0000950170-24-031495 | 10-K | XBRL Viewer

Following Shares of Common Stock Reserved for Future Issuance

The Company had the following shares of common stock reserved for future issuance:


	As of December 31,
	2023		2022
Conversion of convertible preferred stock		—		18,216,847
Issuance of common stock upon exercise of stock options		5,817,339		3,316,671
Issuance of common stock upon vesting of restricted stock units		78,505		—
Equity awards available for grant under equity plans		1,574,426		906,265
Shares available for issuance under the Employee Stock Purchase Plan		402,757		—
Total common stock reserved for future issuance		7,873,027		22,439,783

Income Taxes - Schedule of Difference Between Effective Tax Rate and U.S. Federal Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Federal income tax	(21.00%)	(21.00%)
State income tax, less federal benefits	(5.30%)	(6.70%)
Permanent differences	0.30%	1.50%
Limitation on executive compensation	1.50%	0.00%
Change in valuation allowance	26.00%	26.70%
Credits	(1.20%)	(0.50%)
Other	(0.30%)	0.00%
Effective tax rate	0.00%	0.00%

Leases - Additional Information (Details)	1 Months Ended			12 Months Ended
Leases - Additional Information (Details)	Apr. 30, 2022	Mar. 31, 2021 USD ($)	Jun. 30, 2020 ft²	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)	Mar. 01, 2021 ft²	Feb. 28, 2021 ft²
Leases [Abstract]
Area of leased office and laboratory space \| ft²			6,782
Lease expiration date			Dec. 30, 2021
Square feet of office space leased \| ft²				18,170		9,277	2,495
Lease and rental expense		$ 12,000		$ 300,000	$ 200,000
Remaining lease term				1 year
Lease renewal term for office space extended date	Dec. 30, 2024
Lease commencement date				Jul. 31, 2022
Incremental borrowing rate of right of used assets and lease liabilities				400.00%
Remaining lease liabilities				$ 300,000	600,000
Remaining operating lease right of use assets				300,000	600,000
Variable lease costs				400,000	300,000
Impairment losses				$ 0	$ 0

Common Stock - Following Shares of Common Stock Reserved for Future Issuance (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Feb. 23, 2023
Class of Stock [Line Items]
Conversion of convertible preferred stock	0	18,216,847	18,216,847
Issuance of common stock upon exercise of stock options	5,817,339	3,316,671
Issuance of common stock upon vesting of restricted stock units	78,505	0
Equity awards available for grant under equity plans	1,574,426	906,265
Common stock reserved for future issuance	7,873,027	22,439,783
Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock reserved for future issuance	402,757	0

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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Stock-Based Compensation - Summary of Restricted Stock Award and Restricted Stock Units Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance	50,457	97,903
Number of Shares, Granted		0
Number of Shares, Vested	(42,977)	(47,446)
Number of Shares, Forfeited		0
Number of Shares, Unvested, Ending Balance	7,480	50,457
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance	$ 0.14	$ 0.14
Weighted-Average Grant Date Fair Value, Granted		0
Weighted-Average Grant Date Fair Value, Vested	0.14	0.14
Weighted-Average Grant Date Fair Value, Forfeited		0
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance	$ 0.14	$ 0.14
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance	0	0
Number of Shares, Granted	85,692	0
Number of Shares, Vested	(7,187)	0
Number of Shares, Forfeited	0	0
Number of Shares, Unvested, Ending Balance	78,505	0
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance	$ 0	$ 0
Weighted-Average Grant Date Fair Value, Granted	14.99	0
Weighted-Average Grant Date Fair Value, Vested	22.75	0
Weighted-Average Grant Date Fair Value, Forfeited	0	0
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance	$ 14.28	$ 0

Organization, Description of Business and Liquidity - Additional Information (Details)				12 Months Ended
	Jun. 23, 2023 USD ($)	Feb. 23, 2023 USD ($) Director shares	Apr. 01, 2021 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares
Organization, Description of Business and Liquidity [Line Items]
Entity incorporation date				Jun. 12, 2019
Reverse stock split		1-for-4
Business acquisition, exchange ratio		0.2951%
Common stock, shares issued \| shares		41,011,501		41,292,027	3,570,019
Common stock, shares outstanding \| shares		41,011,501		41,292,027	3,570,019
Majority number of initial members of board of directors \| Director		8
Common stock, par value $0.001 and $0.0001 at December 31, 2023 and 2022, respectively; authorized shares - 100,000,000 and 26,264,364 at December 31, 2023 and 2022, respectively; issued and outstanding shares - 41,292,027 and 3,570,019 at December 31, 2023 and 2022, respectively		$ 164,500,000		$ 41,000	$ 1,000
Accumulated deficit				(154,448,000)	(82,864,000)
Contingent value right		one
Payments received or paid under CVR Agreement				0
Cash, cash equivalents and marketable securities				253,100,000
Aggregate gross proceeds of common stock issued and sold				$ 161,365,000	$ 0
Common stock issued and sold \| shares		34,426,351
Sales agreement
Organization, Description of Business and Liquidity [Line Items]
Common stock issued and sold \| shares				0
Milestone One
Organization, Description of Business and Liquidity [Line Items]
Payments to be received under contingent value rights agreement		$ 10,000,000
Milestone Two
Organization, Description of Business and Liquidity [Line Items]
Payments to be received under contingent value rights agreement		$ 50,000,000
Maximum
Organization, Description of Business and Liquidity [Line Items]
Equity and debt offerings available	$ 400,000,000
Maximum \| Sales agreement
Organization, Description of Business and Liquidity [Line Items]
Common stock, aggregate offering price	$ 200,000,000
Maximum \| Prior Sales Agreement
Organization, Description of Business and Liquidity [Line Items]
Aggregate gross proceeds of common stock issued and sold			$ 75,000,000
Merger Agreement
Organization, Description of Business and Liquidity [Line Items]
Business acquisition, common shares issued \| shares		34,426,351

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended		55 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Provision for income taxes	$ 0	$ 0
Changes in valuation allowance	23,200,000	10,100,000
Net operating loss carryforwards not subject to expiration	$ 177,300,000		$ 177,300,000
Net operating loss carryforwards, limitations on use	The 2017 Tax Cuts and Jobs Act (“TCJA”) generally allows losses incurred after 2017 to be carried over indefinitely but limits the net operating loss deduction to the lesser of the net operating loss carryover or 80% of a corporation’s taxable income (subject to IRC Section 382). Additionally, there is no carryback for losses incurred after 2017. Losses incurred prior to 2018 are generally deductible to the extent of the lesser of a corporation’s net operating loss carryover or 100% of its taxable income and are available for twenty years from the period the loss was generated.
Tax-related penalties or interest			0
Unrecognized tax benefits	$ 32,144,000	164,000	32,144,000	$ 47,000
California
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	126,700,000	68,500,000	126,700,000
Colorado
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	4,000		4,000
Massachusetts
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	124,200,000		124,200,000
Deferred tax assets reduced by net operating loss carryforwards	65,700,000		65,700,000
Deferred tax assets reduced by credits carryforwards	800,000		800,000
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	185,300,000	39,500,000	185,300,000
Net operating loss carryforwards subject to expiration	$ 8,000,000		8,000,000
Net operating loss carryforwards expiration year	2037
Research and development credit carryforwards subject to expiration	$ 10,500,000	400,000	10,500,000
Research and development credit carryforwards expiration year	2043
Deferred tax assets reduced by net operating loss carryforwards	$ 900,000		900,000
Deferred tax assets reduced by credits carryforwards	$ 8,800,000		8,800,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration year	2043
Research and development credit carryforwards subject to expiration	$ 1,300,000	$ 200,000	$ 1,300,000
Research and development credit carryforwards expiration year	2038

Stock-Based Compensation - Summary of Stock-Based Compensation Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility		80.00%
Risk-free interest rate, minimum	3.30%	1.60%
Risk-free interest rate, maximum	4.80%	3.00%
Expected dividend yield	0.00%	0.00%
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 months
Expected volatility	84.00%
Risk-free interest rate	5.30%
Expected dividend yield	0.00%
Minimum \| Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 9 months 18 days	5 years 9 months 18 days
Expected volatility	82.00%
Maximum \| Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 1 month 6 days	6 years 3 months 18 days
Expected volatility	84.00%

Stock-Based Compensation - Additional Information (Details)				1 Months Ended				12 Months Ended			19 Months Ended
	Feb. 23, 2023 shares	Aug. 09, 2022 USD ($) $ / shares shares	Mar. 11, 2020 shares	Aug. 31, 2022 shares	Dec. 31, 2020 shares	Apr. 30, 2020 shares	Jun. 30, 2019 $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021	Dec. 31, 2020 USD ($) shares	Jul. 31, 2019 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance								7,873,027	22,439,783
Reverse stock split	1-for-4
Stock issued during period, value, new issues \| $								$ 159,544,000
Allocated share based compensation expense \| $								$ 12,914,000	$ 3,191,000
Remaining weighted-average vesting period								7 years 10 months 24 days	8 years 3 months 18 days	9 years 1 month 6 days
Total intrinsic values of exercised and vested stock options \| $								$ 4,500,000	$ 100,000
Share-based compensation award, weighted-average fair value \| $ / shares								$ 15.62	$ 4
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated share based compensation expense \| $		$ 1,000,000
Minimum exercise price for repriced options \| $ / shares		$ 4.68
Maximum exercise price for repriced options \| $ / shares		$ 7.56
Repricing vested and unvested stock options outstanding		2,209,826
Incremental stock compensation expense for option repricing for vested stock options. \| $		$ 300,000
Incremental stock compensation expense for option repricing for unvested stock options \| $		$ 700,000
Remaining weighted-average vesting period		2 years 10 months 24 days
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted									0
Shares subject to repurchase								0	41,499
Restricted Stock Awards \| Enliven Inc.
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted							3,000,000
Issued shares in restricted common stock to its founders , per share \| $ / shares							$ 0.0003
Restricted Stock Awards \| Enliven Inc. \| Vested Upon Issuance
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares vested immediately upon issuance							25.00%
Restricted Stock Awards \| Employees and Consultants \| Enliven Inc.
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock shares issued											197,262
Restricted stock shares issued value \| $											$ 27,000
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost not yet recognized \| $								$ 1,100,000
Expected to be recognized over a weighted-average period								3 years 7 months 6 days
Number of Shares, Granted								85,692	0
Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation cost not yet recognized \| $								$ 34,600,000
Expected to be recognized over a weighted-average period								2 years 7 months 6 days
Maximum \| Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period								5 years
Maximum \| Restricted Stock Awards \| Enliven Inc.
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining shares vesting period							48 months
Minimum \| Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period								4 years
Minimum \| Restricted Stock Awards \| Enliven Inc.
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining shares vesting period							36 months
2019 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized				4,681,244
Number of additional shares authorized				885,315
Common stock reserved for future issuance												0
2019 Equity Incentive Plan \| Enliven Inc.
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized					3,795,929	2,584,138					3,795,929
Number of additional shares authorized					1,211,791	2,210,062
2019 Equity Incentive Plan \| Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Excercise price for repriced options \| $ / shares		$ 2.48
2019 Equity Incentive Plan \| Maximum \| Enliven Inc.
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized												374,076
2016 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			0
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance								1,574,426
Award expiration period from date of grant	10 years
Award vesting period	4 years
Reverse stock split	1-to-4
Reverse stock split conversion ratio	0.25
Number of shares of common stock that may be issued accordance with plan	4,275,000
Description of changes in the number of shares reserved for issuance								The number of shares reserved shall be annually increased on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2024 and continuing until, and including, the fiscal year commencing January 1, 2032, equal to the least of (i) 4.5% of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (ii) an amount determined by the Company’s board of directors.
Common stock outstanding percent	4.50%
2020 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance								402,757
Exercise price per share of stock options as percentage of fair market value of common stock			85.00%
Reverse stock split conversion ratio	0.25
Number of shares of common stock that may be issued accordance with plan	407,133
Common stock outstanding percent	1.00%
Stock issued during period, value, new issues \| $								$ 0	$ 0
Share based compensation liability \| $								53,000	$ 0
Stock-based compensation cost not yet recognized \| $								$ 100,000
Expected to be recognized over a weighted-average period								6 months

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases

6. Leases

Facility lease

In June 2020, the Company executed a sublease agreement for 6,782 square feet of office and laboratory space, which was set to expire on December 30, 2021. In March 2021, the Company amended its sublease agreement, increasing the leased space by 2,495 square feet to 9,277 square feet and monthly rent to $12,000. In April 2022, the lease term was extended to December 30, 2024. In addition, the Company’s leased space was increased to 18,170 square feet commencing in July 2022, and the rental payments were increased by an equally proportionate amount to reflect the increase in floor space. The monthly rent is subject to annual increases through the lease term. The Company is required to pay base rent expense as well as its proportionate share of the facilities operating expenses. The non-lease components, consisting primarily of common area maintenance, are paid separately based on actual costs incurred. Therefore, the variable non-lease components were not included in the ROU assets and lease liabilities and are reflected as expense in the period incurred.

