0000950170-24-021253 | 10-K | XBRL Viewer | Syndax Pharmaceuticals INC

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Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$ 807	$ 692
Interest receivable on investments	1,227	583
PrepaidSubscriptions	769	446
Prepaid state and local taxes	264	3
Prepaid rent	163	74
Other	63	117
Total prepaid expenses and other current assets	$ 3,293	$ 1,915

Nature of Business	12 Months Ended
Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	1. Nature of Business Syndax Pharmaceuticals, Inc. (“the Company” or “Syndax”) is a clinical-stage biopharmaceutical company developing an innovative pipeline of cancer therapies. The Company's two lead product candidates are revumenib and axatilimab. The Company is developing revumenib, a potent, selective, small molecule inhibitor of the menin-MLL binding interaction for the treatment of KMT2A rearranged, (“KMT2Ar”), also known as mixed lineage leukemia rearranged, (“MLLr”), acute leukemias including acute lymphoblastic leukemia, (“ALL”), and acute myeloid leukemia, or AML, and nucleophosmin 1, also known as NPM1, mutant AML. The Company is also exploring the use of revumenib as a treatment in solid tumors, specifically its activity in metastatic colorectal cancer. The Company is developing axatilimab, a monoclonal antibody that blocks the colony stimulating factor 1 receptor, (“CSF-1R”), in chronic graft-versus-host disease, (“cGVHD”), as well as idiopathic pulmonary fibrosis, (“IPF”). The Company plans to continue to leverage the technical and business expertise of its management team and scientific collaborators to license, acquire and develop additional therapeutics to expand its pipeline. Since its inception, the Company has devoted its efforts principally to research and development and raising capital. The Company is subject to risks common to companies in the development stage, including, but not limited to, successful development of therapeutics, obtaining additional funding, protection of proprietary therapeutics, compliance with government regulations, fluctuations in operating results, dependence on key personnel and collaborative partners, and risks associated with industry changes. The Company’s long-term success is dependent upon its ability to successfully develop and market its product candidates, expand its oncology drug pipeline, earn revenue, obtain additional capital when needed, and ultimately, achieve profitable operations. The Company anticipates that it will be several years before any of its product candidates is approved, if ever, and the Company begins to generate revenue from sales of such product candidates. Accordingly, management expects to incur substantial losses on the ongoing development of its product candidates and does not expect to achieve positive cash flow from operations for the foreseeable future, if ever. As a result, the Company will continue to require additional capital to move forward with its business plan. While certain amounts of this additional capital were raised in the past, there can be no assurance that funds necessary beyond these amounts will be available in amounts or on terms sufficient to ensure ongoing operations. The Company’s management believes that the cash, cash equivalents and short-term investments balances as of December 31, 2023, should enable the Company to maintain its planned operations for at least 12 months from the issuance date of these financial statements. The Company’s ability to fund all of its planned operations internally beyond that date, including the completion of its ongoing and planned clinical trial activities, may be substantially dependent upon whether the Company can obtain sufficient funding on terms acceptable to the Company. Proceeds from additional capital transactions would allow the Company to accelerate and/or expand its planned research and development activities. In the event that sufficient funds were not available, the Company may be required to delay or reduce expenditures to conserve cash, which could involve scaling back or curtailing development and selling, general and administrative activities. The Company is subject to challenges and risks specific to its business and ability to execute on the strategy, as well as risks and uncertainties common to companies in the pharmaceutical industry with development and commercial operations, including, without limitation, risks and uncertainties associated with: obtaining regulatory approval of the Company’s late-stage product candidate; delays or problems in the supply of the Company’s products, loss of single source suppliers or failure to comply with manufacturing regulations; identifying, acquiring or in-licensing additional products or product candidates; pharmaceutical product development and the inherent uncertainty of clinical success; and the challenges of protecting and enhancing the Company’s intellectual property rights; complying with applicable regulatory requirements.

Nature of Business

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Business

1. Nature of Business

Syndax Pharmaceuticals, Inc. (“the Company” or “Syndax”) is a clinical-stage biopharmaceutical company developing an innovative pipeline of cancer therapies. The Company's two lead product candidates are revumenib and axatilimab. The Company is developing revumenib, a potent, selective, small molecule inhibitor of the menin-MLL binding interaction for the treatment of KMT2A rearranged, (“KMT2Ar”), also known as mixed lineage leukemia rearranged, (“MLLr”), acute leukemias including acute lymphoblastic leukemia, (“ALL”), and acute myeloid leukemia, or AML, and nucleophosmin 1, also known as NPM1, mutant AML. The Company is also exploring the use of revumenib as a treatment in solid tumors, specifically its activity in metastatic colorectal cancer. The Company is developing axatilimab, a monoclonal antibody that blocks the colony stimulating factor 1 receptor, (“CSF-1R”), in chronic graft-versus-host disease, (“cGVHD”), as well as idiopathic pulmonary fibrosis, (“IPF”). The Company plans to continue to leverage the technical and business expertise of its management team and scientific collaborators to license, acquire and develop additional therapeutics to expand its pipeline.

Since its inception, the Company has devoted its efforts principally to research and development and raising capital. The Company is subject to risks common to companies in the development stage, including, but not limited to, successful development of therapeutics, obtaining additional funding, protection of proprietary therapeutics, compliance with government regulations, fluctuations in operating results, dependence on key personnel and collaborative partners, and risks associated with industry changes. The Company’s long-term success is dependent upon its ability to successfully develop and market its product candidates, expand its oncology drug pipeline, earn revenue, obtain additional capital when needed, and ultimately, achieve profitable operations. The Company anticipates that it will be several years before any of its product candidates is approved, if ever, and the Company begins to generate revenue from sales of such product candidates. Accordingly, management expects to incur substantial losses on the ongoing development of its product candidates and does not expect to achieve positive cash flow from operations for the foreseeable future, if ever. As a result, the Company will continue to require additional capital to move forward with its business plan. While certain amounts of this additional capital were raised in the past, there can be no assurance that funds necessary beyond these amounts will be available in amounts or on terms sufficient to ensure ongoing operations.

The Company’s management believes that the cash, cash equivalents and short-term investments balances as of December 31, 2023, should enable the Company to maintain its planned operations for at least 12 months from the issuance date of these financial statements. The Company’s ability to fund all of its planned operations internally beyond that date, including the completion of its ongoing and planned clinical trial activities, may be substantially dependent upon whether the Company can obtain sufficient funding on terms acceptable to the Company. Proceeds from additional capital transactions would allow the Company to accelerate and/or expand its planned research and development activities. In the event that sufficient funds were not available, the Company may be required to delay or reduce expenditures to conserve cash, which could involve scaling back or curtailing development and selling, general and administrative activities.

The Company is subject to challenges and risks specific to its business and ability to execute on the strategy, as well as risks and uncertainties common to companies in the pharmaceutical industry with development and commercial operations, including, without limitation, risks and uncertainties associated with: obtaining regulatory approval of the Company’s late-stage product candidate; delays or problems in the supply of the Company’s products, loss of single source suppliers or failure to comply with manufacturing regulations; identifying, acquiring or in-licensing additional products or product candidates; pharmaceutical product development and the inherent uncertainty of clinical success; and the challenges of protecting and enhancing the Company’s intellectual property rights; complying with applicable regulatory requirements.

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 12,000	$ 33,000

Fair Value Measurements - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Fair Value Disclosures [Abstract]
Realized gains or losses recognized on the sale or maturity of available-for-sale securities	$ 0

Loan Payable	12 Months Ended
Dec. 31, 2023
Debt Disclosure [Abstract]
Loan Payable	14. Loan Payable In February 2020, the Company entered into a loan and security agreement (the “Loan Agreement”) with Hercules Capital, Inc. (“Hercules”). In December 2021, the Company entered into Amendment No. 1 to the Company’s Loan Agreement (the “First Amendment” and the Loan Agreement, as amended, the “Amended Loan Agreement”) with several banks and financial institutions or entities from time-to-time party thereto (collectively, the “Lender”) and Hercules, in its capacity as administrative agent for itself and the Lender. On September 23, 2022, the Company made a prepayment of $21.5 million to satisfy in full all of the Company's principal and interest obligations and related fees under the Amended Loan Agreement. The payoff amount paid by the Company in connection with the termination of the Amended Loan Agreement was pursuant to a payoff letter with Hercules and included payment of (a) $1.0 million as an end-of term fee and (b) $0.4 million as a pre-payment fee. Hercules released all security interests held on the assets of the Company and its subsidiaries. The Amended Loan Agreement was fully terminated as of September 23, 2022. During the year ended December 31, 2022, the Company recognized $2.1 million, which included $0.4 million of pre-payment fee, of interest expense related to the initial advance pursuant to the Amended Loan Agreement.

Loan Payable

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Loan Payable

14. Loan Payable

In February 2020, the Company entered into a loan and security agreement (the “Loan Agreement”) with Hercules Capital, Inc. (“Hercules”). In December 2021, the Company entered into Amendment No. 1 to the Company’s Loan Agreement (the “First Amendment” and the Loan Agreement, as amended, the “Amended Loan Agreement”) with several banks and financial institutions or entities from time-to-time party thereto (collectively, the “Lender”) and Hercules, in its capacity as administrative agent for itself and the Lender.

On September 23, 2022, the Company made a prepayment of $21.5 million to satisfy in full all of the Company's principal and interest obligations and related fees under the Amended Loan Agreement. The payoff amount paid by the Company in connection with the termination of the Amended Loan Agreement was pursuant to a payoff letter with Hercules and included payment of (a) $1.0 million as an end-of term fee and (b) $0.4 million as a pre-payment fee. Hercules released all security interests held on the assets of the Company and its subsidiaries. The Amended Loan Agreement was fully terminated as of September 23, 2022.

During the year ended December 31, 2022, the Company recognized $2.1 million, which included $0.4 million of pre-payment fee, of interest expense related to the initial advance pursuant to the Amended Loan Agreement.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

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+ Details

Stock-Based Compensation - Summary of Restricted Stock Units Activity (Detail) - Non-Vested Restricted Stock Units (RSUs) [Member]

12 Months Ended

Dec. 31, 2023

$ / shares

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

Number of Shares, Unvested, Beginning balance | shares

224,788

Number of Shares, Granted | shares

308,550

^[1]

Number of Shares, Vested | shares

(9,102)

Number of Shares, Forfeited | shares

(4,800)

Number of Shares, Unvested, Ending balance | shares

519,436

Weighted Average Grant Date Fair Value, Unvested, Beginning balance | $ / shares

$ 18.02

Weighted Average Grant Date Fair Value, Granted | $ / shares

24.94

^[1]

Weighted Average Grant Date Fair Value, Vested | $ / shares

13.87

Weighted Average Grant Date Fair Value, Forfeited | $ / shares

20.36

Weighted Average Grant Date Fair Value, Unvested, Ending balance | $ / shares

$ 22.17

[1]	RSUs granted in 2023 and 2022 had a weighted average grant date fair value of $24.94 and $15.79, respectively. The fair values of RSUs vested in 2023 and 2022 totaled $126,000 and $705,000, respectively.

Supplemental Cash Flow Information - Supplemental Disclosures of Cash Flow (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplemental Disclosures of Non-Cash Investing and Financing Activities:
Interest paid	$ 0	$ 2,059	$ 1,997
Issuance costs included in accounts payable and accrued expenses	$ 250	$ 131	$ 134

Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended					12 Months Ended
	May 26, 2023	Jan. 24, 2023	Dec. 31, 2023	May 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	May 09, 2023	Apr. 12, 2023	Mar. 08, 2016
Class Of Stock [Line Items]
Common stock, shares authorized			200,000,000		100,000,000			200,000,000	100,000,000
Proceeds from issuance of common stock in follow-on public stock offering, net						$ 81,200
Common stock, new shares issued		86,000	12,432,431		7,840,909	3,802,144
Common Stock, Capital Shares Reserved for Future Issuance			23,906,260					23,906,260
Number Of Pre Funded Warrants Exercised For Common Stock		85,998									498,137	272,996
Offering price			$ 18.5		$ 22
Gross proceeds from offering			$ 230,000		$ 172,500
Common stock, par value			$ 0.0001		$ 0.0001			$ 0.0001	$ 0.0001
Common stock issued at fair value										$ 24,848
Incyte Collaboration Agreement and Share Purchase Agreement [Member]
Class Of Stock [Line Items]
Proceeds from issuance of common stock in follow-on public stock offering, net						$ 35,000
Common stock, new shares issued						1,421,523
Common stock issued at fair value						$ 24,800		$ 14,000	$ 10,500
Pre-Funded Warrants [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance			285,714					285,714				273,000
Number Of Pre Funded Warrants Exercised For Common Stock											498,142
Warrants issued (in shares)						1,142,856				1,142,856
Offering price						$ 17.4999
Common Stock [Member]
Class Of Stock [Line Items]
Common stock, new shares issued										1,421,523
Series Warrants [Member]
Class Of Stock [Line Items]
Offering price						$ 17.5
At The Market Equity Offering Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from issuance of common stock in follow-on public stock offering, net	$ 25,000							$ 42,100
Common stock, new shares issued								2,719,744
Cowen and Company LLC [Member] \| At The Market Equity Offering Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from issuance of common stock in follow-on public stock offering, net				$ 200,000			$ 75,000
Initial Public Offering [Member]
Class Of Stock [Line Items]
Common stock, shares authorized													200,000,000

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 295,394	$ 74,356
Short-term investments	275,304	401,446
Short-term deposits	6,885	8,595
Collaboration receivable, net	0	3,474
Prepaid expenses and other current assets	3,293	1,915
Total current assets	580,876	489,786
Long-Term Investments	29,829	5,469
Property and equipment, net	8	20
Right-of-use asset	1,487	1,039
Restricted cash	217	115
Other assets	463	807
Total assets	612,880	497,236
Current liabilities:
Accounts payable	9,961	4,350
Collaboration payable, net	7,232	0
Accrued expenses and other current liabilities	39,856	24,276
Current portion of right-of-use liability	1,035	434
Current Portion Of Capital Lease	12	5
Total current liabilities	58,096	29,065
Long-term liabilities:
Right-of-use liability, less current portion	578	709
Capital Lease Less Current Portion	10	13
Total long-term liabilities	588	722
Total liabilities	58,684	29,787
Commitments and contingencies (Note 16)
Stockholders' equity:
Preferred stock, $0.001 par value, 10,000,000 shares authorized; 0 shares outstanding at December 31, 2023 and December 31, 2022	0	0
Common stock, $0.0001 par value, 200,000,000 and 100,000,000 shares authorized at December 31, 2023 and December 31, 2022, respectively; 84,826,632 and 68,111,385 shares outstanding at December 31, 2023 and December 31, 2022, respectively	8	7
Additional paid-in capital	1,456,370	1,161,288
Accumulated other comprehensive income (loss)	218	(806)
Accumulated deficit	(902,400)	(693,040)
Total stockholders' equity	554,196	467,449
Total liabilities and stockholders' equity	$ 612,880	$ 497,236

Loan Payable - Additional Information (Detail) - USD ($) $ in Thousands		12 Months Ended
	Sep. 23, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Payment on term loan		$ 0	$ 20,996	$ 0
Prepayment Fee			400
Hercules [Member] \| Loan Agreement [Member]
Debt Instrument [Line Items]
Payment on term loan	$ 21,500
Payment for end-of term fees	1,000
Payments for Other Fees	$ 400
Interest expense related to the loan agreement			$ 2,100

- 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.

