounts on deposit may at times exceed federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash, cash equivalents and short-term investments that are recorded on its balance sheet. Per policy, the Company mitigates its risk by investing in high-grade instruments and limiting the concentration in any one issuer, which limits its exposure. The Company has not experienced any losses on its cash, cash equivalents and short-term investments. The Company is subject to certain risks and uncertainties and believes that changes in any of the following areas could have a material adverse effect on the Company's future financial position or results of its operations: ability to obtain future financing; regulatory requirements for approval and market acceptance of, and reimbursement for, product candidates; performance of third-party clinical research organizations and manufacturers upon which the Company relies; development of sales channels; protection of the Company’s intellectual property; litigation or claims against the Company based on intellectual property, patent, product, regulatory or other factors; changes to the market landscape; and the Company’s ability to attract and retain employees necessary to support its growth. The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs. Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures, which requires incremental disclosure of segment information on an interim and annual basis. This ASU is effective for public entities for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Retrospective application to all prior periods presented in the financial statements is required for public entities. The Company is currently evaluating the effect of this update on its financial statement disclosures. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) – Improvements to Income Tax Disclosures, which enhances the transparency and decision usefulness of income tax disclosures by requiring disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. The ASU is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. The Company is currently evaluating the effect of this update on its financial statement disclosures.

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net loss	$ (62,412)	$ (42,393)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	12,644	9,447
Depreciation expense	23	6
Accretion of discounts on short-term investments, net	(1,292)	(599)
Amortization of operating right-of-use assets	93	83
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	837	1,396
Deposits and other long-term assets	47	(18)
Accounts payable	2,204	4,379
Accrued expenses and other current liabilities	(1,765)	1,810
Operating lease liabilities	(108)	(96)
Net cash used in operating activities	(49,729)	(25,985)
Cash flows from investing activities
Cash paid for purchase of short-term investments	(47,162)	(160,014)
Proceeds from maturity of short-term investments	136,450	148,847
Cash paid for purchase of property and equipment	0	(26)
Net Cash provided by (used) in investing activities	89,288	(11,193)
Cash flows from financing activities
Proceeds from issuance of common stock upon stock option exercises	48	1,184
Cash provided by financing activities	48	1,184
Net increase (decrease) in cash and cash equivalents	39,607	(35,994)
Cash and cash equivalents, beginning of period	230,784	85,262
Cash and cash equivalents, end of period	$ 270,391	$ 49,268

Balance Sheet Items - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 185	$ 208

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 270,391	$ 230,784
Short-term investments	47,553	135,563
Prepaid expenses and other current assets	8,090	8,927
Total current assets	326,034	375,274
Property and equipment, net	185	208
Operating lease right-of-use asset	259	352
Deposits and other long-term assets	167	214
Total assets	326,645	376,048
Current Liabilities:
Accounts payable	4,780	2,576
Accrued expenses and other current liabilities	24,759	26,524
Current portion of operating lease liabilities	300	408
Total current liabilities	29,839	29,508
Total liabilities	29,839	29,508
Commitments and contingencies (Note 6)
Stockholders' equity
Common stock, $0.001 par value; 500,000,000 shares authorized as of March 31, 2024 and December 31, 2023; 87,377,163 and 87,227,132 shares issued and outstanding as of Mach 31, 2024 and December 31, 2023, respectively	9	9
Additional paid-in-capital	817,799	805,107
Accumulated other comprehensive loss	(5)	9
Accumulated deficit	(520,997)	(458,585)
Total stockholders' equity	296,806	346,540
Total liabilities and stockholders' equity	$ 326,645	$ 376,048

Condensed Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 40,210	$ 27,828
General and administrative	26,557	18,027
Total operating expenses	66,767	45,855
Loss from operations	(66,767)	(45,855)
Investment income, net	4,365	3,466
Other expense, net	(10)	(4)
Net loss attributable to common stockholders	$ (62,412)	$ (42,393)
Net loss per share, basic	$ (0.72)	$ (0.59)
Net loss per share, diluted	$ (0.72)	$ (0.59)
Weighted-average number of common shares used in computing net loss per share, basic	86,679,282	71,972,888
Weighted-average number of common shares used in computing net loss per share, diluted	86,679,282	71,972,888

Subsequent Event	3 Months Ended
Subsequent Event	Mar. 31, 2024
Subsequent Events [Abstract]
Subsequent Event	11. Subsequent Event On April 23, 2024, the FDA approved the Company's NDAs for the tablet formulation and for the powder solution formulation of OJEMDA for the treatment of patients 6 months of age and older with relapsed or refractory pLGG harboring a BRAF fusion or rearrangement, or BRAF V600 mutation. With the approval, the Company received a rare pediatric disease priority review voucher from the FDA. Per the terms of the Viracta License Agreement, a $9.0 million payment is due to Viracta for the achievement of this milestone.

Description of Business and Organization

3 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of Business and Organization

Organization and Business

Day One Biopharmaceuticals, Inc., or the Company, is a commercial-stage biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ages with life-threatening diseases. The Company was formed as a limited liability company under the laws of the State of Delaware in November 2018, under the name Hero Therapeutics Holding Company, LLC. Subsequently, the Company changed its name to Day One Therapeutics Holding Company, LLC in December 2018 and to Day One Biopharmaceuticals Holding Company, LLC, or Day One Holding LLC, in March 2020. On May 26, 2021, the Company completed a conversion by filing a certificate of conversion with the Secretary of State of the State of Delaware and changed its name to Day One Biopharmaceuticals, Inc.

