Atrium Therapeutics, Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

For the quarterly period ended JUNE 30,2026

OR

Commission File Number:001-43008

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code: (619)876-0700

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

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 is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐No☒

As of August 3, 2026, the registrant had 17,105,643 shares of common stock, $0.001 par value per share, outstanding.

Cautionary Statement Regarding Forward-Looking Statements

This Quarterly Report on Form 10-Q (this “Quarterly Report”) contains forward-looking statements about us that involve substantial risks and uncertainties. All statements other than statements of historical facts contained in this Quarterly Report, including statements regarding our plans, objectives, goals, strategies, future events, financing needs, plans or intentions relating to product candidates and markets and business trends, are forward-looking statements. In some cases, you can identify forward-looking statements by words such as “anticipate,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “possible,” “potential,” “predict,” “project,” “design,” “seek,” “should,” “target,” “will,” “would,” or the negative of these words or other comparable terminology. These forward-looking statements include, but are not limited to, statements about:

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the initiation, timing, progress, potential registrational quality, and results of our research and development programs, preclinical studies, any clinical trials, investigational new drug (“IND”), and other regulatory submissions;

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the beneficial characteristics, including potential safety, efficacy and therapeutic effects of our product candidates and the potential advantages of our product candidates compared to alternative therapies;

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the success and capabilities of the ribonucleic acid (“RNA”) delivery platform;

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the prevalence of certain diseases and conditions we intend to treat and our estimates of the potential market opportunity for our product candidates;

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the number of patients that we will enroll in our clinical trials;

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the timing of and costs involved in obtaining and maintaining regulatory approval of our current product candidates and any future product candidates that we may identify or develop;

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our ability to meet future regulatory standards with respect to our product candidates, if approved;

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our plans relating to the further development and manufacturing of our product candidates, including for additional indications that we may pursue;

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the rate and degree of market acceptance and therapeutic benefits of our product candidates, if approved;

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our ability to develop or partner and progress our current and future product candidates;

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the implementation of our strategic plans for our business, product candidates, research programs and technologies;

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the scope of protection we are able to establish and maintain for intellectual property rights covering our product candidates;

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anticipated developments related to our competitors and our industry;

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our competitive position and the success of competing therapies that are or may become available;

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our ability to maintain our current license agreements and collaborations and identify and enter into future license agreements and collaborations;

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the expected potential benefits of strategic collaborations with third parties and our ability to attract collaborators with development, regulatory, manufacturing or commercialization expertise;

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our reliance on third parties to conduct preclinical studies and clinical trials of our product candidates;

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our ability to efficiently and cost-effectively conduct our current and future clinical trials;

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our reliance on third parties for the manufacture of our product candidates;

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our plans relating to sales strategy, manufacturing and commercializing our product candidates, if approved;

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anticipated regulatory developments in the United States and foreign countries in which we may seek regulatory approval for our product candidates in the future;

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the timing and likelihood of the achievement of milestones pursuant to our existing collaboration, license and research agreements, including those with Bristol Myers Squibb Company and Eli Lilly and Company (the “Third Party Agreements”);

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our ability to attract and retain key scientific and management personnel;

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the costs of operating as a public company;

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the accuracy of our estimates regarding future expenses, future revenue, capital requirements and the need for additional financing;

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the period over which we estimate our existing cash, cash equivalents, and short-term investments will be sufficient to fund our future operating expenses and capital expenditure requirements;

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our ability to obtain funding for our operations necessary to complete further development and commercialization of our current and future product candidates; and

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our anticipated use of our existing resources, estimates of our expenses, capital requirements and needs for additional financing.

These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including those described in the section titled “Risk Factors” elsewhere in this Quarterly Report and reflect our management’s beliefs and views with respect to future events and are based on estimates and assumptions as of the date of this Quarterly Report. Moreover, we operate in a very competitive and rapidly changing environment, and new risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed in this Quarterly Report may not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this Quarterly Report, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements.

You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances reflected in the forward-looking statements will be achieved or occur. We undertake no obligation to update publicly any forward-looking statements for any reason after the date of this Quarterly Report to conform these statements to new information, actual results or to changes in our expectations, except as required by law.

You should read this Quarterly Report and the documents that we file with the SEC with the understanding that our actual future results, levels of activity, performance, and events and circumstances may be materially different from what we expect.

Special Note Regarding Company References

Throughout this Quarterly Report, the “Company,” “we”, “us”, “our”, and “Atrium” refer to Atrium Therapeutics, Inc.

Special Note Regarding Trademarks

Solely for convenience, we refer to trademarks in this Quarterly Report without the ® or the ™ or symbols, but such references are not intended to indicate that we will not assert, to the fullest extent under applicable law, our rights to our own trademarks. Other service marks, trademarks and trade names referred to in this Quarterly Report, if any, are the property of their respective owners, although for presentational convenience we may not use the ® or the ™ symbols to identify such trademarks.