0000950170-24-036814 | 10-K | XBRL Viewer

Equity	12 Months Ended
Dec. 31, 2023
Equity [Abstract]
Equity	8. Equity The Company had 150,000,000 authorized shares of common stock, par value $0.00001 per share, of which 49,350,788 and 37,771,918 shares were issued and outstanding at December 31, 2023 and 2022, respectively. In addition, the Company had 10,000,000 authorized shares of preferred stock, par value $0.00001 per share, all of which shares of preferred stock will be undesignated. No authorized shares of preferred stock were issued and outstanding at December 31, 2023 and December 31, 2022. Financings On November 9, 2023, the Company issued and sold 11,000,000 shares of common stock at a price to the public of $9.00 per share for aggregate gross proceeds of $99.0 million in the 2023 Follow-On Offering. The Company received approximately $92.6 million in net proceeds from the 2023 Follow-On Offering after deducting underwriting discounts and commissions and offering expenses. On December 5, 2022, the Company issued and sold 7,705,000 shares of common stock, including the full exercise of the underwriters’ option to purchase additional shares at a price to the public of $12.00 per share for aggregate gross proceeds of $92.5 million in the 2022 Follow-On Offering. The Company received approximately $86.7 million in net proceeds from the 2022 Follow-On Offering after deducting underwriting discounts, commissions and offering expenses. On November 1, 2022, the Company filed the 2022 Shelf with the SEC in relation to the registration of up to an aggregate offering price of $250.0 million of common stock, preferred stock, debt securities, warrants and units or any combination thereof. The Company also simultaneously entered into the Sales Agreement with the Sales Agent to provide for the offering, issuance and sale by the Company of up to an aggregate of $75.0 million of common stock from time to time in the ATM under the 2022 Shelf and subject to the limitations thereof. The Company issued 261,807 shares of common stock at an average price of $12.49 for aggregate gross proceeds of $3.3 million during the year ended December 31, 2023 under the ATM. In addition, the Company issued 732,189 shares of common stock at an average price of $12.51 for aggregate gross proceeds of $9.2 million as of December 31, 2022 under the ATM.

Equity

12 Months Ended

Dec. 31, 2023

8. Equity

The Company had 150,000,000 authorized shares of common stock, par value $0.00001 per share, of which 49,350,788 and 37,771,918 shares were issued and outstanding at December 31, 2023 and 2022, respectively.

In addition, the Company had 10,000,000 authorized shares of preferred stock, par value $0.00001 per share, all of which shares of preferred stock will be undesignated. No authorized shares of preferred stock were issued and outstanding at December 31, 2023 and December 31, 2022.

Financings

On November 9, 2023, the Company issued and sold 11,000,000 shares of common stock at a price to the public of $9.00 per share for aggregate gross proceeds of $99.0 million in the 2023 Follow-On Offering. The Company received approximately $92.6 million in net proceeds from the 2023 Follow-On Offering after deducting underwriting discounts and commissions and offering expenses.

On December 5, 2022, the Company issued and sold 7,705,000 shares of common stock, including the full exercise of the underwriters’ option to purchase additional shares at a price to the public of $12.00 per share for aggregate gross proceeds of $92.5 million in the 2022 Follow-On Offering. The Company received approximately $86.7 million in net proceeds from the 2022 Follow-On Offering after deducting underwriting discounts, commissions and offering expenses.

On November 1, 2022, the Company filed the 2022 Shelf with the SEC in relation to the registration of up to an aggregate offering price of $250.0 million of common stock, preferred stock, debt securities, warrants and units or any combination thereof. The Company also simultaneously entered into the Sales Agreement with the Sales Agent to provide for the offering, issuance and sale by the Company of up to an aggregate of $75.0 million of common stock from time to time in the ATM under the 2022 Shelf and subject to the limitations thereof. The Company issued 261,807 shares of common stock at an average price of $12.49 for aggregate gross proceeds of $3.3 million during the year ended December 31, 2023 under the ATM. In addition, the Company issued 732,189 shares of common stock at an average price of $12.51 for aggregate gross proceeds of $9.2 million as of December 31, 2022 under the ATM.

- Definition

The entire disclosure for equity.

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+ Details

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Summary of Accrued Expenses and Other Current Liabilities

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


	December 31, 2023		December 31, 2022
Accrued research and development expenses	$	3,445	$	1,543
Accrued compensation		3,503		2,705
Other		935		325
Accrued expenses and other current liabilities	$	7,883	$	4,573

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 41,063	$ 121,582
Marketable securities	185,087	67,229
Restricted cash and deposits	19	20
Prepaid expenses and other current assets	5,625	7,871
Total current assets	231,794	196,702
Restricted cash and deposits, net of current portion	768	768
Right of use assets - operating lease	18,854	20,671
Other long-term assets	509	423
Property and equipment, net	3,150	5,371
Total Assets	255,075	223,935
Current liabilities:
Accounts payable	1,787	2,921
Short-term operating lease liability	2,687	2,963
Accrued expenses and other current liabilities	7,883	4,573
Total current liabilities	12,357	10,457
Long-term operating lease liability	16,870	17,895
Total Liabilities	29,227	28,352
Commitments and Contingencies (Note 12)
Stockholders' Equity:
Common stock, $0.00001 par value, 150,000,000 authorized at December 31, 2023 and December 31, 2022, and 49,350,788 and 37,771,918 shares issued and outstanding at December 31, 2023 and December 31, 2022, respectively
Additional paid-in capital	512,617	406,555
Accumulated deficit	(287,308)	(210,900)
Accumulated other comprehensive loss	539	(72)
Total Stockholders' Equity	225,848	195,583
Total Liabilities, Convertible Preferred Stock, and Stockholders' Equity	$ 255,075	$ 223,935

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Follow-On Offering
Stock issuance cost, net	$ 444	$ 263
ATM
Stock issuance cost, net		$ 336

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Jan. 01, 2023	Nov. 01, 2021	Jan. 01, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 8,772	$ 6,412
Weighted-average grant date fair value of stock options granted	$ 7.5	$ 10.79
Total intrinsic value of options exercised	$ 1,500	$ 800
Unrecognized compensation expense related to stock options	$ 15,100
Unrecognized compensation expense weighted average period	2 years 6 months 3 days
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 9,400
Unrecognized compensation expense weighted average period	3 years 1 month 2 days
Restricted stock units vesting increments	25.00%
Restricted stock units vesting duration	4 years
Number of awards vested	43,162
Restricted stock units vested with fair value	$ 600
2021 Stock Option and Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for issuance			6,850,986	3,352,166
Common stock outstanding percentage	5.00%
Cumulative increase in shares of common stock	3,352,166
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future issuance	3,307,871
Number of shares reserved for issuance	947,639		962,550		335,217
Share-based compensation expense	$ 100
Percentage of the lower of the fair market value of common stock	85.00%
Common stock outstanding percentage	1.00%

Stock-Based Compensation

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

9. Stock-Based Compensation

2018 Stock Option and Incentive Plan

On December 12, 2018, the Company adopted the Aura Biosciences, Inc. 2018 Equity Incentive Plan, or the 2018 Plan. The 2018 Plan will expire in 2028. Under the 2018 Plan, Aura may grant incentive stock options, non-qualified stock options, restricted and unrestricted stock awards and stock rights. The Board of Directors, or the Board, has determined not to make any further awards under the 2018 Plan as of November 2, 2021. However, the 2018 Plan will continue to govern outstanding equity awards granted thereunder.

2021 Stock Option and Incentive Plan

The 2021 Stock Option and Incentive Plan, or the 2021 Plan, was adopted by the Board on October 7, 2021, approved by the Company’s stockholders on October 22, 2021 and became effective on November 1, 2021. The 2021 Plan permits the granting of both options to purchase common stock intended to qualify as incentive stock options under Section 422 of the Code and options that do not so qualify. The number of shares initially reserved for issuance under the 2021 Plan was 3,352,166, which increased on January 1, 2022 and will continue to increase each January 1 thereafter, by 5% of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Company’s compensation committee. The maximum number of shares of common stock that may be issued in the form of incentive stock options shall not exceed the initial limit, cumulatively increased on January 1, 2022 and on each January 1 thereafter by the lesser of the annual increase for such year or 3,352,166 shares of common stock. On January 1, 2023, the shares reserved for issuance was increased to 6,850,986 shares.

2021 Employee Stock Purchase Plan

The 2021 Employee Stock Purchase Plan, or the ESPP, was adopted by the Board on October 7, 2021, approved by the Company’s stockholders on October 22, 2021 and became effective on November 1, 2021. A total of 335,217 shares of common stock were initially reserved for issuance under this plan, which increased on January 1, 2022 and will continue to increase each January 1 thereafter through January 1, 2031, by the least of (i) 335,217 shares of common stock, (ii) 1% of the outstanding number of shares of common stock on the immediately preceding December 31 or (iii) such lesser number of shares of common stock as determined by the administrator of the ESPP. On January 1, 2023, the shares reserved for issuance was increased to 962,550 shares. The purchase price of the shares under the ESPP are at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the purchase date. As of December 31, 2023, 947,639 shares were available to be issued under the ESPP. The Company recognized $0.1 million share-based compensation expense related to the ESPP for the year ended December 31, 2023.

Stock Options

With the transfer of the available options from the 2018 Plan to the 2021 Plan, there were 3,307,871 options available for grant under the 2021 Plan at December 31, 2023.

The Board is authorized to administer the 2021 Plan. In accordance with the provisions of the 2021 Plan, the Board determines the terms of Aura options and other awards issued pursuant thereto, including the following:

▪

which employees, directors and consultants shall be granted awards;

▪

the number of shares of common stock subject to options and other awards;

▪

the exercise price of each option, which generally shall not be less than fair market value of the common stock on the date of grant;

▪

the termination or cancellation provisions applicable to options;

▪

the terms and conditions of other awards, including conditions for repurchase, termination or cancellation, issue price and repurchase price; and

▪

all other terms and conditions upon which each award may be granted in accordance with the 2018 Plan.

In addition, the Board may award restricted shares of common stock and restricted stock units to participants subject to such conditions and restrictions as it may determine. The Board or any committee to which the Board delegates authority may, with the consent of the affected plan participants, re-price or otherwise amend outstanding awards consistent with the terms of the 2021 Plan.