Defined Contribution Plan	3 Months Ended
Defined Contribution Plan	Mar. 31, 2024
Retirement Benefits [Abstract]
Defined Contribution Plan	10. Defined Contribution Plan The Company maintains an employee savings plan pursuant to Section 401(k) of the Internal Revenue Code. All employees are eligible to participate provided that they meet the requirements of the plan. For each of the three months ended March 31, 2024 and 2023, the Company made matching contributions of $0.6 million and $0.8 million, respectively.

Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Mar. 31, 2024	Jun. 30, 2023	Dec. 31, 2023
Class of Stock [Line Items]
Common Stock, Shares Authorized		500,000,000		500,000,000
Common Stock, Par or Stated Value Per Share		$ 0.0001		$ 0.0001
Common Stock, Shares Issued		87,377,163		87,227,132
Common Stock, Shares Outstanding		87,377,163		87,227,132
Common stock shares reserved for future issuance		20,651,259
Common Shares Purchase Agreement
Class of Stock [Line Items]
Common Stock, Shares Authorized		500,000,000
Common Stock, Par or Stated Value Per Share		$ 0.0001
Sales Agreement with Piper Sandler and Jones Services LLC
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share	$ 15		$ 13
Common Stock, Shares Issued	11,500,000		13,269,231
Common stock shares reserved for future issuance	1,500,000		1,730,769
Proceeds from the issuance of common stock	$ 161.6	$ 250.0	$ 161.4

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482987/272-10-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27)(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
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-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 3
-Subparagraph (SX 210.6-03(i)(1))
-Publisher FASB
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

+ Details

Defined Contribution Plan (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Retirement Benefits [Abstract]
Matching Contribution	$ 0.6	$ 0.8

Common Stock - Schedule of Common Stock Shares Reserved for Future Issuance (Details) (Details)	Mar. 31, 2024 shares
Class of Stock [Line Items]
Common stock shares reserved for future issuance	20,651,259
Employee Stock Option
Class of Stock [Line Items]
Common stock shares reserved for future issuance	3,409,984
Restricted Stock Units (RSUs)
Class of Stock [Line Items]
Common stock shares reserved for future issuance	2,243,998
Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock shares reserved for future issuance	2,593,187
Common Stock
Class of Stock [Line Items]
Common stock shares reserved for future issuance	12,404,090

- Definition

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

+ References

+ Details

Balance Sheet Items - Summary of Prepaid and Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid research and development expenses	$ 4,577	$ 5,657
Prepaid insurance	384	918
Other prepaid expenses and other assets	3,129	2,352
Total prepaid expenses and other current assets	$ 8,090	$ 8,927

Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Summary of Basic and Diluted Net Loss Per Share Attributable to Common Shareholders/Stockholders

Basic and diluted net loss per share attributable to common stockholders is calculated as follows (in thousands except share and per share amounts):


	Three Months Ended March 31,
	2024			2023
Net loss attributable to common stockholders	$	(62,412	)	$	(42,393	)
Net loss per share, basic and diluted	$	(0.72	)	$	(0.59	)
Weighted-average number of common shares used in computing net loss per share, basic and diluted		86,679,282			71,972,888

Summary of Outstanding Potentially Dilutive Securities Have Been Excluded From Calculation of Diluted Net Loss Per Share

The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive:


	As of March 31,
	2024		2023
Stock options		12,404,090		9,292,431
Unvested common shares		543,239		1,449,724
Restricted stock units		2,243,998		964,700
Shares committed under ESPP		100,753		47,099
Total		15,292,080		11,753,954

Net Loss Per Share - Summary of Outstanding Potentially Dilutive Securities Have Been Excluded From Calculation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options	15,292,080	11,753,954
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options	12,404,090	9,292,431
Unvested common shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options	543,239	1,449,724
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options	2,243,998	964,700
Shares committed under ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options	100,753	47,099

Share-based Compensation - Additional Information (Detail) - USD ($)		3 Months Ended
	May 31, 2021	Mar. 31, 2024	Mar. 31, 2023	Oct. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issuance of common stock upon exercise of stock options, Amount		$ 48,000	$ 1,184,000
Common stock shares reserved for future issuance		20,651,259
Allocated share based compensation expense		$ 12,644,000	9,447,000
Restricted Stock [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unamortized stock-based compensation for stock options		$ 32,900,000
Weighted-average period expected to be recognized		3 years 2 months 12 days
2021 Equity Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issuance of common stock upon exercise of stock options, Amount		$ 100,000	600,000
Total fair value of options		$ 7,900	$ 6,300,000
Number of shares issued upon conversion	4,719,605
Common stock shares reserved for future issuance	6,369,000
Share based compensation by share based payment arrangement non vested options granted during the period		2,277,282
Weighted-average period expected to be recognized		8 years 3 months 18 days
Granted		2,277,282
2021 Equity Incentive Plan \| PSOs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation by share based payment arrangement non vested options granted during the period weighted average grant date fair value		$ 9.31	$ 16.63
Unamortized stock-based compensation for stock options		$ 69,300,000
Weighted-average period expected to be recognized		2 years 7 months 6 days
2021 Equity Incentive Plan \| Incremental Shares Reserved for Future Issuance [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-Based Compensation Arrangement by Share-Based Payment Award, Percentage of Outstanding Stock Maximum	5.00%
2021 Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock shares reserved for future issuance	603,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Percentage of Outstanding Stock Maximum	1.00%
Allocated share based compensation expense		$ 200,000	$ 200,000
Issuance of common stock pursuant to Employee Stock Purchase Plan, Shares		236,187
2022 Equity Inducement Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock shares reserved for future issuance				1,000,000
Unvested Common Stock [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unamortized stock-based compensation for stock options		$ 2,800,000
Weighted-average period expected to be recognized		10 months 24 days

Common Stock

3 Months Ended

Mar. 31, 2024

Stockholders' Equity Note [Abstract]

Common Stock

Pursuant to its certificate of incorporation, the Company is authorized to issue 500.0 million shares of common stock at a par value of $0.0001 per share. As of March 31, 2024, 87,377,163 shares of common stock were issued and outstanding.

