0000950170-24-122821 | 10-Q | XBRL Viewer

Commitments and Contingencies	9 Months Ended
Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Legal proceedings From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated. The Company is not party to any litigation and does not have contingency reserves established for any litigation liabilities. Other The Company enters into standard indemnification agreements in the ordinary course of business. Pursuant to the agreements, the Company agrees to indemnify, hold harmless, and to reimburse the indemnified party for losses suffered or incurred by the indemnified party, including in connection with any U.S. patent or any copyright or other intellectual property infringement claim by any third-party with respect to the Company’s products. Further, the Company indemnifies its directors and officers who are, or were, serving at the Company’s request in such capacities. The Company’s maximum exposure under these arrangements is unknown as of September 30, 2024. The Company does not anticipate recognizing any significant losses relating to these arrangements. The term of these indemnification agreements is generally perpetual any time after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements may be unlimited. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

7. Commitments and Contingencies

Legal proceedings

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated.

The Company is not party to any litigation and does not have contingency reserves established for any litigation liabilities.

Other

The Company enters into standard indemnification agreements in the ordinary course of business. Pursuant to the agreements, the Company agrees to indemnify, hold harmless, and to reimburse the indemnified party for losses suffered or incurred by the indemnified party, including in connection with any U.S. patent or any copyright or other intellectual property infringement claim by any third-party with respect to the Company’s products. Further, the Company indemnifies its directors and officers who are, or were, serving at the Company’s request in such capacities. The Company’s maximum exposure under these arrangements is unknown as of September 30, 2024. The Company does not anticipate recognizing any significant losses relating to these arrangements. The term of these indemnification agreements is generally perpetual any time after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements may be unlimited. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements.

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Summary of Stock Options Activity

Stock option activity for the nine months ended September 30, 2024, was as follows:


	Stock Options			Weighted-Average Exercise Price
Outstanding as of December 31, 2023		4,233,203		$	10.83
Granted		1,974,483		$	15.04
Exercised		(203,847	)	$	10.82
Canceled/Forfeited		(333,086	)	$	13.37
Outstanding as of September 30, 2024		5,670,753		$	12.15

Summary of Restricted Stock Units

A summary of the Company’s RSU and PSU activity and related information for the nine months ended September 30, 2024 is as follows:


	Time-Based RSUs			PSUs		Weighted-Average Grant Date Fair Value
Outstanding as of December 31, 2023		—			—	$	—
Granted		77,645			28,555		10.64
Vested		—			—		—
Forfeited		(3,380	)		—		10.64
Issued and unvested as of September 30, 2024		74,265			28,555	$	10.64

Summary of Stock-based Compensation Expense

Stock-based compensation expense associated with stock options, RSUs, PSUs, and the Company’s ESPP included in the accompanying unaudited condensed consolidated statements of operations and comprehensive loss is as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	1,419	$	785	$	3,433	$	2,167
General and administrative		1,807		1,156		4,677		2,959
Total stock-based compensation expense	$	3,226	$	1,941	$	8,110	$	5,126

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net loss	$ (21,384)	$ (23,290)	$ (67,739)	$ (59,131)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation			1,125	830
Stock-based compensation expense			8,110	5,126
Amortization and interest accretion related to operating lease			2,811	(212)
Amortization and accretion of premium and discounts on marketable securities, net			(2,905)
Other non-cash adjustments			20
Changes in operating assets and liabilities:
Prepaids and other current and non-current assets			(1,239)	757
Accounts payable			4,916	2,561
Accrued expenses and other non-current liabilities			(5,750)	1,985
Operating lease liabilities, current and non-current			(2,246)	(1,489)
Net cash used in operating activities			(62,897)	(49,573)
Cash flows from investing activities:
Purchases of property and equipment			(269)	(2,415)
Purchases of marketable securities			(123,900)
Maturities of marketable securities			60,000
Net cash used in investing activities			(64,169)	(2,415)
Cash flows from financing activities:
Issuance of common stock upon initial public offering, net of underwriters' fees			76,878
Payment of offering costs			(511)	(430)
Issuance of common stock from At-the-Market Sales Agreement, net of underwriters' fees			9,900
Proceeds from employee equity plans			2,354	215
Net cash provided by financing activities			88,621	(215)
Effect of exchange rate changes on cash			(40)	64
Net decrease in cash, cash equivalents and restricted cash			(38,485)	(52,139)
Cash, cash equivalents and restricted cash at beginning of period			82,322	183,225
Cash, cash equivalents and restricted cash at end of period	43,837	131,086	43,837	131,086
Components of cash, cash equivalents and restricted cash
Cash and cash equivalents	42,289	129,538	42,289	129,538
Restricted Cash	1,548	1,548	1,548	1,548
Total cash, cash equivalents and restricted cash at end of period	$ 43,837	$ 131,086	43,837	131,086
Supplemental noncash investing and financing activities
Property and equipment included in accounts payable and accrued expenses			14	123
Deferred offering costs in accounts payable and accrued expenses				$ 12
Cash paid for taxes			$ 71

Property and Equipment, Net (Tables)

9 Months Ended

Sep. 30, 2024

Property, Plant and Equipment [Abstract]

Summary of Cost and Accumulated Depreciation of Property and Equipment

The cost and accumulated depreciation of property and equipment were as follows (in thousands):


	September 30, 2024			December 31, 2023
Lab equipment	$	4,989		$	4,821
Computer and office equipment		1,557			1,446
Construction in process	45				69
Total property and equipment		6,591			6,336
Less: accumulated depreciation		(2,690	)		(1,572	)
Total property and equipment, net	$	3,901		$	4,764