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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Collaborative Research and License Agreements - Additional Information (Detail) - USD ($)		1 Months Ended				12 Months Ended
	Jan. 24, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2021
Research And Development Arrangement Contract To Perform For Others [Line Items]
Proceeds from Incyte Share Purchase Agreement shares	86,000	12,432,431	7,840,909	3,802,144
Aggregate purchase price				$ 81,200,000
Common stock issued at fair value						$ 24,848,000
Collaboration receivable, net		$ 0	$ 3,474,000
Incyte Agreement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Proceeds from Incyte Share Purchase Agreement shares				1,421,523
Purchase price per share				$ 24.62		$ 24.62
Aggregate purchase price				$ 35,000,000
Common stock issued at fair value				24,800,000
Allocated consideration received to derivative liability				600,000
Upfront payments returned upon termination of agreement				117,000,000
Total transaction price				126,600,000
Estimated standalone selling price of license agreement				126,600,000
Revenue recognized upon transfer of license agreement						$ 126,600,000
Collaboration receivable, net		2,200,000
Collaboration expense due to counterparty		$ 9,500,000
Incyte Agreement [Member] \| Non-Refundable Cash Payments [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront milestone payable				117,000,000	$ 117,000,000
Incyte Agreement [Member] \| Maximum [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential milestone payments to be made				220,000,000		220,000,000
Commercialization milestones and tiered royalties				$ 230,000,000		$ 230,000,000
Incyte Agreement [Member] \| Global and U.S. [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Development costs associated with clinical trials					45.00%
Incyte Agreement [Member] \| Global and U.S. [Member] \| Incyte Corporation [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Development costs associated with clinical trials					55.00%
Incyte Agreement [Member] \| Ex-U.S. Countries [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Development costs associated with clinical trials					100.00%

Stock-Based Compensation - Additional Information (Detail)

1 Months Ended

3 Months Ended

12 Months Ended

Jan. 01, 2024

Oct. 31, 2021

USD ($)

Employee

Sep. 30, 2015

Mar. 31, 2023

Dec. 31, 2023

USD ($)

$ / shares

Dec. 31, 2022

USD ($)

$ / shares

Dec. 31, 2021

USD ($)

$ / shares

Dec. 31, 2019

Dec. 31, 2017

Dec. 06, 2023

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

Shares available for issuance

23,906,260

Share-based compensation, stock options granted

3,800,691

Share-based compensation, stock options vested

10,684,858

Stock compensation expense | $

$ 30,951,000

$ 16,019,000

$ 13,317,000

Weighted-average grant date fair value of options granted | $ / shares

$ 16.2

$ 12.64

$ 14.7

Stock options exercised, shares

662,042

1,300,000

842,424

Stock options exercised | $

$ 5,128,000

$ 11,459,000

$ 6,336,000

Intrinsic value of options exercised | $

9,500,000

17,000,000

10,100,000

Contributions by the company | $

$ 1,300,000

712,000

444,000

2019 Performance Awards

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

Stock compensation expense | $

128,000

2019 Performance Awards | Employees [Member]

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

Stock option granted to certain employees

583,000

Two Thousand Twenty Three Performance Awards [Member] | Employees [Member]

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

Stock option granted to certain employees

129,550

2022 Performance Awards [Member]

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

Share-based compensation, stock options vested

140,000

Share-based compensation, stock options cancelled

Stock compensation expense | $

$ 258,000

$ 479,000

Stock option granted to certain employees

140,000

Restricted Stock Units (RSUs) [Member]

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

Vesting period, description

one – year anniversary date of the related grant or ii) 25% on each anniversary for 4 years

Restricted stock units granted

^[1]

308,550

Fair value of restricted stock units vested | $

$ 126,000

$ 705,000

Restricted stock units vested

9,102

Weighted average grant date fair value per share | $ / shares

$ 24.94

$ 15.79

Maximum [Member]

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

Vesting period

4 years

Minimum [Member]

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

Vesting period

3 years

2015 Plan [Member]

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

Common stock reserved for issuance

1,750,000

Shares available for issuance

2,191,732

Common stock outstanding

4.00%

2015 Plan [Member] | Maximum [Member]

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

Shares available for issuance

3,393,065

2023 Inducement Plan [Member]

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

Common stock reserved for issuance

1,900,000

1,100,000

Shares available for issuance

1,211,650

2007 and 2015 [Member]

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

Unrecognized compensation expense related to stock option | $

$ 74,800,000

Weighted average period to recognize compensation expense

2 years 9 months 18 days

2007 Plan [Member]

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

Share-based compensation, stock options vested

34,728

Number of employees retirement | Employee

Stock compensation expense | $

$ 800,000

Employee Stock Purchase Plan [Member]

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

Stock compensation expense | $

$ 308,000

$ 166,000

$ 175,000

Number of shares issued under plan

34,797

28,999

Expiration of the ESPP

1.00%

expiration of the ESPP shares

250,000

Employee Stock Purchase Plan [Member] | Subsequent Event [Member]

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

Periodic payroll deductions offering periods

6 months

Offering period discount rate

15.00%

Employee Stock Purchase Plan [Member] | Maximum [Member]

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

Shares authorized for issuance

250,000

Employee Stock Purchase Plan [Member] | Maximum [Member] | Subsequent Event [Member]

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

Shares available for issuance

1,982,614

[1]	RSUs granted in 2023 and 2022 had a weighted average grant date fair value of $24.94 and $15.79, respectively. The fair values of RSUs vested in 2023 and 2022 totaled $126,000 and $705,000, respectively.

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Share Based Compensation Expense Related to Issuance of Stock Option Awards to Employees and Non Employees Related to Employee Stock Purchase Plan

The Company recognized stock-based compensation expense related to the issuance of stock option awards to employees and non-employees and related to the Employee Stock Purchase Plan in the consolidated statements of operations as follows (in thousands):


	Years Ended December 31,
	2023		2022		2021
Research and development	$	14,147	$	6,016	$	4,398
Selling, general and administrative		16,804		10,003		8,919
Total	$	30,951	$	16,019	$	13,317

Grant Date Fair Values of Options Issued to Employees and Non-employees Estimated Using Black-Scholes Option Pricing Model

The grant date fair values of options issued to employees and non-employees were estimated using the Black-Scholes option-pricing model with the following assumptions:


	Years Ended December 31,
	2023			2022			2021
Expected term (in years)		6.03			6.04			6.02
Volatility rate		75.13	%		77.87	%		85.84	%
Risk-free interest rate		3.65	%		2.52	%		0.67	%
Expected dividend yield		0.00	%		0.00	%		0.00	%

Summary of Employee and Non-Employee Option Activity

A summary of employee and non-employee option activity under the Company’s equity award plans is presented below (in thousands, except share data):


	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Outstanding—January 1, 2023		7,981,677		$	14.42		7.3	$	88,016
Granted		3,800,691		$	23.75
Exercised		(662,042	)	$	8.08
Cancelled, forfeited or expired		(435,468	)	$	23.14
Outstanding—December 31, 2023		10,684,858		$	17.78		7.3	$	55,091
Exercisable—December 31, 2023		5,468,638		$	14.32		5.7	$	43,160
Options vested, or expected to vest—December 31, 2023		10,684,858		$	17.78		7.3	$	55,091

Summary of Restricted Stock Units Activity

The following table summarizes our RSU activity:


	Number of Shares			Weighted Average Grant Date Fair Value
Unvested—December 31, 2022		224,788		$	18.02
Granted (1)		308,550		$	24.94
Vested		(9,102	)	$	13.87
Cancelled/Forfeited		(4,800	)	$	20.36
Unvested—December 31, 2023		519,436		$	22.17

(1) RSUs granted in 2023 and 2022 had a weighted average grant date fair value of $24.94 and $15.79, respectively. The fair values of RSUs vested in 2023 and 2022 totaled $126,000 and $705,000, respectively.

Fair Value Measurements - Schedule of Fair Values of Financial Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 275,304	$ 401,446
Long-term investments	29,829	5,469
Carrying Value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	295,394	74,356
Short-term investments	275,304	401,446
Long-term investments	29,829	5,469
Total assets	600,527	481,271
Quoted Prices in Active Markets Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	295,394	59,496
Total assets	295,394	59,496
Significant Other Observable Inputs Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		14,860
Short-term investments	275,304	401,446
Long-term investments	29,829	5,469
Total assets	$ 305,133	$ 421,775

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Common stock, par value	$ 0.0001	$ 0.0001
At-the-market, offering expenses			$ 159
Direct Placement Offering [Member]
Direct offering, offering expenses	$ 14,044	$ 10,535	$ 5,332
Follow-on Public Offering One [Member]
At-the-market, offering expenses	$ 1,086	$ 600

Significant Agreements - Additional Information (Detail) - USD ($)	1 Months Ended					3 Months Ended			12 Months Ended
	Jul. 31, 2020	Oct. 31, 2017	Jul. 31, 2016	Dec. 31, 2007	Mar. 31, 2007	Jun. 30, 2022	Dec. 31, 2017	Sep. 30, 2016	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense									$ 163,032,000	$ 118,499,000	$ 88,248,000
Accrued expenses									39,856,000	$ 24,276,000
Allergan License Agreement [Member] \| Vitae Pharmaceuticals Inc [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront milestone payable							$ 5,000,000
Potential milestone payments to be made		$ 99,000,000
Aggregate potential milestone payable		$ 70,000,000
License expiration year		10 years
Research and development expense												$ 5,000,000
Development and regulaotry milestones expenses														$ 8,000,000
Milestone expenses paid														$ 2,000,000
UCB License Agreement [Member] \| UCB Biopharma [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront milestone payable								$ 5,000,000
Potential milestone payments to be made			$ 119,500,000
Aggregate potential milestone payable			$ 250,000,000
License expiration year			10 years
Research and development expense	$ 6,000,000								$ 10,000,000				$ 5,000,000
Milestone payment payable						$ 5,800,000
License Agreement [Member] \| Bayer Pharma AG [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				$ 2,000,000
Up-front license fee paid					$ 2,000,000
License Agreement [Member] \| Bayer Pharma AG [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate payment obligation					$ 150,000,000

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

16. Commitments and Contingencies

License Agreements

Incyte – In September 2021, the Company entered into the Incyte Agreement and Incyte Stock Purchase Agreement. Under the terms of the Incyte Agreement, Incyte will receive exclusive commercialization rights of axatilimab outside of the United States. In the United States, Incyte and the Company will co-commercialize axatilimab, with the Company having the right to co-promote the product with Incyte. In exchange for these rights, Incyte agreed to pay a non-refundable cash payment of $117 million and in addition a $35 million equity investment. In certain cases, the Company is required to assist Incyte and is responsible for 45% of development costs associated with global and U.S. specific clinical trials.

Eddingpharm—In April 2013, the Company entered into a License and Development Agreement (the “Eddingpharm License Agreement”) and a Series B-1 purchase agreement (the “Eddingpharm Purchase Agreement”) with Eddingpharm International Company Limited (“Eddingpharm”). Under the terms of the Eddingpharm License Agreement, Eddingpharm, in exchange for rights to develop and commercialize entinostat in China and certain other Asian countries, purchased $5.0 million of Series B-1 and agreed to make certain contingent milestone and royalty payments based on revenue targets. In certain cases, the Company is required to assist Eddingpharm, and Eddingpharm is required to reimburse the Company for any out-of-pocket expenses incurred in providing this assistance, including reimbursement for person-hours above a certain cap.

From time to time, the Company may be subject to various claims and proceedings in the ordinary course of business. If the potential loss from any claim, asserted or unasserted, or proceeding is considered probable and the amount is reasonably estimable, the Company will accrue a liability for the estimated loss. There were no contingent liabilities recorded as of December 31, 2023, or 2022.