The Company has reserved shares of common stock for future issuances as follows:


	March 31, 2024
Common stock options issued and outstanding		12,404,090
Common stock available for future grants		3,409,984
Common stock available for ESPP		2,593,187
Restricted stock units issued and outstanding		2,243,998
Total		20,651,259

June 2023 Follow-On Offering

In June 2023, the Company completed a follow-on offering and issued and sold 13,269,231 shares of common stock (including the exercise by the underwriters of their option to purchase an additional 1,730,769 shares of common stock) at a price to the public of $13.00 per share for net proceeds of approximately $161.4 million, after deducting underwriting discounts, commissions, and offering costs.

At-The-Market Offering

The Company has entered into an equity distribution agreement, or the Equity Distribution Agreement, with Piper Sandler & Co. and JonesTrading Institutional Services LLC, as sales agents, relating to the issuance and sale of shares of the Company’s common stock for an aggregate offering price of up to $250.0 million under an at-the-market offering program, or the ATM. The Company has no obligation to sell any shares and could at any time suspend solicitations and offers under the ATM. No shares of the Company’s common stock have been sold under the ATM as of March 31, 2024.

June 2022 Follow-On Offering

In June 2022, the Company completed a follow-on offering and issued and sold 11,500,000 shares of common stock (including the exercise by the underwriters of their option to purchase an additional 1,500,000 shares of common stock) at a price to the public of $15.00 per share for net proceeds of approximately $161.6 million, after deducting underwriting discounts, commissions, and offering costs.

- Definition

The entire disclosure for equity.

+ References

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+ Details

Significant Agreements - Additional Information (Detail) - USD ($) $ in Millions				3 Months Ended
	Mar. 04, 2024	May 26, 2021	Dec. 16, 2019	Mar. 31, 2024
Takeda Asset Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront of cash payment			$ 1.0
Takeda Asset Agreement [Member] \| Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of Series B redeemable convertible preferred shares for cash, net of issuance costs, shares		6,470,382
Takeda Asset Agreement [Member] \| Series A Redeemable Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock Issued During Period, Shares, New Issues			9,857,143
Stock Issued During Period, Value, New Issues			$ 9.9
Issuance of Series B redeemable convertible preferred shares for cash, net of issuance costs, shares		9,857,143
Merck License Agreement [Member] \| Research And Development Expense
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment				$ 8.0
Merck License Agreement [Member] \| Research And Development Expense \| Maximum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments not yet paid				364.5
Viracta License Agreement [Member] \| Research And Development Expense
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment	$ 5.0
Upfront of cash payment				2.0
Sprint Bioscience Agreement [Member] \| Research And Development Expense
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment				3.0
Payment of Milestones				49.0
Sprint Bioscience Agreement [Member] \| Research And Development Expense \| Maximum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments not yet paid				$ 309.0

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Summary of Future Lease Obligations

As of March 31, 2024, the future lease obligations were as follows (in thousands):


	March 31, 2024
Remaining in 2024	$	308
Total future minimum lease payments		308
Less: imputed interest		(8	)
Present value of operating lease liabilities		300
Less: current portion of operating lease liabilities		(300	)
Operating lease liabilities	$	-

Share-based Compensation - Summary of Restricted Stock Units Activity (Detail) - Restricted Stock Units - 2021 Equity Incentive Plan	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unvested restricted stock, beginning balance \| shares	1,031,545
Granted \| shares	1,390,330
Vested \| shares	(157,724)
Forfeiture \| shares	(20,153)
Unvested restricted stock, ending balance \| shares	2,243,998
Weighted Average Grant Date Fair Value Per Share, Beginning Balance \| $ / shares	$ 18.27
Grant date fair value \| $ / shares	14.45
Vested \| $ / shares	17.17
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	17.55
Weighted Average Grant Date Fair Value Per Share, Ending Balance \| $ / shares	$ 15.99

Commitments and Contingencies - Summary of Future Lease Obligations (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Remaining in 2024	$ 308
Total future minimum lease payments	308
Less: Imputed interest	(8)
Present value of operating lease liabilities	300
Less: Current portion of operating lease liabilities	(300)	$ (408)
Operating lease liabilities	$ 0