The Company has one operating lease, as described above, with a remaining lease term of 1.0 year. The incremental borrowing rate used to calculate the Company’s ROU assets and lease liabilities is 4%. The incremental borrowing rate was estimated based on the Company's estimated borrowing rate on a collateralized loan. As of December 31, 2023, the remaining ROU assets and lease liabilities were $0.3 million and $0.3 million, respectively. As of December 31, 2022, the remaining ROU assets and lease liabilities were $0.6 million and $0.6 million, respectively.

Under the facility sublease, the Company recognized rent expense of $0.3 million and $0.2 million for the years ended December 31, 2023 and 2022, respectively, and variable lease costs of $0.4 million and $0.3 million for the years ended December 31, 2023 and 2022, respectively.

As of December 31, 2023, the future minimum lease payments under the facilities operating sublease were as follows (in thousands):


	As of
	December 31, 2023
Year ending December 31,
2024	$	341
Thereafter		—
Total future minimum lease payments		341
Less: amount representing interest		(6	)
Present value of lease liabilities		335
Less: current portion of lease liabilities		(335	)
Lease liabilities, non-current	$	—

No impairment losses were recognized during the years ended December 31, 2023 and 2022.

Marketable Securities - Additional Information (Details)	Dec. 31, 2022 USD ($)
Marketable Securities [Abstract]
Marketable Securities	$ 0

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

13. Income Taxes

There was no provision for income taxes for the years ended December 31, 2023 and 2022, because the Company has incurred significant losses since its inception.

The difference between the effective tax rate and the U.S. federal tax rate is as follows:


	Year Ended December 31,
	2023	2022
Federal income tax	(21.0%)	(21.0%)
State income tax, less federal benefits	(5.3%)	(6.7%)
Permanent differences	0.3%	1.5%
Limitation on executive compensation	1.5%	0.0%
Change in valuation allowance	26.0%	26.7%
Credits	(1.2%)	(0.5%)
Other	(0.3%)	0.0%
Effective tax rate	0.0%	0.0%

Significant components of the Company’s deferred income taxes consist of the following (in thousands). For the year ended December 31, 2022, Stock-based compensation, Accruals and other expenses not currently deductible, and Lease liability were included within the 'Other' category. Additionally, Right-of-use asset was named ‘Goodwill differences.’ The presentation has been revised to separately disclose these deferred tax assets and to rename the Right-of-use asset for enhanced transparency and clarity in financial reporting.


	As of December 31,
	2023			2022
Deferred tax assets:
Intangible asset basis differences	$	40		$	43
Net operating loss carryforwards		19,745			12,894
Tax credit carryforwards		1,535			399
Capitalized research and development costs		19,313			5,422
Stock-based compensation		1,370			243
Accruals and other expenses not currently deductible		834			594
Lease liability		94			180
Total deferred tax assets		42,931			19,775
Deferred tax liabilities:
Fixed asset basis difference		(55	)		(49	)
Right-of-use asset		(90	)		(175	)
Total deferred tax liabilities		(145	)		(224	)
Valuation allowance		(42,786	)		(19,551	)
Net deferred tax assets	$	—		$	—

Realization of tax assets is dependent upon future earnings, the timing and amount of which are uncertain. Accordingly, the U.S. net deferred tax assets have been fully offset by a valuation allowance. The changes in the valuation allowance for the years ended December 31, 2023 and 2022 were $23.2 million and $10.1 million, respectively. The increase in deferred tax assets and valuation allowance during the current year was primarily related to the generation of net operating losses and the capitalization of research and development costs, as well as the Merger.

As of December 31, 2023 and 2022, the Company had federal net operating loss carryforwards of approximately $185.3 million and $39.5 million, respectively. The 2017 Tax Cuts and Jobs Act (“TCJA”) generally allows losses incurred after 2017 to be carried over indefinitely but limits the net operating loss deduction to the lesser of the net operating loss carryover or 80% of a corporation’s taxable income (subject to IRC Section 382). Additionally, there is no carryback for losses incurred after 2017. Losses incurred prior to 2018 are generally deductible to the extent of the lesser of a corporation’s net operating loss carryover or 100% of its taxable income and are available for twenty years from the period the loss was generated. The Company has federal net operating losses generated following 2017 of $177.3 million, which do not expire. The federal net operating losses generated prior to 2018 of $8.0 million will expire beginning in 2037.

As of December 31, 2023 and 2022, the Company had California net operating loss carryforwards of approximately $126.7 million and $68.5 million, respectively. At December 31, 2023, the Company also had Colorado and Massachusetts net operating loss carryforwards of approximately $4,000 and $124.2 million, respectively. The state net operating loss carryforwards will expire at various dates through 2043.

As of December 31, 2023 and 2022, the Company had federal research and development credit carryforwards of approximately $10.5 million and $0.4 million, respectively, which are available to offset future federal income tax liabilities and expire at various dates through 2043. As of December 31, 2023 and 2022, the Company had state research and development credit carryforwards of approximately $1.3 million and $0.2 million, respectively, which are available to reduce future state tax liabilities and will expire at various dates through 2038.

Section 382 and Section 383, and corresponding provisions of state law, impose limitations on the use of net operating loss carryforwards when the stock ownership of one or more 5% stockholders (stockholders owning 5% or more of the Company’s outstanding capital stock) has increased on a cumulative basis by more than 50 percentage points. There is a risk of an ownership change beyond the control of the Company that could trigger a limitation of the use of the loss carryover. As of December 31, 2023, the Company has completed an analysis and determined ownership changes occurred under Section 382 in the past, as well as in 2023 due to the Merger. The Company's deferred tax assets have been reduced by $0.9 million and $65.7 million of net operating

loss carryforwards expected to expire unused due to the limitation for Federal and Massachusetts, respectively. The Company's deferred tax assets have also been reduced by $8.8 million and $0.8 million of credit carryforwards expected to expire due to the limitation for Federal and Massachusetts, respectively. Additionally, in the future, the Company may experience ownership changes which, if they occur, could substantially limit its ability to utilize its net operating loss and other tax carryforwards. A full valuation allowance has been established against the deferred tax assets related to the Company's net operating losses and tax credit carryforwards. Any future adjustments would be entirely offset by an adjustment to the valuation allowance.

The Company adopted the provisions of FASB ASC 740-10, Accounting for Uncertainty in Income Taxes, upon the date of incorporation. ASC 740-10 prescribes a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of any uncertain tax positions that have been taken or expected to be taken on a tax return. It is the Company’s policy to include penalties and interest expense related to income taxes as a component of its provision for income taxes, as necessary. As of December 31, 2023, the Company has not recognized any tax-related penalties or interest. At December 31, 2023 and 2022, the gross unrecognized tax benefit was $32.1 million and $0.2 million, respectively, none of which if recognized would reduce the effective tax rate in a future period, due to the Company’s full valuation allowance on U.S. net deferred tax assets. The increase related to prior year positions in 2023 is primarily related to certain attributes from the Merger following the Section 382 and 383 analysis performed in the current year. The Company does not expect that its uncertain tax positions will materially change in the next twelve months. The following table summarizes the changes to the Company’s unrecognized tax benefits (in thousands):


	As of December 31,
	2023		2022
Balance, beginning of the period	$	164	$	47
Increase related to prior year positions		28,698		7
Increase related to current year positions		3,282		110
Balance, end of the period	$	32,144	$	164

The Company has filed a U.S. federal income tax return and state tax returns in California, Colorado, Florida, New Jersey, and Massachusetts. The federal and state income tax returns are generally subject to examination for the tax years ended December 31, 2020 through the present. To the extent that the Company has tax attribute carryforwards, the tax year in which the attributes were generated may still be adjusted upon examination by the Internal Revenue Service or State taxing authorities to the extent utilized in a future period. The Company is not currently under examination by any tax authorities.

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.

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Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (71,584)	$ (37,662)

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

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Preferred Stock and Convertible Preferred Stock - Additional Information (Details) - $ / shares	Feb. 23, 2023	Dec. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Preferred stock, shares authorized		10,000,000	0
Preferred stock, par value		$ 0.001	$ 0.001
Business acquisition, exchange ratio	0.2951%
Preferred stock, shares issued		0	0
Preferred stock, shares outstanding		0	0
Merger Agreement
Class Of Stock [Line Items]
Business acquisition, common shares issued	34,426,351
Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares authorized		0	61,730,064
Preferred stock, par value		$ 0.0001	$ 0.0001
Business acquisition, exchange ratio	0.2951%
Preferred stock, shares issued		0	61,730,064
Preferred stock, shares outstanding		0	61,730,064
Convertible Preferred Stock \| Merger Agreement
Class Of Stock [Line Items]
Preferred stock, shares issued		0	0

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.

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

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Summary of Stock Option Activity

The following table summarizes stock option activity:


	Stock Options Outstanding			Weighted-Average Exercise Price		Weighted-Average Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding - January 1, 2022		3,075,403		$	3.64		9.1	$	9,657
Options granted		391,653			5.66
Options exercised and vested		(141,462	)		3.72
Options cancelled and forfeited		(8,923	)		4.68
Outstanding - December 31, 2022		3,316,671			2.20		8.3		1,194
Assumption of options in connection with the Merger		449,900			28.40		—
Options granted		2,563,778			21.65		—
Options exercised and vested		(316,194	)		2.42		—
Options cancelled and forfeited		(196,816	)		28.32		—
Outstanding - December 31, 2023		5,817,339			11.90		7.9		35,692
Exercisable - December 31, 2023		2,457,579			6.41		6.7		24,169
Vested and expected to vest - December 31, 2023		5,817,339			11.90		7.9		35,692

Summary of Stock-Based Compensation Expense

The allocation of stock-based compensation expense was as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development	$	6,000	$	1,893
General and administrative		6,914		1,298
Total stock-based compensation expense	$	12,914	$	3,191

Summary of Stock-Based Compensation Fair Value Assumptions

The assumptions used in the Black-Scholes model to determine the fair value of stock option grants and stock purchase rights under the ESPP were as follows:


	Year Ended December 31,
Stock Options	2023	2022
Expected term (years)	5.8 - 6.1	5.8 - 6.3
Expected volatility	82% - 84%	80%
Risk-free interest rate	3.3% - 4.8%	1.6% - 3.0%
Expected dividend yield	—%	—%


	Year Ended December 31,
ESPP	2023	2022
Expected term (years)	0.5	N/A
Expected volatility	84%	N/A
Risk-free interest rate	5.3%	N/A
Expected dividend yield	—%	N/A

Restricted Stock Awards

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

Summary of Restricted Stock Award and Restricted Stock Units Activity

The following table summarizes restricted stock award activity (excluding founders' shares discussed above):


	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested - January 1, 2022		97,903		$	0.14
Granted		—			—
Vested		(47,446	)		0.14
Forfeited		—			—
Unvested - December 31, 2022		50,457			0.14
Granted
Vested		(42,977	)		0.14
Forfeited
Unvested - December 31, 2023		7,480		$	0.14

Restricted Stock Units

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

Summary of Restricted Stock Award and Restricted Stock Units Activity

Restricted Stock Units ("RSUs") are valued at the market price of a share of the Company’s common stock on the date of grant. The following table summarizes RSU activity:


	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested - January 1, 2022		—		$	—
Granted		—			—
Vested		—			—
Forfeited		—			—
Unvested - December 31, 2022		—			—
Granted		85,692			14.99
Vested		(7,187	)		22.75
Forfeited		—			—
Unvested - December 31, 2023		78,505		$	14.28

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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Summary of Significant Accounting Policies

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During our last fiscal quarter, the following director(s) and officer(s), as defined in Rule 16a-1(f), adopted a “Rule 10b5-1 trading arrangement” as defined in Regulation S-K Item 408, as follows: On October 19, 2023, Helen Collins, M.D., our Chief Medical Officer, adopted a Rule 10b5-1 trading arrangement providing for the sale from time to time of an aggregate of up to 110,000 shares of our common stock. The trading arrangement is/was intended to satisfy the affirmative defense in Rule 10b5-1(c). The duration of the trading arrangement is until February 16, 2026, or earlier if all transactions under the trading arrangement are completed. No other officers or directors, as defined in Rule 16a-1(f), adopted and/or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” as defined in Regulation S-K Item 408, during the last fiscal quarter.
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
Helen Collins, M.D.
Trading Arrangements, by Individual
Name	Helen Collins, M.D.
Title	Chief Medical Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	October 19, 2023
Termination Date	February 16, 2026
Aggregate Available	110,000

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements have been prepared in conformity with U.S. GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP, as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB").

Reclassifications

Certain prior period balances have been reclassified to conform to current period presentation of the Company’s consolidated financial statements and accompanying notes. Such reclassifications have no effect on previously reported results of operations, accumulated deficit, subtotals of operating, investing or financing cash flows or consolidated balance sheet totals. For the year ended December 31, 2022, the Company reclassified $1.2 million of deferred offering costs included in accrued liabilities and $0.6 million of deferred offering costs included in accounts payable within the supplemental disclosure of non-cash investing and financial activities in the consolidated statements of cash flows.

Use of estimates

The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to stock-based compensation and accrued research and development expenses. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when facts and circumstances dictate. Actual results may differ from those estimates or assumptions.