The following table summarizes stock option activity under the 2018 Plan and 2021 Plan for the year ended December 31, 2023:


	Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022		4,303,336		$	8.06		7.92	$	16,204
Granted		1,608,975			10.10
Exercised		(258,990	)		5.31
Cancelled/Forfeited		(622,970	)		11.28
Outstanding at December 31, 2023		5,030,351		$	8.46		7.54	$	10,353
Exercisable at December 31, 2023		2,638,834		$	7.06		6.49	$	8,516

The weighted-average grant date fair value of stock options granted during the years ended December 31, 2023 and 2022 was $7.50 and $10.79 per share, respectively. The total intrinsic value of options exercised was $1.5 million and $0.8 million for the years ended December 31, 2023 and 2022, respectively.

The fair value of the stock options issued as of December 31, 2023 and 2022 was measured with the following weighted-average assumptions:


	Twelve Months Ended December 31,
	2023			2022
Risk-free interest rate		3.94	%		3.00	%
Expected term (years)		6.04			5.91
Expected volatility of the underlying stock		86.15	%		78.10	%
Expected dividend rate		—	%		—	%

Restricted Stock Units

The Company has granted restricted stock units with service-based vesting conditions. Unvested shares of restricted common stock may not be sold or transferred by the holder.

A summary of the restricted stock unit activity during the year ended December 31, 2023 is as follows:


	Restricted Stock Units			Weighted- Average Grant Date Fair Value
Unvested at December 31, 2022		153,950		$	14.00
Granted		1,110,820			9.97
Vested/Released		(43,162	)		14.00
Forfeited		(128,206	)		10.90
Unvested at December 31, 2023		1,093,402		$	10.27

As a result of the 2021 Equity Incentive Plan, the Company granted restricted stock units which vest in increments of 25% annually over a period of four years. During the year ended December 31, 2023, 43,162 restricted stock units vested with a fair value of $0.6 million.

Stock-based Compensation Expense

The Company recorded stock-based compensation expense as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development	$	3,929	$	2,389
General and administrative		4,843		4,023
Total	$	8,772	$	6,412

As of December 31, 2023, there was $15.1 million of unrecognized compensation expense related to stock options, which is expected to be recognized over a weighted-average period of 2.51 years.

As of December 31, 2023, there was $9.4 million of unrecognized compensation expense related to restricted stock units, which is expected to be recognized over a weighted-average period of 3.09 years.

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)	$ (76,408)	$ (58,763)

- Definition

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

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-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
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Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
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-Subparagraph (f)
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 36: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
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-Subparagraph (a)
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Reference 37: http://www.xbrl.org/2003/role/disclosureRef
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Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
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-Paragraph 2
-Subparagraph (SX 210.5-03(20))
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Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Stock-Based Compensation - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Beginning Balance \| shares	153,950
Granted \| shares	1,110,820
Vested/Released \| shares	(43,162)
Forfeited \| shares	(128,206)
Ending Balance \| shares	1,093,402
Unvested, Weighted -Average Grant Date Fair Value \| $ / shares	$ 14
Granted, Weighted-Average Grant Date Fair Value \| $ / shares	9.97
Vested/Released, Weighted-Average Grant Date Fair Value \| $ / shares	14
Forfeited, Weighted -Average Grant Date Fair Value \| $ / shares	10.9
Unvested, Weighted -Average Grant Date Fair Value \| $ / shares	$ 10.27

Commitments and Contingencies - Additional Information (Details) € in Thousands		1 Months Ended											12 Months Ended
	May 16, 2022 USD ($)	Sep. 30, 2022 USD ($)	Aug. 31, 2022 OperatingLease	Jan. 31, 2022 USD ($)	Oct. 31, 2020 USD ($)	Jul. 31, 2019 USD ($)	Dec. 31, 2014 USD ($) LicensedProduct	Jan. 31, 2014 USD ($)	Sep. 30, 2013 USD ($)	Jul. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Nov. 30, 2009 EUR (€)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2023 OperatingLease
Lessee Lease Description [Line Items]
Estimated payments due													$ 30,474,000
Recognized loss on lease														$ 296,000
Operating lease liabilities													19,557,000
Research and development expenses													65,232,000	42,238,000
Biologic Materials License Agreement
Lessee Lease Description [Line Items]
One time non refundable license issuance fee											$ 20,000.00
Milestone payments or royalties											$ 0
National Institute of Health
Lessee Lease Description [Line Items]
License issue royalty fee									$ 100,000
Sales milestone payments									600,000
Development and regulatory milestone payments									$ 700,000
Expenses for patent licensing fees													200,000	20,000.00
Patent licensing reimbursement fees													30,000.00
Royalty Bearing Patent License Agreement
Lessee Lease Description [Line Items]
Expenses													0	0
License agreement term												10 years
Royalty Bearing Patent License Agreement \| IND Filings
Lessee Lease Description [Line Items]
Potential milestone payments \| €												€ 10
Clearside
Lessee Lease Description [Line Items]
Expenses													1,000,000	0
Upfront payment						$ 100,000
Royalties on net sales						20.00%
License agreement expiration period						10 years
Clearside \| Maximum
Lessee Lease Description [Line Items]
Aggregate milestones payment						$ 21,000,000
LI-COR, Inc. \| Exclusive License and Supply Agreement
Lessee Lease Description [Line Items]
One-time upfront license issuance fee								$ 100,000
Research and development expenses													0	0
License agreement term								10 years
LI-COR, Inc. \| Exclusive License and Supply Agreement \| Maximum
Lessee Lease Description [Line Items]
Aggregate milestone payments								$ 200,000
LI-COR, Inc. \| 2014 Non- Exclusive Agreement
Lessee Lease Description [Line Items]
License issue fee							$ 30,000.00
Research and development expenses													30,000.00	100,000
Milestone payments													0	0
LI-COR, Inc. \| 2014 Non- Exclusive Agreement \| Maximum
Lessee Lease Description [Line Items]
License issue fee							300,000
Payments for development and commercial milestones							400,000
Life Technologies
Lessee Lease Description [Line Items]
Non-refundable, Non- creditable fee							$ 300,000
Number of licensed products \| LicensedProduct							5
Initial license fee							$ 100,000
Annual development fee							100,000
Change of control fees		$ 500,000					$ 200,000
Expenses														50,000.00	$ 100,000
One time perpetual license agreement fee				$ 50,000.00
Initial license fee for first licensed product		400,000
Initial license fee for additional licensed product		500,000
Payment for sublicense		200,000
Payment for use of cell line document package		30,000.00
Expense related to agreement including sublicense													0	400,000
Dr. John Schiller \| 2014 Non- Exclusive Agreement
Lessee Lease Description [Line Items]
Required amendment payment		$ 40,000.00
Required amendment payment due period		30 days
Dr. John Schiller \| Collaboration Research and Development Agreement
Lessee Lease Description [Line Items]
Annual development fee										$ 30,000.00
Agreement term										2 years
First payment due										30 days
Subsequent payments due										30 days
Research collaboration fees													0	$ 0
Required amendment payment					$ 40,000.00
Required amendment payment due period					30 days
Dr. John Schiller \| Collaboration Research and Development Agreement \| 10th Anniversary
Lessee Lease Description [Line Items]
Required amendment payment		$ 30,000.00			$ 30,000.00
Required amendment payment due period		30 days			30 days
Office and Laboratory Facility
Lessee Lease Description [Line Items]
Estimated payments due	$ 35,200,000
Number of operating lease \| OperatingLease																1
Number of operating lease terminated \| OperatingLease			1
Lease commencement date	Aug. 01, 2022
Operating lease, option to extend term	7 years
Letters of credit	$ 800,000
Maximum reimbursement cost	$ 500,000
Incurred of expenses related to expansion													100,000
Reimbursed expenses													$ 100,000

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Income Tax Benefit (Provision)

The Company's income tax benefit (provision), net consisted of the following:


	2023		2022
Component of income tax provision:
Current:
Federal	$	137	$	—
State		—		—
Foreign		—		—
Total Current		137		—
Deferred:
Federal		—		—
State		—		—
Foreign		—		—
Total Deferred		—		—

Total Provision	$	137	$	—

Summary of Reconciliation of Federal Statutory Income Tax Rate to Company's Effective Tax Rate

A reconciliation of the federal statutory income tax rate to the Company’s effective tax rate as of December 31, 2023 and 2022 is as follows:


	2023			2022
Tax provision at statutory rate		21.0	%		21.0	%
State taxes, net of federal benefit		6.6	%		5.6	%
Federal tax credits		2.3	%		2.9	%
Permanent items		(1.0	)%		(1.1	)%
Other		(0.1	)%		0.1	%
Decrease in valuation reserve		(28.8	)%		(28.5	)%
Total		0.0	%		0.0	%

Summary of Deferred Tax Assets (Liabilities)

Temporary differences that give rise to significant deferred tax assets (liabilities) as of December 31, 2023 and 2022 are as follows (in thousands):


	2023			2022
Deferred tax assets:
Net operating loss carryforwards	$	45,999		$	40,617
Stock-based compensation expense		2,110			1,235
Capitalized research and development expenses		22,068			10,200
Tax credit carryforwards		10,007			7,924
Accrued expenses		1,018			—
Lease liability		5,282			5,461
Other		766			307
Total deferred tax assets		87,250			65,744
Deferred tax liabilities:
Right of use asset		(5,092	)		(5,412	)
Depreciable assets		(225	)		(207	)
Accrued expenses		—			(93	)
Valuation allowance		(81,933	)		(60,032	)
Net deferred tax asset	$	—		$	—

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Estimated Useful Lives of Assets

The estimated useful lives of the Company’s respective assets are as follows:


		Estimated Useful Life
Leasehold improvements		The shorter of the life of the leasehold improvement or the remaining term of the lease
IT equipment		3 years
Laboratory equipment		5 years
Office furniture		7 years

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid insurance	$ 1,817	$ 2,174
Prepaid research and development expenses	1,399	4,982
Other	2,409	715
Prepaid expenses and other current assets	$ 5,625	$ 7,871

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

14. Income Taxes

The Company has recorded a $0.1 million and $0 million tax provision for the periods presented due to the current state income taxes and the losses incurred and the need for a full valuation allowance on net deferred tax assets. The difference between the income tax expense at the U.S. federal statutory rate and the recorded provision is primarily due to the valuation allowance provided on all deferred tax assets. The Company’s loss before income tax for the periods presented was generated entirely in the United States:

The Company's income tax benefit (provision), net consisted of the following:


	2023		2022
Component of income tax provision:
Current:
Federal	$	137	$	—
State		—		—
Foreign		—		—
Total Current		137		—
Deferred:
Federal		—		—
State		—		—
Foreign		—		—
Total Deferred		—		—