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	The Company’s directors and Section 16 officers (as defined in Rule 16a-1(f) under the Exchange Act) are only permitted to trade in the Company’s securities pursuant to a prearranged trading plan intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act (a “Rule 10b5-1 Plan”). During the three months ended March 31, 2024, the Company’s General Counsel and Chief Compliance Officer adopted a new Rule 10b5-1 Plan. The Plan (as defined below) were entered into during an open trading window in accordance with the Company’s Insider Trading Policy. On February 28, 2024, Adam Dubow, our General Counsel and Chief Compliance Officer entered into a pre-arranged written stock sale plan in accordance with Rule 10b5-1 (the “Dubow Rule 10b5-1 Plan”) under the Exchange Act for the sale of shares of our common stock. The Dubow Rule 10b5-1 Plan was entered into during an open trading window in accordance with our policies regarding transactions in our securities and is intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act. The Dubow Rule 10b5-1 Plan provides for the potential sale of shares of our common stock, including upon the vesting and settlement of restricted stock units/vesting and exercise of stock options, so long as the market price of our common stock is higher than certain minimum threshold prices specified in the Dubow Rule 10b5-1 Plan, between May 29, 2024 and June 30, 2025. The aggregate number of shares of common stock that will be available for sale under the Dubow Rule 10b5-1 Plan is not yet determinable because the shares available will be net of shares sold to satisfy tax withholding obligations that arise in connection with the vesting and settlement of such restricted stock unit awards. As such, for purposes of this disclosure, the aggregate number of shares of common stock available for sale is approximately 62,000, which reflects the aggregate maximum number of shares underlying Adam Dubow’s restricted stock units which may be sold, without excluding the shares that will be sold to satisfy the tax withholding obligations. The Dubow Rule 10b5-1 Plan expires on June 30, 2025.
Adam Dubow [Member]
Trading Arrangements, by Individual
Name	Adam Dubow
Title	General Counsel and Chief Compliance Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	February 28, 2024
Arrangement Duration	32 days
Aggregate Available	62,000
Trd Arr Expiration Date	June 30, 2025

Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Common Shares [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2022	$ 332,039	$ 7	$ 601,771	$ (71)	$ (269,668)
Beginning Balance (In shares) at Dec. 31, 2022		73,458,176
Issuance of common stock upon exercise of stock options (share)		75,184
Issuance of common stock upon exercise of stock options, Amount	1,184		1,184
Issuance of common stock upon release of restricted stock units, shares		60,673
Unvested common stock forfeiture		(21,400)
Share-based compensation expenses	9,447		9,447
Unrealized (loss) gain on available-for-sale securities	138			138
Net loss attributable to common stockholders	(42,393)				(42,393)
Ending Balance at Mar. 31, 2023	300,415	$ 7	612,402	67	(312,061)
Ending Balance (In shares) at Mar. 31, 2023		73,572,633
Beginning Balance at Dec. 31, 2023	346,540	$ 9	805,107	9	(458,585)
Beginning Balance (In shares) at Dec. 31, 2023		87,227,132
Issuance of common stock upon exercise of stock options (share)		4,862
Issuance of common stock upon exercise of stock options, Amount	48		48
Issuance of common stock upon release of restricted stock units, shares		157,724
Unvested common stock forfeiture		(12,555)
Share-based compensation expenses	12,644		12,644
Unrealized (loss) gain on available-for-sale securities	(14)			(14)
Net loss attributable to common stockholders	(62,412)				(62,412)
Ending Balance at Mar. 31, 2024	$ 296,806	$ 9	$ 817,799	$ (5)	$ (520,997)
Ending Balance (In shares) at Mar. 31, 2024		87,377,163

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details

Subsequent Event (Additional Information) (Details) $ in Millions	Apr. 23, 2024 USD ($)
Subsequent Event [Member]
Subsequent Event [Line Items]
Payment of Milestones	$ 9.0

Common Stock (Tables)

3 Months Ended

Mar. 31, 2024

Stockholders' Equity Note [Abstract]

Schedule of Common Stock Shares Reserved for Future Issuance

The Company has reserved shares of common stock for future issuances as follows:


	March 31, 2024
Common stock options issued and outstanding		12,404,090
Common stock available for future grants		3,409,984
Common stock available for ESPP		2,593,187
Restricted stock units issued and outstanding		2,243,998
Total		20,651,259

Condensed Consolidated Statements of Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net loss	$ (62,412)	$ (42,393)
Other comprehensive loss:
Unrealized (loss) gain on available-for-sale securities	(14)	138
Total comprehensive loss	$ (62,426)	$ (42,255)

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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+ Details

Share-based Compensation - Summary of The Unvested Common Stock (Detail) - Unvested Common Stock [Member]	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares, Unvested Common Stock, Beginning balance \| shares	747,679
Vested \| shares	(191,885)
Number of Shares, Forfeited \| shares	(12,555)
Number of Shares, Unvested Common Stock, Ending balance \| shares	543,239
Weighted Average Grant Date Fair Value Per Share, Beginning Balance \| $ / shares	$ 16
Vested \| $ / shares	16
Forfeiture \| $ / shares	16
Weighted Average Grant Date Fair Value Per Share, Ending Balance \| $ / shares	$ 16

- Definition

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

+ References

+ Details

Recurring Fair Value Measurements

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Recurring Fair Value Measurements

The following table sets forth the Company’s financial instruments as of March 31, 2024 and December 31, 2023, which are measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	March 31, 2024
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	71,447	$	—	$	—	$	71,447
U.S. treasury securities		—		149,855		—		149,855
U.S. government agency securities		—		81,216		—		81,216
Total assets measured at fair value	$	71,447	$	231,071	$	—	$	302,518


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	47,003	$	—	$	—	$	47,003
U.S. treasury securities		—		246,208		—		246,208
U.S. government agency securities		—		63,202		—		63,202
Total assets measured at fair value	$	47,003	$	309,410	$	—	$	356,413

The Company's money market funds are classified as Level 1 because they are measured using observable inputs from active markets for identical assets.