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Outstanding unvested stock options \| $	$ 5,670,753
Expected recognition period of unrecognized compensation cost related to unvested share options	2 years 8 months 1 day
Unrecognized compensation cost related to unvested share options \| $	$ 32,600
Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average grant date fair value of options granted \| $ / shares	$ 10.83
Time Based RSU
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation costs related to unvested RSUs \| $	$ 300
Expected recognition period of unrecognized compensation cost related to unvested share options	4 months 24 days
PSUs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation cost related to unvested share options \| $	$ 300
Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted Average Grant Date Fair Value, Granted \| $ / shares	$ 10.64
2022 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock outstanding percentage	5.00%
Shares remaining available for issuance \| shares	740,948
2022 Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares authorized and reserved for issuance \| shares	421,924
2024 Inducement Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares authorized and reserved for issuance \| shares	1,000,000
Shares remaining available for issuance \| shares	797,184

Income Taxes

9 Months Ended

Sep. 30, 2024

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

The Company recorded income tax expense of nil for the three months ended September 30, 2024 and 2023 and for the nine months ended September 30, 2024 and 2023.

On January 1, 2022, or the Transfer Date, the Company’s wholly owned subsidiary, PepGen Limited, transferred all intellectual property, or IP, assets to the parent company, PepGen, in an arm’s length transaction at fair value pursuant to an asset transfer agreement. The fair value of the IP assets is a non-recurring fair value measurement. The Company engaged valuation specialists to calculate the IP value, and the IP value was measured using the historical cost method. The historical cost method estimated the fair value of the IP assets using the historical cost base of the IP assets and the expected market return as of the Transfer Date. The significant assumption inherent in estimating the fair value using the historical cost method was the expected market return. The Company utilized a 40% expected market return, which a third-party investor may expect as a return on their investment, and which is based on studies of venture capital investment returns. The Company calculated the fair value of the IP assets by computing the present value of the historical cost base using the 40% expected market return. The assumptions used in the estimation of the IP assets represent level 3 inputs of the fair value hierarchy.

The transfer of the IP assets resulted in an estimated tax charge during 2022 to His Majesty’s Revenue & Customs, or HMRC, after considering net operating loss carryforwards, of $4.4 million, inclusive of the $0.7 million uncertain tax position. The Company paid amounts owed to HMRC in September 2023.

The Company recognizes the impact of an uncertain income tax position taken on its income tax returns at the amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will be recognized if it has less than a 50% likelihood of being sustained. The tax positions are analyzed at least quarterly, and adjustments are made as events occur that warrant adjustments for those positions. As of September 30, 2024, the Company maintains the liability for the uncertain tax position related to the IP transfer of $0.7 million, which is accounted for in accrued expenses on the unaudited condensed consolidated balance sheet.

- Definition

The entire disclosure for income tax.

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+ Details

Related Party Transactions

9 Months Ended

Sep. 30, 2024

Related Party Transactions

6. Related Party Transactions

Technology License Agreement with Oxford University Innovation Limited

In March 2018, the Company, Oxford University Innovation Limited, or OUI, and the Medical Research Council of United Kingdom Research and Innovation, or MRC, or collectively, the Licensors, entered into a license of technology agreement, which was subsequently amended in December 2018, further amended and restated in November 2020, and further amended in February 2022, referred to, as so amended, as the License Agreement. The Licensors and affiliates held shares of Series A-1 and Series A-2 preferred stock, Series B preferred stock and Class A common stock. The License Agreement provides the Company with an exclusive world wide license to licensed data and technology owned by OUI and MRC in respect of cell-penetrating peptides for the treatment of Duchenne muscular dystrophy, spinal muscular atrophy, and other conditions. The License Agreement provides the Company with the rights to grant and authorize sublicenses to make, use, sell, and import products and otherwise exploit the patent rights.

As consideration for the license, the Company made an initial upfront payment in 2018, as well as a Restatement Completion Fee and a License Data Fee (each as defined in the License Agreement) in 2020 totaling $0.1 million.

The Company could be required to make milestone payments to the Licensors upon achievement of certain patent and commercial milestones related to the patents and commercialization of certain of the Company’s product candidates. The aggregate potential milestone payments are $0.1 million. The Company also agreed to pay the Licensors low single digit royalties on net sales of any licensed products that are commercialized by the Company in excess of a threshold amount between £20 million and £30 million ($26.7 million and $40.1 million as of September 30, 2024), subject to certain adjustments. The term of the License Agreement continues until the later of (i) the date on which all the patents and patent applications covered thereunder have been abandoned or allowed to lapse or expired or been rejected or revoked or (ii) 20 years from the date of the original license agreement.

Upon completion of the IPO, the Company became obligated to pay OUI an exit fee between 0.5% to 2% of the value determined in an acquisition or initial public offering, not to exceed £5 million ($6.2 million as of the IPO date). The exit fee due to OUI, based on the proceeds of the IPO, was $1.4 million, which was paid during the second quarter of 2022 and included in research and development expense on the condensed consolidated statement of operations.

During the three and nine months ended September 30, 2024, one member of the Company’s board of directors, Dr. Christopher Ashton, was employed by Oxford Science Enterprises, or OSE, which is an affiliate of OUI. On September 19, 2024, the Company announced that Dr. Ashton had resigned from the board of directors, effective as of September 30, 2024.

As of September 30, 2024, OSE owned 14.6% of the Company’s outstanding common stock. Pursuant to the terms of Dr. Ashton's employment agreement with OSE, he was obligated to transfer any cash compensation from the Company to OSE. Fees paid in cash for Dr. Ashton's service on the Company's board of directors were paid directly to OSE and were included within general and administrative expense on the unaudited condensed consolidated statement of operations. The Company paid $13,125 and $11,875 for the three months ended September 30, 2024 and 2023, respectively and $36,875 and $35,625 for the nine months ended September 30, 2024 and 2023, respectively to OSE as compensation for Dr. Ashton's service on the board of directors.