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (209,360)	$ (149,338)	$ 24,926
Adjustments to reconcile net loss to net cash provided (used in) operating activities:
Depreciation	12	33	43
(Accretion) amortization of investments	(14,803)	(3,382)	644
Non-cash operating lease expense	739	421	413
Non-cash interest income (expense)	0	1,103	(225)
Changes in fair value of derivative liability	0	(187)	(389)
Stock-based compensation	30,951	16,019	13,317
Other	0	0	(1)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	676	(2,972)	(1,394)
Collaboration receivable, net	10,706	(3,474)	0
Accounts payable	5,611	(1,319)	2,161
Deferred revenue	0	0	(13,133)
Accrued expenses and other liabilities	14,867	9,421	2,769
Net cash (used in) provided by operating activities	(160,601)	(133,675)	29,131
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	0	0	(129)
Proceeds from sales of equipment	0	225	0
Purchases of short and long-term investments	(354,606)	(495,346)	(294,719)
Proceeds from sales and maturities of short-term investments	472,215	308,933	253,975
Net cash provided by (used in) investing activities	117,609	(186,188)	(40,873)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment on term loan	0	(20,996)	0
Proceeds from ESPP	910	401	367
Proceeds from stock option exercises	5,128	11,459	6,336
Net cash provided by financing activities	264,132	172,254	118,464
NET (DECREASE) INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	221,140	(147,609)	106,722
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—beginning of year	74,471	222,080	115,358
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—end of year	295,611	74,471	222,080
Cash and cash equivalents	295,394	74,356	221,965
Restricted cash	217	115	115
Incyte Share Purchase Agreement [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock in follow-on public stock offering, net	0	0	24,848
Follow-on Public Offerings [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock in follow-on public stock offering, net	215,955	161,965	81,206
At-the-Market Offering [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock in follow-on public stock offering, net	42,139	19,425	5,131
Derivative Liability [Member] \| Incyte Share Purchase Agreement [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock in follow-on public stock offering, net	$ 0	$ 0	$ 576

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues:
License fees	$ 0	$ 0	$ 139,709
Total revenues	$ 0	$ 0	$ 139,709
Type of revenue [extensible list]	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember
Operating expenses:
Research and development	$ 163,032	$ 118,499	$ 88,248
Selling, general and administrative	66,922	33,258	25,241
Total operating expenses	229,954	151,757	113,489
(Loss) income from operations	(229,954)	(151,757)	26,220
Other income (expense):
Interest expense	(208)	(3,137)	(1,899)
Interest income	21,163	5,872	403
Other (expense) income, net	(361)	(316)	202
Total other income (expense)	20,594	2,419	(1,294)
Net (loss) income	(209,360)	(149,338)	24,926
Net (loss) income attributable to common stockholders	$ (209,360)	$ (149,338)	$ 24,926
Net (loss) income Per Share:
Basic (loss) earnings per share attributable to common stockholders	$ (2.98)	$ (2.46)	$ 0.48
Diluted (loss) earnings per share attributable to common stockholders	$ (2.98)	$ (2.46)	$ 0.46
Weighted-average common shares used in calculating:
Basic (loss) earnings per share attributable to common stockholders	70,370,519	60,760,906	52,064,809
Diluted (loss) earnings per share attributable to common stockholders	70,370,519	60,760,906	53,622,904

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2023
Accounting Policies [Abstract]
Estimates	Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of costs and expenses during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis. The Company’s actual results may differ from these estimates under different assumptions or conditions. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s consolidated financial statements.
Cash Equivalents	Cash Equivalents Cash equivalents include all highly liquid investments maturing within 90 days or less from the date of purchase. Cash equivalents include money market funds, corporate debt securities, U.S. government agency notes, and overnight deposits.
Restricted Cash	Restricted Cash The Company classifies as restricted cash all cash pledged as collateral to secure long-term obligations and all cash whose use is otherwise limited by contractual provisions. Amounts are reported as non-current unless restrictions are expected to be released in the next 12 months.
Marketable Securities	Marketable Securities All investments in marketable securities are classified as available-for-sale and are reported at fair value with unrealized gains and losses excluded from earnings and reported net of tax in accumulated other comprehensive income, which is a component of stockholders’ equity. Unrealized losses that are determined to be other-than-temporary, based on current and expected market conditions, are recognized in earnings. Declines in fair value determined to be credit related are charged to earnings. The cost of marketable securities sold is determined by the specific identification method.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision-making group, in making decisions regarding resource allocation and assessing performance. The Company has one operating segment.
Concentrations of Credit Risk	Concentrations of Credit Risk Cash and cash equivalents, restricted cash, and short and long-term investments are financial instruments that potentially subject the Company to concentrations of credit risk. Substantially all of the Company’s cash, cash equivalents, and short and long-term investments were deposited in accounts at two financial institutions, and at times, such deposits may exceed federally insured limits. The Company has not experienced any losses in such accounts, and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company’s available-for-sale investments primarily consist of government money market funds, corporate debt securities, commercial paper, credit card asset-backed securities and overnight deposits and potentially subject the Company to concentrations of credit risk.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the assets (three to five years). Assets under capital leases are amortized over the shorter of their useful lives or lease term using the straight-line method. Major replacements and improvements are capitalized, while general repairs and maintenance are expensed as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. When such events occur, the Company compares the carrying amounts of the assets to their undiscounted expected future cash flows. If this comparison indicates that there is impairment, the amount of impairment is calculated as the difference between the carrying value and fair value. To date, no such impairments have been recognized.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. The Company recognize revenue following the five – step model prescribed under FASB Accounting Standards Codification (ASC 606), Revenue from Contracts with Customers: (i) identify contract(s) with customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy the performance obligations. Licenses of Intellectual Property: Revenue from non-refundable, up-front fees allocated to the licenses related to the Company's intellectual property, are recognized as the license is transferred to the customer and the customer is able to use and benefit from the license. This generally takes place over the related know-how transfer period, or if applicable, over the term of transfer of future updates to the intellectual property. Development Milestone Payments: The Company evaluates whether milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license fees and earnings in the period of adjustment. Commercial Milestone Payments and Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of commercial sales, and the license is deemed to be the predominant item to which the royalties or commercial milestones relate, the Company will recognize revenue at the later of when the related sales occur or when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date no commercial milestone payments or royalties have been achieved. When no performance obligations are required of the Company, or following the completion of the performance obligation period, such amounts are recognized as revenue upon transfer of control of the goods or services to the customer. Generally, all amounts received or due other than sales-based milestones and royalties are classified as license fees. Deferred revenue arises from amounts received in advance of the culmination of the earnings process and is recognized as revenue in future periods as performance obligations are satisfied. Deferred revenue expected to be recognized within the next twelve months is classified as a current liability. Upfront payment contract liabilities resulting from the Company’s license agreements do not represent a financing component as the payment is not financing the transfer of goods or services, and the technology underlying the licenses granted reflects research and development expenses already incurred by the Company. For additional information on our collaboration and license arrangements, please read Note 4, Collaborative Research and License Agreements, to these consolidated financial statements.
Research and Development	Research and Development Research and development costs are expensed as incurred. Research and development expenses include payroll and personnel expenses, consulting costs, external contract research and development expenses, and allocated overhead, including rent, equipment depreciation, and utilities. Research and development costs that are paid in advance of performance are capitalized as a prepaid expense and amortized over the service period as the services are provided. The Company expenses upfront license payments related to acquired technologies that have not yet reached technological feasibility and have no alternative future use. In instances where the Company enters into cost-sharing arrangements, all research and development costs reimbursed by the collaborators are accounted for as reductions to research and development expense. During the years ended December 31, 2023 and 2022, the Company has incurred external costs related to Incyte cost-sharing collaboration. During the year ended December 31, 2021, the Company incurred no external costs related to cost-sharing collaborations.
Clinical Costs	Clinical Costs Clinical study and trial costs are a component of research and development expenses. The Company expenses clinical trial activities performed by third parties based on an evaluation of the progress to completion of specific contract tasks using data such as patient enrollment, clinical site activations, or other information provided to us by our vendors. Depending on the progression of the contract and timing of invoicing and payment the research and development expense can be an accrued expense or a prepaid expense. Prepaid clinical study and trial costs are included in short-term deposits on the accompanying consolidated balance sheet.
Income Taxes	Income Taxes The Company records deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the Company’s financial statement carrying amounts and the tax bases of assets and liabilities and for loss and credit carryforwards using enacted tax rates expected to be in effect in the years in which the differences reverse. A valuation allowance is provided to reduce the net deferred tax assets to the amount that will more likely than not be realized. The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more-likely-than-not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes.
Guarantees and Indemnifications	Guarantees and Indemnifications As permitted under Delaware law, the Company indemnifies its officers, directors, and employees for certain events or occurrences that happen by reason of the relationship with, or position held at, the Company. The Company has standard indemnification arrangements under office leases (as described in Note 5, Leases to these consolidated financial statements) that require it to indemnify the landlord against all costs, expenses, fines, suits, claims, demands, liabilities, and actions directly resulting from any breach, violation, or nonperformance of any covenant or condition of the Company’s lease. Through December 31, 2023, the Company had not experienced any losses related to these indemnification obligations and no claims were outstanding. The Company does not expect significant claims related to these indemnification obligations, and consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for all stock option awards granted to employees and non-employees using a fair value method. Stock-based compensation is measured at the grant date fair value of the stock option grants and is recognized over the requisite service period of the awards (usually the vesting period) on a straight-line basis. For equity awards that have a performance condition, the Company recognizes compensation expense based on its assessment of the probability that the performance condition will be achieved. The Company accounts for forfeitures as they occur.
(Loss) Earnings Per Share	(Loss) Earnings Per Share Basic earnings per share is computed by dividing undistributed net income attributable to Syndax by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed based on the treasury method by dividing net income by the weighted-average number of common shares outstanding during the period plus potentially dilutive common equivalent shares outstanding.
Recently Issued and Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board FASB or other accounting standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed below, we do not believe that the adoption of recently issued standards have or may have a material impact on our consolidated financial statements or disclosures.

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ (209,360)	$ (149,338)	$ 24,926

- Definition

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

+ References

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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Increase (decrease) in valuation allowance	$ 72,900	$ 35,900
Valuation allowance for deferred tax assets, description	The Company has provided a valuation allowance for the full amount of the net deferred tax assets as the realization of the deferred tax assets is not determined to be more likely than not. The valuation allowance increased by $72.9 million in 2023 due to the increase in deferred tax assets, primarily driven by the generation of net operating losses and capitalized research expenses, and capitalized start-up costs. The valuation allowance increased by $35.9 million in 2022 due to the increase in deferred tax assets, primarily driven by the generation of net operating losses and capitalized start-up costs, partially offset by a decrease to other deferred tax assets.
Federal net operating losses	$ 136,400
State net operating losses	63,500
Uncertain tax positions	100
Deferred tax asset	79,600
Deferred tax assets, Expenses required to be capitalized	53,700
Internal Revenue Service [Member]
Income Taxes [Line Items]
Interest or penalties recorded during the period	0	$ 0
Unrecognized income tax benefits that would affect effective tax rate	$ 0
Federal [Member]
Income Taxes [Line Items]
Operating loss carryforward expiration period	2026
Deferred tax assets research credits	$ 8,900
Deferred tax assets research credits expiration period	2024
Federal [Member] \| Indefinite Carryforward Period [Member]
Income Taxes [Line Items]
Federal net operating losses	$ 114,300
State net operating losses	900
Federal [Member] \| Begin to Expire in 2026 [Member]
Income Taxes [Line Items]
Federal net operating losses	22,100
State [Member]
Income Taxes [Line Items]
Current State Income Expense	$ 300
Operating loss carryforward expiration period	2026
Deferred tax assets research credits	$ 3,800
Deferred tax assets research credits expiration period	2024
State [Member] \| Begin to Expire in 2026 [Member]
Income Taxes [Line Items]
Federal net operating losses	$ 62,600

Leases

12 Months Ended

Dec. 31, 2023

Lessee Disclosure [Abstract]

Leases

5. Leases

Leases

The Company accounts for leases in accordance with ASC 842, Leases, and determines whether an arrangement is a lease at inception. Operating lease right-of-use (“ROU”) assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. Lease agreements with lease and non-lease components are accounted for separately. For leases that do not provide an implicit rate, the Company uses the incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The ROU asset also includes any lease

payments made and excludes lease incentives and initial direct costs incurred. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Leases with an initial term of 12 months or less are not recorded on the balance sheet as the Company has elected to apply the short-term lease exemption. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term.

The Company identified three existing long-term building leases under ASC 842 that are classified as operating leases. In September 2016, the Company entered into a five-year operating lease for 12,207 square feet of office space in Waltham, MA, with a lease commencement date of March 1, 2017. On August 17, 2021, the Company signed a 36-month extension to the lease for the Waltham, MA office with aggregate payments of $1.6 million, with a lease commencement date of March 1, 2022.

In December 2015, the Company entered into a 62-month operating lease for 4,039 square feet of space in New York, NY, which commenced on January 1, 2016. In February 2021, the Company signed an 18-month extension to the lease for the New York office, which commenced on March 1, 2021. In August 2022, the Company signed a 36-month extension to the lease for the New York office, with aggregate payments of $689,000, with a lease commencement date of September 1, 2022.

In May 2023, the Company entered into a 27-month operating lease for an additional 12,217 square feet of space in New York, NY, with aggregate payments of $1.6 million, with a lease commencement date of June 1, 2023.

The remaining lease terms as of December 31, 2023, for the facility in Waltham, MA and the two facilities in New York, NY, were 14 months and 20 months, respectively.