Cash and cash equivalents

The Company considers all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents are recorded at cost, which approximates fair value. As of December 31, 2023 and 2022, cash and cash equivalents consisted primarily of checking and money market funds composed of U.S. government obligations.

Restricted cash

The Company classifies all cash whose use is limited by contractual provisions as restricted cash. Restricted cash arises from the requirement for the Company to maintain cash of $54,000 as collateral for a sublease with the facility’s landlord. As of December 31, 2023, $54,000 of restricted cash was reflected as current assets in the balance sheets. As of December 31, 2022, $54,000 of restricted cash was reflected as long-term assets in the balance sheets.

Marketable securities

The Company’s marketable securities primarily consist of U.S. Treasury securities. The Company classifies its marketable securities as available-for-sale and records such assets at estimated fair value in the consolidated balance sheets, with unrealized gains and losses, if any, reported as a component of other comprehensive income (loss) within the consolidated statements of operations and comprehensive loss and as a separate component of stockholders’ equity (deficit). The Company classifies marketable securities with remaining maturities greater than one year as current assets due to their highly liquid nature and because such marketable securities represent the investment of cash that is available to fund the Company’s current operations. Interest and dividends on marketable securities are included in interest income. The cost of marketable securities sold is based on the specific identification

method, with any realized gains and losses recorded as interest income. There were no realized gains and losses during the periods presented.

At each balance sheet date, the Company assesses available-for-sale debt securities in an unrealized loss position to determine whether the unrealized loss or any potential credit losses should be recognized in net income (loss). For available-for-sale debt securities in an unrealized loss position, the Company first assesses whether it intends to sell, or it is more likely than not that it will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through net income (loss). For available-for-sale securities that do not meet the aforementioned criteria, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Company considers the severity of the impairment, any changes in interest rates, underlying credit ratings and forecasted recovery, among other factors. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded as an allowance in interest income. There have been no impairment or credit losses recognized during the periods presented.

Concentrations of credit risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities, as well as restricted cash. The Company maintains deposits in U.S. federally insured financial institutions in excess of federally insured limits. The Company has established guidelines regarding approved investments, credit quality, diversification, liquidity and maturities of investments, which are designed to maintain safety and liquidity. Although management currently believes that the financial institutions with whom it does business will be able to fulfill their commitments to the Company, there is no assurance that those institutions will be able to continue to do so. As of December 31, 2023, the Company has not experienced any losses in its accounts and believes it is not exposed to significant credit risk on its cash balances.

Fair value measurements

Financial assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the price the Company would receive to sell an investment in a timely transaction or pay to transfer a liability in a timely transaction with an independent buyer in the principal market, or in the absence of a principal market, the most advantageous market for the investment or liability. A framework is used for measuring fair value utilizing a three-tier hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3).

The three levels of the fair value hierarchy are as follows:

•

Level 1—Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

•

Level 2—Quoted prices (other than quoted prices in Level 1) in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and

•

Level 3—Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

Financial instruments are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3.

The Company monitors the availability of inputs that are significant to the measurement of fair value to assess the appropriate categorization of financial instruments within the fair value hierarchy. Changes in economic conditions or model-based valuation techniques may require the transfer of financial instruments from one fair value level to another. In such instances, the Company’s policy is to recognize significant transfers between levels at the end of the reporting period. The significance of transfers between levels is evaluated based upon the nature of the financial instrument and size of the transfer relative to total net assets available for benefits.

The Company’s cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate their fair value due to their short maturities.

Deferred offering costs

Deferred offering costs represent legal, accounting and other direct costs related to the Company’s efforts to raise capital through a public or private sale of the Company’s common stock. These costs are generally deferred until the completion of the applicable offering, at which time such costs are reclassified to additional paid-in-capital as a reduction of the proceeds. In the instance where a planned equity financing is abandoned, terminated or significantly delayed, the deferred offering costs are recorded as expense in the period of such determination.

Property and equipment, net

Property and equipment are stated at cost, net of accumulated depreciation and amortization. Expenditures for repairs and maintenance are expensed as incurred. When assets are retired or disposed of, the assets and related accumulated depreciation are eliminated from the accounts, and any resulting gain or loss is included in the determination of net income or loss. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset.

The Company’s property and equipment consist of laboratory equipment and employee-related computers with estimated useful lives of three to five years.

Impairment of long-lived assets

The Company evaluates long-lived assets, which consist of laboratory equipment and computers, for impairment at least annually, or whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. As of December 31, 2023, no impairments have been recognized in the Company’s financial statements.

Leases

At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, the Company records the associated lease liability and corresponding right-of-use ("ROU") asset upon commencement of the lease using the implicit rate or a discount rate based on a credit-adjusted secured borrowing rate commensurate with the term of the lease. Certain leases include renewal options at the lessee’s election, which are included when recording the lease if it is reasonably certain that the renewal option will be exercised. Operating lease assets represent a right to use an underlying asset for the lease term and operating lease liabilities represent an obligation to make lease payments arising from the lease. Operating lease liabilities with a term greater than one year and their corresponding ROU assets are recognized on the balance sheet at the commencement date of the lease based on the present value of lease payments over the expected lease term. Lease cost is recognized on a straight-line basis over the lease term and variable lease payments are recognized as operating expenses in the period in which the obligation for those payments is incurred. Variable lease payments primarily include common area maintenance, utilities, real estate taxes, insurance, and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company has elected the practical expedient not to separate between lease and non-lease components.

Operating ROU assets are reflected in operating lease right-of-use assets on the balance sheets. Operating lease liabilities are reflected in accrued expenses and other current liabilities and long-term liabilities on the balance sheets.

Contingent Value Right Asset and Liability

The Company evaluates its contracts to determine if those contracts qualify as derivatives under ASC 815, Derivatives and Hedging. For derivative financial instruments that are accounted for as assets or liabilities, the derivative instrument is initially recorded at its fair value and is then re-valued at each reporting date. Any changes in fair value are recorded as other income or expense for each reporting period. Derivative instrument assets or liabilities are classified in the balance sheet as current or non-current based on

whether or not net-cash settlement of the derivative instrument is probable within the next 12 months from the balance sheet date. The Company determined that certain contingent payments under the CVR Agreement and milestone payments related to the asset sales prior to the merger qualified as derivatives under ASC 815. Upon such time that these payments are assessed a fair value, they would be recorded as a liability and asset, respectively, on the balance sheet. These values are then remeasured for future expected payout or receipt, as well as the increase in fair value due to the time value of money. These gains or losses, if any, are recognized in the consolidated statements of operations and comprehensive loss within Other income (expense), net.

The Company applies a scenario-based method and weighs them based on the possible achievement of certain milestones for both the asset and liability recognized. The fair value measurements are based on significant inputs not observable in the market and thus represent a Level 3 measurement as defined in ASC 820, Fair Value Measurement. The estimated value of the CVR and milestone consideration are based upon available information and certain assumptions, which the Company's management believes are reasonable under the circumstances.

Convertible preferred stock

The Company classifies convertible preferred stock outside of stockholders’ equity (deficit) on its balance sheet as the requirements of triggering a deemed liquidation event are not within the Company’s control. In the event of a deemed liquidation event, the proceeds from the event are distributed in accordance with liquidation preferences (Note 11). The Company records the issuance of convertible preferred stock at the issuance price less related issuance costs and less any discount arising on allocation of proceeds to one or more derivative features. The Company has not adjusted the carrying values of the convertible preferred stock to its liquidation preference because of the uncertainty as to whether a deemed liquidation event may occur. In February 2023, all outstanding shares of convertible preferred stock were converted into common shares upon the closing of the Merger.

Research and development expenses

The Company expenses research and development costs as incurred. Research and development expenses consist primarily of costs incurred for the discovery and development of its product candidates and include consultants and supplies to conduct clinical, preclinical, and non-clinical studies, costs to acquire, develop and manufacture supplies for preclinical and clinical testing and other studies, expenses incurred under agreements with contract research organizations, and salaries and related costs, including stock-based compensation, as well as depreciation and other allocated facility-related and overhead expenses. Advance payments for goods or services for future research and development activities are deferred and expensed as the goods are delivered or the related services are performed.

The Company estimates clinical and preclinical study expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on the Company’s behalf. In addition, clinical, preclinical, and non-clinical study materials are manufactured by contract manufacturing organizations. In accruing for these services, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. These estimates are based on communications with the third-party service providers and the Company’s estimates of accrued expenses and on information available at each balance sheet date. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly.

Stock-based compensation

The Company measures and records the expense related to stock-based payment awards based on the estimated grant date fair value of those awards. The Company recognizes stock-based compensation expense over the requisite service period on a straight-line basis for all stock-based awards to employees, non-employees and directors, including grants of stock options and other stock-based awards. The Company uses the Black-Scholes option pricing model to determine the fair value of the stock awards. The Black-Scholes option pricing model requires the Company to make assumptions and judgements about the variables used in the calculations, including the fair value of common stock, expected term, expected volatility of its common stock, risk-free interest rate and expected dividend yield. As the stock-based compensation is based on awards ultimately expected to vest, it is reduced by forfeitures, which the Company accounts for as they occur.

The Company classifies equity-based compensation expense in the statement of operations and comprehensive loss in the same manner in which the award recipients’ payroll costs are classified or in which the award recipients’ service payments are classified.

Black-Scholes requires the use of subjective assumptions, which determine the fair value of stock-based awards. These assumptions include:

•

Fair Value of Common Stock—Prior to the Merger, as there had been no public market for the Company’s common stock, the estimated fair value of the Company’s common stock was determined by the board of directors as of the date of each option grant with input from management, considering the most recently available third-party valuation of common stock. Following the Merger, the fair value of common stock is based on the closing stock price on the date of grant as reported on the Nasdaq Global Select Market.

•

Expected Term—The expected term represents the period that the Company’s options are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term). The Company has very limited historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants.

•

Expected Volatility—The expected stock price volatilities are estimated based on the historical and implied volatilities of comparable publicly traded companies as the Company does not have sufficient history of trading its common stock.

•

Risk-Free Interest Rate—The risk-free interest rates are based on U.S. Treasury yields in effect at the grant date for notes with comparable terms as the awards.

•

Expected Dividend Yield—The Company has never paid dividends on its common stock and has no plans to do so in the future. Therefore, the Company used an expected dividend of zero.

The assumptions underlying these valuations represented the Company’s board of directors' and management’s best estimates, which involved inherent uncertainties and the application of management’s judgment. As a result, if the Company had used significantly different assumptions or estimates, the fair value of its stock-based compensation expense could be materially different.

Income taxes

Income taxes are accounted for using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or the Company’s tax return. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement carrying amounts or existing assets and liabilities and their respective tax bases using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. The Company has generated significant net losses since its inception and accordingly has not recorded a provision for income taxes.

The Company evaluates its uncertain tax positions using the provisions of ASC Topic 740, Income taxes, which prescribes a recognition threshold that a tax position is required to meet before being recognized in the consolidated financial statements by using a "more-likely-than-not" criteria for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The Company recognizes a tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, which are considered appropriate as well as the related net interest and penalties. As of December 31, 2023, there have been no interest or penalties charged in relation to the unrecognized tax benefits.

Net loss per share

The Company calculates basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities. Convertible preferred stock is a participating security in distributions of the Company. The net loss attributable to common stockholders is not allocated to the convertible preferred shares as the holders of convertible preferred shares do not have a contractual obligation to share in losses. Cumulative dividends on preferred shares are added to net loss to arrive at net loss available to common stockholders.

Under the two-class method, basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period. The weighted-average number of shares of common stock

outstanding used in the basic net loss per share calculation does not include unvested restricted common stock as these shares are considered contingently issuable shares until they vest.

Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as convertible preferred stock, stock options and unvested early exercised common stock and unvested restricted common stock, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. For all periods presented, basic and diluted net loss per share were the same, as any additional share equivalents would be anti-dilutive.

Segments

The Company operates in one segment and, accordingly, no segment disclosures have been presented herein. The Company's long-lived assets are primarily located in the United States. The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for allocating and evaluating financial performance.

Comprehensive income (loss)

Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources, which includes net income (loss) and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses on marketable securities, other than losses attributable to a credit loss, which are included in other income and expense. The Company's only component of other comprehensive income (loss) is related to unrealized gains and losses on marketable securities.

Emerging growth company status

The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Recently adopted accounting pronouncements

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. ASU 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. This guidance was effective for fiscal years beginning after December 15, 2021. The Company adopted ASU 2019-12 on January 1, 2022, and the adoption did not have a material impact on the Company's financial statements.