RA Capital Management, L.P.

Entities affiliated with RA Capital Management, L.P., or RA Capital, purchased common stock in the Company’s IPO in May 2022 and the Company’s Follow-on Offering in February 2024. As of September 30, 2024, entities affiliated with RA Capital owned 32.8% of the Company’s outstanding common stock.

Two members of the Company’s board of directors, Dr. Joshua Resnick and Habib Dable, are affiliated with RA Capital. Pursuant to the governing legal documents of RA Capital, Dr. Resnick is obligated to transfer any cash compensation from the Company to RA Capital. Fees paid in cash for Dr. Resnick's service on the Company's board of directors were paid directly to RA Capital and are included within general and administrative expense on the unaudited condensed consolidated statement of operations. The Company paid $12,000 and $10,750 for the three months ended September 30, 2024 and 2023, respectively and $33,500 and $32,250 for the nine months ended September 30, 2024 and 2023, respectively to RA Capital for Dr. Resnick’s service on the board of directors.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

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+ Details

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accrued Liabilities, Current [Abstract]
Research and development expenses	$ 2,679	$ 9,521
Employee-related expenses	3,142	2,368
Professional services	1,113	715
Other	875	918
Total accrued expenses	$ 7,809	$ 13,522

Fair Value Measurements - Summary of Fair Value of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of financial assets	$ 132,042	$ 106,010
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of financial assets	132,042	106,010
US Treasury-Backed Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	35,474	64,397
US Treasury-Backed Money Market Funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	35,474	64,397
U.S. Treasury Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents		11,980
Marketable Securities	96,568	29,633
U.S. Treasury Notes \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents		11,980
Marketable Securities	$ 96,568	$ 29,633

Nature of Business and Basis of Presentation

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Business and Basis of Presentation

1. Nature of Business and Basis of Presentation

PepGen Inc., hereinafter referred to as PepGen or the Company, is a clinical-stage biotechnology company advancing the next generation of oligonucleotide therapeutics with the goal of transforming the treatment of severe neuromuscular and neurologic diseases. The Company's principal offices are located in Boston, Massachusetts.

The Company was initially formed as PepGen Limited on January 25, 2018, in the United Kingdom, or the U.K. On November 9, 2020, PepGen Limited completed a corporate reorganization, or the Reorganization. As part of the Reorganization, PepGen Limited formed PepGen, a Delaware corporation with nominal assets and liabilities, for the purpose of consummating the Reorganization. In connection with the Reorganization, the existing stockholders of PepGen Limited exchanged each of its classes of shares of PepGen Limited for the same number and class of common stock of PepGen on a one-to-one basis. The newly issued stock of PepGen had substantially identical rights to the exchanged shares of PepGen Limited. As a result of the exchange, PepGen became the sole stockholder of PepGen Limited. Upon the completion of the Reorganization on November 23, 2020, the historical financial statements of PepGen Limited became the historical financial statements of PepGen as the Reorganization was deemed to be between entities under common control.

Liquidity and Capital Resources

Since inception, the Company has not generated any revenue from product sales or other sources and has incurred significant operating losses and negative cash flows from operations. The Company’s primary uses of cash, cash equivalents, and marketable securities to date have been funding research and development activities, business planning, establishing and maintaining the Company’s intellectual property portfolio, hiring personnel, leasing premises and associated capital expenditures, raising capital, and providing general and administrative support for these operations. As of September 30, 2024, the Company had an accumulated deficit of $249.2 million. To date, the Company has funded operations primarily through private placements of convertible preferred stock, the sale of shares of common stock in its initial public offering, or IPO, the sale of shares of common stock under its At-the-Market Equity Offering Sales Agreement, or Sales Agreement, with Stifel, Nicolaus & Company, Incorporated, or Stifel, and through the sale of shares of common stock in a follow-on public offering, referred to as the Follow-on Offering. As of September 30, 2024, the Company had cash, cash equivalents, and marketable securities of $138.9 million. The Company believes that its cash, cash equivalents, and marketable securities as of September 30, 2024, will be sufficient to fund its currently planned operations for at least the next 12 months from the issuance of these unaudited condensed consolidated financial statements.

The Company filed a shelf registration statement on Form S-3 with the United States Securities and Exchange Commission, or SEC, which covers the offering, issuance and sale of an amount up to $300.0 million in the aggregate of shares of common stock, preferred stock, debt securities, warrants, and/or units or any combination thereof, which was declared effective on June 16, 2023. On August 8, 2023, the Company filed a prospectus supplement and entered into the Sales Agreement with Stifel, as sales agent, which provides for the issuance and sale by the Company of up to $100.0 million of shares of common stock from time to time in “at-the-market” offerings. The sales agent is entitled to receive a commission of up to 3.0% of gross proceeds from sales under the Sales Agreement. On February 5, 2024, the Company sold 1,000,000 shares of common stock at a price of $10.00 per share under the Sales Agreement, resulting in net proceeds of $9.9 million. On February 9, 2024, the Company sold 7,530,000 shares of common stock in the Follow-on Offering, pursuant to an underwriting agreement with Leerink Partners LLC dated as of February 6, 2024, at a price of $10.635 per share resulting in net proceeds of $76.4 million after deducting underwriting fees and offering costs of $3.7 million. Net proceeds from sales under the Sales Agreement and Follow-on Offering, after deducting underwriters' fees and costs, were $86.3 million. On June 28, 2024, the Company filed a second shelf registration statement on Form S-3 with the SEC, which covers the offering, issuance and sale of an amount up to $250.0 million in the aggregate of shares of common stock, preferred stock, debt securities, warrants, and/or units or any combination thereof, which was declared effective on July 8, 2024.