Total Provision	$	137	$	—

A reconciliation of the federal statutory income tax rate to the Company’s effective tax rate as of December 31, 2023 and 2022 is as follows:


	2023			2022
Tax provision at statutory rate		21.0	%		21.0	%
State taxes, net of federal benefit		6.6	%		5.6	%
Federal tax credits		2.3	%		2.9	%
Permanent items		(1.0	)%		(1.1	)%
Other		(0.1	)%		0.1	%
Decrease in valuation reserve		(28.8	)%		(28.5	)%
Total		0.0	%		0.0	%

Temporary differences that give rise to significant deferred tax assets (liabilities) as of December 31, 2023 and 2022 are as follows (in thousands):


	2023			2022
Deferred tax assets:
Net operating loss carryforwards	$	45,999		$	40,617
Stock-based compensation expense		2,110			1,235
Capitalized research and development expenses		22,068			10,200
Tax credit carryforwards		10,007			7,924
Accrued expenses		1,018			—
Lease liability		5,282			5,461
Other		766			307
Total deferred tax assets		87,250			65,744
Deferred tax liabilities:
Right of use asset		(5,092	)		(5,412	)
Depreciable assets		(225	)		(207	)
Accrued expenses		—			(93	)
Valuation allowance		(81,933	)		(60,032	)
Net deferred tax asset	$	—		$	—

As of December 31, 2023, the Company had federal gross net operating loss carryforwards of approximately $174.4 million which may be available to offset future taxable income, of which $44.2 million begin to expire in 2029 and go through 2037 and $130.2 million do not expire. The Company had state gross operating loss carryforwards of $148.5 million, which may be available to offset future taxable income and which would begin to expire in 2030, except for $0.7 million of state NOLs that do not expire. The Company had foreign gross operating loss carryforwards of $0.1 million, which may be available to offset future taxable income and which do not expire. As of December 31, 2023, the Company had federal and state research and experimentation credit carryforwards of $8.2 million and $2.3 million, respectively, which may be available to offset future income tax liabilities and which would begin to expire in 2029 and 2028, respectively.

The Company’s ability to use its operating loss carryforwards and tax credit carryforwards to offset taxable income is subject to restrictions under Sections 382 and 383 of the United States Internal Revenue Code, or the Internal Revenue Code. Under the Internal Revenue Code provisions, certain substantial changes in the Company’s ownership, including the sale of the Company or significant changes in ownership due to sales of equity, have limited and may limit in the future, the amount of net operating loss carryforwards which could be used annually to offset future taxable income. The Company has not yet completed an analysis of ownership changes. The Company may also experience ownership changes in the future as a result of subsequent shifts in our stock ownership, some of which may be outside the Company’s control. As a result, the Company’s ability to use our pre-change NOLs to offset U.S. federal taxable income may be subject to limitations, which could potentially result in increased future tax liability to the Company. In addition, at the state level, there may be periods during which the use of NOLs is suspended or otherwise limited, which could accelerate or permanently increase state taxes owed. All Federal NOLs generated post tax reform have an indefinite life, are not subject to carryback provisions, and limited to 80% of income in any year.

The Company has not conducted a study of its research and development credit carryforwards. A study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed, and any adjustment is known, no amounts will be presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credit carryforwards and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the balance sheet or statement of operations at this time, if an adjustment were required.

Management has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which are principally comprised of NOL carryforwards and tax credit carryforwards. Management has determined that it is more likely than not that the Company will not realize the benefits of its deferred tax assets, and as a result, a valuation allowance of $81.9 million has been recorded at December 31, 2023. The increase in the valuation allowance of $21.9 million during the year ended December 31, 2023 was primarily due to the increase in net operating loss generated by the Company and capitalized R&D expenses related to the Section 174 requirements.

As of December 31, 2023 and 2022, the Company had no unrecognized tax benefits. Interest and penalty charges, if any, related to income taxes would be classified as a component of the provision for income taxes in the consolidated statements of operations. The Company does not expect any significant change in its uncertain tax positions in the next twelve months.

The Company files income tax returns in the United States federal tax jurisdiction and several state tax jurisdictions. Since the Company is in a loss carryforward position, it is generally subject to examination by federal and state tax authorities for all tax years in which a loss carryforward is available.

With respect to the income of its foreign subsidiary, the Company asserts the position that the undistributed earnings of its foreign subsidiary is permanently invested in that jurisdiction. As a result, no additional income taxes have been provided on the possible repatriation of these earnings to the parent company. The Company does not have any unremitted earnings as of December 31, 2023.

The Tax Cuts and Jobs Act subjects a U.S. shareholder to tax on Global Intangible Low-taxes Income, or GILTI, earned by certain foreign subsidiaries. Pursuant to the FASB Staff Q&A, Topic 740 No.5. Accounting for Global Intangible Low-taxed Income, the Company is allowed to make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as period expense only. The Company has elected to account for GILTI in the year the tax is incurred.

- Definition

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

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

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 officer, 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 November 14, 2023, Cadmus C. Rich, M.D., our former Chief Medical Officer, modified his existing Rule 10b5-1(c) trading arrangement, originally adopted on April, 20, 2022. The modified trading arrangement is intended to satisfy the affirmative defense of Rule 10b5-1(c) for the sale of up to 139,787 shares of our common stock. The modified trading arrangement terminates on April 15, 2024, or upon the earlier completion of all authorized transactions under the trading arrangement.
Name	Cadmus C. Rich, M.D.
Title	Chief Medical Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	April, 20, 2022
Rule 10b5-1 Arrangement Terminated	true
Termination Date	April 15, 2024
Aggregate Available	139,787
Rule 10b5-1 Arrangement Modified	true
Modified Date	November 14, 2023

Fair Value of Assets and Liabilities - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets
Financial assets	$ 225,638	$ 185,811
Money Market Funds
Assets
Financial assets	40,551	118,582
Commercial Paper
Assets
Financial assets	9,137	27,476
Corporate Bonds
Assets
Financial assets	6,187	18,099
U.S. Government Agencies
Assets
Financial assets	166,002	21,654
Yankee bonds
Assets
Financial assets	2,982
Asset-backed securities
Assets
Financial assets	779
Level 1
Assets
Financial assets	40,551	118,582
Level 1 \| Money Market Funds
Assets
Financial assets	40,551	118,582
Level 2
Assets
Financial assets	185,087	67,229
Level 2 \| Commercial Paper
Assets
Financial assets	9,137	27,476
Level 2 \| Corporate Bonds
Assets
Financial assets	6,187	18,099
Level 2 \| U.S. Government Agencies
Assets
Financial assets	166,002	$ 21,654
Level 2 \| Yankee bonds
Assets
Financial assets	2,982
Level 2 \| Asset-backed securities
Assets
Financial assets	$ 779

Compensation - Additional Information (Details) - 401(k) Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Contribution Plan Disclosure [Line Items]
Matching contribution by employer, percentage	100.00%
Employer matching contribution, percent of employees contribution	6.00%
Matching contributions from employer	$ 0.7	$ 0.5

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 3,445	$ 1,543
Accrued compensation	3,503	2,705
Other	935	325
Accrued expenses and other current liabilities	$ 7,883	$ 4,573

Common Stock Warrants - Additional Information (Details) - Series B Warrants - Common Stock Warrants - $ / shares	1 Months Ended
	May 31, 2015	Feb. 28, 2015	Dec. 31, 2023	Nov. 02, 2021	Jun. 30, 2021
Class Of Warrant Or Right [Line Items]
Number of Warrants converted				12,686
Exercise price of warrants				$ 17.03
Warrants outstanding			12,686		173,827
Series B Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Number of warrants issued	887,536	1,650,098
Exercise price of warrants	$ 1.24235	$ 1.24235
Warrants expiration period	10 years	10 years

Net Loss Per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss Per Share

13. Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is the same as basic net loss per share for the periods presented since the effects of potentially dilutive securities are antidilutive given the net loss of the Company

The Company has calculated basic and diluted net loss per share for the years ended December 31, 2023 and 2022 as follows (in thousands, except share and per share data):


	Year Ended December 31,
	2023			2022
Numerator:
Net loss	$	(76,408	)	$	(58,763	)
Denominator:
Weighted-average common stock outstanding—basic and diluted		39,620,036			29,937,228
Net loss per common share—basic and diluted	$	(1.93	)	$	(1.96	)

The following potentially dilutive securities were excluded from the computation of the diluted net loss per share for the periods presented because their effect would have been antidilutive:


	Twelve Months Ended December 31,
	2023		2022
Stock options to purchase common stock		5,030,351		4,303,336
Restricted stock units that vest into common stock		1,093,402		153,950
Warrants to purchase common stock		12,686		12,686
Total potential dilutive shares		6,136,439		4,469,972

Income Taxes - Summary of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 45,999	$ 40,617
Stock-based compensation expense	2,110	1,235
Capitalized research and development expenses	22,068	10,200
Tax credit carryforwards	10,007	7,924
Accrued expenses	1,018
Lease liability	5,282	5,461
Other	766	307
Total deferred tax assets	87,250	65,744
Deferred tax liabilities:
Right of use asset	(5,092)	(5,412)
Depreciable assets	(225)	(207)
Accrued expenses		(93)
Valuation allowance	$ (81,933)	$ (60,032)

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (76,408)	$ (58,763)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	1,295	1,177
Accretion on marketable securities	(3,992)	(527)
Stock-based compensation expense	8,772	6,412
(Loss) gain on disposal of property and equipment	208	(22)
Non-cash lease expense	1,837	968
Changes in operating assets and liabilities:
Prepaid expenses and other assets	3,579	(3,253)
Other long-term assets	(86)	(423)
Accounts payable	(1,040)	340
Accrued expenses and other liabilities	3,310	234
Operating lease liabilities	(1,322)	(744)
Net cash used in operating activities	(63,847)	(54,601)
Cash flows from investing activities:
Purchases of property and equipment	(709)	(1,094)
Purchase of marketable securities	(233,651)	(119,784)
Maturities of marketable securities	120,397	53,009
Net cash used in investing activities	(113,963)	(67,869)
Cash flows from financing activities:
Proceeds from exercise of stock options	1,376	430
Proceeds from issuance of common stock under ATM facility, net of issuance costs	3,170	8,549
Proceeds from follow-on issuance of common stock	92,616	86,650
Proceeds from ESPP purchase	128
Net cash provided by financing activities	97,290	95,629
Net (decrease) increase in cash, cash equivalents and restricted cash	(80,520)	(26,841)
Cash, cash equivalents and restricted cash at beginning of period	122,370	149,211
Cash, cash equivalents and restricted cash at end of period	41,850	122,370
Supplemental disclosure of cash flow information:
Purchases of property and equipment in accounts payable and accrued expenses and other liabilities	94	180
Initial measurement of right-of-use assets and lease liabilities	20
Right-of-use assets obtained in exchange for operating lease liabilities		21,210
Loss on termination of operating lease		$ 296
Disposal of equipment	$ 1,333