Accounting pronouncements not yet adopted

In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Updated and Simplification Initiative, which amends the disclosure or presentation requirements related to various subtopics in the FASB Accounting Standards Codification. ASU 2023-06 was issued in response to the SEC's August 2018 final rule that updated and simplified disclosure requirements and is intended to align U.S. GAAP requirements with those of the SEC and to facilitate the application of U.S. GAAP for all entities. For entities subject to the SEC’s existing disclosure requirements and for entities required to file or furnish financial statements with or to the SEC in preparation for the sale of or for purposes of issuing securities that are not subject to contractual restrictions on transfer, the effective date for each amendment will be the date on which the SEC removes that related disclosure from its rules. However, if by June 30, 2027, the SEC has not removed the related disclosure from its regulations, the amendments will be removed from the Codification and not become effective for any entity. The Company is currently evaluating the impact of this guidance, but does not expect the adoption of this guidance to have a material impact on its consolidated financial statements and disclosures.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which are intended to improve reportable segment disclosure requirements. ASU 2023-07 expands public entities’ segment disclosures by requiring disclosure of significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss, an amount and description of its composition for other segment items, and interim disclosures of a reportable segment’s profit or loss and assets. The amendments are effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact that this guidance will have on its consolidated financial statements and disclosures.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. ASU 2023-09 improves the transparency and decision usefulness of income tax disclosures by requiring consistent categorization and greater disaggregation of information in the effective tax rate reconciliation and income taxes paid, disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This guidance will be effective for the annual periods beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact that this guidance will have on its consolidated financial statements and disclosures.

The Merger (Tables)

12 Months Ended

Dec. 31, 2023

Business Combination and Asset Acquisition [Abstract]

Summary of Fair Value of Identifiable Assets Acquired and Liabilities Assumed as Part of Recapitalization

The following table summarizes the fair value of identifiable assets acquired and liabilities assumed as part of the recapitalization (in thousands):


Cash and cash equivalents	$	81,821
Other current assets		1,044
Accrued liabilities		(2,624	)
Net assets acquired	$	80,241

Preferred Stock and Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of Convertible Preferred Stock and Liquidation

The authorized, issued and outstanding shares of the convertible preferred stock and liquidation preferences of Former Enliven as of December 31, 2022 were as follows (in thousands, except share and per share amounts):


	Authorized Shares		Shares Issued and Outstanding		Per Share Liquidation Preference		Aggregate Liquidation Amount (in thousands)		Proceeds Net of Issuance Costs (in thousands)
Series Seed convertible preferred stock		14,507,038		14,507,038	$	0.71	$	10,300	$	10,211
Series A convertible preferred stock		25,114,089		25,114,089		1.80		45,300		45,170
Series B convertible preferred stock		22,108,937		22,108,937		3.84		84,920		84,689
Total convertible preferred stock		61,730,064		61,730,064			$	140,520	$	140,070

Marketable Securities - Schedule of Available-for-sale Marketable Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Marketable Securities [Line Items]
Amortized Cost	$ 152,866
Unrealized Gains	147
Unrealized Losses	(6)
Estimated Fair Value	153,007
U.S. Treasury securities
Marketable Securities [Line Items]
Amortized Cost	152,866
Unrealized Gains	147
Unrealized Losses	(6)
Estimated Fair Value	$ 153,007
Maturity (in years)	1 or less

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

8. Accrued Expenses and Other Current Liabilities

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


	As of December 31,
	2023		2022
Accrued employee compensation costs	$	3,328	$	2,130
Accrued research and development costs		10,433		1,918
Accrued deferred offering costs		—		1,190
Lease liability		335		323
Accrued legal and professional fees		902		269
Other		364		447
Accrued expenses and other current liabilities	$	15,362	$	6,277

Fair Value Measurements - Additional Information (Details) - USD ($)		12 Months Ended
	Feb. 23, 2023	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payments received or paid under CVR Agreement		$ 0
Fair value assessment of payments under CVR Agreement	$ 0
CVR asset		10,000,000
CVR liability		$ 10,000,000
Milestone One
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of CVR asset and liability upon expected probability		100.00%
Milestone Two
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assessment of milestone payments under CVR Agreement		$ 0

Income Taxes - Schedule of Significant Components of Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Intangible asset basis differences	$ 40	$ 43
Net operating loss carryforwards	19,745	12,894
Tax credit carryforwards	1,535	399
Capitalized research and development costs	19,313	5,422
Stock-based compensation	1,370	243
Accruals and other expenses not currently deductible	834	594
Lease liability	94	180
Total deferred tax assets	42,931	19,775
Deferred tax liabilities:
Fixed asset basis difference	(55)	(49)
Right-of-use asset	(90)	(175)
Total deferred tax liabilities	(145)	(224)
Valuation allowance	(42,786)	(19,551)
Net deferred tax assets	$ 0	$ 0

CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 100,141,000	$ 75,536,000
Marketable securities	153,007,000	0
Restricted cash	54,000	0
Prepaid expenses and other current assets	2,949,000	2,217,000
Contingent value right asset	10,000,000
Total current assets	266,151,000	77,753,000
Property and equipment, net	742,000	890,000
Operating lease right-of-use assets	320,000	626,000
Deferred offering costs	563,000	3,975,000
Restricted cash	0	54,000
Other long-term assets	4,091,000	0
Total assets	271,867,000	83,298,000
Current liabilities:
Accounts payable	532,000	3,438,000
Accrued expenses and other current liabilities	15,362,000	6,277,000
Contingent value right liability	10,000,000
Total current liabilities	25,894,000	9,715,000
Long-term liabilities	67,000	659,000
Total liabilities	25,961,000	10,374,000
Commitments and contingencies (Note 9):
Preferred stock, value
Stockholders' equity (deficit):
Preferred stock, value
Common stock, par value $0.001 and $0.0001 at December 31, 2023 and 2022, respectively; authorized shares - 100,000,000 and 26,264,364 at December 31, 2023 and 2022, respectively; issued and outstanding shares - 41,292,027 and 3,570,019 at December 31, 2023 and 2022, respectively	41,000	1,000
Additional paid-in capital	400,172,000	6,038,000
Accumulated other comprehensive loss	141,000	0
Accumulated deficit	(154,448,000)	(82,864,000)
Total stockholders' equity (deficit)	245,906,000	(76,825,000)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	271,867,000	83,298,000
Convertible Preferred Stock
Current liabilities:
Preferred stock, value	0	149,749,000
Stockholders' equity (deficit):
Preferred stock, value	$ 0	$ 149,749,000

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

9. Commitments and Contingencies

Litigation

From time to time, the Company may be involved in legal proceedings or be subject to claims arising in the ordinary course of its business. The Company is not currently a party to any legal proceedings. Regardless of outcome, any proceedings or claims can have an adverse impact on the Company because of defense and settlement costs, diversion of resources and other factors, and there can be no assurances that favorable outcomes will be obtained.

Following the filing of the preliminary proxy statement/registration statement in connection with the Company’s stockholder meeting to consider the merger between the Company (then-named Imara Inc.) and Former Enliven, the Company and its board of directors were named in a shareholder complaint captioned Juerling v. Imara Inc., et al., 1:22-cv-09986 (S.D.N.Y. filed November 23, 2022) (the “Complaint”) and also received demand letters from certain stockholders (collectively, the “Demands” and with the Complaint, the “Actions”).

The Complaint generally alleged violations of Sections 14(a) and 20(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), in connection with the filing of the preliminary proxy statement/registration statement. In particular, the Complaint generally alleged that the registration statement contained materially misleading and incomplete information concerning, among other things: (i) certain conflicts of interest involving the Company and its board of directors; (ii) the background and sales process leading up to the Merger Agreement; (iii) the Company’s and Former Enliven’s financial projections; and (iv) the data and inputs underlying the financial analyses performed by SVB Securities, which acted as the Company’s financial advisor for the Merger. As relief, the complaint sought (i) an injunction of the proposed Merger; (ii) recission in the event the Merger is consummated or, alternatively, rescissory damages; (iii) an injunction requiring the individual defendants to file a new registration statement that is not false or misleading; (iv) an award of costs, including attorneys’ and experts’ fees; and (v) any further relief that the court deems just and proper.

Following discussions between the Company and counsel in the Actions, on December 19, 2022 and February 13, 2023, the Company filed a Form S-4/A and Form 8-K, respectively, with the SEC that contained additional information that mooted the disclosure claims asserted in the Actions (the “Supplemental Disclosures”). In connection with the filing of the Supplemental Disclosures, counsel in the Actions informed Defendants that, in light of the mootness of the stockholders’ claims, that stockholders would voluntarily dismiss the Complaint by filing a notice of voluntary dismissal, and agreed to not further pursue the actions contemplated by the Demands. On January 19, 2023, the Complaint was voluntarily dismissed by plaintiff.

The Company subsequently agreed to pay a mootness fee of an immaterial amount.

Indemnification agreements

In the ordinary course of business, the Company has provided and may provide indemnification of varying scope and terms to vendors, consultants, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims under indemnification arrangements, and it has not accrued any liabilities related to such obligations in its consolidated financial statements as of December 31, 2023 and 2022.