As the Company continues to pursue its business plan to successfully develop and obtain regulatory approval for its product candidates, it expects to finance its operations through the sale of equity, debt financings or other capital resources, which could include income from collaborations, strategic partnerships or marketing, distribution, licensing or other strategic arrangements with third parties, or from grants. However, there can be no assurance that any additional financing or strategic transactions will be available to the Company on acceptable terms, if at all. If events or circumstances occur such that the Company does not obtain additional funding, it may need to delay, reduce or eliminate its product development or future commercialization efforts, which could have a material adverse effect on the Company’s business, results of operations or financial condition.

Basis of Presentation and Consolidation

The accompanying condensed consolidated financial statements are unaudited and have been prepared in conformity with generally accepted accounting principles in the United States of America, or GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Update of the Financial Accounting Standards Board.

Restricted cash on the condensed consolidated balance sheet as of December 31, 2023, previously included in other assets, has been presented as a separate line item. The condensed consolidated financial statements have otherwise been prepared on the same basis as the audited annual financial statements. Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. These condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position as of September 30, 2024, and results of operations for the interim periods ended September 30, 2024 and September 30, 2023.

The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the audited financial statements as of and for the years ended December 31, 2023 and 2022, and the notes thereto, included in the Company’s Annual Report on Form 10-K, filed with the SEC on March 6, 2024, or Form 10-K, as amended by the Form 10-K/A filed on March 29, 2024.

Stock-Based Compensation - Summary of Stock Options Activity (Details)	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock Options Outstanding as of December 31, 2023 \| shares	4,233,203
Stock Options, Granted \| shares	1,974,483
Exercise of stock options, Shares \| shares	(203,847)
Stock Options, Canceled/Forfeited \| shares	(333,086)
Stock Options, Outstanding as of September 30, 2024 \| shares	5,670,753
Weighted Average Exercise Price, Outstanding as of December 31, 2023 \| $ / shares	$ 10.83
Weighted Average Exercise Price, Granted \| $ / shares	15.04
Weighted average exercise price, exercised \| $ / shares	10.82
Weighted average exercise price, canceled/forfeited \| $ / shares	13.37
Weighted Average Exercise Price, Outstanding as of September 30, 2024 \| $ / shares	$ 12.15

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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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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+ Details

Property and Equipment, Net - Summary of Cost and Accumulated Depreciation of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 6,591	$ 6,336
Less: accumulated depreciation	(2,690)	(1,572)
Total property and equipment, net	3,901	4,764
Lab Equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	4,989	4,821
Computer and Office Equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	1,557	1,446
Construction in Process
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 45	$ 69

Property and Equipment, Net

9 Months Ended

Sep. 30, 2024

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

4. Property and Equipment, Net

The cost and accumulated depreciation of property and equipment were as follows (in thousands):


	September 30, 2024			December 31, 2023
Lab equipment	$	4,989		$	4,821
Computer and office equipment		1,557			1,446
Construction in process	45				69
Total property and equipment		6,591			6,336
Less: accumulated depreciation		(2,690	)		(1,572	)
Total property and equipment, net	$	3,901		$	4,764

Depreciation expense was $0.4 million and $0.3 million for the three months ended September 30, 2024 and September 30, 2023, respectively. Depreciation expense was $1.1 million and $0.8 million for the nine months ended September 30, 2024 and September 30, 2023, respectively.

Related Party Transactions - Additional Information (Details) £ in Millions			3 Months Ended			9 Months Ended
	May 31, 2022 GBP (£)	May 31, 2022 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2024 GBP (£)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)
RA Capital Management, L.P
Related Party Transaction [Line Items]
Percentage of holding in outstanding common stock			32.80%			32.80%	32.80%
Rent expense			$ 12,000	$ 10,750			$ 33,500	$ 32,250
Oxford University Innovation Limited
Related Party Transaction [Line Items]
Percentage of holding in outstanding common stock			14.60%			14.60%	14.60%
Rent expense			$ 13,125,000	$ 11,875,000			$ 36,875,000	$ 35,625,000
Technology License Agreement
Related Party Transaction [Line Items]
Additional payments of restatement completion fee and license data fee							100,000
Aggregate potential milestone payments							$ 100,000
Term of license agreement						20 years	20 years
Technology License Agreement \| Minimum
Related Party Transaction [Line Items]
Sublicensees threshold amount						£ 20	$ 40,100,000
Technology License Agreement \| Maximum
Related Party Transaction [Line Items]
Sublicensees threshold amount						£ 30	$ 26,700,000
Technology License Agreement \| Oxford University Innovation Limited \| IPO
Related Party Transaction [Line Items]
Required to pay exit fee amount					$ 1,400,000
Technology License Agreement \| Oxford University Innovation Limited \| Minimum \| IPO
Related Party Transaction [Line Items]
Percentage of exit fee	0.50%	0.50%
Technology License Agreement \| Oxford University Innovation Limited \| Maximum \| IPO
Related Party Transaction [Line Items]
Percentage of exit fee	2.00%	2.00%
Required to pay exit fee amount	£ 5	$ 6,200,000

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2024

Accrued Liabilities, Current [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	September 30, 2024		December 31, 2023
Research and development expenses	$	2,679	$	9,521
Employee-related expenses		3,142		2,368
Professional services		1,113		715
Other		875		918
Total accrued expenses	$	7,809	$	13,522