As of December 31, 2023, the consolidated balance sheet includes a $1.5 million operating lease ROU asset and a $1.6 million ROU liability. The Company used a weighted average discount rate of 14% to calculate its lease obligations, and an increase or decrease in the rate does not have a significant impact on the ROU asset or ROU liability. The ROU asset is amortized on a straight-line basis over the remainder of the lease term. For the year ended December 31, 2023, the Company recorded approximately $743,000 in operating lease expense and made approximately $924,000 in lease payments.

Future minimum lease payments under the Company’s operating leases, were as follows:


Maturity of lease liabilities	As of
(in thousands)	December 31, 2023
2024	$	1,196
2025		606
Thereafter		—
Total lease payments	$	1,802
Less: imputed interest		(189	)
Total operating lease liability	$	1,613

Future minimum lease payments under the Company’s capital leases as of December 31, 2023 and 2022, were $25,864 and $22,441, respectively.

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Lessee Disclosure [Abstract]

Summary of Future Minimum Lease Payments under Operating Leases

Future minimum lease payments under the Company’s operating leases, were as follows:


Maturity of lease liabilities	As of
(in thousands)	December 31, 2023
2024	$	1,196
2025		606
Thereafter		—
Total lease payments	$	1,802
Less: imputed interest		(189	)
Total operating lease liability	$	1,613

Common Stock (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Schedule of Common Stock Reserved for Future Issuance

The Company has reserved for future issuance the following shares of common stock pursuant to the following outstanding securities or equity plans:


	December 31, 2023
Common stock issuable under pre-funded warrants		285,714
At-the-market program		7,280,256
RSUs and Options to purchase common stock		11,204,294
Equity plans		3,403,382
2015 Employee Stock Purchase Plan (the “ESPP”)		1,732,614
Total		23,906,260

Property and Equipment, net

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment, net

8. Property and Equipment, net

Property and equipment, net, consisted of the following (in thousands):


	December 31,
	2023			2022
Equipment	$	84		$	84
Leasehold improvements		167			167
Furniture and fixtures		134			134
Office and computer equipment		34			34
Total property and equipment		419			419
Accumulated depreciation		(411	)		(399	)
Property and equipment, net	$	8		$	20

Depreciation expense was $12,000 and $33,000 for the years ended December 31, 2023 and 2022, respectively.

Supplemental Cash Flow Information

12 Months Ended

Dec. 31, 2023

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

17. Supplemental Cash Flow Information


	Years Ended December 31,
		2023		2022	2021
	(In thousands)
Supplemental Disclosures of Cash Flow Information
Interest paid	$	—	$	2,059	$	1,997
Supplemental Disclosures of Non-Cash Investing and Financing Activities:
Issuance costs included in accounts payable and accrued expenses	$	250	$	131	$	134

Income Taxes - Summary of Reconciliation of Company's Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefit--beginning of year	$ 143	$ 163	$ 163
Decreases related to prior period positions	0	(20)	0
Unrecognized tax benefit--end of year	$ 143	$ 143	$ 163

Stock-Based Compensation

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

13. Stock-Based Compensation

In September 2015, the Company’s board of directors adopted its 2015 Omnibus Incentive Plan (“2015 Plan”), which was subsequently approved by its stockholders and became effective upon the closing of the IPO on March 8, 2016. The 2015 Plan replaced the 2007 Stock Plan (“2007 Plan”) and allows for the granting of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock, unrestricted stock, stock units, dividend equivalent rights, performance awards, annual incentive awards, and other equity-based awards to the Company’s executives and other employees, non-employee members of the board of directors, and consultants of the Company. Any options or awards outstanding under the Company’s 2007 Plan remain outstanding and continue to govern the terms of any equity grants that remain outstanding under the 2007 Plan. Any shares of common stock related to awards outstanding under the 2007 Plan that thereafter terminate by expiration, forfeiture, cancellation or otherwise without the issuance of such shares will be added to, and included in, the 2015 Plan reserve amount. The Company initially reserved 1,750,000 shares of its common stock for the issuance of awards under the 2015 Plan. The 2015 Plan provides that the number of shares reserved and available for issuance under the 2015 Plan will automatically increase each January 1, beginning on January 1, 2017, by 4% of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Company’s board of directors. On January 1, 2024, the shares available for issuance under the 2015 was increased to 3,393,065.

In February 2023, the Company's board of directors adopted its 2023 Inducement Plan (the “2023 Inducement Plan”), which became effective March 1, 2023. The 2023 Inducement Plan allows for the granting of nonqualified stock options, restricted stock units, and other awards under the 2023 Inducement Plan to persons not previously an employee or director of the Company, or following a bona fide period of non-employment, an inducement material to such persons entering into employment with the Company. The Company initially reserved 1,900,000 shares of its common stock for the issuance of awards under the 2023 Inducement Plan. On December 6, 2023, the Company's board of directors increased the reserve by 1,100,000 shares.

As of December 31, 2023, there were 2,191,732 shares available for issuance under the 2015 Plan and 1,211,650 shares available for issuance under the 2023 Inducement Plan.


	Years Ended December 31,
	2023		2022		2021
Research and development	$	14,147	$	6,016	$	4,398
Selling, general and administrative		16,804		10,003		8,919
Total	$	30,951	$	16,019	$	13,317

Stock Options and Restricted Stock Units

As of December 31, 2023, there was $74.8 million of unrecognized compensation cost related to employee and non-employee unvested stock options and RSUs granted under the 2015 Plan and the 2023 Inducement Plan, which is expected to be recognized over a weighted-average remaining service period of 2.8 years. Stock compensation costs have not been capitalized by the Company.

Our stock-based awards are subject to either service or performance-based vesting conditions. Compensation expense related to awards to employees, directors and non-employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards to employees with performance-based vesting conditions is recognized based on the grant date fair value over the requisite service period using the straight-line method to the extent achievement of the performance condition is probable.

In 2019, the Company granted to certain employees 583,000 stock options that contain performance-based vesting criteria (“2019 Performance Awards”), primarily related to the achievement of certain clinical and regulatory development milestones related to product candidates. In the fourth quarter of 2020, one performance milestone, for the 2019 Performance Awards, was achieved. The Company recorded approximately $128,000 of stock compensation related to the achievement of the performance milestone for years ended December 31, 2022. As of December 31, 2022, all other performance milestones were not achieved, and the associated awards have been cancelled.

In 2022, the Company granted to certain employees 140,000 performance-based stock options (“2022 Performance Awards”), primarily related to the achievement of certain regulatory development milestones related to product candidates. Recognition of stock-based compensation expense associated with these performance-based stock options commences when the performance condition is considered probable of achievement, using management’s best estimates, which consider the inherent risk and uncertainty regarding the future outcomes of the milestones.

In the first quarter of 2022, management estimated one of the milestones, for the 2022 Performance Awards, was probable of achievement. The Company recorded approximately $258,000 and $479,000 of stock compensation expense for these awards for the year ended December 31, 2023 and 2022, respectively. As of December 31, 2023, 140,000 stock options outstanding were unvested, and no options had been cancelled.

In the first quarter of 2023, the Company granted to certain employees 129,550 performance-based RSUs, primarily related to the achievement of certain regulatory development milestones related to product candidates. Recognition of stock-based compensation expense associated with these performance-based RSUs commences when the performance condition is considered probable of achievement, using management’s best estimates, which consider the inherent risk and uncertainty regarding the future outcomes of the milestones.

In October 2021, in connection with the retirement of two employees, the Company entered into severance and consulting agreements. Under these agreements the Company extended the vesting term for an aggregate of 34,728 unvested options, which would not have otherwise vested and extended the exercise period of the vested options post termination of the consulting agreement. The Company accounted for the change as a modification of an equity award under ASC 718. As a result of the modifications, the Company recognized approximately $0.8 million of incremental stock compensation expense in 2021.

The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model with the weighted-average assumptions noted in the table below. Expected volatility for the Company’s common stock was determined based on an average of the historical volatility of the Company's public stock price. The Company estimated the expected term of its employee stock options using the “simplified” method, whereby, the expected term equals the average of the vesting term and the original contractual term of the option. The contractual life of the option was used for the estimated life of the non-employee grants. The assumed dividend yield is based upon the Company’s expectation of not paying dividends in the foreseeable future. The risk-free interest rate for periods within the expected life of the option is based upon the U.S. Treasury yield curve in effect at the time of grant. The Company accounts for forfeitures when they occur. The grant date fair values of options issued to employees and non-employees were estimated using the Black-Scholes option-pricing model with the following assumptions:


	Years Ended December 31,
	2023			2022			2021
Expected term (in years)		6.03			6.04			6.02
Volatility rate		75.13	%		77.87	%		85.84	%
Risk-free interest rate		3.65	%		2.52	%		0.67	%
Expected dividend yield		0.00	%		0.00	%		0.00	%

A summary of employee and non-employee option activity under the Company’s equity award plans is presented below (in thousands, except share data):


	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Outstanding—January 1, 2023		7,981,677		$	14.42		7.3	$	88,016
Granted		3,800,691		$	23.75
Exercised		(662,042	)	$	8.08
Cancelled, forfeited or expired		(435,468	)	$	23.14
Outstanding—December 31, 2023		10,684,858		$	17.78		7.3	$	55,091
Exercisable—December 31, 2023		5,468,638		$	14.32		5.7	$	43,160
Options vested, or expected to vest—December 31, 2023		10,684,858		$	17.78		7.3	$	55,091

The weighted-average grant date fair value of options granted during the years ended December 31, 2023, 2022 and 2021, was $16.20, $12.64, and $14.70 per share, respectively. The fair value is being expensed over the vesting period of the options (usually three to four years) on a straight-line basis as the services are being provided.

There were 662,042 options exercised for the year ended December 31, 2023, resulting in total proceeds of $5.1 million; 1.3 million options exercised for the year ended December 31, 2022, resulting in total proceeds of $11.5 million; and 842,424 options exercised for the year ended December 31, 2021, resulting in total proceeds of 6.3 million. The intrinsic value of options exercised during the years ended December 31, 2023, 2022 and 2021 was $9.5 million, $17.0 million, and $10.1 million, respectively. In accordance with the Company’s policy, the shares were issued from a pool of shares reserved for issuance under the 2015 Plan and 2023 Inducement Plan.

Restricted Stock Units

RSUs awarded to Board of Directors or employees vest on either i) one – year anniversary date of the related grant or ii) 25% on each anniversary for 4 years. The following table summarizes our RSU activity:


	Number of Shares			Weighted Average Grant Date Fair Value
Unvested—December 31, 2022		224,788		$	18.02
Granted (1)		308,550		$	24.94
Vested		(9,102	)	$	13.87
Cancelled/Forfeited		(4,800	)	$	20.36
Unvested—December 31, 2023		519,436		$	22.17

Employee Stock Purchase Plan

In September 2015, the Company’s Board adopted the ESPP, which was subsequently approved by the Company’s stockholders and became effective in 2016. The ESPP authorized the initial issuance of up to a total of 250,000 shares of common stock to the Company’s employees. The number of shares of common stock available under the ESPP will automatically increase on January 1st of each year, continuing until the expiration of the ESPP, in an amount equal to the lesser of (a) 1% of the total number of shares of common stock outstanding on December 31st of the preceding calendar year, or (b) 250,000 shares. On January 1, 2024, the shares of common stock reserved for issuance under the ESPP was increased to 1,982,614. Under the terms of the ESPP, eligible employees can elect to acquire shares of the Company’s common stock through periodic payroll deductions during a series of six-month offering periods. Purchases under the ESPP are affected on the last business day of each offering period at a 15% discount to the lower of closing price on that day or the closing price on the first day of the offering period. The Company issued 34,797 and 28,999 shares during 2023 and 2022, respectively.

The ESPP is considered a compensatory plan with the related compensation cost expensed over the six-month offering period. For the years ended December 31, 2023, 2022 and 2021 the Company recorded stock-based compensation expense related to the ESPP of $308,000, $166,000, and $175,000 respectively.

Employee Benefit Plan

The Company has a Section 401(k) defined contribution savings plan for its employees. The plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pretax basis, subject to legal limitations. Company contributions to the plan may be made at the discretion of the Board. For the years ended December 31, 2023, 2022 and 2021, the Company made $1.3 million, $712,000, and $444,000 contributions to the plan, respectively.

(Loss) Earnings per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

(Loss) Earnings per Share

6. (Loss) Earnings per Share

Basic and diluted (loss) earnings per share are calculated as follows (in 000s):


	Years Ended December 31,
	2023			2022			2021
Numerator:
Net (loss) income	$	(209,360	)	$	(149,338	)	$	24,926
Net (loss) income attributable to common stockholders	$	(209,360	)	$	(149,338	)	$	24,926
Denominator:
Weighted-average common shares outstanding		70,371			60,761			52,065
Effective of Dilutive Securities
Options to purchase common stock		—			—			1,429
Non - vested restricted stock units (RSUs)		—			—			118
ESPP to purchase common stock		—			—			11
Dilutive potential common shares		—			-			1,558
Shares used in calculating diluted (loss) earnings per share		70,371			60,761			53,623

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares, in 000s):


	December 31,
	2023		2022		2021
Options to purchase common		10,685		7,982		—
Non-vested RSUs		309		131		—
ESPP to purchase common stock		35		17		—

For additional information related to the Company's common stock see Note 12, Common Stock to these consolidated financial statements.