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with U.S. GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP, as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB").
Reclassifications	Reclassifications Certain prior period balances have been reclassified to conform to current period presentation of the Company’s consolidated financial statements and accompanying notes. Such reclassifications have no effect on previously reported results of operations, accumulated deficit, subtotals of operating, investing or financing cash flows or consolidated balance sheet totals. For the year ended December 31, 2022, the Company reclassified $1.2 million of deferred offering costs included in accrued liabilities and $0.6 million of deferred offering costs included in accounts payable within the supplemental disclosure of non-cash investing and financial activities in the consolidated statements of cash flows.
Use of estimates	Use of estimates The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to stock-based compensation and accrued research and development expenses. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when facts and circumstances dictate. Actual results may differ from those estimates or assumptions.
Cash and cash equivalents	Cash and cash equivalents The Company considers all highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents are recorded at cost, which approximates fair value. As of December 31, 2023 and 2022, cash and cash equivalents consisted primarily of checking and money market funds composed of U.S. government obligations.
Restricted cash	Restricted cash The Company classifies all cash whose use is limited by contractual provisions as restricted cash. Restricted cash arises from the requirement for the Company to maintain cash of $54,000 as collateral for a sublease with the facility’s landlord. As of December 31, 2023, $54,000 of restricted cash was reflected as current assets in the balance sheets. As of December 31, 2022, $54,000 of restricted cash was reflected as long-term assets in the balance sheets.
Marketable securities	Marketable securities The Company’s marketable securities primarily consist of U.S. Treasury securities. The Company classifies its marketable securities as available-for-sale and records such assets at estimated fair value in the consolidated balance sheets, with unrealized gains and losses, if any, reported as a component of other comprehensive income (loss) within the consolidated statements of operations and comprehensive loss and as a separate component of stockholders’ equity (deficit). The Company classifies marketable securities with remaining maturities greater than one year as current assets due to their highly liquid nature and because such marketable securities represent the investment of cash that is available to fund the Company’s current operations. Interest and dividends on marketable securities are included in interest income. The cost of marketable securities sold is based on the specific identification method, with any realized gains and losses recorded as interest income. There were no realized gains and losses during the periods presented. At each balance sheet date, the Company assesses available-for-sale debt securities in an unrealized loss position to determine whether the unrealized loss or any potential credit losses should be recognized in net income (loss). For available-for-sale debt securities in an unrealized loss position, the Company first assesses whether it intends to sell, or it is more likely than not that it will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through net income (loss). For available-for-sale securities that do not meet the aforementioned criteria, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Company considers the severity of the impairment, any changes in interest rates, underlying credit ratings and forecasted recovery, among other factors. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded as an allowance in interest income. There have been no impairment or credit losses recognized during the periods presented.
Concentrations of credit risk	Concentrations of credit risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities, as well as restricted cash. The Company maintains deposits in U.S. federally insured financial institutions in excess of federally insured limits. The Company has established guidelines regarding approved investments, credit quality, diversification, liquidity and maturities of investments, which are designed to maintain safety and liquidity. Although management currently believes that the financial institutions with whom it does business will be able to fulfill their commitments to the Company, there is no assurance that those institutions will be able to continue to do so. As of December 31, 2023, the Company has not experienced any losses in its accounts and believes it is not exposed to significant credit risk on its cash balances.
Fair value measurements	Fair value measurements Financial assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the price the Company would receive to sell an investment in a timely transaction or pay to transfer a liability in a timely transaction with an independent buyer in the principal market, or in the absence of a principal market, the most advantageous market for the investment or liability. A framework is used for measuring fair value utilizing a three-tier hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are as follows: • Level 1—Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; • Level 2—Quoted prices (other than quoted prices in Level 1) in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and • Level 3—Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. Financial instruments are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. The Company monitors the availability of inputs that are significant to the measurement of fair value to assess the appropriate categorization of financial instruments within the fair value hierarchy. Changes in economic conditions or model-based valuation techniques may require the transfer of financial instruments from one fair value level to another. In such instances, the Company’s policy is to recognize significant transfers between levels at the end of the reporting period. The significance of transfers between levels is evaluated based upon the nature of the financial instrument and size of the transfer relative to total net assets available for benefits. The Company’s cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate their fair value due to their short maturities.
Deferred offering costs	Deferred offering costs Deferred offering costs represent legal, accounting and other direct costs related to the Company’s efforts to raise capital through a public or private sale of the Company’s common stock. These costs are generally deferred until the completion of the applicable offering, at which time such costs are reclassified to additional paid-in-capital as a reduction of the proceeds. In the instance where a planned equity financing is abandoned, terminated or significantly delayed, the deferred offering costs are recorded as expense in the period of such determination
Property and equipment, net	Property and equipment, net Property and equipment are stated at cost, net of accumulated depreciation and amortization. Expenditures for repairs and maintenance are expensed as incurred. When assets are retired or disposed of, the assets and related accumulated depreciation are eliminated from the accounts, and any resulting gain or loss is included in the determination of net income or loss. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset. The Company’s property and equipment consist of laboratory equipment and employee-related computers with estimated useful lives of three to five years.
Impairment of long-lived assets	Impairment of long-lived assets The Company evaluates long-lived assets, which consist of laboratory equipment and computers, for impairment at least annually, or whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. As of December 31, 2023, no impairments have been recognized in the Company’s financial statements.
Leases	Leases At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, the Company records the associated lease liability and corresponding right-of-use ("ROU") asset upon commencement of the lease using the implicit rate or a discount rate based on a credit-adjusted secured borrowing rate commensurate with the term of the lease. Certain leases include renewal options at the lessee’s election, which are included when recording the lease if it is reasonably certain that the renewal option will be exercised. Operating lease assets represent a right to use an underlying asset for the lease term and operating lease liabilities represent an obligation to make lease payments arising from the lease. Operating lease liabilities with a term greater than one year and their corresponding ROU assets are recognized on the balance sheet at the commencement date of the lease based on the present value of lease payments over the expected lease term. Lease cost is recognized on a straight-line basis over the lease term and variable lease payments are recognized as operating expenses in the period in which the obligation for those payments is incurred. Variable lease payments primarily include common area maintenance, utilities, real estate taxes, insurance, and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company has elected the practical expedient not to separate between lease and non-lease components. Operating ROU assets are reflected in operating lease right-of-use assets on the balance sheets. Operating lease liabilities are reflected in accrued expenses and other current liabilities and long-term liabilities on the balance sheets.
Contingent value right asset and liability	Contingent Value Right Asset and Liability The Company evaluates its contracts to determine if those contracts qualify as derivatives under ASC 815, Derivatives and Hedging. For derivative financial instruments that are accounted for as assets or liabilities, the derivative instrument is initially recorded at its fair value and is then re-valued at each reporting date. Any changes in fair value are recorded as other income or expense for each reporting period. Derivative instrument assets or liabilities are classified in the balance sheet as current or non-current based on whether or not net-cash settlement of the derivative instrument is probable within the next 12 months from the balance sheet date. The Company determined that certain contingent payments under the CVR Agreement and milestone payments related to the asset sales prior to the merger qualified as derivatives under ASC 815. Upon such time that these payments are assessed a fair value, they would be recorded as a liability and asset, respectively, on the balance sheet. These values are then remeasured for future expected payout or receipt, as well as the increase in fair value due to the time value of money. These gains or losses, if any, are recognized in the consolidated statements of operations and comprehensive loss within Other income (expense), net. The Company applies a scenario-based method and weighs them based on the possible achievement of certain milestones for both the asset and liability recognized. The fair value measurements are based on significant inputs not observable in the market and thus represent a Level 3 measurement as defined in ASC 820, Fair Value Measurement. The estimated value of the CVR and milestone consideration are based upon available information and certain assumptions, which the Company's management believes are reasonable under the circumstances.
Convertible preferred stock	Convertible preferred stock The Company classifies convertible preferred stock outside of stockholders’ equity (deficit) on its balance sheet as the requirements of triggering a deemed liquidation event are not within the Company’s control. In the event of a deemed liquidation event, the proceeds from the event are distributed in accordance with liquidation preferences (Note 11). The Company records the issuance of convertible preferred stock at the issuance price less related issuance costs and less any discount arising on allocation of proceeds to one or more derivative features. The Company has not adjusted the carrying values of the convertible preferred stock to its liquidation preference because of the uncertainty as to whether a deemed liquidation event may occur. In February 2023, all outstanding shares of convertible preferred stock were converted into common shares upon the closing of the Merger.
Research and development expenses	Research and development expenses The Company expenses research and development costs as incurred. Research and development expenses consist primarily of costs incurred for the discovery and development of its product candidates and include consultants and supplies to conduct clinical, preclinical, and non-clinical studies, costs to acquire, develop and manufacture supplies for preclinical and clinical testing and other studies, expenses incurred under agreements with contract research organizations, and salaries and related costs, including stock-based compensation, as well as depreciation and other allocated facility-related and overhead expenses. Advance payments for goods or services for future research and development activities are deferred and expensed as the goods are delivered or the related services are performed. The Company estimates clinical and preclinical study expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on the Company’s behalf. In addition, clinical, preclinical, and non-clinical study materials are manufactured by contract manufacturing organizations. In accruing for these services, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. These estimates are based on communications with the third-party service providers and the Company’s estimates of accrued expenses and on information available at each balance sheet date. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly.
Stock-based compensation	Stock-based compensation The Company measures and records the expense related to stock-based payment awards based on the estimated grant date fair value of those awards. The Company recognizes stock-based compensation expense over the requisite service period on a straight-line basis for all stock-based awards to employees, non-employees and directors, including grants of stock options and other stock-based awards. The Company uses the Black-Scholes option pricing model to determine the fair value of the stock awards. The Black-Scholes option pricing model requires the Company to make assumptions and judgements about the variables used in the calculations, including the fair value of common stock, expected term, expected volatility of its common stock, risk-free interest rate and expected dividend yield. As the stock-based compensation is based on awards ultimately expected to vest, it is reduced by forfeitures, which the Company accounts for as they occur. The Company classifies equity-based compensation expense in the statement of operations and comprehensive loss in the same manner in which the award recipients’ payroll costs are classified or in which the award recipients’ service payments are classified. Black-Scholes requires the use of subjective assumptions, which determine the fair value of stock-based awards. These assumptions include: • Fair Value of Common Stock—Prior to the Merger, as there had been no public market for the Company’s common stock, the estimated fair value of the Company’s common stock was determined by the board of directors as of the date of each option grant with input from management, considering the most recently available third-party valuation of common stock. Following the Merger, the fair value of common stock is based on the closing stock price on the date of grant as reported on the Nasdaq Global Select Market. • Expected Term—The expected term represents the period that the Company’s options are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term). The Company has very limited historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. • Expected Volatility—The expected stock price volatilities are estimated based on the historical and implied volatilities of comparable publicly traded companies as the Company does not have sufficient history of trading its common stock. • Risk-Free Interest Rate—The risk-free interest rates are based on U.S. Treasury yields in effect at the grant date for notes with comparable terms as the awards. • Expected Dividend Yield—The Company has never paid dividends on its common stock and has no plans to do so in the future. Therefore, the Company used an expected dividend of zero. The assumptions underlying these valuations represented the Company’s board of directors' and management’s best estimates, which involved inherent uncertainties and the application of management’s judgment. As a result, if the Company had used significantly different assumptions or estimates, the fair value of its stock-based compensation expense could be materially different.
Income taxes	Income taxes Income taxes are accounted for using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or the Company’s tax return. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement carrying amounts or existing assets and liabilities and their respective tax bases using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. The Company has generated significant net losses since its inception and accordingly has not recorded a provision for income taxes. The Company evaluates its uncertain tax positions using the provisions of ASC Topic 740, Income taxes, which prescribes a recognition threshold that a tax position is required to meet before being recognized in the consolidated financial statements by using a "more-likely-than-not" criteria for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The Company recognizes a tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, which are considered appropriate as well as the related net interest and penalties. As of December 31, 2023, there have been no interest or penalties charged in relation to the unrecognized tax benefits.
Net loss per share	Net loss per share The Company calculates basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities. Convertible preferred stock is a participating security in distributions of the Company. The net loss attributable to common stockholders is not allocated to the convertible preferred shares as the holders of convertible preferred shares do not have a contractual obligation to share in losses. Cumulative dividends on preferred shares are added to net loss to arrive at net loss available to common stockholders. Under the two-class method, basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period. The weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation does not include unvested restricted common stock as these shares are considered contingently issuable shares until they vest. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as convertible preferred stock, stock options and unvested early exercised common stock and unvested restricted common stock, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. For all periods presented, basic and diluted net loss per share were the same, as any additional share equivalents would be anti-dilutive.
Segments	Segments The Company operates in one segment and, accordingly, no segment disclosures have been presented herein. The Company's long-lived assets are primarily located in the United States. The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for allocating and evaluating financial performance.
Comprehensive income (loss)	Comprehensive income (loss) Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources, which includes net income (loss) and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses on marketable securities, other than losses attributable to a credit loss, which are included in other income and expense. The Company's only component of other comprehensive income (loss) is related to unrealized gains and losses on marketable securities.
Emerging growth company status	Emerging growth company status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recently adopted and not yet adopted accounting pronouncements	Recently adopted accounting pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. ASU 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. This guidance was effective for fiscal years beginning after December 15, 2021. The Company adopted ASU 2019-12 on January 1, 2022, and the adoption did not have a material impact on the Company's financial statements. Accounting pronouncements not yet adopted In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Updated and Simplification Initiative, which amends the disclosure or presentation requirements related to various subtopics in the FASB Accounting Standards Codification. ASU 2023-06 was issued in response to the SEC's August 2018 final rule that updated and simplified disclosure requirements and is intended to align U.S. GAAP requirements with those of the SEC and to facilitate the application of U.S. GAAP for all entities. For entities subject to the SEC’s existing disclosure requirements and for entities required to file or furnish financial statements with or to the SEC in preparation for the sale of or for purposes of issuing securities that are not subject to contractual restrictions on transfer, the effective date for each amendment will be the date on which the SEC removes that related disclosure from its rules. However, if by June 30, 2027, the SEC has not removed the related disclosure from its regulations, the amendments will be removed from the Codification and not become effective for any entity. The Company is currently evaluating the impact of this guidance, but does not expect the adoption of this guidance to have a material impact on its consolidated financial statements and disclosures. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which are intended to improve reportable segment disclosure requirements. ASU 2023-07 expands public entities’ segment disclosures by requiring disclosure of significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss, an amount and description of its composition for other segment items, and interim disclosures of a reportable segment’s profit or loss and assets. The amendments are effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact that this guidance will have on its consolidated financial statements and disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. ASU 2023-09 improves the transparency and decision usefulness of income tax disclosures by requiring consistent categorization and greater disaggregation of information in the effective tax rate reconciliation and income taxes paid, disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This guidance will be effective for the annual periods beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact that this guidance will have on its consolidated financial statements and disclosures.

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands		12 Months Ended
	Feb. 23, 2023	Dec. 31, 2023
Statement of Stockholders' Equity [Abstract]
Issuance costs incurred	$ 5,000	$ 4,955

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating expenses:
Research and development	$ 64,574	$ 31,022
General and administrative	18,955	7,769
Total operating expenses	83,529	38,791
Loss from operations	(83,529)	(38,791)
Other income (expense), net
Interest income	11,967	1,129
Other expense	(22)	0
Total other income (expense), net	11,945	1,129
Net loss	(71,584)	(37,662)
Other comprehensive income (loss):
Net unrealized gains on marketable securities	141	0
Comprehensive loss	$ (71,443)	$ (37,662)
Net loss per share, basic	$ (2.01)	$ (12.05)
Net loss per share, diluted	$ (2.01)	$ (12.05)
Weighted-average shares outstanding, basic	35,546,215	3,124,274
Weighted-average shares outstanding, diluted	35,546,215	3,124,274

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Difference Between Effective Tax Rate and U.S. Federal Tax Rate


	Year Ended December 31,
	2023	2022
Federal income tax	(21.0%)	(21.0%)
State income tax, less federal benefits	(5.3%)	(6.7%)
Permanent differences	0.3%	1.5%
Limitation on executive compensation	1.5%	0.0%
Change in valuation allowance	26.0%	26.7%
Credits	(1.2%)	(0.5%)
Other	(0.3%)	0.0%
Effective tax rate	0.0%	0.0%

Schedule of Significant Components of Deferred Income Taxes


	As of December 31,
	2023			2022
Deferred tax assets:
Intangible asset basis differences	$	40		$	43
Net operating loss carryforwards		19,745			12,894
Tax credit carryforwards		1,535			399
Capitalized research and development costs		19,313			5,422
Stock-based compensation		1,370			243
Accruals and other expenses not currently deductible		834			594
Lease liability		94			180
Total deferred tax assets		42,931			19,775
Deferred tax liabilities:
Fixed asset basis difference		(55	)		(49	)
Right-of-use asset		(90	)		(175	)
Total deferred tax liabilities		(145	)		(224	)
Valuation allowance		(42,786	)		(19,551	)
Net deferred tax assets	$	—		$	—

Schedule of Changes in Unrecognized Tax Benefits


	As of December 31,
	2023		2022
Balance, beginning of the period	$	164	$	47
Increase related to prior year positions		28,698		7
Increase related to current year positions		3,282		110
Balance, end of the period	$	32,144	$	164

Stock-Based Compensation

12 Months Ended

Dec. 31, 2023

Stock-Based Compensation

12. Stock-Based Compensation

Equity Incentive Plans

2019 Equity Incentive Plan

In July 2019, Former Enliven adopted the 2019 Equity Incentive Plan (the “2019 Plan”) pursuant to which its board of directors may grant non-statutory stock options, stock appreciation rights, restricted stock, and restricted stock units to employees and non-employees and incentive stock options only to employees. After giving effect to the exchange ratio, the 2019 Plan initially authorized grants of awards of up to 374,076 shares of Former Enliven’s common stock. In April 2020, the board of directors increased the number of shares of Former Enliven’s common stock authorized for issuance under the 2019 Plan by 2,210,062 to 2,584,138 shares. Additionally, in December 2020, the board of directors approved an increase in the number of shares of Former Enliven’s common stock authorized for issuance under the 2019 Plan by 1,211,791 to 3,795,929 shares. In August 2022, the board of directors approved an increase in the shares authorized under the 2019 Plan of 885,315 shares, for a total authorized amount of 4,681,244.