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating Expenses [Abstract]
Research and development	$ 17,722	$ 20,540	$ 57,517	$ 51,826
General and administrative	5,449	4,240	15,877	12,129
Total operating expenses	23,171	24,780	73,394	63,955
Operating loss	(23,171)	(24,780)	(73,394)	(63,955)
Other income (expense)
Interest income	1,826	1,578	5,682	5,054
Other (expense) income, net	(39)	(88)	(27)	(230)
Total other income, net	1,787	1,490	5,655	4,824
Net loss before income tax	(21,384)	(23,290)	(67,739)	(59,131)
Net loss	$ (21,384)	$ (23,290)	$ (67,739)	$ (59,131)
Net loss per share, basic	$ (0.66)	$ (0.98)	$ (2.17)	$ (2.49)
Net loss per share, diluted	$ (0.66)	$ (0.98)	$ (2.17)	$ (2.49)
Weighted-average common shares outstanding, basic	32,581,542	23,790,430	31,240,622	23,788,950
Weighted-average common shares outstanding, diluted	32,581,542	23,790,430	31,240,622	23,788,950
Other comprehensive (loss) income:
Cumulative translation adjustment arising during the period	$ (20)	$ (70)	$ (72)	$ 24
Unrealized gain on marketable securities	186		129
Comprehensive loss	$ (21,218)	$ (23,360)	$ (67,682)	$ (59,107)

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Public Offering	ATM	Common Stock	Common Stock Public Offering	Common Stock ATM	Additional Paid-in Capital	Additional Paid-in Capital Public Offering	Additional Paid-in Capital ATM	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning Balance at Dec. 31, 2022	$ 179,631			$ 2			$ 282,566			$ (81)	$ (102,856)
Beginning Balance, shares at Dec. 31, 2022				23,713,196
Exercise of stock options , Shares				68,709
Stock-based compensation expense	1,348						1,348
Cumulative translation adjustment arising during the period	53									53
Exercise of Stock Options	130						130
Net loss	(16,319)										(16,319)
Ending Balance at Mar. 31, 2023	164,843			$ 2			284,044			(28)	(119,175)
Ending Balance, shares at Mar. 31, 2023				23,781,905
Beginning Balance at Dec. 31, 2022	179,631			$ 2			282,566			(81)	(102,856)
Beginning Balance, shares at Dec. 31, 2022				23,713,196
Net loss	(59,131)
Ending Balance at Sep. 30, 2023	125,865			$ 2			287,907			(57)	(161,987)
Ending Balance, shares at Sep. 30, 2023				23,813,547
Beginning Balance at Mar. 31, 2023	164,843			$ 2			284,044			(28)	(119,175)
Beginning Balance, shares at Mar. 31, 2023				23,781,905
Exercise of stock options , Shares				31,642
Stock-based compensation expense	1,837						1,837
Cumulative translation adjustment arising during the period	41									41
Exercise of Stock Options	85						85
Net loss	(19,522)										(19,522)
Ending Balance at Jun. 30, 2023	147,284			$ 2			285,966			13	(138,697)
Ending Balance, shares at Jun. 30, 2023				23,813,547
Stock-based compensation expense	1,941						1,941
Cumulative translation adjustment arising during the period	(70)									(70)
Net loss	(23,290)										(23,290)
Ending Balance at Sep. 30, 2023	125,865			$ 2			287,907			(57)	(161,987)
Ending Balance, shares at Sep. 30, 2023				23,813,547
Beginning Balance at Dec. 31, 2023	108,421			$ 2			289,867			34	(181,482)
Beginning Balance, shares at Dec. 31, 2023				23,823,241
Exercise of stock options , Shares				36,194
Stock-based compensation expense	2,022						2,022
Unrealized gain (loss) on marketable securities	(20)									(20)
Cumulative translation adjustment arising during the period	(51)									(51)
Exercise of Stock Options	395						395
Issuance of common stock		$ 76,352	$ 9,900		$ 1			$ 76,351	$ 9,900
Issuance of common stock, Shares					7,530,000	1,000,000
Net loss	(18,020)										(18,020)
Ending Balance at Mar. 31, 2024	178,999			$ 3			378,535			(37)	(199,502)
Ending Balance, shares at Mar. 31, 2024				32,389,435
Beginning Balance at Dec. 31, 2023	108,421			$ 2			289,867			34	(181,482)
Beginning Balance, shares at Dec. 31, 2023				23,823,241
Net loss	(67,739)
Ending Balance at Sep. 30, 2024	137,455			$ 3			386,582			91	(249,221)
Ending Balance, shares at Sep. 30, 2024				32,589,702
Beginning Balance at Mar. 31, 2024	178,999			$ 3			378,535			(37)	(199,502)
Beginning Balance, shares at Mar. 31, 2024				32,389,435
Exercise of stock options , Shares				128,354
Issuance of stock under the employee stock purchase plan (in shares)				32,614
Stock-based compensation expense	2,862						2,862
Unrealized gain (loss) on marketable securities	(37)									(37)
Cumulative translation adjustment arising during the period	(1)									(1)
Exercise of Stock Options	1,403						1,403
Issuance of stock under the employee stock purchase plan	149						149
Net loss	(28,335)										(28,335)
Ending Balance at Jun. 30, 2024	155,040			$ 3			382,949			(75)	(227,837)
Ending Balance, shares at Jun. 30, 2024				32,550,403
Exercise of stock options , Shares				39,299
Stock-based compensation expense	3,226						3,226
Unrealized gain (loss) on marketable securities	186									186
Cumulative translation adjustment arising during the period	(20)									(20)
Exercise of Stock Options	407						407
Net loss	(21,384)										(21,384)
Ending Balance at Sep. 30, 2024	$ 137,455			$ 3			$ 386,582			$ 91	$ (249,221)
Ending Balance, shares at Sep. 30, 2024				32,589,702

Stockholders' Equity - Additional Information (Details)	9 Months Ended
Stockholders' Equity - Additional Information (Details)	Sep. 30, 2024 USD ($) Vote $ / shares shares	Sep. 30, 2023 USD ($)
Class of Stock [Line Items]
Common stock, shares authorized \| shares	500,000,000
Common stock, par value \| $ / shares	$ 0.0001
Cash dividend \| $	$ 0	$ 0
Number of Common Stock Vote \| Vote	1
Undesignated Preferred Stock
Class of Stock [Line Items]
Preferred stock authorized \| shares	10,000,000
Preferred stock par value \| $ / shares	$ 0.0001