Leases - Additional Information (Detail)		1 Months Ended					12 Months Ended
Leases - Additional Information (Detail)	Aug. 17, 2021 USD ($)	May 31, 2023 USD ($) ft²	Aug. 31, 2022 USD ($)	Feb. 28, 2021	Sep. 30, 2016 ft²	Dec. 31, 2015 ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Lessee Lease Description [Line Items]
Lease option to extend								true
Lease option to termination								true
Right-of-use asset, net							$ 1,487,000	$ 1,039,000
Operating lease liabilities							$ 1,613,000
Operating lease discount rate							14.00%
Operating lease expense							$ 743,000
Lease payments							924,000
Future minimum lease payments under capital leases							$ 25,864,000	$ 22,441,000
Waltham, Massachusetts [Member]
Lessee Lease Description [Line Items]
Operating lease term of contract					5 years
Area of leased property \| ft²					12,207
Lease Commencement Date	Mar. 01, 2022				Mar. 01, 2017
Remaining lease term							14 months
Lease payments	$ 1,600,000
Lessee, Operating Lease, Option to Extend							On August 17, 2021, the Company signed a 36-month extension to the lease for the Waltham, MA office with aggregate payments of $1.6 million, with a lease commencement date of March 1, 2022.
New York [Member]
Lessee Lease Description [Line Items]
Operating lease term of contract		27 months	36 years	18 months		62 months
Area of leased property \| ft²		12,217				4,039
Lease Commencement Date		Jun. 01, 2023	Sep. 01, 2022	Mar. 01, 2021		Jan. 01, 2016
Remaining lease term							20 years
Lease payments		$ 1,600,000	$ 689,000

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Direct Placement Offering [Member]	Common Stock [Member]	Common Stock [Member] Direct Placement Offering [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Direct Placement Offering [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2020	$ 252,188		$ 5		$ 820,815		$ (4)	$ (568,628)
Beginning balance, Shares at Dec. 31, 2020			47,881,223
Proceeds from "at-the-market" offering, net, Value	5,131				5,131
Proceeds from "at-the-market" offering, net, Shares			277,629
Proceeds from direct offering, net, value		$ 81,206		$ 1		$ 81,205
Proceeds from direct offering,net, Shares				3,802,144
Stock purchase under ESPP, Shares			26,878
Pre-funded warrant cashless exercise, shares			725,784
Proceeds from Incyte Share Purchase Agreement	24,848				24,848
Proceeds from Incyte Share Purchase Agreement shares			1,421,523
Stock-based compensation expense	13,317				13,317
Unrealized (gain) loss on investments	49						49
Vesting of RSU, Shares			5,500
Employee withholdings ESPP	367				367
Proceeds from exercise of stock options	$ 6,336				6,336
Proceeds from exercise of stock options, Shares	842,424		842,424
Net Income (Loss)	$ 24,926							24,926
Ending balance at Dec. 31, 2021	408,368		$ 6		952,019		45	(543,702)
Ending balance, Shares at Dec. 31, 2021			54,983,105
Proceeds from "at-the-market" offering, net, Value	19,425				19,425
Proceeds from "at-the-market" offering, net, Shares			1,111,111
Proceeds from direct offering, net, value		161,966		$ 1		161,965
Proceeds from direct offering,net, Shares				7,840,909
Stock purchase under ESPP, Shares			28,999
Pre-funded warrant cashless exercise, shares			2,832,151
Stock-based compensation expense	16,019				16,019
Unrealized (gain) loss on investments	(851)						(851)
Vesting of RSU, Shares			38,749
Employee withholdings ESPP	401				401
Proceeds from exercise of stock options	$ 11,459				11,459
Proceeds from exercise of stock options, Shares	1,300,000		1,276,361
Net Income (Loss)	$ (149,338)							(149,338)
Ending balance at Dec. 31, 2022	467,449		$ 7		1,161,288		(806)	(693,040)
Ending balance, Shares at Dec. 31, 2022			68,111,385
Proceeds from "at-the-market" offering, net, Value	42,139				42,139
Proceeds from "at-the-market" offering, net, Shares			2,719,744
Proceeds from direct offering, net, value		$ 215,955		$ 1		$ 215,954
Proceeds from direct offering,net, Shares				12,432,431
Stock purchase under ESPP, Shares			34,797
Pre-funded warrant cashless exercise, shares			857,131
Stock-based compensation expense	30,951				30,951
Unrealized (gain) loss on investments	1,024						1,024
Vesting of RSU, Shares			9,102
Employee withholdings ESPP	910				910
Proceeds from exercise of stock options	$ 5,128				5,128
Proceeds from exercise of stock options, Shares	662,042		662,042
Net Income (Loss)	$ (209,360)							(209,360)
Ending balance at Dec. 31, 2023	$ 554,196		$ 8		$ 1,456,370		$ 218	$ (902,400)
Ending balance, Shares at Dec. 31, 2023			84,826,632

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (209,360)	$ (149,338)	$ 24,926
Other comprehensive gain (loss):
Unrealized gain (loss) on marketable securities, net of tax	1,024	(851)	49
Comprehensive (loss) income	$ (208,336)	$ (150,189)	$ (24,975)

- Definition

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

+ References

+ Details

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued clinical study and trial costs	$ 16,346	$ 14,375
Accrued compensation and related costs	11,172	5,945
Accrued professional fees	1,450	1,352
Accrued milestone costs	10,000	2,000
Other	888	604
Total accrued expenses and other current liabilities	$ 39,856	$ 24,276

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	100,000,000
Common stock, shares outstanding	84,826,632	68,111,385

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

3. Summary of Significant Accounting Policies

Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of costs and expenses during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis. The Company’s actual results may differ from these estimates under different assumptions or conditions.

Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s consolidated financial statements.

Cash Equivalents

Cash equivalents include all highly liquid investments maturing within 90 days or less from the date of purchase. Cash equivalents include money market funds, corporate debt securities, U.S. government agency notes, and overnight deposits.

Restricted Cash

The Company classifies as restricted cash all cash pledged as collateral to secure long-term obligations and all cash whose use is otherwise limited by contractual provisions. Amounts are reported as non-current unless restrictions are expected to be released in the next 12 months.

Marketable Securities

All investments in marketable securities are classified as available-for-sale and are reported at fair value with unrealized gains and losses excluded from earnings and reported net of tax in accumulated other comprehensive income, which is a component of stockholders’ equity. Unrealized losses that are determined to be other-than-temporary, based on current and expected market conditions, are recognized in earnings. Declines in fair value determined to be credit related are charged to earnings. The cost of marketable securities sold is determined by the specific identification method.

Segment Reporting

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision-making group, in making decisions regarding resource allocation and assessing performance. The Company has one operating segment.

Concentrations of Credit Risk

Cash and cash equivalents, restricted cash, and short and long-term investments are financial instruments that potentially subject the Company to concentrations of credit risk. Substantially all of the Company’s cash, cash equivalents, and short and long-term investments were deposited in accounts at two financial institutions, and at times, such deposits may exceed federally insured limits. The Company has not experienced any losses in such accounts, and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company’s available-for-sale investments primarily consist of government money market funds, corporate debt securities, commercial paper, credit card asset-backed securities and overnight deposits and potentially subject the Company to concentrations of credit risk.

Property and Equipment

Property and equipment are recorded at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the assets (three to five years). Assets under capital leases are amortized over the shorter of their useful lives or lease term using the straight-line method. Major replacements and improvements are capitalized, while general repairs and maintenance are expensed as incurred.

Impairment of Long-Lived Assets

Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. When such events occur, the Company compares the carrying amounts of the assets to their undiscounted expected future cash flows. If this comparison indicates that there is impairment, the amount of impairment is calculated as the difference between the carrying value and fair value. To date, no such impairments have been recognized.

Revenue Recognition

The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. The Company recognize revenue following the five – step model prescribed under FASB Accounting Standards Codification (ASC 606), Revenue from Contracts with Customers: (i) identify contract(s) with customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy the performance obligations.

Licenses of Intellectual Property: Revenue from non-refundable, up-front fees allocated to the licenses related to the Company's intellectual property, are recognized as the license is transferred to the customer and the customer is able to use and benefit from the license. This generally takes place over the related know-how transfer period, or if applicable, over the term of transfer of future updates to the intellectual property.

Development Milestone Payments: The Company evaluates whether milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license fees and earnings in the period of adjustment.

Commercial Milestone Payments and Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of commercial sales, and the license is deemed to be the predominant item to which the royalties or commercial milestones relate, the Company will recognize revenue at the later of when the related sales occur or when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date no commercial milestone payments or royalties have been achieved.

When no performance obligations are required of the Company, or following the completion of the performance obligation period, such amounts are recognized as revenue upon transfer of control of the goods or services to the customer. Generally, all amounts received or due other than sales-based milestones and royalties are classified as license fees.

Deferred revenue arises from amounts received in advance of the culmination of the earnings process and is recognized as revenue in future periods as performance obligations are satisfied. Deferred revenue expected to be recognized within the next twelve months is classified as a current liability. Upfront payment contract liabilities resulting from the Company’s license agreements do not represent a financing component as the payment is not financing the transfer of goods or services, and the technology underlying the licenses granted reflects research and development expenses already incurred by the Company.

For additional information on our collaboration and license arrangements, please read Note 4, Collaborative Research and License Agreements, to these consolidated financial statements.

Research and Development

Research and development costs are expensed as incurred. Research and development expenses include payroll and personnel expenses, consulting costs, external contract research and development expenses, and allocated overhead, including rent, equipment depreciation, and utilities. Research and development costs that are paid in advance of performance are capitalized as a prepaid expense and amortized over the service period as the services are provided. The Company expenses upfront license payments related to acquired technologies that have not yet reached technological feasibility and have no alternative future use.

In instances where the Company enters into cost-sharing arrangements, all research and development costs reimbursed by the collaborators are accounted for as reductions to research and development expense. During the years ended December 31, 2023 and 2022, the Company has incurred external costs related to Incyte cost-sharing collaboration. During the year ended December 31, 2021, the Company incurred no external costs related to cost-sharing collaborations.

Clinical Costs

Clinical study and trial costs are a component of research and development expenses. The Company expenses clinical trial activities performed by third parties based on an evaluation of the progress to completion of specific contract tasks using data such as patient enrollment, clinical site activations, or other information provided to us by our vendors. Depending on the progression of the contract and timing of invoicing and payment the research and development expense can be an accrued expense or a prepaid expense. Prepaid clinical study and trial costs are included in short-term deposits on the accompanying consolidated balance sheet.

Income Taxes

The Company records deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the Company’s financial statement carrying amounts and the tax bases of assets and liabilities and for loss and credit carryforwards using enacted tax rates expected to be in effect in the years in which the differences reverse. A valuation allowance is provided to reduce the net deferred tax assets to the amount that will more likely than not be realized. The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more-likely-than-not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes.

Guarantees and Indemnifications

As permitted under Delaware law, the Company indemnifies its officers, directors, and employees for certain events or occurrences that happen by reason of the relationship with, or position held at, the Company. The Company has standard indemnification arrangements under office leases (as described in Note 5, Leases to these consolidated financial statements) that require it to indemnify the landlord against all costs, expenses, fines, suits, claims, demands, liabilities, and actions directly resulting from any breach, violation, or nonperformance of any covenant or condition of the Company’s lease. Through December 31, 2023, the Company had not experienced any losses related to these indemnification obligations and no claims were outstanding. The Company does not expect significant claims related to these indemnification obligations, and consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established.

Stock-Based Compensation

The Company accounts for all stock option awards granted to employees and non-employees using a fair value method. Stock-based compensation is measured at the grant date fair value of the stock option grants and is recognized over the requisite service period of the awards (usually the vesting period) on a straight-line basis. For equity awards that have a performance condition, the Company recognizes compensation expense based on its assessment of the probability that the performance condition will be achieved. The Company accounts for forfeitures as they occur.

(Loss) Earnings Per Share

Basic earnings per share is computed by dividing undistributed net income attributable to Syndax by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed based on the treasury method by dividing net income by the weighted-average number of common shares outstanding during the period plus potentially dilutive common equivalent shares outstanding.

Recently Issued and Adopted Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board FASB or other accounting standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed below, we do not believe that the adoption of recently issued standards have or may have a material impact on our consolidated financial statements or disclosures.

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

11. Accrued Expenses and Other Current Liabilities

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


	December 31,
	2023		2022
Accrued clinical study and trial costs	$	16,346	$	14,375
Accrued compensation and related costs		11,172		5,945
Accrued professional fees		1,450		1,352
Accrued milestone costs		10,000		2,000
Other		888		604
Total accrued expense and other current liabilities	$	39,856	$	24,276

Income Taxes - Components of Deferred Tax (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets (liabilities):
Net operating loss carryforwards	$ 32,664	$ 23,650
Research and development credits	11,765	8,124
Capitalized start-up and other costs	68,859	45,374
Capitalized research and development costs	79,562	48,917
Equity based compensation	10,276	5,004
Accruals	2,795	1,985
Other temporary differences	36	27
Deferred tax assets before valuation allowance	205,957	133,081
Valuation allowances	(205,957)	(133,081)
Net deferred tax assets	$ 0	$ 0

Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
Document and Entity Information - USD ($) $ in Thousands	Dec. 31, 2023	Feb. 19, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	SNDX
Entity Registrant Name	Syndax Pharmaceuticals, Inc.
Entity Central Index Key	0001395937
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock
Entity Common Stock, Shares Outstanding		84,965,486
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-37708
Entity Tax Identification Number	32-0162505
Entity Address, Address Line One	35 Gatehouse Drive
Entity Address, Address Line Two	Building D
Entity Address, Address Line Three	Floor 3
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	781
Local Phone Number	419-1400
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Security Exchange Name	NASDAQ
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Public Float			$ 1,452,441,662
Auditor Name	Deloitte & Touche LLP
Auditor Location	New York, New York
Auditor Firm ID	34
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement for its 2024 Annual Meeting of Stockholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year ended December 31, 2023, are incorporated by reference into Part III of this Annual Report on Form 10-K.