The Company's U.S. treasury securities and U.S. government agency securities are classified as Level 2 because they are measured with inputs that are either directly or indirectly observable for the asset which include quoted prices for similar assets in active markets and quoted prices for identical or similar assets in markets that are not active.

There were no assets or liabilities classified as Level 3 as of March 31, 2024 and December 31, 2023.

There were no transfers between Level 1, Level 2 or Level 3 categories during the periods presented.

The following tables summarize the estimated fair value of the Company's cash equivalents, available-for-sale securities classified as short-term investments, and associated unrealized gains and losses (in thousands):


	March 31, 2024
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash equivalents:
Money market funds	$	71,447	$	—	$	—		$	71,447
U.S. government agency securities		81,216		—		—			81,216
U.S. treasury securities		102,302		—		—			102,302
Total cash equivalents		254,965		—		—			254,965

Short-term investments
U.S. treasury securities		47,557		—		(4	)		47,553
Total short-term investments	$	47,557	$	—	$	(4	)	$	47,553


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
Cash equivalents:
Money market funds	$	47,003	$	—	$	—	$	47,003
U.S. government agency securities		63,202		—		—		63,202
U.S. treasury securities		110,645		—		—		110,645
Total cash equivalents		220,850		—		—		220,850

Short-term investments
U.S. treasury securities		135,554		9		—		135,563
Total short-term investments	$	135,554	$	9	$	—	$	135,563

The following table summarizes the maturities of our cash equivalents and available-for-sale securities (in thousands):


	March 31, 2024
	Amortized Cost		Fair Value
Mature in one year or less	$	302,522	$	302,518
Total	$	302,522	$	302,518


	December 31, 2023
	Amortized Cost		Fair Value
Mature in one year or less	$	356,404	$	356,413
Total	$	356,404	$	356,413

The Company regularly reviews the changes to the rating of its securities and monitors the surrounding economic conditions to assess the risk of expected credit losses. As of March 31, 2024 and December 31, 2023, there were no securities that were in an unrealized loss position for more than 12 months. As of March 31, 2024, the unrealized losses, if any, on the Company’s short-term investments were primarily caused by interest rate increases. The Company does not expect the issuers to settle any security at a price less than the amortized cost basis of the investment with the contractual cash flows of these investments guaranteed by the issuer. No allowance for credit losses has been recorded since it is not more-likely-than-not that the Company will be required to sell the investments before recovery of their amortized cost basis.

- 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

Share-based Compensation

3 Months Ended

Mar. 31, 2024

Stockholders' Equity Note [Abstract]

Share-based Compensation

Share-based compensation expense recorded in the accompanying condensed statements of operations is as follows (in thousands):


	Three Months Ended March 31,
	2024		2023
Research and development expense	$	4,653	$	3,380
General and administrative expense		7,991		6,067
Total share-based compensation expense	$	12,644	$	9,447

2022 Equity Inducement Plan

In October 2022, the board of directors and stockholders approved the 2022 Equity Inducement Plan, or the 2022 Plan. The 2022 Plan provides for the grant of non-statutory stock options and restricted stock units. The number of shares of common stock reserved for issuance under the 2022 Plan is 1,000,000 shares.

2021 Equity Incentive Plan

In May 2021, in connection with the IPO, the board of directors and stockholders approved, the 2021 Equity Incentive Plan, or the 2021 Plan, which became effective on the day before the date of the effectiveness of the IPO. The 2021 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, awards of restricted stock, restricted stock units and other share-based awards. The number of shares of common stock reserved for issuance under the 2021 Plan is equal to the sum of: (x) 6,369,000 shares of common stock; plus (y) 4,719,605 shares of common stock issued in respect of the conversion of incentive shares that were subject to vesting immediately prior to the effectiveness of the registration statement for the IPO that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by us at their original issuance price pursuant to a contractual repurchase right. The number of shares available for grant and issuance under the 2021 Plan will be automatically increased on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2021 and continuing for each fiscal year until, and including, the fiscal year commencing on January 1, 2031, by the lesser of (a) 5% of the number of shares of all classes of the Company’s common stock, plus the total number of shares of Company common stock issuable upon conversion of any preferred stock or exercise of any warrants to acquire shares of Company common stock for a nominal exercise price issued and outstanding on each December 31 immediately prior to the date of increase or (b) such number of shares determined by the board of directors.

Stock Options

The following table provides a summary of stock option activity during the three months ended March 31, 2024.


	Options			Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2023		10,211,758		$	17.10
Granted		2,277,282		$	14.42
Exercised		(4,862	)	$	9.90			$	31
Forfeiture		(80,088	)	$	17.85
Outstanding at March 31, 2024		12,404,090		$	16.61		8.3	$	16,445
Vested and expected to vest at March 31, 2024		12,338,890		$	16.62		8.3	$	16,362
Exercisable at March 31, 2024		5,485,361		$	16.81		7.7	$	5,330

Aggregate intrinsic value represents the difference between the estimated fair value of the underlying common stock and the exercise price of outstanding, in-the-money options. The total intrinsic value of options exercised during the three months ended March 31, 2024 and 2023 was less than $0.1 million and $0.6 million, respectively.

The total fair value of options that vested during the three months ended March 31, 2024 and 2023 was $7.9 million and $6.3 million, respectively. The weighted-average grant date fair value of options granted during the three months ended March 31, 2024 and 2023 was $9.31 per share and $16.63 per share, respectively.

Unamortized share-based compensation for stock options as of March 31, 2024 was $69.3 million, which is expected to be recognized over a weighted-average period of 2.6 years.