- Definition

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

+ References

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

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

Stock-Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 3,226	$ 1,941	$ 8,110	$ 5,126
Research and development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	1,419	785	3,433	2,167
General and administrative
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 1,807	$ 1,156	$ 4,677	$ 2,959

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2024	Nov. 01, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001835597
Entity Registrant Name	PEPGEN INC.
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		32,595,737
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 $0.0001 per share
Trading Symbol	PEPG
Security Exchange Name	NASDAQ
Entity File Number	001-41374
Entity Tax Identification Number	85-3819886
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	321 Harrison Ave. 8th Floor
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02118
City Area Code	781
Local Phone Number	797-0979
Document Quarterly Report	true
Document Transition Report	false

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Summary of Marketable Securities

The following tables set forth marketable securities as of September 30, 2024 and December 31, 2023 (in thousands):


	As of September 30, 2024
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total
U.S. Treasury notes	$	96,439	$	144	$	(15	)	$	96,568
Total	$	96,439	$	144	$	(15	)	$	96,568


	As of December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Total
U.S. Treasury notes		29,622		11		—		29,633
Total	$	29,622	$	11	$	—	$	29,633

Summary of Fair Value of Financial Assets Measured at Fair Value on Recurring Basis

The following tables set forth the fair value of the Company’s financial assets measured at fair value on a recurring basis and indicate the level within the fair value hierarchy utilized to determine such values as of September 30, 2024 and December 31, 2023 (in thousands):


	As of September 30, 2024
	Total		Level 1		Level 2		Level 3
Cash Equivalents:
U.S. Treasury-backed money market funds	$	35,474	$	35,474	$	—	$	—
Marketable Securities:
U.S. Treasury notes		96,568		96,568		—		—
Total	$	132,042	$	132,042	$	—	$	—


	As of December 31, 2023
	Total		Level 1		Level 2		Level 3
Cash Equivalents:
U.S. Treasury-backed money market funds	$	64,397	$	64,397	$	—	$	—
U.S. Treasury notes	$	11,980	$	11,980	$	—	$	—
Marketable Securities:
U.S. Treasury notes	$	29,633	$	29,633	$	—	$	—
Total	$	106,010	$	106,010	$	—	$	—

Stockholders' Equity

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Stockholders' Equity

8. Stockholders’ Equity

Under the Third Amended and Restated Certificate of Incorporation, dated May 10, 2022, as amended on June 20, 2024, as currently in effect, the Company has the authority to issue a total of 500,000,000 shares of common stock (par value of $0.0001 per share) and 10,000,000 shares of undesignated preferred stock (par value of $0.0001 per share). Each share of common stock has the right to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding having priority rights as to dividends. No cash dividends were declared by the board of directors during the three or nine months ended September 30, 2024 and September 30, 2023.

The Company has reserved shares of common stock for issuance, on an as-converted basis, as follows:


	September 30, 2024		December 31, 2023
Stock options issued and outstanding		5,670,753		4,233,203
Unvested restricted stock and performance stock units		102,820		—
Authorized for future stock awards or option grants under the 2022 Plan		740,948		1,091,187
Authorized for future stock awards or option grants under the 2024 Inducement Plan		797,184		—
Stock options issued and outstanding under the employee stock purchase plan		421,924		216,306
Stock options issued and outstanding		7,733,629		5,540,696

- Definition

The entire disclosure for equity.

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+ Details

Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for Issuance, on an As-Converted Basis

The Company has reserved shares of common stock for issuance, on an as-converted basis, as follows:


	September 30, 2024		December 31, 2023
Stock options issued and outstanding		5,670,753		4,233,203
Unvested restricted stock and performance stock units		102,820		—
Authorized for future stock awards or option grants under the 2022 Plan		740,948		1,091,187
Authorized for future stock awards or option grants under the 2024 Inducement Plan		797,184		—
Stock options issued and outstanding under the employee stock purchase plan		421,924		216,306
Stock options issued and outstanding		7,733,629		5,540,696

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (21,384)	$ (28,335)	$ (18,020)	$ (23,290)	$ (19,522)	$ (16,319)	$ (67,739)	$ (59,131)

- 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/1943274/2147478524/942-220-S99-1

+ Details

Stock-Based Compensation - Summaey of Restricted Stock Units (Details)	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted Average Grant Date Fair Value, Granted \| $ / shares	$ 10.64
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	10.64
Weighted Average Grant Date Fair Value, Issued and unvested \| $ / shares	$ 10.64
Time Based RSU
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares, Granted	77,645
Number of Shares, Forfeited	(3,380)
Number of Shares, Issued and unvested	74,265
PSUs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares, Granted	28,555
Number of Shares, Issued and unvested	28,555

Stockholders' Equity - Schedule of Reserved Shares of Common Stock for Issuance, on an As-Converted Basis (Details) - shares	Sep. 30, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Reserved shares of common stock for issuance	7,733,629	5,540,696
Stock Options Issued and Outstanding
Class of Stock [Line Items]
Reserved shares of common stock for issuance	5,670,753	4,233,203
Unvested Restricted Stock and Performance Stock Units
Class of Stock [Line Items]
Reserved shares of common stock for issuance	102,820
Authorized for Future Stock Awards or Option Grants \| 2022 Plan
Class of Stock [Line Items]
Reserved shares of common stock for issuance	740,948	1,091,187
Authorized for Future Stock Awards or Option Grants \| 2024 Inducement Plan
Class of Stock [Line Items]
Reserved shares of common stock for issuance	797,184
Stock Options Issued and Outstanding Under Employee Stock Purchase Plan
Class of Stock [Line Items]
Reserved shares of common stock for issuance	421,924	216,306