Marketable Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) Security
Marketable Securities [Line Items]
Impairments of asset	$ 0
Unrealized losses of marketable securities with contractual maturities of one year or less	$ 30,000.00
Number of marketable securities \| Security	13
Asset-backed Securities And U.S. Government Agencies Securities
Marketable Securities [Line Items]
Marketable securities fair value, maturities of one to two years	$ 58,700,000

Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net loss	$ (76,408)	$ (58,763)
Denominator:
Weighted average common stock outstanding - basic	39,620,036	29,937,228
Weighted average common stock outstanding - diluted	39,620,036	29,937,228
Net loss per common share - basic	$ (1.93)	$ (1.96)
Net loss per common share - diluted	$ (1.93)	$ (1.96)

- Definition

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

+ References

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- Definition

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

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+ Details

- Definition

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

+ References

+ Details

Commitments and Contingencies - Summary of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease costs	$ 3,517	$ 1,879
Variable lease costs	883	1,258
Short-term lease costs	7	8
Total lease costs	4,407	3,145
Cash paid for amounts included in the measurement of lease liabilities--operating leases	$ 3,002	$ 1,690
Weighted-average remaining lease term—operating leases (years)	8 years 7 months 2 days	9 years 7 months 2 days
Weighted-average discount rate—operating leases	10.71%	10.71%

Description of Business

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of Business

1. Description of Business

Aura Biosciences, Inc., or the Company or Aura, is a clinical-stage biotechnology company developing precision immunotherapies to treat a range of solid tumors designed to preserve the function of organs afflicted with cancer. Within these consolidated financial statements, unless the context otherwise requires, references to the Company or Aura refer to Aura Biosciences, Inc. and its subsidiaries on a consolidated basis. The Company’s initial focus is in ocular and urologic oncology, both areas of high unmet medical need where local targeted therapies may enable early intervention. The Company’s proprietary platform is designed to enable the targeting of a broad range of solid tumors using Virus-Like Particles, or VLPs, that can be conjugated with drugs or loaded with nucleic acids to create Virus-Like Drug Conjugates, or VDCs. The Company’s VDCs are largely agnostic to tumor type and can recognize a subset of modified tumor associated glycosaminoglycans that are part of the heparan sulphate chain of HSPGs expressed on the cell surface of many tumor cells and in the tumor microenvironment. The Company’s lead candidate bel-sar is in late-stage clinical development for the treatment of patients with primary choroidal melanoma, and other ocular oncology indications as well as in early-stage clinical development in bladder cancer. The Company intends to assess the safety and efficacy of bel-sar in treating a range of other solid tumors, including bladder cancer as an alternative to Bacillus Calmette–Guérin therapy. Aura’s headquarters are located in Boston, Massachusetts.

The Company’s operations to date have consisted primarily of conducting research and development and raising capital.

The Company is subject to risks common to companies in the biotechnology industry, including, but not limited to, the successful development and commercialization of products, fluctuations in operating results and financial risks, need for additional financing or alternative means of financial support or both to fund its current operating plan, protection of proprietary technology and patent risks, compliance with government regulations, dependence on key personnel and collaborative partners, competition, customer demand, management of growth, and the effectiveness of marketing by the Company.

Liquidity

Through December 31, 2023, the Company has funded its operations primarily with proceeds from the initial and additional closings of its convertible preferred stock financings, and through its IPO, follow-on offering and at-the-market offering, or ATM. On November 9, 2023, the Company issued and sold 11,000,000 shares of common stock at a price to the public of $9.00 per share for aggregate gross proceeds of $99.0 million, or the 2023 Follow-On Offering. The Company received approximately $92.6 million in net proceeds from the 2023 Follow-On Offering after deducting underwriting discounts and commissions and offering expenses. On December 5, 2022, the Company issued and sold 7,705,000 shares of common stock, including the full exercise of the underwriters’ option to purchase additional shares at a price to the public of $12.00 per share for aggregate gross proceeds of $92.5 million, or the 2022 Follow-On Offering. The Company received approximately $86.7 million in net proceeds from the 2022 Follow-On Offering after deducting underwriting discounts, commissions and offering expenses. On November 1, 2022, the Company filed a shelf registration statement on Form S-3, or the 2022 Shelf, with the SEC in relation to the registration of up to an aggregate offering price of $250.0 million of common stock, preferred stock, debt securities, warrants and units or any combination thereof. The Company also simultaneously entered into the Open Market Sale AgreementSM, or Sales Agreement, with Jefferies LLC, or the Sales Agent, to provide for the offering, issuance and sale by the Company of up to an aggregate of $75.0 million of common stock from time to time in the ATM under the 2022 Shelf and subject to the limitations thereof. The Company issued 261,807 shares of common stock at an average price of $12.49 for aggregate gross proceeds of $3.3 million during the year ended December 31, 2023 under the ATM. In addition, the Company issued 732,189 shares of common stock at an average price of $12.51 for aggregate gross proceeds of $9.2 million as of December 31, 2022 under the ATM. In connection with the 2023 Follow-On Offering, on November 6, 2023, the Company delivered written notice to Jefferies that the Company was suspending and terminating the prospectus related to the shares issuable in the ATM pursuant to the terms of the Sales Agreement. As a result, the Company will not make any sales of its securities pursuant to the Sales Agreement, unless and until a new prospectus, prospectus supplement, or a new registration statement relating to the shares eligible to be sold in the ATM is filed. Other than the termination of the prospectus, the Sales Agreement remains in full force and effect.

As of the issuance date of these consolidated financial statements for the year ended December 31, 2023, the Company expects that its cash and cash equivalents and marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements through at least 12 months from the issuance of these consolidated financial statements. The future viability of the Company beyond that point is dependent on its ability to raise additional capital to finance its operations.

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Summary of Lease Costs

The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s leases for the years ended December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023		2022
Lease Cost
Operating lease costs		3,517		1,879
Variable lease costs		883		1,258
Short-term lease costs		7		8
Total lease costs	$	4,407	$	3,145


Cash paid for amounts included in the measurement of lease liabilities—operating leases	$	3,002		$	1,690
Weighted-average remaining lease term—operating leases (years)		8.59			9.59
Weighted-average discount rate—operating leases		10.71	%		10.71	%

Summary of Future Minimum Commitments of Operating Lease Liabilities

The following table reconciles the future minimum commitments to the Company’s operating lease liabilities at December 31, 2023 (in thousands):


	Operating lease payments as of December 31, 2023
2024		2,822
2025		3,306
2026		3,405
2027		3,507
2028		3,611
Thereafter		13,823
Total lease payments		30,474
Less: interest		(10,917	)
Total lease liabilities at December 31, 2023		19,557
Less: current portion of lease liabilities		2,687
Lease liabilities, net of current portion	$	16,870

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable Securities

Marketable securities consist of the following (in thousands):


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Commercial paper	$	9,144	$	—	$	(7	)	$	9,137
Corporate bonds		6,186		3		(2	)	$	6,187
U.S. Government agencies		165,453		563		(14	)	$	166,002
Yankee bonds		2,985		—		(3	)	$	2,982
Asset-backed securities		780		—		(1	)	$	779
Total	$	184,548	$	566	$	(27	)	$	185,087


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Commercial paper	$	27,476	$	—	$	—		$	27,476
Corporate bonds		18,191		—		(92	)	$	18,099
U.S. Government agencies		21,635		20		(1	)	$	21,654
Total	$	67,302	$	20	$	(93	)	$	67,229

Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Nov. 09, 2023	Dec. 05, 2022	Nov. 01, 2022	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock, shares authorized				150,000,000	150,000,000
Common stock, par value				$ 0.00001	$ 0.00001
Common stock, shares issued				49,350,788	37,771,918
Common stock, shares outstanding				49,350,788	37,771,918
Preferred stock, shares authorized				10,000,000	10,000,000
Preferred stock, par value				$ 0.00001	$ 0.00001
Preferred stock, shares issued				0	0
Preferred stock, shares outstanding				0	0
Aggregate offering price			$ 250.0
At-the-Market Offering
Class of Stock [Line Items]
Proceeds from issuance of common stock				$ 3.3	$ 9.2
Sale of common stock through agreement			$ 75.0
Common Stock \| Follow-On Offering
Class of Stock [Line Items]
Shares issued and sold	11,000,000	7,705,000		11,000,000	7,705,000
Share price	$ 9	$ 12
Proceeds from issuance of common stock	$ 99.0	$ 92.5
Net proceeds from follow-on offering	$ 92.6	$ 86.7
Common Stock \| At-the-Market Offering
Class of Stock [Line Items]
Shares issued and sold				261,807	732,189
Share price				$ 12.49	$ 12.51

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Combined Stock Option Activity under 2018 Plan and 2021 Plan

The following table summarizes stock option activity under the 2018 Plan and 2021 Plan for the year ended December 31, 2023:


	Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022		4,303,336		$	8.06		7.92	$	16,204
Granted		1,608,975			10.10
Exercised		(258,990	)		5.31
Cancelled/Forfeited		(622,970	)		11.28
Outstanding at December 31, 2023		5,030,351		$	8.46		7.54	$	10,353
Exercisable at December 31, 2023		2,638,834		$	7.06		6.49	$	8,516

Schedule of Fair Value of Stock Options, Valuation Assumptions

The fair value of the stock options issued as of December 31, 2023 and 2022 was measured with the following weighted-average assumptions:


	Twelve Months Ended December 31,
	2023			2022
Risk-free interest rate		3.94	%		3.00	%
Expected term (years)		6.04			5.91
Expected volatility of the underlying stock		86.15	%		78.10	%
Expected dividend rate		—	%		—	%

Schedule of Nonvested Restricted Stock Units Activity

A summary of the restricted stock unit activity during the year ended December 31, 2023 is as follows:


	Restricted Stock Units			Weighted- Average Grant Date Fair Value
Unvested at December 31, 2022		153,950		$	14.00
Granted		1,110,820			9.97
Vested/Released		(43,162	)		14.00
Forfeited		(128,206	)		10.90
Unvested at December 31, 2023		1,093,402		$	10.27

Summary of Stock-Based Compensation Expense

The Company recorded stock-based compensation expense as follows (in thousands):