The Company used the Black-Scholes option pricing model to estimate the fair value of stock option awards granted with the following assumptions:


	Three Months Ended March 31,
	2024	2023
Expected term (in years)	5.77 - 6.74	5.86 - 6.25
Expected volatility	68.27% - 70.57%	80.79% - 81.98%
Risk-free interest rate	3.90% - 4.31%	3.55% - 4.08%
Expected dividend yield	—	—

Restricted Stock Units

The following table provides a summary of restricted stock units activity during the three months ended March 31, 2024:


	Number of Shares			Weighted Average Grant Date Fair Value Per Share
Unvested restricted stock units at December 31, 2023		1,031,545		$	18.27
Granted		1,390,330		$	14.45
Vested		(157,724	)	$	17.17
Forfeiture		(20,153	)	$	17.55
Unvested restricted stock units at March 31, 2024		2,243,998		$	15.99

Unamortized share-based compensation for restricted stock units as of March 31, 2024 was $32.9 million, which is expected to be recognized over a weighted-average period of 3.2 years.

Restricted Stock Awards

The following table provides a summary of the unvested common stock awards activity during the three months ended March 31, 2024.


	Number of Shares			Weighted Average Grant Date Fair Value Per Share
Unvested common stock as of December 31, 2023		747,679		$	16.00
Vested		(191,885	)	$	16.00
Forfeiture		(12,555	)	$	16.00
Unvested common stock as of March 31, 2024		543,239		$	16.00

Unamortized share-based compensation for restricted stock awards as of March 31, 2024 was $2.8 million, which is expected to be recognized over a weighted-average period of 0.9 years.

2021 Employee Stock Purchase Plan

In May 2021, the board of directors adopted and the stockholders approved the 2021 Employee Stock Purchase Plan, or the ESPP, which became effective on May 26, 2021. A total of 603,000 shares of common stock were initially reserved for issuance under the ESPP. The number of shares of the common stock reserved for issuance under the ESPP will automatically increase on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2021 and continuing for each fiscal year until, and including, the fiscal year commencing on January 1, 2031, by the lesser of: (a) 1% of the total number of outstanding shares of common stock of the Company (on an as converted basis outstanding on the immediately preceding December 31 (rounded down to the nearest whole share)) and (b) an amount determined by the board of directors. 236,187 shares have been issued under the ESPP as of March 31, 2024. The Company recognized compensation expense related to the ESPP of $0.2 million for each of the three months ended March 31, 2024 and 2023.

For the three months ended March 31, 2024 and 2023, the Company has not issued any shares pursuant to the ESPP.

Share-based Compensation - Summary of Share/Stock-based Compensation Expense Recorded in The Accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-Based Payment Arrangement, Expense	$ 12,644	$ 9,447
Research And Development Expense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-Based Payment Arrangement, Expense	4,653	3,380
General And Administrative Expense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-Based Payment Arrangement, Expense	$ 7,991	$ 6,067

Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share Attributable to Common Shareholders/Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net loss attributable to common stockholders	$ (62,412)	$ (42,393)
Net loss per share, basic	$ (0.72)	$ (0.59)
Net loss per share, diluted	$ (0.72)	$ (0.59)
Weighted-average number of common shares used in computing net loss per share, basic	86,679,282	71,972,888
Weighted-average number of common shares used in computing net loss per share, diluted	86,679,282	71,972,888

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482635/260-10-55-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (e)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

- Definition

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

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+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

+ Details

Summary of Significant Accounting Policies - Additional Information (Detail) - shares	Mar. 31, 2024	Dec. 31, 2023
Accounting Policies [Line Items]
Common Stock, Shares Outstanding	87,377,163	87,227,132

Recurring Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Schedule of fair value, assets and liabilities measured on recurring basis


	March 31, 2024
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	71,447	$	—	$	—	$	71,447
U.S. treasury securities		—		149,855		—		149,855
U.S. government agency securities		—		81,216		—		81,216
Total assets measured at fair value	$	71,447	$	231,071	$	—	$	302,518


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Financial assets:
Money market funds	$	47,003	$	—	$	—	$	47,003
U.S. treasury securities		—		246,208		—		246,208
U.S. government agency securities		—		63,202		—		63,202
Total assets measured at fair value	$	47,003	$	309,410	$	—	$	356,413

Schedule of cash equivalents, marketable securities, and unrealized gains and losses


	March 31, 2024
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash equivalents:
Money market funds	$	71,447	$	—	$	—		$	71,447
U.S. government agency securities		81,216		—		—			81,216
U.S. treasury securities		102,302		—		—			102,302
Total cash equivalents		254,965		—		—			254,965

Short-term investments
U.S. treasury securities		47,557		—		(4	)		47,553
Total short-term investments	$	47,557	$	—	$	(4	)	$	47,553


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
Cash equivalents:
Money market funds	$	47,003	$	—	$	—	$	47,003
U.S. government agency securities		63,202		—		—		63,202
U.S. treasury securities		110,645		—		—		110,645
Total cash equivalents		220,850		—		—		220,850

Short-term investments
U.S. treasury securities		135,554		9		—		135,563
Total short-term investments	$	135,554	$	9	$	—	$	135,563

Schedule of maturities of available-for-sale marketable securities

The following table summarizes the maturities of our cash equivalents and available-for-sale securities (in thousands):


	March 31, 2024
	Amortized Cost		Fair Value
Mature in one year or less	$	302,522	$	302,518
Total	$	302,522	$	302,518