- Definition

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

+ References

+ Details

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 42,289	$ 80,774
Marketable securities	96,568	29,633
Prepaid expenses and other current assets	3,512	2,271
Total current assets	142,369	112,678
Property and equipment, net	3,901	4,764
Operating lease right-of-use asset	21,990	23,620
Restricted cash	1,548	1,548
Other assets	426	442
Total assets	170,234	143,052
Current liabilities:
Accounts payable	5,930	1,005
Accrued expenses	7,809	13,522
Operating lease liability	3,071	3,004
Total current liabilities	16,810	17,531
Operating lease liability, net of current portion	15,969	17,100
Total liabilities	32,779	34,631
Commitments and contingencies (Note 7)
Stockholders' equity (deficit)
Preferred stock
Common stock	3	2
Additional paid-in capital	386,582	289,867
Accumulated other comprehensive income	91	34
Accumulated deficit	(249,221)	(181,482)
Total stockholders' equity	137,455	108,421
Total liabilities and stockholders' equity	$ 170,234	$ 143,052

Income Taxes - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jan. 01, 2022	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Income tax expense
Uncertain tax position		$ 0.7		$ 0.7
Expected market return	40.00%
Her Majesty's Revenue and Customs \| Accrued Expenses
Income Taxes [Line Items]
Income tax liabilities						$ 4.4
Uncertain tax position						$ 0.7

- Definition

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

+ References

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-Topic 235
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+ Details

Accrued Expenses

9 Months Ended

Sep. 30, 2024

Accrued Liabilities, Current [Abstract]

Accrued Expenses

5. Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	September 30, 2024		December 31, 2023
Research and development expenses	$	2,679	$	9,521
Employee-related expenses		3,142		2,368
Professional services		1,113		715
Other		875		918
Total accrued expenses	$	7,809	$	13,522

Fair Value Measurements - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Option, Quantitative Disclosures [Line Items]
Amortized Cost	$ 96,439	$ 29,622
Unrealized Gains	144	11
Unrealized Losses	(15)
Total	96,568	29,633
US Treasury-Backed Money Market Funds
Fair Value, Option, Quantitative Disclosures [Line Items]
Amortized Cost	96,439	29,622
Unrealized Gains	144	11
Unrealized Losses	(15)
Total	$ 96,568	$ 29,633

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Nature of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands						3 Months Ended	9 Months Ended
	Jun. 28, 2024	Feb. 09, 2024	Feb. 05, 2024	Aug. 08, 2023	Jun. 16, 2023	Mar. 31, 2024	Sep. 30, 2024	Feb. 06, 2024	Dec. 31, 2023
Subsidiary, Sale of Stock [Line Items]
Cash, cash equivalents and marketable securities							$ 138,900
Accumulated deficit							249,221		$ 181,482
Net proceeds issuance or sale of equity					$ 300,000
Issuance and sale of shares of common stock							$ 9,900
Maximum
Subsidiary, Sale of Stock [Line Items]
Net proceeds issuance or sale of equity	$ 250,000
IPO
Subsidiary, Sale of Stock [Line Items]
Underwriter's fees and offering costs						$ 3,730
IPO \| Common stock
Subsidiary, Sale of Stock [Line Items]
Number of shares sold						7,530,000
Follow-on Offering
Subsidiary, Sale of Stock [Line Items]
Underwriter's fees and offering costs		$ 3,700
Public offering price per share								$ 10.635
Net proceeds issuance or sale of equity		$ 76,400
Follow-on Offering \| Common stock
Subsidiary, Sale of Stock [Line Items]
Number of shares sold		7,530,000
Shares Sales agreement and Follow-on Offering
Subsidiary, Sale of Stock [Line Items]
Net proceeds issuance or sale of equity		$ 86,300
Shares sales agreement
Subsidiary, Sale of Stock [Line Items]
Public offering price per share			$ 10
Net proceeds issuance or sale of equity			$ 9,900
Shares sales agreement \| Common stock
Subsidiary, Sale of Stock [Line Items]
Number of shares sold			1,000,000
At-the-Market Equity Offering Sales Agreement \| Stifel, Nicolaus & Company
Subsidiary, Sale of Stock [Line Items]
Issuance and sale of shares of common stock				$ 100,000
Commission to sales agent for gross proceeds from sales				3.00%

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2024

Accounting Policies [Abstract]

Recently Issued Accounting Pronouncements Not Yet Adopted

In November 2023, the Financial Accounting Standards Board issued ASU 2023-07, Segment Reporting (Topic 280). This update expands segment disclosure requirements, including new segment disclosure requirements for entities with a single reportable segment among other disclosure requirements. This update is effective for the Company in the consolidated financial statements for the year ending December 31, 2024, and interim periods beginning on January 1, 2025. The adoption of this standard only impacts disclosures and is not expected to have a material impact on the Company’s consolidated financial statements.

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Depreciation expenses	$ 0.4	$ 0.3	$ 1.1	$ 0.8

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY(UNAUDITED) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Public Offering
Net of issuance costs	$ 3,730
ATM
Net of issuance costs	$ 100

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

The Company’s significant accounting policies are disclosed in the audited financial statements for the year ended December 31, 2023 included in the Form 10-K. Since the date of those financial statements, there have been no changes to the Company’s significant accounting policies.