	Year Ended December 31,
	2023		2022
Research and development	$	3,929	$	2,389
General and administrative		4,843		4,023
Total	$	8,772	$	6,412

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

7. Accrued Expenses and Other Current Liabilities

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


	December 31, 2023		December 31, 2022
Accrued research and development expenses	$	3,445	$	1,543
Accrued compensation		3,503		2,705
Other		935		325
Accrued expenses and other current liabilities	$	7,883	$	4,573

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Tax provision	$ 137,000	$ 0
Federal net operating loss carryback percentage limited to income in any year	80.00%
Deferred tax assets, valuation allowance	$ 81,933,000	60,032,000
Increase in valuation allowance	21,900,000
Unrecognized tax benefits	0	0
Gross deferred tax assets	87,250,000	$ 65,744,000
Federal
Operating Loss Carryforwards [Line Items]
Gross operating loss carryforwards	174,400,000
Operating loss carryforwards not subject to expiration	$ 130,200,000
Federal \| Earliest Tax Year
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards begin to expire period	2029
Federal \| Latest Tax Year
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards begin to expire period	2037
Federal \| 2029 through 2037
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards subject to expiration	$ 44,200,000
Federal \| Research and Experimentation
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward	$ 8,200,000
Tax credit carryforwards begin to expire period	2029
State
Operating Loss Carryforwards [Line Items]
Gross operating loss carryforwards	$ 148,500,000
Operating loss carryforwards not subject to expiration	$ 700,000
Operating loss carryforwards begin to expire period	2030
State \| Research and Experimentation
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward	$ 2,300,000
Tax credit carryforwards begin to expire period	2028
Foreign
Operating Loss Carryforwards [Line Items]
Gross operating loss carryforwards	$ 100,000

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Follow-On Offering	ATM	Common Stock	Common Stock Follow-On Offering	Common Stock ATM	Additional Paid-in Capital	Additional Paid-in Capital Follow-On Offering	Additional Paid-in Capital ATM	Accumulated Deficit	Accumulated Other Comprehensive Loss Amount
Beginning Balance at Dec. 31, 2021	$ 152,315						$ 304,452			$ (152,137)
Beginning Balance, Shares at Dec. 31, 2021				29,211,643
Issuance of common stock		$ 86,650	$ 8,549					$ 86,650	$ 8,549
Issuance of common stock, Shares					7,705,000	732,189
Stock-based compensation expense	6,412						6,412
Vesting of restricted stock, Shares				51,444
Stock options exercises	430						430
Stock options exercises, Shares				71,642
Unrealized gain (loss) on marketable securities	(72)										$ (72)
Other	62						62
Net loss	(58,763)									(58,763)
Ending Balance at Dec. 31, 2022	195,583						406,555			(210,900)	(72)
Ending Balance, Shares at Dec. 31, 2022				37,771,918
Issuance of common stock		$ 92,616	$ 3,170					$ 92,616	$ 3,170
Issuance of common stock, Shares					11,000,000	261,807
Stock-based compensation expense	8,772						8,772
Vesting of restricted stock							0
Vesting of restricted stock, Shares				43,162
Stock options exercises	1,376						1,376
Stock options exercises, Shares				258,990
Employee Stock Purchase Plan Issuance	128						128
Employee Stock Purchase Plan Issuance, Shares				14,911
Unrealized gain (loss) on marketable securities	611						0				611
Net loss	(76,408)									(76,408)
Ending Balance at Dec. 31, 2023	$ 225,848						$ 512,617			$ (287,308)	$ 539
Ending Balance, Shares at Dec. 31, 2023				49,350,788

Net Loss Per Share - Summary of Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	6,136,439	4,469,972
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	5,030,351	4,303,336
Restricted Stock Units that Vest into Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	1,093,402	153,950
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	12,686	12,686

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 1,295	$ 1,177

Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2023

Prepaid Expense and Other Assets, Current [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

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


	December 31, 2023		December 31, 2022
Prepaid insurance	$	1,817	$	2,174
Prepaid research and development expenses		1,399		4,982
Other		2,409		715
Prepaid expenses and other current assets	$	5,625	$	7,871

Fair Value of Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values as of December 31, 2023 and 2022 (in thousands):


Description	December 31, 2023		Quoted prices active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant other observable inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds		40,551	$	40,551	$	—	$	—
Marketable securities:
Commercial paper		9,137		—		9,137		—
Corporate bonds		6,187		—		6,187		—
U.S. Government agencies		166,002		—		166,002		—
Yankee bonds		2,982		—		2,982		—
Asset-backed securities		779		—		779		—
Total financial assets	$	225,638	$	40,551	$	185,087	$	—


Description	December 31, 2022		Quoted prices active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant other observable inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	118,582	$	118,582	$	—	$	—
Marketable securities:
Commercial paper		27,476		—		27,476		—
Corporate bonds		18,099		—		18,099		—
U.S. Government agencies		21,654		—		21,654		—
Total financial assets	$	185,811	$	118,582	$	67,229	$	—

Consolidated Statements of Cash Flows - Reconciliation of Cash, Cash Equivalents, and Restricted Cash - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents, end of period	$ 41,063	$ 121,582
Short-term restricted cash, end of period	19	20
Long-term restricted cash, end of period	768	768
Cash, cash equivalents and restricted cash at end of period	$ 41,850	$ 122,370

Income Taxes - Schedule of Income Tax Benefit (Provision) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Current:
Federal	$ 137	$ 0
Total Current	137	0
Deferred:
Total Provision	$ 137	$ 0

- Definition

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

+ References + Details

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

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


	December 31, 2023			December 31, 2022
Assets under construction	$	391		$	1,805
IT equipment		289			133
Lab equipment		7,506			7,297
	$	8,186		$	9,235
Less—accumulated depreciation		(5,036	)		(3,864	)
Property and equipment, net	$	3,150		$	5,371

Compensation

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Compensation

11. Compensation

In January 2012, the Company adopted the Aura Biosciences 401(k) Profit Sharing Plan and Trust, or the 401(k) Plan, for its employees, which is designed to be qualified under Section 401(k) of the Internal Revenue Code. Eligible employees are permitted to contribute to the 401(k) Plan within statutory and 401(k) Plan limits. The Company makes matching contributions of 100% of the first 6% of employee contributions. The Company made matching contributions in the amount of $0.7 million and $0.5 million for the years ended December 31, 2023 and 2022, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//715/tableOfContent

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Common Stock Warrants

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Common Stock Warrants

10. Common Stock Warrants

In February 2015 and May 2015, the Company issued warrants to purchase 1,650,098 and 887,536 shares of Series B convertible preferred stock, respectively, at an exercise price of $1.24235 per share, or the Series B Warrants. Each Series B Warrant was immediately exercisable and expires ten years from the original date of issuance. Pursuant to FASB ASC Topic 480, Distinguishing Liabilities from Equity, the Series B Warrants were classified as a liability and were re-measured to fair value at each balance sheet date. A total of 173,827 of the Series B Warrants were outstanding and were converted into warrants to purchase 12,686 shares of common stock with an exercise price of $17.03 upon the completion of the IPO in November 2021. As a result, the 12,686 common stock warrants were converted into equity instruments and remain outstanding as of December 31, 2023.

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2023	Mar. 20, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	AURA BIOSCIENCES, INC.
Entity Central Index Key	0001501796
Entity File Number	001-40971
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	32-0271970
Entity Address, Address Line One	80 Guest Street
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02135
City Area Code	617
Local Phone Number	500-8864
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
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, par value $0.00001 per share
Trading Symbol	AURA
Security Exchange Name	NASDAQ
Document Annual Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		49,504,405
Auditor Name	Ernst & Young LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	42
Entity Public Float			$ 224.6

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Assets (Details)	12 Months Ended
	Dec. 31, 2023
Leasehold Improvements
Property Plant And Equipment [Line Items]
Estimated Useful Life	The shorter of the life of the leasehold improvement or the remaining term of the lease
IT Equipment
Property Plant And Equipment [Line Items]
Estimated Useful Life	3 years
Laboratory Equipment
Property Plant And Equipment [Line Items]
Estimated Useful Life	5 years
Office Furniture
Property Plant And Equipment [Line Items]
Estimated Useful Life	7 years

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	49,350,788	37,771,918
Common stock, shares outstanding	49,350,788	37,771,918

Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Marketable securities [Line items]
Amortized Cost	$ 184,548	$ 67,302
Unrealized Gains	566	20
Unrealized Losses	(27)	(93)
Fair Value	185,087	67,229
Commercial Paper
Marketable securities [Line items]
Amortized Cost	9,144	27,476
Unrealized Losses	(7)
Fair Value	9,137	27,476
Corporate Bonds
Marketable securities [Line items]
Amortized Cost	6,186	18,191
Unrealized Gains	3
Unrealized Losses	(2)	(92)
Fair Value	6,187	18,099
U.S. Government Agencies
Marketable securities [Line items]
Amortized Cost	165,453	21,635
Unrealized Gains	563	20
Unrealized Losses	(14)	(1)
Fair Value	166,002	$ 21,654
Yankee bonds
Marketable securities [Line items]
Amortized Cost	2,985
Unrealized Losses	(3)
Fair Value	2,982
Asset-backed securities
Marketable securities [Line items]
Amortized Cost	780
Unrealized Losses	(1)
Fair Value	$ 779

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating Expenses:
Research and development expenses	$ 65,232	$ 42,238
General and administrative	19,759	18,057
Total operating expenses	84,991	60,295
Total operating loss	(84,991)	(60,295)
Other income (expense):
Interest income, including amortization and accretion income	8,588	1,864
Gain (loss) from disposal of assets	208	(318)
Other income (expense)	(76)	(14)
Total other income (expense)	8,720	1,532
Loss before income taxes	(76,271)	(58,763)
Income tax benefit (provision), net	(137)	0
Net loss	$ (76,408)	$ (58,763)
Net loss per common share - basic	$ (1.93)	$ (1.96)
Net loss per common share - diluted	$ (1.93)	$ (1.96)
Weighted average common stock outstanding - basic	39,620,036	29,937,228
Weighted-average common stock outstanding - diluted	39,620,036	29,937,228
Comprehensive loss:
Net loss	$ (76,408)	$ (58,763)
Other comprehensive items:
Unrealized gain (loss) on marketable securities	611	(72)
Total other comprehensive income (loss)	611	(72)
Total comprehensive loss	$ (75,797)	$ (58,835)

Stock-Based Compensation - Schedule of Fair Value of Stock Options, Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Risk-free interest rate	3.94%	3.00%
Expected term (years)	6 years 14 days	5 years 10 months 28 days
Expected volatility of the underlying stock	86.15%	78.10%
Expected dividend rate	0.00%	0.00%

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or U.S. GAAP. The consolidated financial statements include those accounts of the Company and its subsidiaries after elimination of all intercompany accounts and transactions.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant items subject to such estimates and assumptions include the fair value of stock-based compensation and accrued research and development costs. Management bases its estimates on historical experience and on various other market-specific relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Segment Information

Operating segments are defined as components of an entity about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment operating exclusively in the United States.