	December 31, 2023
	Amortized Cost		Fair Value
Mature in one year or less	$	356,404	$	356,413
Total	$	356,404	$	356,413

Share-based Compensation - Summary of The Black-Scholes Option Pricing Model to Estimate The Fair Value of Stock Option Granted (Detail) - Two Thousand And Twenty One Equity Incentive Plan [Member]	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	6 years 8 months 26 days	6 years 3 months
Expected volatility	70.57%	81.98%
Risk-free interest rate	4.31%	4.08%
Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	5 years 9 months 7 days	5 years 10 months 9 days
Expected volatility	68.27%	80.79%
Risk-free interest rate	3.90%	3.55%

- Definition

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

+ References

+ Details

Net Loss Per Share

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Net Loss Per Share

Basic and diluted net loss per share attributable to common stockholders is calculated as follows (in thousands except share and per share amounts):


	Three Months Ended March 31,
	2024			2023
Net loss attributable to common stockholders	$	(62,412	)	$	(42,393	)
Net loss per share, basic and diluted	$	(0.72	)	$	(0.59	)
Weighted-average number of common shares used in computing net loss per share, basic and diluted		86,679,282			71,972,888

The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive:


	As of March 31,
	2024		2023
Stock options		12,404,090		9,292,431
Unvested common shares		543,239		1,449,724
Restricted stock units		2,243,998		964,700
Shares committed under ESPP		100,753		47,099
Total		15,292,080		11,753,954

Balance Sheet Items - Summary of Accrued expenses and other current liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 16,273	$ 12,643
Accrued payroll related expenses	4,087	9,165
Accrued professional service expenses	3,525	3,675
Other	874	1,041
Total accrued expenses and other current liabilities	$ 24,759	$ 26,524

Significant Agreements

3 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Significant Agreements

Takeda asset purchase agreement

On December 16, 2019, a subsidiary of the Company entered into an asset purchase agreement, or the Takeda Asset Agreement, with Millennium Pharmaceuticals, Inc., a related party and an affiliate of Takeda Pharmaceutical Company Limited, or Takeda. Effective December 31, 2021, the subsidiary was merged with and into the Company, with the Company being the surviving corporation and assuming the subsidiary’s obligations under the Takeda Assets Purchase Agreement. Pursuant to the Takeda Asset Agreement, the Company purchased certain technology rights and know-how related to TAK-580 (which is now OJEMDA™ (tovorafenib)) that provides a new approach for treating patients with primary brain tumors or brain metastases of solid tumors. The Company also received clinical inventory supplies to use in the Company's research and development activities of such RAF-inhibitor and an assigned investigator clinical trial agreement. Takeda also assigned to the Company its exclusive license agreement, or the Viracta License Agreement, with Viracta Therapeutics, Inc. (f/k/a Sunesis Pharmaceuticals, Inc.), or Viracta. Takeda also granted the Company a worldwide, sublicensable exclusive license under specified patents and know-how and non-exclusive license under other patents and know-how generated by Takeda under the Takeda Asset Agreement. The Company also granted Takeda a grant back license, as defined in the Takeda Asset Agreement, which is terminable either automatically or by the Company in the event Takeda does not achieve specified development milestones within the applicable timeframes set forth under the Takeda Asset Agreement. This grant back license to Takeda was terminated at the time of conversion in connection with the Millennium Stock Exchange Agreement.

The term of the Takeda Asset Agreement will expire on a country-by-country basis upon expiration of all assigned patent rights and all licensed patent rights in such country. Takeda may terminate the Takeda Asset Agreement prior to the Company's first commercial sale of a product if the Company ceases conducting any development activities for a continuous and specified period of time and such cessation is not agreed upon by the parties and is not done in response to guidance from a regulatory authority. Additionally, Takeda can terminate the Takeda Asset Agreement in the event of the Company's bankruptcy. In the event of termination of the Takeda Asset Agreement by Takeda as a result of the Company's cessation of development or bankruptcy, all assigned patents, know-how and contracts (other than the Viracta License Agreement) will be assigned back to Takeda and Takeda will obtain a reversion license under patents and know-how generated to exploit all such terminated products.

In consideration for the sale and assignment of assets and the grant of the license under the Takeda Asset Agreement, the Company made an upfront payment of $1.0 million in cash and issued 9,857,143 shares of Series A redeemable convertible preferred stock in the Company’s subsidiary in December 2019. The fair value of issued shares was estimated as $9.9 million, based on the price paid by other investors for issued shares in the Series A financing of the Company’s subsidiary. Based on the terms of the Millennium Stock Exchange Agreement, Takeda exchanged the 9,857,143 shares of Series A redeemable convertible preferred stock of the Company’s subsidiary for 6,470,382 shares of the Company's common stock upon the effectiveness of the conversion, on May 26, 2021.

Viracta license agreement

On December 16, 2019, a subsidiary of the Company amended and restated the Viracta License Agreement that was assigned pursuant to the Takeda Asset Agreement. Effective December 31, 2021, the subsidiary was merged with and into the Company, with the Company being the surviving corporation and assuming the subsidiary’s obligations under Viracta License Agreement. Under the Viracta License Agreement, the Company received a worldwide exclusive license under specified patent rights and know-how to develop, use, manufacture, and commercialize products containing compounds binding the RAF protein family.

The term of the Viracta License Agreement will expire on a licensed product-by-licensed product and country-by-country basis upon the expiration of the Company’s obligation to pay royalties to Viracta with respect to such product in such country. The Company has the right to terminate the Viracta License Agreement with respect to any or all of the licensed products at will upon a specified notice period.