The 2019 Plan was terminated as of the close of the Merger, and no shares remain available for future issuance under the 2019 Plan. Any options outstanding under the 2019 Plan remained outstanding and effective.

2016 Stock Incentive Plan

The Company’s 2016 Stock Incentive Plan (the “2016 Plan”) provided for the grant of restricted stock, restricted stock units, stock appreciation rights, incentive stock options, non-statutory stock options and other stock-based awards to employees, officers, members of the board of directors, consultants and advisors of the Company. As of the effective date of the 2020 Equity Incentive Plan, no shares remained available for future issuance under the 2016 Plan. Any options or awards outstanding under the 2016 Plan remained outstanding and effective.

2020 Equity Incentive Plan

On October 1, 2019, the Company’s board of directors adopted, and on February 26, 2020 the Company’s stockholders approved, the 2020 Equity Incentive Plan, which became effective on March 11, 2020 (the “2020 Plan”). The 2020 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards.

On November 8, 2022, the Company’s board of directors adopted, and on February 22, 2023, the Company’s stockholders approved, the amendment and restatement of the 2020 Plan. Following the 1-to-4 reverse stock split effected on February 23, 2023, the number of shares reserved for issuance under the 2020 Plan is equal to 4,275,000 shares of the Company’s common stock. The number of shares reserved shall be annually increased on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2024 and continuing until, and including, the fiscal year commencing January 1, 2032, equal to the least of (i) 4.5% of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (ii) an amount determined by the Company’s board of directors. The shares of common stock underlying any awards that expire, terminate, or are otherwise surrendered, cancelled, forfeited or repurchased by the Company under the 2020 Plan will be added back to the shares of common stock available for issuance under the 2020 Plan. As of December 31, 2023, 1,574,426 shares of the Company’s common stock remained available for issuance under the 2020 Plan.

Awards granted under the Company’s equity plans expire no later than 10 years from the date of grant. Options and restricted stock granted to employees typically vest over a four-year period but may have been granted with different vesting terms.

2020 Employee Stock Purchase Plan

On October 1, 2019, the Company’s board of directors adopted, and on February 26, 2020, the Company’s stockholders approved the 2020 Employee Stock Purchase Plan (the “ESPP”), which became effective on March 11, 2020. The ESPP permits eligible employees who elect to participate, in six-month offering periods, to purchase shares of common stock through payroll deductions at a price equal to 85% of the fair market value of the common stock on the first or last business day of each applicable six-month offering period, whichever is lower. Purchase dates under the ESPP occur on or about June 13 and December 13 each year.

On November 8, 2022, the Company’s board of directors adopted, and on February 22, 2023, the Company’s stockholders approved, an amendment to the ESPP to increase its share reserve. Following the 1-to-4 reverse stock split effected on February 23, 2023, the number of shares reserved for issuance under the ESPP is equal to 407,133 shares of the Company’s common stock. The number of shares reserved shall be annually increased on the first day of each fiscal year, beginning with the fiscal year commencing on January

1, 2024 and continuing until, and including, the fiscal year commencing January 1, 2043, equal to the least of (i) 407,133 shares of the Company’s common stock, (ii) 1% of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (iii) an amount determined by the Company’s board of directors. As of December 31, 2023, 402,757 shares of the Company’s common stock remained available for issuance under the ESPP.

The Company did not issue any shares under the ESPP during the years ended December 31, 2023 and 2022. The Company had an outstanding liability of $53,000 and $0 at December 31, 2023 and 2022, respectively, which is included in accrued expenses and other current liabilities on the consolidated balance sheets, for employee contributions to the ESPP for shares pending issuance at the end of the offering period. As of December 31, 2023, total stock-based compensation cost not yet recognized related to stock purchase rights under the ESPP was $0.1 million, which is expected to be recognized over a weighted-average period of 0.5 years.

Stock Options

Effective August 9, 2022, Former Enliven’s board of directors repriced certain previously granted and still outstanding vested and unvested stock option awards under the 2019 Plan. As a result, the exercise price for these awards was lowered to $2.48 per share, which was the fair value of Former Enliven’s common stock on August 9, 2022. No other terms of the repriced stock options were modified, and the repriced stock options will continue to vest according to their original vesting schedules and will retain their original expiration dates. As a result of the repricing, 2,209,826 vested and unvested stock options outstanding as of August 9, 2022, with original exercise prices ranging from $4.68 to $7.56, were repriced. The repricing on August 9, 2022 resulted in incremental stock-based compensation expense of $1.0 million, of which $0.3 million related to vested stock option awards and was expensed on the repricing date, and $0.7 million related to unvested stock option awards is being amortized on a straight-line basis over the remaining weighted-average vesting period of those awards of 2.9 years.

The following table summarizes stock option activity:


	Stock Options Outstanding			Weighted-Average Exercise Price		Weighted-Average Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding - January 1, 2022		3,075,403		$	3.64		9.1	$	9,657
Options granted		391,653			5.66
Options exercised and vested		(141,462	)		3.72
Options cancelled and forfeited		(8,923	)		4.68
Outstanding - December 31, 2022		3,316,671			2.20		8.3		1,194
Assumption of options in connection with the Merger		449,900			28.40		—
Options granted		2,563,778			21.65		—
Options exercised and vested		(316,194	)		2.42		—
Options cancelled and forfeited		(196,816	)		28.32		—
Outstanding - December 31, 2023		5,817,339			11.90		7.9		35,692
Exercisable - December 31, 2023		2,457,579			6.41		6.7		24,169
Vested and expected to vest - December 31, 2023		5,817,339			11.90		7.9		35,692

The aggregate intrinsic values presented in the table above were calculated as the difference between the fair value of the Company’s common stock and the exercise price of outstanding stock options that had strike prices below the fair value of the Company’s common stock. The total intrinsic values of exercised and vested stock options during the years ended December 31, 2023 and 2022 were $4.5 million and $0.1 million, respectively, and were calculated on the difference between the exercise price and the fair value of the Company’s common stock as of the exercise date.

The weighted-average grant date fair value of options granted during the years ended December 31, 2023 and 2022 were $15.62 and $4.00 per share, respectively.

As of December 31, 2023, total compensation cost not yet recognized related to unvested stock options was $34.6 million, which is expected to be recognized over a weighted-average period of 2.6 years.

Restricted stock awards

Upon formation of Former Enliven in June 2019, Former Enliven issued approximately 3.0 million shares in restricted common stock to its founders at approximately $0.0003 per share. 25% of the shares vested immediately upon issuance, with the remaining shares vesting evenly over 36 or 48 months. Vesting may be accelerated upon a change in control, as defined in the holder agreements. If the holders cease to have a business relationship with the Company, any unvested shares held by these individuals may be repurchased at their original purchase price. The unvested restricted stock is not considered outstanding for accounting purposes until the shares vest. As of December 31, 2023 and 2022, there were 0 and 41,499 founders' shares subject to repurchase, respectively.

Additionally, between 2019 and 2020, Former Enliven issued a total of 197,262 shares of restricted stock to employees and consultants for aggregate consideration of $27,000. The purchase price of the restricted stock was the estimated fair value on the grant date. The restricted stock awards are subject to vesting over a period of four to five years, and vesting may be accelerated upon a change in control, as defined in the holder agreements. If the holders cease to have a business relationship with the Company, any unvested shares held by these individuals may be repurchased at their original purchase price. The unvested restricted stock is not considered outstanding for accounting purposes until the shares vest.

The following table summarizes restricted stock award activity (excluding founders' shares discussed above):


	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested - January 1, 2022		97,903		$	0.14
Granted		—			—
Vested		(47,446	)		0.14
Forfeited		—			—
Unvested - December 31, 2022		50,457			0.14
Granted
Vested		(42,977	)		0.14
Forfeited
Unvested - December 31, 2023		7,480		$	0.14

As of December 31, 2023, total compensation cost not yet recognized was immaterial.

Restricted stock units

Restricted Stock Units ("RSUs") are valued at the market price of a share of the Company’s common stock on the date of grant. The following table summarizes RSU activity:


	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested - January 1, 2022		—		$	—
Granted		—			—
Vested		—			—
Forfeited		—			—
Unvested - December 31, 2022		—			—
Granted		85,692			14.99
Vested		(7,187	)		22.75
Forfeited		—			—
Unvested - December 31, 2023		78,505		$	14.28

As of December 31, 2023, total compensation cost not yet recognized related to unvested RSUs was $1.1 million, which is expected to be recognized over a weighted-average period of 3.6 years.

Stock-based compensation expense

The allocation of stock-based compensation expense was as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development	$	6,000	$	1,893
General and administrative		6,914		1,298
Total stock-based compensation expense	$	12,914	$	3,191

The assumptions used in the Black-Scholes model to determine the fair value of stock option grants and stock purchase rights under the ESPP were as follows:


	Year Ended December 31,
Stock Options	2023	2022
Expected term (years)	5.8 - 6.1	5.8 - 6.3
Expected volatility	82% - 84%	80%
Risk-free interest rate	3.3% - 4.8%	1.6% - 3.0%
Expected dividend yield	—%	—%


	Year Ended December 31,
ESPP	2023	2022
Expected term (years)	0.5	N/A
Expected volatility	84%	N/A
Risk-free interest rate	5.3%	N/A
Expected dividend yield	—%	N/A

Organization, Description of Business and Liquidity

12 Months Ended

Dec. 31, 2023

Organization Description Of Business And Liquidity [Abstract]

Organization Description of Business and Liquidity

1. Organization, Description of Business and Liquidity

Business

Enliven Inc. (formerly, Enliven Therapeutics, Inc.) (“Former Enliven”) was incorporated in the State of Delaware on June 12, 2019. Enliven Therapeutics, Inc. (formerly Imara Inc.) (the “Company”) is headquartered in Boulder, Colorado. The Company is a clinical-stage biopharmaceutical company focused on the discovery and development of small molecule inhibitors to help patients with cancer not only live longer, but live better. The Company aims to address existing and emerging unmet needs with a precision oncology approach that improves survival and enhances overall patient well-being. Its discovery process combines deep insights in clinically validated biological targets and differentiated chemistry with the goal of designing therapies for unmet needs.

Since its inception, the Company has devoted substantially all of its efforts to research and development activities, business planning, establishing and maintaining its intellectual property portfolio, hiring personnel, raising capital, and providing general and administrative support for these activities. To date, the Company has funded its operations primarily through private placements of its common and convertible preferred stock.

The Merger, Exchange Ratio and Financing Transaction

On October 13, 2022, the Company entered into an agreement and plan of merger (“Merger Agreement” and such transactions considered by the Merger Agreement, the “Merger”) with Former Enliven.

On February 23, 2023, the Company completed the Merger with Former Enliven in accordance with the Merger Agreement. Prior to the effective time of the Merger, the Company effected a 1-for-4 reverse stock split (the “Reverse Stock Split”), and right after the Merger, the Company changed its name to Enliven Therapeutics, Inc. Subject to the terms and conditions of the Merger Agreement, at the closing of the Merger, (a) each outstanding share of Former Enliven common stock (including common stock issued upon the conversion of its preferred stock) was converted into the right to receive a number of shares of the Company’s common stock (“Company Common Stock”) (after giving effect to the Reverse Stock Split) equal to the exchange ratio per the Merger Agreement; and (b) each then outstanding Former Enliven stock option that had not previously been exercised prior to the closing of the Merger was assumed by the Company. At closing of the Merger, the Company issued an aggregate of 34,426,351 shares of Company Common Stock to Former Enliven’s stockholders, based on an exchange ratio of approximately 0.2951 shares of Company Common Stock for each share of Former Enliven common stock outstanding immediately prior to the Merger, including those shares of common stock issued upon conversion of the Former Enliven preferred stock, resulting in 41,011,501 shares of Company Common Stock being issued and outstanding immediately following the effective time of the Merger. The Company also assumed all of the outstanding and unexercised stock options to purchase shares of Former Enliven common stock. The assumed options continue to be governed by the terms of the 2019 Equity Incentive Plan (as further discussed in Note 12) under which the options were originally granted, with such options hence forth representing the right to purchase a number of shares of Company Common Stock equal to approximately 0.2951 multiplied by the number of shares of Former Enliven common stock previously represented by such options.