Cash and Restricted Cash

Cash consists of standard checking accounts. As of December 31, 2023, the restricted cash account is comprised of a $0.8 million security deposit held by the lessor for the Company’s operating lease, and a less than $0.02 million deposit that is collateral for the Company’s corporate credit card.

Cash Equivalents

Cash equivalents are highly liquid investments with an original maturity of 90 days or less at the date of purchase and consist of time deposits and investments in money market funds that invest in U.S. Treasury obligations and government funds with commercial banks and financial institutions.

Marketable Securities

All marketable securities have original maturities greater than 90 days. The Company has classified its investments with maturities beyond one year as short-term, based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. The Company considers its investment portfolio of marketable securities to be available-for-sale. Accordingly, these investments are recorded at fair value. When the fair value is below the amortized cost of the asset, an estimate of expected credit losses is made. The credit-related impairment amount is recognized in net income (loss); the remaining impairment amount and unrealized gains are reported as a component of accumulated other comprehensive items in stockholders’ equity. Credit losses are recognized through the use of an allowance for credit losses account and subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance for credit losses account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in the consolidated statements of operations and comprehensive loss. Regardless of the Company’s intent to sell a security, it performs additional analysis on all securities with unrealized losses to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where the Company does not expect to receive cash flows sufficient to recover the amortized cost basis of a security. Unrealized gains and losses are reported as the accumulated other comprehensive items in stockholders’ equity. Amortization and accretion of premiums and discounts are recorded in other income (expense) within the consolidated statements of operations and comprehensive loss. Realized gains or losses are included in interest income or interest expense, respectively. If any adjustment to fair value reflects a decline in value of the investment, the Company considers all available evidence such as industry, financial inputs, and capital markets data to evaluate the extent to which the decline is other than temporary and, if so, marks the investment to market on the Company’s consolidated statement of operations and comprehensive loss.

Fair Value Measurements

Accounting Standards Codification 820, Fair Value Measurement, or ASC 820, establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs).

Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances.

ASC 820 identifies fair value as the exchange price, or exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following:

▪

Level 1—Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities.

▪

Level 2—Inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

▪

Level 3—Inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.

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. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains its cash in bank deposit accounts which, at times, may exceed federally insured limits. The Company has not experienced any losses in such accounts. The Company believes it is not exposed to any significant credit risk on cash.

Property and Equipment

Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful life of the assets. Upon sale or retirement, the cost and accumulated depreciation is eliminated from their respective accounts and the resulting gain or loss is included in income or loss for the period. Repair and maintenance expenditures are charged to expense as incurred. The estimated useful lives of the Company’s respective assets are as follows:


		Estimated Useful Life
Leasehold improvements		The shorter of the life of the leasehold improvement or the remaining term of the lease
IT equipment		3 years
Laboratory equipment		5 years
Office furniture		7 years

Costs for capital assets not yet placed into service are capitalized as assets under construction and depreciated in accordance with the above guidelines once placed into service. Upon retirement or disposal of property and equipment, the cost and related accumulated depreciation are removed from the consolidated balance sheet and any gain or loss is reflected in the consolidated statements of operations and comprehensive loss.

Impairment of Long-Lived Assets

The Company reviews all long-lived assets for impairment whenever events or circumstances indicate the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by comparison of the carrying value of the assets to the future undiscounted net cash flows expected to be generated by the asset. If such asset is considered to be unrecoverable, the impairment recognized is measured by the difference between the estimated fair value of the asset and its carrying value. The Company did not recognize any impairments during the years ended December 31, 2023 or 2022.

Research and Development

Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, third-party license fees, and external costs of outside vendors engaged to conduct preclinical development activities and clinical trials as well as to manufacture research and development materials. The Company accrues costs for clinical trial activities and contract manufacturers based upon estimates of the services received and related expenses incurred that have yet to be invoiced by the contract research organizations, clinical study sites, contract manufacturers, laboratories, consultants, or other vendors that perform the activities.

Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred. Such amounts are expensed as the goods are delivered or the related services are performed or until it is no longer expected that the goods will be delivered, or the services rendered.

Costs incurred in obtaining technology licenses are recognized as research and development expense as incurred if the technology licensed has not reached technological feasibility and has no alternative future uses.

Patent and Trademark Costs

All patents and trademark related costs incurred in connection with filing and prosecuting patent and trademark applications are expensed as incurred due to uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses in the consolidated statements of operations and comprehensive loss.

Leases

Effective January 1, 2021, the Company accounts for leases in accordance with ASU No. 2016-02, Leases (Topic 842), or ASC 842. At contract inception, the Company determines if an arrangement is or contains a lease. A lease conveys the right to control the use of an identified asset for a period of time in exchange for consideration. If determined to be or contain a lease, the lease is assessed for classification as either an operating or finance lease at the lease commencement date, defined as the date on which the leased asset is made available for use by the Company, based on the economic characteristics of the lease. For each lease with a term greater than twelve months, the Company records a right-of-use asset and lease liability.

A right-of-use asset represents the economic benefit conveyed to the Company by the right to use the underlying asset over the lease term. A lease liability represents the obligation to make lease payments arising from the lease. The Company elected the practical expedient to not separate lease and non-lease components for all classes of underlying assets and therefore measures each lease payment as the total of the fixed lease and associated non-lease components. Lease liabilities are measured at lease commencement and calculated as the present value of the future lease payments in the contract using the rate implicit in the contract, when available. If an implicit rate is not readily determinable, the Company uses an incremental borrowing rate measured as the rate at which the Company could borrow, on a fully collateralized basis, a commensurate loan in the same currency over a period consistent with the lease term at the commencement date. Right-of-use assets are measured as the lease liability plus initial direct costs and prepaid lease payments, less lease incentives granted by the lessor. The lease term is measured as the noncancelable period in the contract, adjusted for any options to extend or terminate when it is reasonably certain the Company will extend the lease term via such options based on an assessment of economic factors present as of the lease commencement date. The Company elected the practical expedient to not recognize leases with a lease term of twelve months or less.

Components of a lease are split into three categories: lease components, non-lease components, and non-components. The fixed and in-substance fixed contract consideration (including any consideration related to non-components) are allocated, based on the respective relative fair values, to the lease components and non-lease components. The Company has elected to account for lease and non-lease components together as a single lease component for all underlying assets and allocate all of the contract consideration to the lease component only.

The Company’s operating leases are presented in the consolidated balance sheet as operating lease right-of-use assets, classified as noncurrent assets, and operating lease liabilities, classified as current and noncurrent liabilities. Operating lease expense is recognized on a straight-line basis over the lease term. Variable costs associated with a lease, such as maintenance and utilities, are not included in the measurement of the lease liabilities and right-of-use assets but rather are expensed when the events determining the amount of variable consideration to be paid have occurred.

Income Taxes

The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the Company’s consolidated financial statements and/or tax returns. Deferred tax assets and liabilities are based upon the differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities and for loss and credit carryforwards using enacted tax rates expected to be in effect in the years in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion or all the deferred tax asset will not be realized.

The Company provides reserves related to uncertain tax positions when management determines the related tax benefit is not more likely than not to be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as the consideration of the available facts and circumstances. The Company has no reserves related to uncertain tax positions as of December 31, 2023 and 2022.

Interest and penalty charges, if any, related to uncertain tax positions would be classified as income tax expense in the accompanying consolidated statements of operations and comprehensive loss. As of December 31, 2023 and 2022 the Company had no accrued interest related to uncertain tax positions.

Deferred Offering Costs

The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process preferred stock or common stock financings as deferred offering costs until such financings are consummated. After the closing of the IPO, follow-on offering and the ATM draw downs, these costs were recorded in stockholders' equity as a reduction of additional paid-in capital generated as a result of the financings.

Stock-Based Compensation

The Company recognizes stock-based compensation expense for all stock-based awards based on their grant date fair value.

The Company recognizes compensation expense over the requisite service period, which is generally the vesting period of the award. For awards that include performance-based vesting conditions, expense is recognized using the accelerated attribution method when the performance condition is deemed to be probable of being satisfied. As of December 31, 2023, the Company has no performance-based awards. The Company accounts for forfeitures as they occur. The Company determines the fair value of restricted stock awards in reference to the fair value of its common stock less any applicable purchase price.

The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model, which requires inputs based on certain subjective assumptions, including the expected stock price volatility, the expected term of the option, the risk-free interest rate for a period that approximates the expected term of the option and the Company’s expected dividend yield. The Company determines the volatility for awards granted based on an analysis of reported data for a group of guideline companies that have issued options with substantially similar terms. The expected volatility has been determined using a weighted-average of the historical volatility measures of this group of guideline companies. The Company expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options granted to employees has been determined utilizing the “simplified” method, using the midpoint between the vesting date and the contractual term. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The Company has not paid, and does not anticipate paying, cash dividends on its common stock; therefore, the expected dividend yield is assumed to be zero.

The Company classifies stock-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s cash compensation costs are classified.

Net Loss per Share

Net loss per share attributable to common stockholders is computed by using the two-class method, which is an earnings allocation formula that determines loss per share for the holders of the Company’s common stock and participating securities. All series of preferred stock contain participation rights in any dividend declared or accumulated by the Company and are deemed to be participating securities. Income available to common stockholders and participating convertible preferred stock is allocated to each share on an as-converted basis as if all of the earnings for the period had been distributed. The participating securities do not include a contractual obligation to share in losses of the Company and are not included in the calculation of net loss per share in the periods that have a net loss.

Diluted net income per share is computed using the if-converted method. The Company allocates earnings first to preferred stockholders based on dividend rights and then to common and preferred stockholders based on ownership interests. The weighted-average number of common stock included in the computation of diluted loss gives effect to all potentially dilutive common equivalent shares, including outstanding stock options, warrants, and convertible preferred stock. Common stock equivalent shares are excluded from the computation of diluted loss per share if their effect is antidilutive.

Comprehensive Loss

Comprehensive 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.