The Company paid $2.0 million upfront in cash to Viracta, which was recorded as research and development expenses as the technology does not have an alternative future use. On March 4, 2024, the Company entered into an amendment to the Viracta License Agreement. As part of the amendment, the Company made a one-time payment in March 2024 to Viracta of $5.0 million, which was recorded as research and development expenses, in exchange for reduced future payment obligations ranging from the mid-teens to the high single-digit percentage related to the future sale or use of the priority review voucher received as disclosed in Note 11.

As of March 31, 2024, the Company could be required to make additional milestone payments of up to $49.0 million upon achievement of specified development and regulatory milestones for each licensed product in two indications, with milestones payable for the second indication upon achievement of a specified milestone event being lower than milestones payable for the first indication. Subsequent to March 31, 2024, a milestone related to the Viracta License Agreement was achieved as disclosed in Note 11. Commencing on the first commercial sale of a licensed product in a country, the Company is obligated to pay tiered royalties ranging in the mid-single-digit percentages on net sales of licensed products. The obligation to pay royalties will end on a country-by-country and licensed product-by-licensed product basis commencing on the first commercial sale in a country and continuing until the later of: (i) the expiration of the last valid claim of the Viracta licensed patents, jointly owned collaboration patents or specified patents owned by the Company covering the use or sale of such product in such country, (ii) the expiration of the last statutory exclusivity pertaining to such product in such country or (iii) the tenth anniversary of the first commercial sale of such product in such country.

License agreement with Merck KGaA, Darmstadt, Germany

On February 10, 2021, a subsidiary of the Company entered into a license agreement, or the MRKDG License Agreement, with Merck KGaA, Darmstadt, Germany, a pharmaceutical corporation located in Darmstadt, Germany. Effective December 31, 2021, the subsidiary was merged with and into the Company, with the Company being the surviving corporation and assuming the subsidiary’s obligations under the MRKDG License Agreement.

Under the MRKDG License Agreement, Merck KGaA, Darmstadt, Germany granted to the Company an exclusive worldwide license, with the right to grant sublicenses through multiple tiers, under specified patent rights and know-how for the Company to research, develop, manufacture and commercialize products containing and comprising the pimasertib and MSC2015103B compounds. The Company also received clinical inventory supplies to use in its research and development activities. The Company's exclusive license grant is subject to a non-exclusive license granted by Merck KGaA, Darmstadt, Germany’s affiliate to a cancer research organization and Merck KGaA, Darmstadt, Germany retains the right to conduct, directly or indirectly, certain ongoing clinical studies relating to pimasertib. Under the MRKDG License Agreement, the Company has obligations to use commercially reasonable efforts to develop and commercialize at least two licensed products in at least two specified major market countries by the year 2029.

The term of the MRKDG License Agreement will expire on a licensed product-by-licensed product and country-by-country basis upon the expiration of the Company's obligation to pay royalties to the licensor with respect to such licensed product in such country and will expire in its entirety upon the expiration of all of the Company's payment obligations with respect to all licensed products and all countries under the MRKDG License Agreement.

In consideration for the rights granted under the MRKDG License Agreement and clinical supplies, the Company made an upfront payment of $8.0 million, which was recorded as research and development expenses, as the technology does not have an alternative future use and supplies are used for research activities. As of March 31, 2024, the Company could be required to make additional payments of up to $364.5 million based upon the achievement of specified development, regulatory, and commercial milestones, as well a high, single-digit royalty percentage on future net sales of licensed products, if any. Milestones and royalties are contingent upon future events and will be recorded when the milestones are achieved and when payments are due.

Research Collaboration and License Agreement with Sprint Bioscience AB

On August 15, 2023, the Company entered into a research collaboration and license agreement, or the Sprint License Agreement, with Sprint Bioscience AB, or Sprint, a Swedish corporation located in Huddinge, Sweden. Under the Sprint License Agreement, Sprint granted to the Company an exclusive, worldwide license, with the right to grant sublicenses through multiple tiers, to research, develop, and commercialize pharmaceutical products and to engage in research aimed at discovery, optimization and development of Vaccinia Related Kinase 1, or VRK1.

The term of the Sprint License Agreement will expire on a licensed product and country basis upon the expiration of the royalty term with respect to such licensed product and such country, unless terminated earlier. The Company has the right to terminate the Sprint License Agreement in its entirety, or on a licensed product-by-licensed product basis, at will upon a specified notice period.

The Company paid $3.0 million upfront in cash to Sprint, which was recorded as research and development expenses as the technology does not have an alternative future use. As of March 31, 2024, the Company could be required to make milestone

payments of up to $309.0 million based upon achievement of specified development, regulatory, and commercial milestones for each licensed product, as well as tiered royalties ranging in the single-digit percentages on future net sales of licensed products, if any. Milestones and royalties are contingent upon future events and will be recorded when the milestones are achieved and when payments are due.

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2024	May 01, 2024
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Registrant Name	DAY ONE BIOPHARMACEUTICALS, INC.
Entity Central Index Key	0001845337
Entity File Number	001-40431
Entity Tax Identification Number	83-2415215
Entity Incorporation, State or Country Code	DE
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Address, Address Line One	2000 Sierra Point Parkway
Entity Address, Address Line Two	Suite 501
Entity Address, City or Town	Brisbane
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94005
City Area Code	650
Local Phone Number	484-0899
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	DAWN
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		87,389,859