The Merger was accounted for as a reverse recapitalization in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”). Under this method of accounting, Former Enliven was deemed to be the accounting acquirer for financial reporting purposes. This determination was primarily based on the expectation that, immediately following the Merger: (i) Former Enliven stockholders will own a substantial majority of the voting rights; (ii) Former Enliven will designate a majority (eight of nine) of the initial members of the board of directors of the combined company; (iii) Former Enliven’s executive management team will become the management team of the combined company; and (iv) the combined company will be named Enliven Therapeutics, Inc. and be headquartered in Boulder, Colorado. Accordingly, for accounting purposes, the Merger was treated as the equivalent of Former Enliven issuing stock to acquire the net assets of the Company. As a result of the Merger, the net assets of the Company were recorded at their acquisition-date fair value in the financial statements of Former Enliven and the reported operating results prior to the Merger will be those of Former Enliven. Historical common share figures of Former Enliven have been retroactively restated based on the exchange ratio of approximately 0.2951.

On February 23, 2023, prior to the effective time of the Merger, the Company entered into a Contingent Value Rights Agreement (the “CVR Agreement”) with a rights agent, pursuant to which the Company’s pre-Merger common stockholders received one contingent value right (each, a “CVR”) for each outstanding share of the Company’s common stock held by such stockholder as of February 22, 2023. Each CVR represents the contractual right to receive payments upon the occurrence of certain events related to

the Company’s sale of certain assets prior to the completion of the Merger, in each case subject to, and in accordance with, the terms and conditions of the CVR Agreement. Under the CVR Agreement, the Company is only liable to the CVR holders once it has received payments from the third-party that purchased the assets, which will only occur upon the third-party achieving certain development milestones related to the assets purchased. In accordance with the CVR Agreement, any distributions to the Company for these milestone payments are then subsequently remitted to the CVR holders, net of qualifying expenses. Pursuant to the terms of an asset purchase agreement with a third-party, the Company is eligible to receive two potential milestones, one for $10.0 million and a second for $50.0 million. The Company has no involvement, control or influence over the development of such assets.

Concurrently with the execution of the Merger Agreement, and in order to provide Former Enliven with additional capital for its development programs prior to the closing of the Merger, certain new and current investors purchased an aggregate of $164.5 million of common stock of Former Enliven (the “Financing Transaction”).

Risks and uncertainties

The Company is subject to risks common to development-stage companies in the biotechnology industry including, but not limited to, risks of failure of preclinical studies and clinical trials, new technological innovations, protection of proprietary technology, dependence on key personnel, reliance on third-party organizations, risks of obtaining regulatory approval for any product candidate that it may develop, compliance with government regulations and the need to obtain additional financing.

The Company continues to closely monitor macroeconomic and geopolitical developments, including inflation, instability in the banking and financial services sector, tightening of the credit markets, the Russia-Ukraine and Israel-Hamas conflicts, and COVID-19. The extent of the impact of these developments on the Company’s business, operations and research and development timelines and plans remains uncertain and will depend on numerous factors, including the impact, if any, on the Company’s personnel, responses of governmental entities, and the responses of third parties, such as contract research organizations, contract manufacturing organizations and other third parties with whom the Company does business. Any prolonged material disruption to the Company’s employees or suppliers could adversely impact the Company’s development activities, financial condition and results of operations, including its ability to obtain financing. The Company is monitoring the potential impact of these developments on its business and consolidated financial statements. To date, the Company has not experienced material business disruptions or incurred impairment losses in the carrying values of its assets as a result of these developments, and it is not aware of any specific related event or circumstance that would require it to revise its estimates reflected in these consolidated financial statements.

Liquidity considerations

In order to complete the development of the Company’s product candidates and to build the sales, marketing and distribution infrastructure that the Company believes will be necessary to commercialize its product candidates, if approved, the Company will require substantial additional capital. Until the Company can generate a sufficient amount of revenue from the commercialization of its product candidates, the Company may seek to raise any necessary additional capital through equity or debt financings, loans or other capital sources, which could include income from collaborations, partnerships or other marketing, distribution, licensing or other strategic arrangements with third parties, or from grants. Because of the numerous risks and uncertainties associated with research, development and commercialization of product candidates, the Company is unable to estimate the exact amount and timing of its capital requirements. The Company does not expect to generate any meaningful revenue unless and until the Company obtains regulatory approval of and commercializes any of its product candidates, and the Company does not know when, or if, that will occur.

The Company has incurred significant losses and negative cash flows from operations since inception. As of December 31, 2023, the Company had an accumulated deficit of $154.4 million. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future as the Company continues to develop its product candidates. The Company currently expects that its cash, cash equivalents and marketable securities of $253.1 million as of December 31, 2023 will be sufficient to fund operating expenses and capital requirements for at least 12 months from the date the consolidated financial statements are issued.

On June 23, 2023, the Company filed a shelf registration statement on Form S-3 with the Securities and Exchange Commission (the "SEC"), which was declared effective by the SEC on July 3, 2023, which allows the Company to undertake various equity and debt offerings up to $400.0 million. On June 23, 2023, the Company also entered into an Open Market Sale AgreementSM (the “Sales Agreement”) with Jefferies LLC (the "Sales Agent”), pursuant to which the Company may offer and sell shares of Company Common Stock, from time to time through an “at-the-market” program under the Securities Act of 1933 (the “Securities Act”), having an aggregate offering price of up to $200.0 million through the Sales Agent. Sales of Company Common Stock made pursuant to the Sales Agreement, if any, will be made under the Company’s shelf registration statement on Form S-3. On July 6, 2023, the Company

filed a prospectus supplement to the shelf registration statement that covers the offering, issuance and sale of Company Common Stock under the Sales Agreement. As of December 31, 2023, there have been no sales of Company Common Stock pursuant to the Sales Agreement.

On April 1, 2021, the Company entered into a Controlled Equity Offering Sales Agreement (the “Prior Sales Agreement”) with

Cantor Fitzgerald & Co., as agent (“Cantor Fitzgerald”), pursuant to which the Company was permitted to issue and sell shares of Company Common Stock having an aggregate offering price of up to $75.0 million, from time to time through Cantor Fitzgerald. In connection with the Company’s entry into the Sales Agreement, on June 23, 2023, the Prior Sales Agreement was terminated.

Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net Income (Loss)	$ (71,584)	$ (37,662)
Denominator:
Weighted-average common shares outstanding (including vested and unvested shares)	35,702,864	3,548,829
Less: weighted-average unvested common stock issued upon early exercise of common stock options	(119,154)	(194,966)
Less: weighted-average unvested restricted shares of common stock	(37,495)	(229,589)
Weighted-average shares outstanding, basic	35,546,215	3,124,274
Weighted-average shares outstanding, diluted	35,546,215	3,124,274
Net loss per share, basic	$ (2.01)	$ (12.05)
Net loss per share, diluted	$ (2.01)	$ (12.05)

Common Stock

12 Months Ended

Dec. 31, 2023

Common Stock

10. Common Stock

As of December 31, 2023, the Company’s Amended and Restated Certificate of Incorporation authorized the Company to issue 100,000,000 shares of $0.001 par value common stock, of which 41,292,027 shares were issued and outstanding. As of December 31, 2023 and 2022, there were 86,153 and 252,652 shares subject to repurchase, respectively. The liability related to shares subject to repurchase totaled $0.4 million and $0.6 million as of December 31, 2023 and 2022, respectively, of which $0.1 million and $0.3 million were recorded as long-term liabilities as of December 31, 2023 and 2022, respectively.

Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the Company’s board of directors, if any. No dividends have been declared or paid by the Company through December 31, 2023.

Upon completion of the Merger on February 23, 2023, the Company issued an aggregate of 34,426,351 shares of its common stock to Former Enliven stockholders, based on an exchange ratio of approximately 0.2951 share of the Company’s common stock for each share of Former Enliven common stock outstanding immediately prior to the Merger, including those shares of common stock issued upon conversion of the Former Enliven preferred stock (18,216,847 common shares) and those shares issued with its pre-merger financing of $164.5 million (12,638,636 common shares).

On June 23, 2023, the Company entered into the Sales Agreement with the Sales Agent, pursuant to which the Company may offer and sell shares of its common stock, from time to time, having an aggregate offering price of up to $200.0 million through the Sales Agent. Sales of the Company’s common stock made pursuant to the Sales Agreement, if any, will be made under the Company’s shelf registration statement on Form S-3, which was declared effective by the SEC on July 3, 2023. As of December 31, 2023, there have been no sales of common stock pursuant to the Sales Agreement.

The Company had the following shares of common stock reserved for future issuance:


	As of December 31,
	2023		2022
Conversion of convertible preferred stock		—		18,216,847
Issuance of common stock upon exercise of stock options		5,817,339		3,316,671
Issuance of common stock upon vesting of restricted stock units		78,505		—
Equity awards available for grant under equity plans		1,574,426		906,265
Shares available for issuance under the Employee Stock Purchase Plan		402,757		—
Total common stock reserved for future issuance		7,873,027		22,439,783

The entire disclosure for equity.

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Property, Plant and Equipment [Abstract]

Net Loss Per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss Per Share

15. Net Loss Per Share

Basic and diluted net loss per common share were calculated as follows (in thousands, except share and per share amounts):


	Year Ended December 31,
	2023			2022
Numerator:
Net loss	$	(71,584	)	$	(37,662	)
Denominator:
Weighted-average common shares outstanding (including vested and unvested shares)		35,702,864			3,548,829
Less: weighted-average unvested common stock issued upon early exercise of common stock options		(119,154	)		(194,966	)
Less: weighted-average unvested restricted shares of common stock		(37,495	)		(229,589	)
Weighted-average shares used to compute net loss per common share, basic and diluted		35,546,215			3,124,274
Net loss per share, basic and diluted	$	(2.01	)	$	(12.05	)

The Company’s potentially dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be antidilutive. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share is the same. The following potentially dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect:


	As of December 31,
	2023		2022
Convertible preferred stock (as converted)		—		18,216,847
Stock options outstanding		5,817,339		3,316,671
Unvested restricted stock awards		7,480		91,953
Unvested restricted stock units		78,505		—
ESPP shares pending issuance		5,254		—
Total		5,908,578		21,625,471

Leases - Summary of Future Minimum Lease Payments Under Operating Sublease (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Leases [Abstract]
2024	$ 341
Thereafter	0
Total future minimum lease payments	341
Less: amount representing interest	(6)
Present value of lease liabilities	$ 335
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Accrued Expenses And Other Current Liabilities
Less: current portion of lease liabilities	$ (335)
Lease liabilities, non-current	$ 0

Income Taxes - Schedule of Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Balance, beginning of the period	$ 164	$ 47
Increase related to prior year positions	28,698	7
Increase related to current year positions	3,282	110
Balance, end of the period	$ 32,144	$ 164

Property and Equipment, Net

12 Months Ended

Dec. 31, 2023

Property and Equipment, Net

7. Property and Equipment, Net

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


	Estimated Useful	As of December 31,
	Life in Years	2023			2022
Laboratory equipment	5	$	1,191		$	1,191
Computer equipment	3		222			73
Property and equipment, gross			1,413			1,264
Less: accumulated depreciation			(671	)		(374	)
Property and equipment, net		$	742		$	890

Depreciation expense was $0.3 million and $0.2 million for the years ended December 31, 2023 and 2022, respectively.

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	$ 12,914	$ 3,191
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	6,000	1,893
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	$ 6,914	$ 1,298

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Common Share

Basic and diluted net loss per common share were calculated as follows (in thousands, except share and per share amounts):


	Year Ended December 31,
	2023			2022
Numerator:
Net loss	$	(71,584	)	$	(37,662	)
Denominator:
Weighted-average common shares outstanding (including vested and unvested shares)		35,702,864			3,548,829
Less: weighted-average unvested common stock issued upon early exercise of common stock options		(119,154	)		(194,966	)
Less: weighted-average unvested restricted shares of common stock		(37,495	)		(229,589	)
Weighted-average shares used to compute net loss per common share, basic and diluted		35,546,215			3,124,274
Net loss per share, basic and diluted	$	(2.01	)	$	(12.05	)

Anti Dilutive Potential Common Shares Excluded From Computation of Diluted Net Loss Per Share

The following potentially dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect:


	As of December 31,
	2023		2022
Convertible preferred stock (as converted)		—		18,216,847
Stock options outstanding		5,817,339		3,316,671
Unvested restricted stock awards		7,480		91,953
Unvested restricted stock units		78,505		—
ESPP shares pending issuance		5,254		—
Total		5,908,578		21,625,471

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Compensation Related Costs [Abstract]
Stock Options Outstanding, Beginning Balance	3,316,671	3,075,403
Stock Options Outstanding, Assumption of options in connection with the Merger	449,900
Stock Options Outstanding, Options granted	2,563,778	391,653
Stock Options Outstanding, Options exercised and vested	(316,194)	(141,462)
Stock Options Outstanding, Options cancelled and forfeited	(196,816)	(8,923)
Stock Options Outstanding, Ending Balance	5,817,339	3,316,671	3,075,403
Stock Options Outstanding, Exercisable December 31, 2023	2,457,579
Stock Options Outstanding, Vested and expected to vest - December 31, 2023	5,817,339
Weighted-Average Exercise Price, Beginning Balance	$ 2.2	$ 3.64
Weighted-Average Exercise Price, Assumption of options in connection with the Merger	28.4
Weighted-Average Exercise Price, Options granted	21.65	5.66
Weighted-Average Exercise Price, Options exercised and vested	2.42	3.72
Weighted-Average Exercise Price, Options cancelled and forfeited	28.32	4.68
Weighted-Average Exercise Price, Ending Balance	11.9	$ 2.2	$ 3.64
Weighted-Average Exercise Price, Exercisable - December 31, 2023	6.41
Weighted-Average Exercise Price, Vested and expected to vest - December 31, 2023	$ 11.9
Weighted-Average Remaining Contractual Term, Outstanding	7 years 10 months 24 days	8 years 3 months 18 days	9 years 1 month 6 days
Weighted-Average Contractual Term, Exercisable - December 31, 2023	6 years 8 months 12 days
Weighted-Average Contractual Term, Vested and expected to vest - December 31, 2023	7 years 10 months 24 days
Aggregate Intrinsic Value, Balance	$ 35,692	$ 1,194	$ 9,657
Aggregate Intrinsic Value, Exercisable - December 31, 2023	24,169
Aggregate Intrinsic Value, Vested and expected to vest - December 31, 2023	$ 35,692

401(k) Savings Plan

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

401(k) Savings Plan

14. 401(k) Savings Plan

The Company has a defined-contribution savings plan under IRC Section 401(k). The 401(k) Plan covers all employees who meet the defined minimum age and service requirements and allows participants to make contributions based on their annual compensation, subject to certain limitations. For the years ended December 31, 2023 and 2022, the Company made 401(k) matching contributions of $89,000 and $45,000, respectively.