Recently Adopted Accounting Pronouncements

In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” which was subsequently amended in November 2018 through ASU No. 2018-19, “Codification Improvements to Topic 326, Financial Instruments—Credit Losses.” ASU No. 2016-13 will require entities to estimate lifetime expected credit losses for trade and other receivables, net investments in leases, financing receivables, debt securities and other instruments, which will result in earlier recognition of credit losses. Further, the new credit loss model will affect how entities in all industries estimate their allowance for losses for receivables that are current with respect to their payment terms. ASU No. 2018-19 further clarifies that receivables arising from operating leases are not within the scope of Topic 326. Instead, impairment from receivables of operating leases should be accounted for in accordance with Topic 842, Leases. As per the latest ASU 2020-02, the Financial Accounting Standards Board, or FASB, deferred the timelines for certain small public and private entities, thus the new guidance will be adopted by the Company for the annual reporting period beginning January 1, 2023, including interim periods within that annual reporting period. The standard will apply as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The Company adopted this standard on January 1, 2023 and the standard did not have a material impact on its results of operations, financial condition, and financial statement disclosures.

Accounting Pronouncements Not Yet Adopted

Other accounting standards that have been issued or proposed by FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.

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]
Stock-based compensation expense	$ 8,772	$ 6,412
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	3,929	2,389
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 4,843	$ 4,023

Marketable Securities

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

6. Marketable Securities

Marketable securities consist of the following (in thousands):


	December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Commercial paper	$	9,144	$	—	$	(7	)	$	9,137
Corporate bonds		6,186		3		(2	)	$	6,187
U.S. Government agencies		165,453		563		(14	)	$	166,002
Yankee bonds		2,985		—		(3	)	$	2,982
Asset-backed securities		780		—		(1	)	$	779
Total	$	184,548	$	566	$	(27	)	$	185,087


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Commercial paper	$	27,476	$	—	$	—		$	27,476
Corporate bonds		18,191		—		(92	)	$	18,099
U.S. Government agencies		21,635		20		(1	)	$	21,654
Total	$	67,302	$	20	$	(93	)	$	67,229

As of December 31, 2023, the unrealized losses on the Company’s investments in commercial paper, corporate bonds, U.S. government agencies securities, Yankee bonds, and asset-backed securities were caused by interest rate increases. The current credit ratings are all within the guidelines of the investment policy of the Company and the Company does not expect the issuers to settle any security at a price less than the amortized cost basis of the investment. The Company does not intend to sell the investments and it is not probable that the Company will be required to sell the investments before recovery of their amortized cost basis.

As of December 31, 2023, 13 marketable securities with contractual maturities of one year or less were in an unrealized loss position totaling $0.03 million.

As of December 31, 2023, $0.03 million unrealized losses were associated with marketable securities with contractual maturities of one year or less.

As of December 31, 2023, all marketable securities held by the Company had remaining contractual maturities of one year or less, except for asset-backed securities and U.S. government agencies securities with a fair value of $58.7 million that had maturities of one to two years.

There were no impairments of the Company’s assets measured and carried at fair value during the year ended December 31, 2023.

Commitments and Contingencies- Summary of Future Minimum Commitments of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
2024	$ 2,822
2025	3,306
2026	3,405
2027	3,507
2028	3,611
Thereafter	13,823
Total lease payments	30,474
Less: interest	(10,917)
Total operating lease liabilities at December 31, 2023	19,557
Less: current portion of lease liabilities	2,687	$ 2,963
Lease liabilities, net of current portion	$ 16,870	$ 17,895

Income Taxes - Summary of Reconciliation of Federal Statutory Income Tax Rate to Company's Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Tax provision at statutory rate	21.00%	21.00%
State taxes, net of federal benefit	6.60%	5.60%
Federal tax credits	2.30%	2.90%
Permanent items	(1.00%)	(1.10%)
Other	(0.10%)	0.10%
Decrease in valuation reserve	(28.80%)	(28.50%)
Total	0.00%	0.00%

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Presentation and Principles of Consolidation

Use of Estimates

Segment Information

Cash and Restricted Cash

Cash Equivalents

Marketable Securities

Fair Value Measurements

▪

Level 1—Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities.

▪

Level 2—Inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

▪

Concentration of Credit Risk

Property and Equipment


		Estimated Useful Life
Leasehold improvements		The shorter of the life of the leasehold improvement or the remaining term of the lease
IT equipment		3 years
Laboratory equipment		5 years
Office furniture		7 years

Impairment of Long-Lived Assets

Research and Development

Patent and Trademark Costs

Leases

Income Taxes

Deferred Offering Costs

Stock-Based Compensation

The Company recognizes stock-based compensation expense for all stock-based awards based on their grant date fair value.

Net Loss per Share

Comprehensive Loss

Comprehensive 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.

Recently Adopted Accounting Pronouncements

Accounting Pronouncements Not Yet Adopted

Description of Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	Nov. 09, 2023	Dec. 05, 2022	Nov. 01, 2022	Dec. 31, 2023	Dec. 31, 2022
Description Of Business [Line Items]
Net losses				$ 76,408	$ 58,763
Accumulated deficit				287,308	210,900
Net proceeds from the IPO				92,616	86,650
Aggregate offering price			$ 250,000
At-the-Market Offering
Description Of Business [Line Items]
Sale of common stock through agreement			$ 75,000
Proceeds from issuance of common stock				$ 3,300	$ 9,200
Common Stock \| 2023 Follow-On Offering
Description Of Business [Line Items]
Shares issued and sold	11,000,000
Share price	$ 9
Aggregate gross proceeds from follow-on offering	$ 99,000
Net proceeds from follow-on offering	$ 92,600
Common Stock \| At-the-Market Offering
Description Of Business [Line Items]
Shares issued and sold				261,807	732,189
Share price				$ 12.49	$ 12.51
Common Stock \| Follow-On Offering
Description Of Business [Line Items]
Shares issued and sold	11,000,000	7,705,000		11,000,000	7,705,000
Share price	$ 9	$ 12
Proceeds from issuance of common stock	$ 99,000	$ 92,500
Net proceeds from follow-on offering	$ 92,600	$ 86,700

Fair Value of Assets and Liabilities

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value of Assets and Liabilities

3. Fair Value of Assets and Liabilities


Description	December 31, 2023		Quoted prices active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant other observable inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds		40,551	$	40,551	$	—	$	—
Marketable securities:
Commercial paper		9,137		—		9,137		—
Corporate bonds		6,187		—		6,187		—
U.S. Government agencies		166,002		—		166,002		—
Yankee bonds		2,982		—		2,982		—
Asset-backed securities		779		—		779		—
Total financial assets	$	225,638	$	40,551	$	185,087	$	—


Description	December 31, 2022		Quoted prices active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant other observable inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	118,582	$	118,582	$	—	$	—
Marketable securities:
Commercial paper		27,476		—		27,476		—
Corporate bonds		18,099		—		18,099		—
U.S. Government agencies		21,654		—		21,654		—
Total financial assets	$	185,811	$	118,582	$	67,229	$	—

There have been no transfers between levels for the years ended December 31, 2023 and 2022.

- Definition

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

+ References + Details

Property and Equipment, Net

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

4. Property and Equipment, Net

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


	December 31, 2023			December 31, 2022
Assets under construction	$	391		$	1,805
IT equipment		289			133
Lab equipment		7,506			7,297
	$	8,186		$	9,235
Less—accumulated depreciation		(5,036	)		(3,864	)
Property and equipment, net	$	3,150		$	5,371

Depreciation expense was $1.3 million and $1.2 million for the years ended December 31, 2023 and 2022, respectively.

Commitment and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

12. Commitments and Contingencies

Lease Commitments

The Company has historically entered into lease arrangements for its facilities. The Company has one operating lease for its office and laboratory facility with required future minimum payments as of September 30, 2023 and one operating lease that was terminated in August 2022.

On May 16, 2022, the Company entered into an office and laboratory lease in Boston, MA with an initial 10-year term and one renewal option to extend the lease for an additional seven years which has not been deemed probable by the Company as of December 31, 2023. The lease commenced on August 1, 2022, and estimated payments due under the initial term total $35.2 million. The lease requires a letter of credit totaling $0.8 million which is classified as long-term restricted cash and deposits on the consolidated balance sheet. The landlord will reimburse the Company up to $0.5 million for certain costs related to expansion of the laboratory space. As of December 31, 2023, the Company has incurred $0.1 million of expenses related to the expansion, and has been reimbursed for $0.1 million of these expenses.


	Year Ended December 31,
	2023		2022
Lease Cost
Operating lease costs		3,517		1,879
Variable lease costs		883		1,258
Short-term lease costs		7		8
Total lease costs	$	4,407	$	3,145


Cash paid for amounts included in the measurement of lease liabilities—operating leases	$	3,002		$	1,690
Weighted-average remaining lease term—operating leases (years)		8.59			9.59
Weighted-average discount rate—operating leases		10.71	%		10.71	%

The following table reconciles the future minimum commitments to the Company’s operating lease liabilities at December 31, 2023 (in thousands):


	Operating lease payments as of December 31, 2023
2024		2,822
2025		3,306
2026		3,405
2027		3,507
2028		3,611
Thereafter		13,823
Total lease payments		30,474
Less: interest		(10,917	)
Total lease liabilities at December 31, 2023		19,557
Less: current portion of lease liabilities		2,687
Lease liabilities, net of current portion	$	16,870

License Agreements

The Company has entered into the following key agreements that relate to the core technology under development:

LI-COR Exclusive License and Supply Agreement

In January 2014, the Company entered into an Exclusive License and Supply Agreement, or the LI-COR Exclusive License agreement with LI-COR, Inc., or LI-COR, for the license of IRDye 700DC and related licensed patent (now expired) for the treatment and diagnosis of ocular cancers in humans as amended in January 2016, July 2017, April 2018 and April 2019. The LI-COR Exclusive License Agreement required a one-time upfront license issue fee of $0.1 million and aggregate milestone payments of up to $0.2 million upon certain regulatory and development milestones. The Company is also required to pay LI-COR low-single digit royalties on net sales. The term of the LI-COR Exclusive Agreement expires on a country-by-country basis, until the longer of (i) ten years from the first commercial sale of a licensed product in such country and (ii) the last to expire valid claim in such country.

The Company recognized no expenses related to this agreement and related amendments for the years ended December 31, 2023 and 2022.