Stock-Based Compensation - Summary of Restricted Stock Units Activity (Parenthetical) (Details) - Restricted Stock Units (RSUs) [Member] - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average grant date fair value per share	$ 24.94	$ 15.79
Fair value of restricted stock units vested	$ 126,000	$ 705,000

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Commitments and Contingencies - Additional Information (Detail) - USD ($)	1 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Apr. 30, 2013
Commitment And Contingencies [Line Items]
Contingent liabilities			$ 0	$ 0
Eddingpharm Purchase Agreement [Member]
Commitment And Contingencies [Line Items]
Purchase agreement obligation					$ 5,000,000
Incyte Agreement [Member] \| Global and U.S. [Member]
Commitment And Contingencies [Line Items]
Development costs associated with clinical trials		45.00%
Incyte Agreement [Member] \| Non-Refundable Cash Payments [Member]
Commitment And Contingencies [Line Items]
Upfront milestone payable	$ 117,000,000	$ 117,000,000
Incyte Agreement [Member] \| Equity Investment [Member]
Commitment And Contingencies [Line Items]
Upfront milestone payable		$ 35,000,000

(Loss) Earnings per Share - Computation of Basic and Diluted Earnings (Loss) per Share (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net Income (Loss)	$ (209,360)	$ (149,338)	$ 24,926
Net (loss) income attributable to common stockholders	$ (209,360)	$ (149,338)	$ 24,926
Denominator:
Weighted-average common shares outstanding	70,370,519	60,760,906	52,064,809
Dilutive potential common shares			1,558,000
Shares used in calculating diluted earnings (loss) per share	70,370,519	60,760,906	53,622,904
Employee Stock Option
Denominator:
Dilutive potential common shares			1,429,000
Non-Vested Restricted Stock Units (RSUs) [Member]
Denominator:
Dilutive potential common shares			118,000
ESPP to Purchase Common Stock
Denominator:
Dilutive potential common shares			11,000

(Loss) Earnings per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Computation of Basic and Diluted Earnings (Loss) per Share

Basic and diluted (loss) earnings per share are calculated as follows (in 000s):


	Years Ended December 31,
	2023			2022			2021
Numerator:
Net (loss) income	$	(209,360	)	$	(149,338	)	$	24,926
Net (loss) income attributable to common stockholders	$	(209,360	)	$	(149,338	)	$	24,926
Denominator:
Weighted-average common shares outstanding		70,371			60,761			52,065
Effective of Dilutive Securities
Options to purchase common stock		—			—			1,429
Non - vested restricted stock units (RSUs)		—			—			118
ESPP to purchase common stock		—			—			11
Dilutive potential common shares		—			-			1,558
Shares used in calculating diluted (loss) earnings per share		70,371			60,761			53,623

Potential Dilutive Securities Excluded from Computation of Diluted Net Loss per Common Share


	December 31,
	2023		2022		2021
Options to purchase common		10,685		7,982		—
Non-vested RSUs		309		131		—
ESPP to purchase common stock		35		17		—

For additional information related to the Company's common stock see Note 12, Common Stock to these consolidated financial statements.

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2023 USD ($) Segment Claim	Dec. 31, 2022	Dec. 31, 2021 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segment	1
Impairment charge	$ 0
ASU No. 2019-12 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
Guarantees and Indemnifications [Member]
Summary Of Significant Accounting Policies [Line Items]
Indemnification obligations, claims outstanding \| Claim	0
Indemnification obligations claims, reserves established	$ 0
Cost-Sharing Collaborations [Member]
Summary Of Significant Accounting Policies [Line Items]
External costs related to cost-sharing collaborations			$ 0
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Percentage of income tax contingency realized	50.00%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	5 years

(Loss) Earnings per Share - Additional Information (Detail) - shares		1 Months Ended
	Jan. 24, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share Basic [Line Items]
Proceeds from Incyte Share Purchase Agreement shares	86,000	12,432,431	7,840,909	3,802,144

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Schedule of Accrued Expenses and Other Current Liabilities

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


	December 31,
	2023		2022
Accrued clinical study and trial costs	$	16,346	$	14,375
Accrued compensation and related costs		11,172		5,945
Accrued professional fees		1,450		1,352
Accrued milestone costs		10,000		2,000
Other		888		604
Total accrued expense and other current liabilities	$	39,856	$	24,276

Property and Equipment, Net - Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 419	$ 419
Accumulated depreciation	(411)	(399)
Property and equipment, net	8	20
Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	84	84
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	167	167
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	134	134
Office and Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 34	$ 34

Stock-Based Compensation - Grant Date Fair Values of Options Issued to Employees and Non-employees Estimated Using Black-Scholes Option Pricing Model (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected term (in years)	6 years 10 days	6 years 14 days	6 years 7 days
Volatility rate	75.13%	77.87%	85.84%
Risk-free interest rate	3.65%	2.52%	0.67%
Expected dividend yield	0.00%	0.00%	0.00%

Significant Agreements

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Significant Agreements

7. Significant Agreements

Vitae Pharmaceuticals, Inc.

In October 2017, the Company entered into a license agreement (the “Allergan License Agreement”) with Vitae Pharmaceuticals, Inc., a subsidiary of Allergan (“Allergan”), under which Allergan granted the Company an exclusive, sublicensable, worldwide license to a portfolio of preclinical, orally available, small molecule inhibitors of the interaction of menin with Mixed Lineage Leukemia (“MLL”) protein (the “Menin Assets”). The Company made a nonrefundable upfront payment of $5.0 million to Allergan in the fourth quarter of 2017. Additionally, subject to the achievement of certain milestone events, the Company may be required to pay Allergan up to $99.0 million in one-time development and regulatory milestone payments over the term of the Allergan License Agreement. In the event that the Company or any of its affiliates or sublicensees commercializes the Menin Assets, the Company will also be obligated to pay Allergan low single to low double-digit royalties on sales, subject to reduction in certain circumstances, as well as up to an aggregate of $70.0 million in potential one-time, sales-based milestone payments based on achievement of certain annual sales thresholds. Under certain circumstances, the Company may be required to share a percentage of non-royalty income from sublicensees, subject to certain deductions, with Allergan. The Company is solely responsible for the development and commercialization of the Menin Assets. Each party may terminate the Allergan License Agreement for the other party’s uncured material breach or insolvency; and the Company may terminate the Allergan License Agreement at will at any time upon advance written notice to Allergan. Allergan may terminate the Allergan License Agreement if the Company or any of its affiliates or sublicensees institutes a legal challenge to the validity, enforceability, or patentability of the licensed patent rights. Unless terminated earlier in accordance with its terms, the Allergan License Agreement will continue on a country-by-country and product-by-product basis until the later of: (i) the expiration of all of the licensed patent rights in such country; (ii) the expiration of all regulatory exclusivity applicable to the product in such country; and (iii) 10 years from the date of the first commercial sale of the product in such country.

As of the date of the Allergan License Agreement, the asset acquired had no alternative future use nor had it reached a stage of technological feasibility. As the processes or activities that were acquired along with the license do not constitute a “business,” the transaction has been accounted for as an asset acquisition. As a result, in 2017, the upfront payment of $5.0 million was recorded as research and development expense in the consolidated statements of operations. Since the inception of the agreement, the Company achieved certain development and regulatory milestones resulting in $8.0 million in expense, which included $2.0 million paid in the first quarter of 2023.

UCB Biopharma Sprl

In July 2016, the Company entered into a license agreement (the “UCB License Agreement”) with UCB Biopharma Sprl (“UCB”), under which UCB granted to the Company a worldwide, sublicensable, exclusive license to UCB6352, which the Company refers to as axatilimab, an Investigational New Drug Application-ready anti-CSF-1R monoclonal antibody. The Company made a nonrefundable upfront payment of $5.0 million to UCB in the third quarter of 2016. Additionally, subject to the achievement of certain milestone events, the Company may be required to pay UCB up to $119.5 million in one-time development and regulatory milestone payments over the term of the UCB License Agreement. In the event that the Company or any of its affiliates or sublicensees commercializes axatilimab, the Company will also be obligated to pay UCB low double-digit royalties on sales, subject to reduction in certain circumstances, as well as up to an aggregate of $250.0 million in potential one-time, sales-based milestone payments based on achievement of certain annual sales thresholds. Under certain circumstances, the Company may be required to share a percentage of non-royalty income from sublicensees, subject to certain deductions, with UCB. The Company will be solely responsible for the development and commercialization of axatilimab, except that UCB is performing a limited set of transitional chemistry, manufacturing and control tasks related to axatilimab. Each party may terminate the UCB License Agreement for the other party’s uncured material breach or insolvency; and the Company may terminate the UCB License Agreement at will at any time upon advance written notice to UCB. UCB may terminate the UCB License Agreement if the Company or any of its affiliates or sublicensees institutes a legal challenge to the validity, enforceability, or patentability of the licensed patent rights. Unless terminated earlier in accordance with its terms, the UCB License Agreement will continue on a country-by-country and product-by-product basis until the later of: (i) the expiration of all of the licensed patent rights in such country; (ii) the expiration of all regulatory exclusivity applicable to the product in such country; and (iii) 10 years from the date of the first commercial sale of the product in such country.

As of the date of the UCB License Agreement, the asset acquired had no alternative future use nor had it reached a stage of technological feasibility. As the processes or activities that were acquired along with the license do not constitute a “business,” the transaction has been accounted for as an asset acquisition. As a result, in 2016, the upfront payment of $5.0 million was recorded as research and development expense in the consolidated statements of operations. Since the start of the license agreement, the Company achieved certain development and regulatory milestones and has recorded $6.0 million as research and development expense. Additionally, in connection with its most recent amendment of the UCB License Agreement, in the second quarter of 2022 the Company paid UCB $5.8 million, which is recognized as a milestone expense. In the fourth quarter of 2023, UCB achieved a development and regulatory milestone resulting in a $10.0 million expense, which has been recorded in accrued expenses as of December 31, 2023. The Company paid the amount to UCB in the first quarter of 2024.

Bayer Pharma AG (formerly known as Bayer Schering Pharma AG)

In March 2007, the Company entered into a license agreement (the “Bayer Agreement”) with Bayer Schering Pharma AG (“Bayer”) for a worldwide, exclusive license to develop and commercialize entinostat and any other products containing the same active ingredient. Under the terms of the Bayer Agreement, the Company paid a nonrefundable up-front license fee of $2.0 million and is responsible for the development and marketing of entinostat. The Company recorded the $2.0 million license fee as research and development expense during the year ended December 31, 2007, as it had no alternative future use. The Company will pay Bayer royalties on a sliding scale based on net sales, if any, and make future milestone payments to Bayer of up to $150.0 million in the event that certain specified development and regulatory goals and sales levels are achieved.

Property and Equipment, net (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment, net, consisted of the following (in thousands):


	December 31,
	2023			2022
Equipment	$	84		$	84
Leasehold improvements		167			167
Furniture and fixtures		134			134
Office and computer equipment		34			34
Total property and equipment		419			419
Accumulated depreciation		(411	)		(399	)
Property and equipment, net	$	8		$	20

Depreciation expense was $12,000 and $33,000 for the years ended December 31, 2023 and 2022, respectively.

Common Stock - Schedule of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2023	Apr. 12, 2023
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	23,906,260
Pre-Funded Warrants [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	285,714	273,000
Equity plans [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	3,403,382
Employee Stock Option
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	11,204,294
At-the-market program [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	7,280,256
Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	1,732,614

- 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
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Collaborative Research and License Agreements

12 Months Ended

Dec. 31, 2023

Research and Development [Abstract]

Collaborative Research and License Agreements

4. Collaborative Research and License Agreements

Incyte Collaboration

In September 2021, the Company entered into license and collaboration agreement (the "Incyte License and Collaboration Agreement") with Incyte Corporation ("Incyte") covering the worldwide development and commercialization of axatilimab. Also, in September 2021 the Company entered into a share purchase agreement with Incyte, ("Incyte Share Purchase Agreement" and together with Incyte License and Collaboration Agreement, the Incyte Agreements"). Under the terms of the Incyte Agreements, Incyte will receive exclusive commercialization rights outside of the United States, subject to its royalty payment obligations set forth below. In the United States, Incyte and the Company will co-commercialize axatilimab, with the Company having the right to co-promote axatilimab with Incyte, subject to the Company’s exercise of its co-promotion option. Incyte will be responsible for leading all aspects of commercialization of axatilimab in the United States. The Company and Incyte will share equally the profits and losses from co-commercialization efforts in the United States. The Company and Incyte have agreed to co-develop axatilimab and to share development costs associated with global and U.S. – specific clinical trials, with Incyte responsible for 55% of such costs and the Company responsible for 45% of such costs. Each company will be responsible for funding any of its own independent development activities. Incyte is responsible for 100% of future development costs for trials that are specific to ex-U.S. countries. All development costs related to the collaboration with Incyte will be subject to a joint development plan.

Under the terms of the Incyte Agreements, in December 2021, Incyte paid the Company a non-refundable cash payment of $117.0 million and the Company issued 1,421,523 shares of common stock with an aggregate purchase price of $35.0 million, or $24.62 per share. Additionally, under the terms of the Incyte Agreements, the Company is eligible to receive up to $220.0 million in future contingent development and regulatory milestones and up to $230.0 million in commercialization milestones as well as tiered royalties ranging in the mid-teens percentage on net sales of the licensed product comprising axatilimab in Europe and Japan and low double digit percentage in the rest of the world outside of the United States. The Company's right to receive royalties in any particular country will expire upon the last to occur of (a) the expiration of licensed patent rights covering the licensed product in that particular country, (b) a specified period of time after the first post - marketing authorization sale of a licensed product in that country, and (c) the expiration of any regulatory exclusivity for that licensed product in that country.