Recently Issued Accounting Pronouncements Not Yet Adopted

Stock-Based Compensation

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

9. Stock-Based Compensation

The Company maintains four equity compensation plans; the 2020 Stock Plan, or the 2020 Plan, the 2022 Stock Option and Incentive Plan, or the 2022 Plan, the 2022 Employee Stock Purchase Plan, or the ESPP, and the 2024 Inducement Plan, or the Inducement Plan. As of the Company's IPO in May 2022, the Company's board of directors determined that no further awards would be made under the 2020 Plan. The number of shares of common stock that may be issued under the 2022 Plan is subject to increase by the number of shares under any outstanding stock options forfeited and not exercised under the 2020 Plan. Additionally, the number of shares reserved for issuance under the 2022 Plan automatically increases on the first day of each fiscal year in an amount equal to the lower of (1) 5% of the shares of common stock outstanding on such date and (2) an amount determined by the Company’s board of directors. The 2022 Plan allows the board of directors to grant incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, unrestricted stock awards, cash-based awards, and dividend equivalent rights to

the Company’s officers, employees, directors and other key persons. As of September 30, 2024, 740,948 shares remained available for grant under the 2022 Plan and 421,924 shares remained available for issuance under the ESPP.

2024 Inducement Plan

In August 2024, the Company's board of directors adopted the Inducement Plan. The Inducement Plan provides for the grant of non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units unrestricted stock awards, dividend equivalent rights and other stock-based awards with respect to an aggregate of 1,000,000 shares of common stock (subject to adjustment as provided in the Inducement Plan). Awards under the Inducement Plan may only be granted to new employees who were not previously employed by the Company or its affiliates in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4).

As of September 30, 2024, 797,184 shares remained available for issuance under the Inducement Plan.

Stock Option Activity

Stock option activity for the nine months ended September 30, 2024, was as follows:


	Stock Options			Weighted-Average Exercise Price
Outstanding as of December 31, 2023		4,233,203		$	10.83
Granted		1,974,483		$	15.04
Exercised		(203,847	)	$	10.82
Canceled/Forfeited		(333,086	)	$	13.37
Outstanding as of September 30, 2024		5,670,753		$	12.15

The weighted-average grant date fair value of options granted during the nine months ended September 30, 2024 was $10.83 per share. The Company had 5,670,753 unvested stock options outstanding as of September 30, 2024. As of September 30, 2024, total unrecognized compensation cost related to stock options was $32.6 million. This amount is expected to be recognized over a weighted average period of approximately 2.67 years.

Restricted Stock Units

A restricted stock unit, or RSU, represents the right to receive one share of common stock upon vesting of the RSU. In February 2024, the Company granted employees a one-time RSU award that vests fully on the one-year anniversary of the grant date, provided that the employee remains employed with the Company. Certain employees, including employees who are executive officers of the Company, received a one-time RSU award that vests upon the achievement of certain performance-based clinical development milestones, or PSUs. Such awards cannot vest in less than one year, regardless of when the performance milestone is achieved. The Company’s chief executive officer did not receive any RSU or PSU awards. A summary of the Company’s RSU and PSU activity and related information for the nine months ended September 30, 2024 is as follows:


	Time-Based RSUs			PSUs		Weighted-Average Grant Date Fair Value
Outstanding as of December 31, 2023		—			—	$	—
Granted		77,645			28,555		10.64
Vested		—			—		—
Forfeited		(3,380	)		—		10.64
Issued and unvested as of September 30, 2024		74,265			28,555	$	10.64

The weighted average grant date fair value of the time-based RSUs and the PSUs granted during the nine months ended September 30, 2024 was $10.64. As of September 30, 2024, there was $0.3 million of unrecognized compensation costs related to unvested time-based RSUs, which are expected to be recognized over a weighted-average period of 0.4 years, and $0.3 million of unrecognized compensation costs related to unvested PSUs, which are dependent upon achievement of the aforementioned clinical development milestones.

Stock-Based Compensation Expense


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	1,419	$	785	$	3,433	$	2,167
General and administrative		1,807		1,156		4,677		2,959
Total stock-based compensation expense	$	3,226	$	1,941	$	8,110	$	5,126

Fair Value Measurements

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

The following tables present information about the Company’s financial assets that have been measured at fair value as of September 30, 2024 and December 31, 2023, and indicate the fair value of the hierarchy of the valuation inputs utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities. Fair value determined by Level 2 inputs utilize observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted market prices in markets that are not active or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities. Fair values determined by Level 3 inputs are unobservable data points for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. The following tables set forth marketable securities as of September 30, 2024 and December 31, 2023 (in thousands):


	As of September 30, 2024
	Amortized Cost		Unrealized Gains		Unrealized Losses			Total
U.S. Treasury notes	$	96,439	$	144	$	(15	)	$	96,568
Total	$	96,439	$	144	$	(15	)	$	96,568


	As of December 31, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses		Total
U.S. Treasury notes		29,622		11		—		29,633
Total	$	29,622	$	11	$	—	$	29,633


	As of September 30, 2024
	Total		Level 1		Level 2		Level 3
Cash Equivalents:
U.S. Treasury-backed money market funds	$	35,474	$	35,474	$	—	$	—
Marketable Securities:
U.S. Treasury notes		96,568		96,568		—		—
Total	$	132,042	$	132,042	$	—	$	—


	As of December 31, 2023
	Total		Level 1		Level 2		Level 3
Cash Equivalents:
U.S. Treasury-backed money market funds	$	64,397	$	64,397	$	—	$	—
U.S. Treasury notes	$	11,980	$	11,980	$	—	$	—
Marketable Securities:
U.S. Treasury notes	$	29,633	$	29,633	$	—	$	—
Total	$	106,010	$	106,010	$	—	$	—

Money market funds are highly liquid investments that are valued based on quoted market prices in active markets, which represent a Level 1 measurement within the fair value hierarchy. These money market funds are classified on the unaudited condensed consolidated balance sheet under cash and cash equivalents.

- 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.

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+ Details