Adicet Bio, Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31,2025

OR

For the transition period from to

Commission File No.001-38359

(Exact name of registrant as specified in its charter)

131 Dartmouth Street,3rd Floor

Boston, MA 02116

(650) 503-9095

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. ☐ Yes ☒No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. ☐ Yes ☒No

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. ☒Yes ☐ No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). ☒Yes ☐ No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☐

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act.): ☐ Yes☒No

As of June 30, 2025, the aggregate market value of the registrant’s voting and non-voting common stock held by non-affiliates was approximately $50.5 million based on a closing price of $0.61 per share as quoted by The Nasdaq Global Market on June 30, 2025. In determining the market value of non-affiliate common stock, shares of the registrant’s common stock beneficially owned by officers, directors and affiliates have been excluded. This determination of affiliate status is not necessarily a conclusive determination for other purposes.

As of March 10, 2026, there were 9,596,407 shares of common stock, $0.0001 par value per share, outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Part III of this Annual Report on Form 10-K incorporates by reference certain information from the registrant’s definitive Proxy Statement for its 2026 annual meeting of shareholders, scheduled to be held on June 17, 2026, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year end of December 31, 2025. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.

Summary of the Material and Other Risks Associated with Our Business

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We have a limited operating history and face significant challenges and expenses as we build our capabilities.

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Our business is highly dependent on the success of prula-cel (formerly ADI-001). If we are unable to obtain regulatory approval for prula-cel in one or more indications and effectively commercialize this product candidate for the treatment of patients in indications for which we receive approval (if any), our business would be significantly harmed.

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Our gamma delta T cell candidates represent a novel approach to the treatment of autoimmune diseases and cancer indications that creates significant challenges for us.

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Our product candidates are based on novel technologies, which makes it difficult to predict the likely success of such product candidates and the time and cost of product candidate development and obtaining regulatory approval.

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Our clinical trials may fail to demonstrate the safety and efficacy of any of our product candidates, which would prevent or delay regulatory approval and commercialization.

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We may not be able to file Investigational New Drug (IND) applications, or comparable regulatory submissions, to commence additional clinical trials on the timelines we expect, and even if we are able to, the U.S. Food and Drug Administration (FDA) or analogous regulatory authorities may not permit us to proceed.

•

We may encounter substantial delays in our clinical trials, or may not be able to conduct our trials on the timelines we expect.

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The market opportunities for our product candidates may be limited to those patients who are ineligible for or have failed prior treatments and may be small.

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We may not realize the anticipated benefits of our workforce reduction and strategic pipeline prioritization.

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Although we have commenced manufacturing operations at our manufacturing facility, we currently depend on the ability of our third-party suppliers and manufacturers with whom we contract to perform adequately, particularly with respect to the timely production and delivery of our product candidates, including prula-cel. This reliance on third parties increases the risk that we will not have sufficient quantities of our product candidates or products or such quantities at an acceptable cost, which could delay, prevent or impair our development or commercialization efforts.

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We are highly dependent on our key personnel, and if we are not successful in attracting and retaining highly qualified personnel, we may not be able to successfully implement our business strategy.

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We will need substantial additional financing to develop our product candidates and implement our operating plans. If we fail to obtain additional financing, we may be unable to complete the development and commercialization of our product candidates.

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The pharmaceutical industry in China is highly regulated and such regulations, including the Foreign Investment Law and the “negative list,” are subject to change which may affect development, approval and commercialization of our product candidates.

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The uncertainties in the People’s Republic of China’s legal system regarding the Foreign Investment Law may subject our contractual arrangements to different interpretations or enforcement challenges, subject us to severe penalties or force us to relinquish our interests in our operations.

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Business disruptions, including armed conflicts, could substantially delay our clinical trials or seriously harm our future revenue and financial condition and increase our costs and expenses.

•

A variety of risks associated with conducting research and clinical trials abroad and marketing our product candidates internationally could materially adversely affect our business, including the potential impact of global conflicts on our supply or clinical trials.

•

We have in the past failed and may in the future fail to achieve and maintain effective internal control over financial reporting, which could harm our business and negatively impact the value of our common stock.

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If our collaboration with Regeneron Pharmaceuticals, Inc. (Regeneron) is terminated, or if Regeneron materially breaches its obligations thereunder, our business, prospects, operating results, and financial condition would be materially harmed.

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Our existing and future collaborations will be important to our business. If we are unable to maintain any of these collaborations, or if these collaborations are not successful, our business could be adversely affected.

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The FDA regulatory approval process is lengthy and time-consuming, and we may experience significant delays in the clinical development and regulatory approval of our product candidates.

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If our efforts to protect the proprietary nature of the intellectual property related to our technologies are not adequate, we may not be able to compete effectively in our market.

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We depend on intellectual property licensed from third parties and termination of any of these licenses could result in the loss of significant rights, which would harm our business.

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The trading price of our common stock is highly volatile, which could result in substantial losses for purchasers of our common stock. Securities class action or other litigation involving our company or members of our management team could also substantially harm our business, financial condition and results of operations.

•

Unstable market and economic conditions may have serious adverse consequences on our business, financial condition and stock price.

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