The Incyte Agreement and the Incyte Share Purchase Agreement were executed on the same date and negotiated simultaneously. Management therefore concluded that the Incyte Agreements are to be combined for accounting purposes and therefore allocated the total consideration to the units of account identified. The common stock issued to Incyte was recorded at fair value of $24.8 million. Pursuant to the Letter Agreement, Incyte is permitted to terminate the Incyte Agreement, under circumstances under which the upfront payment of $117 million would be returned to Incyte and a cash settlement on the sale of the Company's common stock would be made to make the parties whole (the “Letter Agreement”). In connection with the closing of this transaction in December 2021, the Company determined that the cash settlement feature of the Letter Agreement represented an embedded derivative requiring bifurcation and separate accounting recognition at fair value. The Letter Agreement terminated in March 2022. Accordingly, the Company initially allocated $0.6 million of the total consideration received to the derivative liability. As of December 31, 2022, the fair value of the derivative is zero.

The Company evaluated the terms of the Incyte Agreement and determined it is within the scope of Accounting Standard Update 2018-18, Collaborative Arrangements (Topic 808), and has elements that are within the scope of Topic 606 and Topic 808.

The Company identified the following promises in the Incyte Agreements that were evaluated under the scope of Topic 606: (i) delivery of a license for axatilimab to develop, commercialize, and conduct medical affairs and (ii) services to be performed in accordance with the development plan. The Company also evaluated whether certain options outlined within the Incyte Agreements represented material rights that would give rise to a performance obligation and concluded that none of the options convey a material right to Incyte and therefore are not considered separate performance obligations within the Incyte Agreements.

The Company assessed the above promises and determined that the license for axatilimab represents the only performance obligation within the scope of Topic 606. The license for axatilimab is considered functional

intellectual property and distinct from other promises under the contract as Incyte can benefit from the license on its own or together with other readily available resources. The services performed by the Company to obtain regulatory approval of axatilimab are not complex or specialized, could be performed by another qualified third party, are not expected to significantly modify or customize the license given that axatilimab is late-stage intellectual property that has completed its Phase 1/2 trial and is currently enrolling in a global pivotal Phase 2 trial, and the services are expected to be performed over a short period of time. Therefore, the license represents a separate performance obligation within a contract with a customer under the scope of Topic 606 at contract inception.

The Company considers the collaborative research and development activities and manufacturing activities to be separate units of account within the scope of Topic 808 and are not deliverables under Topic 606. The Company and Incyte are both active participants in the activities and are exposed to significant risks and rewards that are dependent on the commercial success of the activities in the arrangement.

Under the scope of Topic 606, the Company identified contract promises for the license of intellectual property and know-how rights for axatilimab. The Company determined that the license was capable of being distinct from the ongoing collaboration activities. After the allocation to the common stock and derivative liability, the total transaction price to be allocated to the Incyte Agreement is $126.6 million. The Company estimated the standalone selling price of the license to be the entire $126.6 million, based on an application of the income approach by measuring the fair value of the discounted cash flows from commercialization. Significant assumptions included in the valuation included judgments relating to the probability of achieving both regulatory and commercial milestones, forecasted future cash flows and the election of the discount rate. As the Company concluded the license was distinct, revenue of $126.6 million was recognized upon transfer of the license to Incyte in the year ended December 31, 2021.

The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential preclinical, development, and regulatory variable consideration milestone payment under this agreement is zero, as achievement of those milestones is uncertain and highly susceptible to factors outside the Company’s control. Accordingly, all such milestone payments were excluded from the transaction price. Management will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, will adjust the transaction price as necessary. Sales based royalties, including milestones based on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the royalties relate. The company will recognize such revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Company considers the collaborative research and development activities and manufacturing activities to be separate units of account within the scope of Topic 808 and are not deliverables under Topic 606. The Company and Incyte are both active participants in the activities and are exposed to significant risks and rewards that are dependent on the commercial success of the activities in the arrangement.

As of December 31, 2023, the Company has recorded $2.2 million as a collaboration receivable due from Incyte related to the Company's development and pre-commercialization costs under the Incyte Agreements and has recorded approximately $9.5 million as a collaboration payable due to Incyte for development and pre-commercialization costs incurred by Incyte as of December 31, 2023. Both expenses and cost offset are recorded as part of research and development and selling, general and administrative expense.

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

15. Income Taxes

The Company recognized current state income expense of $0.3 million in the year ending December 31, 2023 as a result of investment income earned in Syndax Securities Corporation. The Company recognized no income taxes in the years ended December 31, 2022 and 2021, due to the utilization of tax attributes to offset current year federal and state taxable income, immaterial investment income earned at Syndax Securities Corporation, the historical losses incurred and the need for a full valuation allowance on deferred tax assets. The Company’s current year profit and historical losses before income tax for the periods presented was generated entirely in the United States.

A reconciliation of the provision for income taxes computed at the statutory federal income tax rate to the provision for income taxes as reflected in the financial statements is as follows:


	Years Ended December 31,
	2023			2022			2021
Income tax computed at federal statutory rate		21.0	%		21.0	%		21.0	%
State taxes, net of federal benefit		13.2	%		2.5	%		2.9	%
General business credit carryovers		1.5	%		1.0	%		-5.0	%
Non-deductible expenses		-1.0	%		-0.2	%		-0.5	%
Change in valuation allowance		-34.9	%		-24.1	%		-19.2	%
Return to provision true up		0.0	%		-0.2	%		0.0	%
Other		0.0	%		0.0	%		0.8	%
		-0.2	%		0.0	%		0.0	%

The significant components of the Company’s deferred tax are as follows (in thousands):


	Years Ended December 31,
	2023			2022
Deferred tax assets (liabilities):
Net operating loss carryforwards	$	32,664		$	23,650
Research and development credits		11,765			8,124
Capitalized start-up and other costs		68,859			45,374
Capitalized research and development costs		79,562			48,917
Equity based compensation		10,276			5,004
Accruals		2,795			1,985
Other temporary differences		36			27
Deferred tax assets before valuation allowance		205,957			133,081
Valuation allowances		(205,957	)		(133,081	)
Net deferred tax assets	$	—		$	—

The Company has provided a valuation allowance for the full amount of the net deferred tax assets as the realization of the deferred tax assets is not determined to be more likely than not. The valuation allowance increased by $72.9 million in 2023 due to the increase in deferred tax assets, primarily driven by the generation of net operating losses and capitalized research expenses, and capitalized start-up costs. The valuation allowance increased by $35.9 million in 2022 due to the increase in deferred tax assets, primarily driven by the generation of net operating losses and capitalized start-up costs, partially offset by a decrease to other deferred tax assets.

As of December 31, 2023, the Company had approximately $136.4 million and $63.5 million in federal and state Net Operating Losses (“NOLs”), respectively, which may be available to offset future taxable income. The Company has generated federal NOLs of $114.3 million and state NOLs of $0.9 million which have indefinite carryforward period. The remaining $22.1 million of federal NOLs and $62.6 million the Company’s state NOLs will begin to expire at various dates starting in 2026.

As of December 31, 2023, the Company had federal and state research credits of $8.9 million and $3.8 million, respectively, which began to expire in 2024.

Realization of future tax benefits is dependent on many factors, including the Company’s ability to generate taxable income within the net operating loss carryforward period. Under the Internal Revenue Code provisions, certain substantial changes in the Company’s ownership, including the sale of the Company or significant changes in ownership due to sales of equity, may have limited, or may limit in the future, the amount of net operating loss carryforwards which could be used annually to offset future taxable income. The Company last completed an analysis from January 1, 2021 through December 31, 2022 and determined that no ownership changes had occurred in that period. Prior analyses determined that on March 30, 2007, August 21, 2015 and May 4, 2020, ownership changes had occurred. The Company may also experience ownership changes in the future as a result of subsequent shifts in our stock ownership, some of which may be outside of our control. As a result, its ability to use its pre- change NOLs to offset U.S. federal taxable income may be subject to limitations, which could potentially result in increased future tax liability. In addition, at the state level, there may be periods during which the use of NOLs is suspended or otherwise limited, which could accelerate or permanently increase state taxes owed.

The Coronavirus Aid, Relief and Economic Security Act (the “CARES Act”) was enacted in the United States on March 27, 2020. The CARES Act is an emergency economic stimulus package that includes spending and tax breaks to strengthen the United States economy and fund a nationwide effort to curtail the effect of COVID-19. While the CARES Act provides extensive tax changes in response to the COVID-19 pandemic, the provisions did not have a significant impact on the Company’s financial results. Beginning in 2022, the Tax Cuts and Jobs Act of 2017 (“TCJA”) eliminates the option to deduct research and development expenditures currently and requires taxpayers to amortize them, over five years for domestically incurred expenditures and over fifteen years for foreign incurred expenditures, pursuant to IRC Section 174. As of December 31, 2023, the Company has recorded a deferred tax asset of $79.6 million related to the Capitalized IRC Section 174 expenditures, of which $53.7 million relate to expenses required to be capitalized under the TCJA.

As of December 31, 2023, and 2022, the Company had uncertain tax positions of $0.1 million related to research and development credits, which reduce the deferred tax assets with a corresponding decrease to the valuation allowance. The Company has elected to recognize interest and penalties related to income tax matters as a component of income tax expense, of which no interest or penalties were recorded for the years ended December 31, 2023 and 2022. The Company expects none of the unrecognized tax benefits to decrease within the next 12 months related to expired statutes or settlement with the taxing authorities. Due to the Company’s valuation allowance as of December 31, 2023, none of the Company’s unrecognized tax benefits, if recognized, would affect the effective tax rate.

A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands):


	Years Ended December 31,
	2023		2022			2021
Unrecognized tax benefit--beginning of year	$	143	$	163		$	163
Decreases related to prior period positions		—		(20	)		—
Unrecognized tax benefit--end of year	$	143	$	143		$	163

The Company files tax returns in the U.S. and various states. All tax years since inception (October 11, 2005) remain open to examination by major tax jurisdictions to which the Company is subject, as carryforward attributes generated in years past may still be adjusted upon examination by the Internal Revenue Service or state tax authorities if they have or will be used in a future period. The Company is currently not under examination by the Internal Revenue Service or any other jurisdictions for any tax years.

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

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+ Details

Stock-Based Compensation - Share Based Compensation Expense Related to Issuance of Stock Option Awards to Employees and Non Employees Related to Employee Stock Purchase Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense, total	$ 30,951	$ 16,019	$ 13,317
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense, total	14,147	6,016	4,398
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense, total	$ 16,804	$ 10,003	$ 8,919

- 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

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of Provision for Income Taxes Computed at Statutory Federal Income Tax Rate to Provision for Income Taxes

A reconciliation of the provision for income taxes computed at the statutory federal income tax rate to the provision for income taxes as reflected in the financial statements is as follows:


	Years Ended December 31,
	2023			2022			2021
Income tax computed at federal statutory rate		21.0	%		21.0	%		21.0	%
State taxes, net of federal benefit		13.2	%		2.5	%		2.9	%
General business credit carryovers		1.5	%		1.0	%		-5.0	%
Non-deductible expenses		-1.0	%		-0.2	%		-0.5	%
Change in valuation allowance		-34.9	%		-24.1	%		-19.2	%
Return to provision true up		0.0	%		-0.2	%		0.0	%
Other		0.0	%		0.0	%		0.8	%
		-0.2	%		0.0	%		0.0	%

Components of Deferred Tax

The significant components of the Company’s deferred tax are as follows (in thousands):


	Years Ended December 31,
	2023			2022
Deferred tax assets (liabilities):
Net operating loss carryforwards	$	32,664		$	23,650
Research and development credits		11,765			8,124
Capitalized start-up and other costs		68,859			45,374
Capitalized research and development costs		79,562			48,917
Equity based compensation		10,276			5,004
Accruals		2,795			1,985
Other temporary differences		36			27
Deferred tax assets before valuation allowance		205,957			133,081
Valuation allowances		(205,957	)		(133,081	)
Net deferred tax assets	$	—		$	—

Summary of Reconciliation of Company's Unrecognized Tax Benefits

A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands):


	Years Ended December 31,
	2023		2022			2021
Unrecognized tax benefit--beginning of year	$	143	$	163		$	163
Decreases related to prior period positions		—		(20	)		—
Unrecognized tax benefit--end of year	$	143	$	143		$	163

(Loss) Earnings per Share - Potential Dilutive Securities Excluded from Computation of Diluted Net Loss per Common Share (Detail) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Employee Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per common share	10,685	7,982	0
Non-Vested Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per common share	309	131	0
Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per common share	35	17	0

Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2023

Supplemental Cash Flow Elements [Abstract]

Supplemental Disclosures of Cash Flow Information


	Years Ended December 31,
		2023		2022	2021
	(In thousands)
Supplemental Disclosures of Cash Flow Information
Interest paid	$	—	$	2,059	$	1,997
Supplemental Disclosures of Non-Cash Investing and Financing Activities:
Issuance costs included in accounts payable and accrued expenses	$	250	$	131	$	134

Income Taxes - Schedule of Reconciliation of Provision for Income Taxes Computed at Statutory Federal Income Tax Rate to Provision for Income Taxes (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax computed at federal statutory rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	13.20%	2.50%	2.90%
General business credit carryovers	1.50%	1.00%	(5.00%)
Non-deductible expenses	(1.00%)	(0.20%)	(0.50%)
Change in valuation allowance	(34.90%)	(24.10%)	(19.20%)
Return to provision true up	0.00%	(0.20%)	0.00%
Other	0.00%	0.00%	0.80%
Effective income tax rate	(0.20%)	0.00%	0.00%

Basis of Presentation	12 Months Ended
Basis of Presentation	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	2. Basis of Presentation The Company has prepared the accompanying consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2023

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

Prepaid Expenses and Other Current Assets

10. Prepaid Expenses and Other Current Assets

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


	December 31,
	2023		2022
Prepaid insurance	$	807	$	692
Interest receivable on investments		1,227		583
Prepaid subscriptions		769		446
Prepaid state and local taxes		264		3
Prepaid rent		163		74
Other		63		117
Total prepaid expenses and other current assets	$	3,293	$	1,915

Common Stock

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Common Stock

12. Common Stock

The Company is authorized to issue 200,000,000 shares of common stock. The holders of each share of common stock are entitled to one vote per share held and are entitled to receive dividends, if and when declared by the Board, and to share ratably in the Company’s assets available for distribution to stockholders, in the event of liquidation.