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Feb. 23, 2023	Dec. 31, 2022
Preferred stock, par value	$ 0.001		$ 0.001
Preferred stock, shares authorized	10,000,000		0
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Common stock, par value	$ 0.001		$ 0.0001
Common stock, shares authorized	100,000,000		26,264,364
Common stock, shares issued	41,292,027	41,011,501	3,570,019
Common stock, shares outstanding	41,292,027	41,011,501	3,570,019
Convertible Preferred Stock
Preferred stock, par value	$ 0.0001		$ 0.0001
Preferred stock, shares authorized	0		61,730,064
Preferred stock, shares issued	0		61,730,064
Preferred stock, shares outstanding	0		61,730,064
Preferred stock, liquidation preference, value	$ 0		$ 140,520

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2023	Mar. 01, 2024	Jun. 30, 2023
Cover [Abstract]
Entity Registrant Name	ENLIVEN THERAPEUTICS, INC.
Document Type	10-K
Trading Symbol	ELVN
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		41,347,632
Entity Public Float			$ 382.3
Amendment Flag	false
Entity Central Index Key	0001672619
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common Stock, $0.001 par value per share
Security Exchange Name	NASDAQ
Entity File Number	001-39247
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-1523849
Entity Address, Address Line One	6200 Lookout Road
Entity Address, City or Town	Boulder
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80301
City Area Code	720
Local Phone Number	647-8519
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Auditor Name	Deloitte & Touche LLP
Auditor Firm ID	34
Auditor Location	San Francisco, California
Documents Incorporated by Reference [Text Block]	Portions of the Registrant’s Definitive Proxy Statement relating to the Registrant’s Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. Such Definitive Proxy Statement will be filed with the Securities and Exchange Commission within 120 days after the end of the registrant’s 2023 fiscal year ended December 31, 2023.
Document Financial Statement Error Correction [Flag]	false

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended		55 Months Ended
	Dec. 31, 2023 USD ($) Segment	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)
Summary of Significant Accounting Policies [LineItems]
Deferred offering costs included in accrued liabilities		$ 1,200,000
Deferred offering costs included in accounts payable		600,000
Restricted cash as current assets	$ 54,000	0	$ 54,000
Restricted cash as long-term assets	0	$ 54,000	0
Restricted cash collateral of sublease	$ 54,000
Expected dividend yield	0.00%
Interest or penalties charged in relation to unrecognized tax benefits			0
Number of operating segments \| Segment	1
Impairment of long-lived assets			$ 0
Adoption of accounting standards update [true false]	true		true
Accounting standards update, adoption date	Jan. 01, 2022		Jan. 01, 2022
Accounting Standards Update [Extensible Enumeration]	us-gaap:AccountingStandardsUpdate201912Member
Accounting standards update, immaterial effect [true false]	true		true
Minimum
Summary of Significant Accounting Policies [LineItems]
Property and equipment estimated useful lives	3 years		3 years
Maximum
Summary of Significant Accounting Policies [LineItems]
Property and equipment estimated useful lives	5 years		5 years

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The following tables set forth the fair value of the Company’s financial assets measured at fair value on a recurring basis and indicates the level within the fair value hierarchy utilized to determine such values (in thousands):


As of December 31, 2023	Total		Level 1		Level 2		Level 3
Cash equivalents:
U.S. Treasury backed money market funds	$	99,388	$	99,388	$	—	$	—
Marketable securities:
U.S. Treasury securities		153,007		153,007		—		—
Total	$	252,395	$	252,395	$	—	$	—

As of December 31, 2022	Total		Level 1		Level 2		Level 3
Cash equivalents:
U.S. Treasury backed money market funds	$	74,523	$	74,523	$	—	$	—
Total	$	74,523	$	74,523	$	—	$	—

CVR Asset and Liability

Upon the completion of the Merger in February 2023, the Company assessed the fair value of the payments to be made under the CVR Agreement to be zero as the Company had determined the payments were not probable. During the fourth quarter of 2023, the Company assessed the fair value of the first milestone under the asset purchase agreement at 100% based upon certain information received from the third-party indicating that the milestone was likely to be achieved in early 2024. As such, the Company estimated the fair value of the CVR asset and liability for this first milestone and recorded a $10.0 million CVR asset and $10.0 million CVR liability on its balance sheet as of December 31, 2023. In March 2024, the Company received formal notification from the third-party that the first milestone event as set forth in the asset purchase agreement had been achieved with payment to be made within 30 days of the achievement date. As the second milestone event under this asset purchase agreement relates to the future potential commercialization of the assets, no value has been attributed to this milestone in fiscal year 2023. As of December 31, 2023, no payments have been received or paid under the CVR Agreement.

Schedule of Available-for-sale Marketable Securities

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

+ References + Details

Preferred Stock and Convertible Preferred Stock - Schedule of Convertible Preferred Stock and Liquidation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023
Class of Stock [Line Items]
Preferred stock, shares authorized	0	10,000,000
Series Seed Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized	14,507,038
Shares Issued and Outstanding	14,507,038
Per Share Liquidation Preference	$ 0.71
Preferred stock, liquidation preference, value	$ 10,300
Issuance of convertible preferred stock, net of issuance costs	$ 10,211
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized	25,114,089
Shares Issued and Outstanding	25,114,089
Per Share Liquidation Preference	$ 1.8
Preferred stock, liquidation preference, value	$ 45,300
Issuance of convertible preferred stock, net of issuance costs	$ 45,170
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized	22,108,937
Shares Issued and Outstanding	22,108,937
Per Share Liquidation Preference	$ 3.84
Preferred stock, liquidation preference, value	$ 84,920
Issuance of convertible preferred stock, net of issuance costs	$ 84,689
Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized	61,730,064	0
Shares Issued and Outstanding	61,730,064
Preferred stock, liquidation preference, value	$ 140,520	$ 0
Issuance of convertible preferred stock, net of issuance costs	$ 140,070

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2023

Marketable Securities [Abstract]

The Company’s marketable securities are classified as available-for-sale and are stated at fair value. As of December 31, 2023, marketable securities consisted of the following (in thousands):


As of December 31, 2023	Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
U.S. Treasury securities	1 or less	$	152,866	$	147	$	(6	)	$	153,007
Total		$	152,866	$	147	$	(6	)	$	153,007

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net Income (Loss)	$ (71,584)	$ (37,662)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	297	215
Stock-based compensation	12,914	3,191
Non-cash lease expense	306	0
Amortization of premiums and discounts on marketable securities, net	(4,603)	0
Write-off of deferred IPO costs	0	1,741
Changes in operating assets and liabilities:
Prepaid expenses, other current and long-term assets	(3,703)	(1,590)
Operating lease liabilities	(310)	4
Accounts payable	(2,250)	411
Accrued expenses and other liabilities	7,664	1,613
Net cash used in operating activities	(61,269)	(32,077)
Cash flows from investing activities:
Maturities of marketable securities	120,000	0
Purchases of marketable securities	(268,263)	0
Purchases of property and equipment	(149)	(612)
Net cash used in investing activities	(148,412)	(612)
Cash flows from financing activities:
Proceeds from exercise of stock options	399	591
Payment of deferred offering costs related to the Merger / initial public offering		(2,390)
Payment of deferred offering costs related to the Sales Agreement	(563)	0
Proceeds from the Financing Transaction, net of issuance costs	161,365	0
Cash acquired in connection with the reverse recapitalization	81,821	0
Payment of reverse recapitalization transaction costs	(8,736)	0
Net cash provided by financing activities	234,286	(1,799)
Net increase (decrease) in cash, cash equivalents and restricted cash	24,605	(34,488)
Cash, cash equivalents and restricted cash at the beginning of the period	75,590	110,078
Cash, cash equivalents and restricted cash at the end of the period	100,195	75,590
Components of cash, cash equivalents and restricted cash:
Cash and cash equivalents	100,141	75,536
Restricted cash	54	54
Total cash, cash equivalents and restricted cash	100,195	75,590
Supplemental disclosure of non-cash operating activities:
Lease liabilities obtained in exchange for right-of-use assets	0	387
Deferred offering costs related to the Merger included in accounts payable and accrued expenses and other current liabilities	0	1,846
Receivables from stock option exercises included in prepaid expenses and other current assets	76	0
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock to common stock	$ 149,749	$ 0

The Merger

12 Months Ended

Dec. 31, 2023

Business Combination and Asset Acquisition [Abstract]

The Merger

3. The Merger

As described in Note 1, Former Enliven merged with the Company on February 23, 2023. The Merger was accounted for as a reverse recapitalization with Former Enliven as the accounting acquirer. The primary pre-combination assets of the Company were cash and cash equivalents. Under reverse recapitalization accounting, the assets and liabilities of the Company were recorded at their fair value, which approximated book value due to the short-term nature of the instruments. No goodwill or intangible assets were recognized. Consequently, the consolidated financial statements of the Company reflect the operations of Former Enliven for accounting purposes together with a deemed issuance of shares, equivalent to the shares held by the former stockholders of the legal acquirer and a recapitalization of the equity of the accounting acquirer.

The following table summarizes the fair value of identifiable assets acquired and liabilities assumed as part of the recapitalization (in thousands):


Cash and cash equivalents	$	81,821
Other current assets		1,044
Accrued liabilities		(2,624	)
Net assets acquired	$	80,241

In connection with the Merger and concurrent Financing Transaction, the Company incurred reverse recapitalization transaction costs of $9.0 million and issuance costs of $5.0 million, which were capitalized and recorded on the consolidated balance sheets as deferred offering costs. On February 23, 2023, at the close of the Merger, the deferred offering costs were recorded as contra equity. As of December 31, 2023 and 2022, deferred offering costs related to the Merger and Financing Transaction were $0 and $4.0 million, respectively.

In addition, the Company incurred $1.3 million in stock-based compensation expense as a result of the acceleration of vesting of stock options at the time of the Merger. This amount was recorded in general and administrative expense on the consolidated statements of operations and comprehensive loss for the three months ended March 31, 2023 and year ended December 31, 2023.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of Financial Assets Measured at Fair Value on a Recurring Basis


As of December 31, 2023	Total		Level 1		Level 2		Level 3
Cash equivalents:
U.S. Treasury backed money market funds	$	99,388	$	99,388	$	—	$	—
Marketable securities:
U.S. Treasury securities		153,007		153,007		—		—
Total	$	252,395	$	252,395	$	—	$	—

As of December 31, 2022	Total		Level 1		Level 2		Level 3
Cash equivalents:
U.S. Treasury backed money market funds	$	74,523	$	74,523	$	—	$	—
Total	$	74,523	$	74,523	$	—	$	—

401(k) Savings Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Contribution Plan Disclosure [Line Items]
Matching contributions amount	$ 89,000	$ 45,000

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,413	$ 1,264
Less: accumulated depreciation	(671)	(374)
Property and equipment, net	742	890
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,191	1,191
Property and equipment estimated useful life	5 years
Computer equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 222	$ 73
Property and equipment estimated useful life	3 years

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Summary of Future Minimum Lease Payments Under Operating Sublease

As of December 31, 2023, the future minimum lease payments under the facilities operating sublease were as follows (in thousands):


	As of
	December 31, 2023
Year ending December 31,
2024	$	341
Thereafter		—
Total future minimum lease payments		341
Less: amount representing interest		(6	)
Present value of lease liabilities		335
Less: current portion of lease liabilities		(335	)
Lease liabilities, non-current	$	—

Preferred Stock and Convertible Preferred Stock

12 Months Ended

Dec. 31, 2023