LI-COR Non-Exclusive License and Supply Agreement

In December 2014, the Company entered into a Non-Exclusive License Agreement with LI-COR for the supply of IRDye 700DX to the Company for the treatment and diagnosis of non-ocular solid tumor cancers in humans. Under the 2014 Non-Exclusive, the Company paid a license issue fee of $0.03 million on the effective date. The

Company must also pay LI-COR a non-refundable, non-creditable fee of $0.03 million per each licensed product upon pre-IND designation, as defined of such licensed product, aggregate milestone payments of up to $0.3 million upon certain regulatory and development milestones; and during the term, the Company must pay LI-COR a low-single digit percentage royalty on net sales. LI-COR receives 10% of all sublicensee income within 30 days of the Company’s receipt from the sublicensee. The 2014 Non-Exclusive Agreement also required the Company to make certain payments upon the achievement of specified development and commercial milestones of up to $0.4 million in aggregate. During the years ended December 31, 2023 and 2022, the Company recognized immaterial milestones related to this agreement.

Life Technologies Corporation License Agreement

In December 2014, the Company entered into a non-exclusive, perpetual license agreement with Life Technologies Corporation, or the Life Technologies, which allows for five licensed products. Under this agreement the Company is required to pay an initial license fee of $0.1 million for each product. An annual development fee of $0.1 million is due within a year from payment of the initial license fee and due annually or earlier of (i) payment of a commercialization fee or (ii) all development work is terminated. The commercialization fee is a one-time, non-refundable, non-creditable fee of $0.3 million due upon receipt of approval of a licensed product. In the event of a change of control, there will be a change of control fee of $0.2 million.

In January 2022, the Company entered into the First Amendment to the non-exclusive, perpetual license agreement with Life Technologies for use of the license in an additional indication. The cost of this amendment was a one-time fee of $0.05 million. During the years ended December 31, 2022 and 2021, the Company recognized $0.05 million and $0.1 million of expenses related to this agreement, respectively.

Effective in September 2022, the Company entered into a new non-exclusive, perpetual license agreement with Life Technologies for licensed products. Under this agreement, the Company is required to pay an initial license fee of $0.4 million for the first licensed product and $0.5 million for each additional licensed product. In addition, the agreement allows the Company the right to sublicense which would lead to a $0.2 million payment for each sublicense per licensed product and a $0.03 million payment for use of the cell line document package. In the event of a change of control, there will be a change of control fee of $0.5 million. During the year ended December 31, 2023 and 2022, the Company recognized $0 million and $0.4 million of expenses related to this agreement.

National Institute of Health (NIH)-Biologic Materials License Agreement

In December 2010, the Company entered into a Biologic Materials License Agreement with NIH for a non-exclusive right to use materials described in Schiller et al., Virology 2004 Apr.10, 321(2):205-16. This agreement required a one-time non-refundable license issuance fee of $0.02 million. No future milestone payments or royalties are due under this agreement.

National Institute of Health (NIH)-Collaboration Research and Development Agreement

In July 2011, the Company entered into a Collaboration Research and Development Agreement (CRADA), with Dr. John Schiller at the NIH, for a period of two years with the rights to an exclusive license to all technology generated within the collaboration. Under this agreement, the Company is required to make annual payments of $0.03 million to fund the research activities, the first payment of which was paid within 30 days of the effective date. Subsequent payments are due within 30 days of the anniversary of the effective date. This agreement was first amended in 2012, 2013, 2014, 2015, 2016, 2018 and most recently in September of 2020. During the years ended December 31, 2023 and 2022, the Company paid no research collaboration fees related to this agreement.

A seventh amendment was made in October 2020, requiring payment of $0.04 million within 30 days of October 1, 2020, and another $0.03 million within 30 days of the 10th anniversary of the CRADA, which was paid in July 2021. This seventh amendment extended the term of the CRADA to September 30, 2022. The Company recognized no milestones related to this agreement and related amendments for the years ended December 31, 2023 and 2022.

An eighth amendment was effective in September 2022, requiring payment of $0.04 million within 30 days of November 1, 2022, and payment of another $0.03 million within 30 days of the 12th anniversary of the CRADA, which will be in August 2023. This eighth amendment extended the term of the CRADA to September 30, 2024. During the year ended December 31, 2023 and 2022, the Company recognized $0.03 million and $0.1 million of expenses related to this agreement.

National Institute of Health (NIH)-Exclusive Patent License Agreement

In September 2013, the Company entered into an exclusive patent license agreement, or the NIH Exclusive License Agreement, with the NIH, that required the Company to pay a license issue royalty of $0.1 million and reimburse the NIH for any patent expenses incurred. Under the agreement, the Company is required to make low single-digit percentage royalty payments based on specified levels of annual net sales of licensed products subject to certain specified reductions. The Company is required to make development and regulatory milestone payments of up to $0.7 million in aggregate and sales milestone payments up to $0.6 million in the aggregate. The Company is also required to pay NIH a mid-single to low teen-digit percentage of any sublicensing revenue the Company receives. Additionally, the Company’s payment obligations to the NIH are subject to an annual minimum royalty payment of low five figures. The Company recognized $0.2 million and $0.02 million for patent licensing fees for the years ended December 31, 2023 and 2022, respectively.

In 2015, 2018 and 2019, the Company amended its exclusive patent license to include updates on the status of the commercial development and update/expand the list of licensed patents and patent applications. Each of those amendments required a $0.03 million payment that the Company paid.

Inserm-Transfert License Agreement

In November 2009, the Company entered into an exclusive, royalty-bearing patent license agreement with Inserm-Transfert of France. The agreement expires on a country by country basis based on the last to expire any patent encompassed within the scope of the patent rights or 10 years from the date of the first commercial sales by the Company, whichever is later. The IND filing milestone of €0.01 million was accrued in 2016 and paid in 2017 by the Company. The milestones for the successful Phase I, II and III clinical trials are based on receiving a final report and achieving the primary endpoints defined in that trial, and those milestones have not been achieved as of December 31, 2022. Upon the sublicense by the Company of a product for which royalties are payable under the agreement, low- to mid-single-digit royalty payments would be due by the Company. The non-milestone payments in this agreement are subject to an anti-stacking clause. The Company recognized no expenses related to this agreement for the years ended December 31, 2023 and 2022, respectively.

Clearside License Agreement

In July 2019, the Company entered into an exclusive license agreement with Clearside Biomedical, Inc., or Clearside, for the license of Clearside’s Suprachoroidal Microneedle Technology for use in the treatment of indeterminate lesions and choroidal tumors. Upon execution of the License Agreement, the Company paid Clearside an upfront payment of $0.1 million which was expensed as incurred. Under the Clearside License Agreement, the Company is required to pay milestones up to $21.0 million in the aggregate upon the achievement of specified regulatory and development milestones, and upon the achievement of certain commercial sales milestones. The Company is also required to pay low to mid-single digit royalties on net sales. If the Company sublicenses a product for which royalties are payable, then the Company is required to pay the greater of 20% received or low single digit royalties on net sales.

The Clearside License agreement expires on a country-by-country basis upon the later of the last to expire patent or ten years from the date of the first commercial sale of a product.

The Company recognized $1.0 million and $0 million related to this agreement and related amendments for the years ended December 31, 2023 and 2022.

Stock-Based Compensation - Summary of stock option activity under the 2018 Plan to 2021 Plan (Details) - 2021 Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options Outstanding, Beginning balance	4,303,336
Options, Granted	1,608,975
Options, Exercised	(258,990)
Options, Cancelled/Forfeited	(622,970)
Options Outstanding, Ending balance	5,030,351	4,303,336
Options, Exercisable at December 31, 2023	2,638,834
Weighted Average Exercise Price, Beginning balance	$ 8.06
Weighted Average Exercise Price, Granted	10.10
Weighted Average Exercise Price, Exercised	5.31
Weighted Average Exercise Price, Cancelled/Forfeited	11.28
Weighted Average Exercise Price, Ending balance	8.46	$ 8.06
Weighted Average Exercise Price, Exercisable at December 31, 2023	$ 7.06
Weighted Average Remaining Contractual Term (years)	7 years 6 months 14 days	7 years 11 months 1 day
Weighted Average Remaining Contractual Term (years), Exercisable	6 years 5 months 26 days
Aggregate Intrinsic Value, Outstanding	$ 10,353	$ 16,204
Aggregate Intrinsic Value, Exercisable at December 31, 2023	$ 8,516

Subsequent Events

12 Months Ended

Dec. 31, 2023

Subsequent Events [Abstract]

Subsequent Events

15. Subsequent Events

The Company has not identified any subsequent events that require disclosure.

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	$ 8,186	$ 9,235
Less—accumulated depreciation	(5,036)	(3,864)
Property and equipment, net	3,150	5,371
Assets Under Construction
Property Plant And Equipment [Line Items]
Property and equipment, gross	391	1,805
IT Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	289	133
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 7,506	$ 7,297

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Summary of Basic and Diluted Net Loss Per Share

The Company has calculated basic and diluted net loss per share for the years ended December 31, 2023 and 2022 as follows (in thousands, except share and per share data):


	Year Ended December 31,
	2023			2022
Numerator:
Net loss	$	(76,408	)	$	(58,763	)
Denominator:
Weighted-average common stock outstanding—basic and diluted		39,620,036			29,937,228
Net loss per common share—basic and diluted	$	(1.93	)	$	(1.96	)

Summary of Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share

The following potentially dilutive securities were excluded from the computation of the diluted net loss per share for the periods presented because their effect would have been antidilutive:


	Twelve Months Ended December 31,
	2023		2022
Stock options to purchase common stock		5,030,351		4,303,336
Restricted stock units that vest into common stock		1,093,402		153,950
Warrants to purchase common stock		12,686		12,686
Total potential dilutive shares		6,136,439		4,469,972

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) Segment shares	Dec. 31, 2022 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of operating segments \| Segment	1
Security deposit held by lessor	$ 800,000
Accounting Standards Update [Extensible Enumeration]	us-gaap:AccountingStandardsUpdate201613Member
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2023
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
Reserves related to uncertain tax positions	$ 0	$ 0
Accrued interest related to uncertain tax positions	$ 0	$ 0
Expected dividend yield	0.00%	0.00%
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Collateral deposit for corporate credit card	$ 20,000.00
Performance-based Awards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of stock awards \| shares	0

Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2023

Prepaid Expense and Other Assets, Current [Abstract]

Prepaid Expenses and Other Current Assets

5. Prepaid Expenses and Other Current Assets

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


	December 31, 2023		December 31, 2022
Prepaid insurance	$	1,817	$	2,174
Prepaid research and development expenses		1,399		4,982
Other		2,409		715
Prepaid expenses and other current assets	$	5,625	$	7,871