In March 2021, the Company entered into a sales agreement with Cowen and Company, LLC, or TD Cowen, under which the Company could, from time to time, issue and sell shares of its common stock having aggregate sales proceeds of up to $75.0 million, in a series of one or more at-the-market, or ATM, equity offerings, or the 2021

ATM Program. On May 26, 2023, the Company terminated the 2021 ATM Program. Prior to termination the Company sold shares under the 2021 ATM Program for net proceeds of approximately $25.0 million.

In May 2023, the Company entered into a new sales agreement with TD Cowen under which the Company could, from time to time, issue and sell shares of its common stock having aggregate sales proceeds of up to $200.0 million, in a series of one or more ATM equity offerings, or the 2023 ATM Program. TD Cowen is not required to sell any specific share amounts but acts as the Company’s sales agent, using commercially reasonable efforts consistent with its normal trading and sales practices. Pursuant to the new sales agreement, shares will be sold pursuant to the previous shelf registration statement on Form S-3ASR (Registration No. 333-254661), which became automatically effective upon filing on March 24, 2021. The Company’s common stock will be sold at prevailing market prices at the time of the sale, and as a result, prices may vary. In the year ended December 31, 2023, the Company sold 2,719,744 common shares of common stock under the 2023 ATM Program, with net proceeds of approximately $42.1 million.

In December 2021, the Company issued 3,802,144 shares of common stock and pre-funded warrants to purchase 1,142,856 shares of common stock. The offering price for the securities was $17.50 per share or $17.4999 for each Pre-Funded Warrant, with net proceeds of approximately $81.2 million. On January 24, 2023, 86,000 pre-funded warrants were exercised for 85,998 shares of common stock, under a cashless exercise. On April 12, 2023, 273,000 pre-funded warrants were exercised for 272,996 shares of common stock, under a cashless exercise. On May 9, 2023, 498,142 pre-funded warrants were exercised for 498,137 shares of common stock, under a cashless exercise. As of December 31, 2023, 285,714 pre-funded warrants were considered issued and outstanding.

In December 2021, in connection with the Incyte License and Collaboration Agreement and Share Purchase Agreement, the Company issued 1,421,523 shares of common stock, with net proceeds of approximately $35.0 million. The Company recorded the equity issuance at a fair value of $24.8 million based on the market price of the stock on the date of issuance.

In December 2022, the Company issued 7,840,909 shares of common stock. The offering price for the securities was $22.00 per share, with gross proceeds of approximately $172.5 million, offset by $10.5 million of issuance cost.

In December 2023, the Company issued 12,432,431 shares of common stock. The offering price for the securities was $18.50 per share, with gross proceeds of approximately $230.0 million, offset by $14.0 million of issuance cost.

The Company has reserved for future issuance the following shares of common stock pursuant to the following outstanding securities or equity plans:


	December 31, 2023
Common stock issuable under pre-funded warrants		285,714
At-the-market program		7,280,256
RSUs and Options to purchase common stock		11,204,294
Equity plans		3,403,382
2015 Employee Stock Purchase Plan (the “ESPP”)		1,732,614
Total		23,906,260

Leases - Summary of Future Minimum Lease Payments under Operating Leases (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2024	$ 1,196
2025	606
Thereafter	0
Total lease payments	1,802
Less: imputed interest	(189)
Total operating lease liability	$ 1,613

Insider Trading Arrangements

3 Months Ended

Dec. 31, 2023

Trading Arrangements, by Individual

Material Terms of Trading Arrangement

Change in Control Arrangements

On February 27, 2024, several of our named executive officers entered into amendments to their employment agreements providing, in part, for increases in their change in control benefits. For Mr. Metzger, in the event of an involuntary termination without cause or resignation for good reason within three (3) months prior to, or within twelve (12) months following, a change in control, he will receive (i) an amount equal to 24 months of base salary, payable in a lump sum, (ii) an amount equal to 24 months of the target annual incentive award, payable in a lump sum, and (iii) continuation of health benefits for 24 months. For Drs. Gallagher and Madigan and Messrs. Albrecht and Goldan, in the event of an involuntary termination without cause or resignation for good reason within three (3) months prior to, or within twelve (12) months following, a change in control, each will receive (i) an amount equal to 18 months of base salary, payable in a lump sum, (ii) an amount equal to 18 months of the target annual incentive award, payable in a lump sum, and (iii) continuation of health benefits for 18 months.

Trading Arrangements

During our last fiscal quarter, none of our directors and officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” as defined in Regulation S-K Item 408 for the purchase or sale of our securities, except as set forth below:


Name and Title	Type of Plan	Adoption Date	Duration or End Date	Aggregate Number of Securities to be Sold		Description of Trading Arrangement
Michael Metzger - Chief Executive Officer and Director (1)	Rule 10b5-1 trading arrangement	01/05/2023	12/22/2023		100,000	Sales of shares intended to satisfy the affirmative defense of Rule 10b5–1(c)
Briggs W. Morrison, M.D. - Director (1)	Rule 10b5-1 trading arrangement	02/09/2023	12/06/2023		466,167	Sales of shares intended to satisfy the affirmative


							defense of Rule 10b5–1(c)

(1) Termination of Rule 10b5-1 trading arrangement, each of which the reporting person terminated prior to the sale of all plan securities.

Rule 10b5-1 Arrangement Adopted

false

Non-Rule 10b5-1 Arrangement Adopted

false

Rule 10b5-1 Arrangement Terminated

false

Non-Rule 10b5-1 Arrangement Terminated

false

Michael Metzger [Member]

Trading Arrangements, by Individual

Name

Michael Metzger

^[1]

Title

Chief Executive Officer and Director

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

01/05/2023

Rule 10b5-1 Arrangement Terminated

true

Termination Date

12/22/2023

Aggregate Available

100,000

Briggs W. Morrison [Member]

Trading Arrangements, by Individual

Name

Briggs W. Morrison

^[1]

Title

M.D. - Director

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

02/09/2023

Rule 10b5-1 Arrangement Terminated

true

Termination Date

12/06/2023

Aggregate Available

466,167

[1]	Termination of Rule 10b5-1 trading arrangement, each of which the reporting person terminated prior to the sale of all plan securities.

Fair Value Measurements - Summary of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 304,916	$ 422,581
Unrealized Gains	257
Unrealized Losses	(40)	(806)
Fair Value	305,133	421,775
Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	160,657	321,630
Unrealized Gains	149
Unrealized Losses		(205)
Fair Value	160,806	321,425
Federal Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	28,998	36,192
Unrealized Losses	(40)	(35)
Fair Value	28,958	36,157
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	47,150
Unrealized Gains	62
Fair Value	47,212
U.S. Treasury [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	68,111	64,759
Unrealized Gains	46
Unrealized Losses		(566)
Fair Value	$ 68,157	$ 64,193

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Paragraph 2
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-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 3
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
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-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2023

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

Schedule of Prepaid Expenses and Other Current Assets

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


	December 31,
	2023		2022
Prepaid insurance	$	807	$	692
Interest receivable on investments		1,227		583
Prepaid subscriptions		769		446
Prepaid state and local taxes		264		3
Prepaid rent		163		74
Other		63		117
Total prepaid expenses and other current assets	$	3,293	$	1,915

Stock-Based Compensation - Summary of Company's Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement, Disclosure [Abstract]
Options outstanding, Beginning balance	7,981,677
Options granted	3,800,691
Options exercised	(662,042)	(1,300,000)	(842,424)
Options canceled, forfeited or expired	(435,468)
Options outstanding, Ending balance	10,684,858	7,981,677
Options exercisable, Ending balance	5,468,638
Options vested, exercisable or expected to vest, Ending balance	10,684,858
Options outstanding, Weighted Average Exercise Price, Beginning balance	$ 14.42
Options granted, Weighted Average Exercise Price	23.75
Options exercised, Weighted Average Exercise Price	8.08
Options canceled, forfeited or expired, Weighted Average Exercise Price	23.14
Options outstanding, Weighted Average Exercise Price, Ending balance	17.78	$ 14.42
Options exercisable, Weighted Average Exercise Price, Ending balance	14.32
Options vested, exercisable or expected to vest, Weighted Average Exercise Price, Ending balance	$ 17.78
Options outstanding, Weighted Average Remaining Contractual Term	7 years 3 months 18 days	7 years 3 months 18 days
Options exercisable, Weighted Average Remaining Contractual Term, Ending balance	5 years 8 months 12 days
Options vested, exercisable or expected to vest, Weighted Average Remaining Contractual Term, Ending balance	7 years 3 months 18 days
Options outstanding, Aggregate Intrinsic Value	$ 55,091	$ 88,016
Options Exercised, Aggregate Intrinsic Value	9,500	$ 17,000	$ 10,100
Options exercisable, Aggregate Intrinsic Value	43,160
Options vested, exercisable or expected to vest, Aggregate Intrinsic Value	$ 55,091

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

9. Fair Value Measurements

The carrying amounts of cash and cash equivalents, restricted cash, accounts payable, and accrued expenses approximated their estimated fair values due to the short-term nature of these financial instruments. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value are performed in a manner to maximize the use of observable inputs and minimize the use of unobservable inputs.

The accounting standard describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value, which are the following:

Level 1—Quoted prices (unadjusted) in active markets that are accessible at the market date for identical unrestricted assets or liabilities.

Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs for which all significant inputs are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

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

The table below presents information about the Company’s assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of valuation techniques the Company utilized to determine such fair values (in thousands):


			Fair Value Measurements Using
	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
December 31, 2023
Assets:
Cash equivalents	$	295,394	$	295,394	$	—	$	—
Short-term investments		275,304		—		275,304		—
Long-term investments		29,829		—		29,829		—
Total assets	$	600,527	$	295,394	$	305,133	$	—


December 31, 2022
Assets:
Cash equivalents	$	74,356	$	59,496	$	14,860	$	—
Short-term investments		401,446		—		401,446		—
Long-term investments		5,469		—		5,469		—
Total assets	$	481,271	$	59,496	$	421,775	$	—

There have been no material impairments of our assets measured and carried at fair value during the years ended December 31, 2023, and 2022. In addition, there have been no changes in valuation techniques during the years ended December 31, 2023, and 2022. The fair value of Level 1 instruments classified as cash equivalents are valued using quoted market prices in active markets. The fair value of Level 2 instruments classified as cash equivalents and short and long-term investments was determined other than quoted prices in active markets, which are either directly or indirectly observable as of the reporting date and fair value is determined using models or other valuation methodologies.

The short-term and long-term investments are classified as available-for-sale securities. As of December 31, 2023, the remaining contractual maturities of the available-for-sale securities were 1 to 15 months, and the balance in the Company’s accumulated other comprehensive income was comprised solely of activity related to the Company’s available-for-sale securities. There were no realized gains or losses recognized on the sale or maturity of available-for-sale securities during the three years ended December 31, 2023. As a result, the Company did not reclassify any amounts out of accumulated other comprehensive income for the same periods. The Company has a limited number of available-for-sale securities in insignificant loss positions as of December 31, 2023, which the Company does not intend to sell and has concluded will not be required to sell before recovery of the amortized cost for the investment at maturity.

The following table summarizes the available-for-sale securities (in thousands):


	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Fair Value
December 31, 2023
Commercial paper	$	160,657	$	149	$	—		$	160,806
Corporate bonds		47,150		62		—			47,212
US Treasury		68,111		46		—			68,157
Federal bonds		28,998		—		(40	)		28,958
	$	304,916	$	257	$	(40	)	$	305,133
December 31, 2022
Commercial paper	$	321,630	$	—	$	(205	)	$	321,425
US Treasury		64,759		—		(566	)		64,193
Federal bonds		36,192		—		(35	)		36,157
	$	422,581	$	—	$	(806	)	$	421,775

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of Fair Values of Financial Assets and Liabilities Measured at Fair Value


			Fair Value Measurements Using
	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
December 31, 2023
Assets:
Cash equivalents	$	295,394	$	295,394	$	—	$	—
Short-term investments		275,304		—		275,304		—
Long-term investments		29,829		—		29,829		—
Total assets	$	600,527	$	295,394	$	305,133	$	—


December 31, 2022
Assets:
Cash equivalents	$	74,356	$	59,496	$	14,860	$	—
Short-term investments		401,446		—		401,446		—
Long-term investments		5,469		—		5,469		—
Total assets	$	481,271	$	59,496	$	421,775	$	—

Summary of Available-for-Sale Securities

The following table summarizes the available-for-sale securities (in thousands):


	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Fair Value
December 31, 2023
Commercial paper	$	160,657	$	149	$	—		$	160,806
Corporate bonds		47,150		62		—			47,212
US Treasury		68,111		46		—			68,157
Federal bonds		28,998		—		(40	)		28,958
	$	304,916	$	257	$	(40	)	$	305,133
December 31, 2022
Commercial paper	$	321,630	$	—	$	(205	)	$	321,425
US Treasury		64,759		—		(566	)		64,193
Federal bonds		36,192		—		(35	)		36,157
	$	422,581	$	—	$	(806	)	$	421,775

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details