Immunome Announces U.S. FDA Acceptance of New Drug Application for Varegacestat for the Treatment of Adults with Desmoid Tumors

BOTHELL, Wash. - Immunome, Inc. (Nasdaq: IMNM), a biotechnology company committed to developing first-in-class and best-in-class targeted cancer therapies, today announced the U.S. Food and Drug Administration (FDA or the Agency) has accepted its New Drug Application (NDA) for varegacestat, an investigational, oral, once-daily gamma secretase inhibitor (GSI), for the treatment of adults with desmoid tumors. The FDA assigned a Prescription Drug User Fee Act (PDUFA) target action date of April 28, 2027.

"The FDA's acceptance of our NDA for varegacestat is an important milestone for Immunome and for patients living with desmoid tumors," said Clay Siegall, Ph.D., President and Chief Executive Officer of Immunome. "We believe varegacestat has the potential to provide an important oral treatment option, supported by robust clinical data across all key efficacy endpoints. We look forward to working closely with the FDA throughout the review."

RINGSIDE Phase 3 Trial Results

The NDA is based on results from the Phase 3 RINGSIDE trial evaluating varegacestat in patients with progressing desmoid tumors. Key findings include:

• The registrational trial met its primary endpoint of improving progression-free survival vs. placebo, with a statistically significant and clinically meaningful 84% reduction in the risk of disease progression or death (hazard ratio = 0.16, p<0.0001).
• The trial also met all key secondary endpoints, including achieving an objective response rate of 56% vs. 9% with placebo (p<0.0001), as assessed by blinded independent central review.
• Varegacestat demonstrated statistically significant improvement in worst pain intensity at week 12, with a clinically significant difference observed as early as the first evaluation at week 4.
• In an exploratory analysis, varegacestat showed a median best change in tumor volume of -83% vs. +11% with placebo, as assessed by blinded independent central review.
• Varegacestat was generally well tolerated with a manageable safety profile, consistent with the gamma secretase inhibitor class. The most common adverse events for participants in the treatment arm were diarrhea (82%), fatigue (44%), rash (43%), nausea (35%) and cough (34%). Most (95%) events were grade 1 or 2.

The results were presented in an oral abstract session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting.

About the RINGSIDE Trial

The global, randomized, double-blind, placebo-controlled Phase 3 RINGSIDE trial (ClinicalTrials.gov Identifier: NCT04871282) evaluated the efficacy and safety of varegacestat in patients with progressing desmoid tumors. A total of 156 patients were randomized to receive varegacestat 1.2 mg daily or placebo until disease progression or death, representing the largest randomized study in this population. The primary endpoint of the trial was progression-free survival as assessed by blinded independent central review. Statistically controlled secondary endpoints were confirmed ORR using RECIST v1.1 and change in tumor volume at week 24, both determined by blinded independent central review, as well as change in pain intensity at week 12 as determined using a patient-reported outcome instrument. Additional secondary endpoints included duration of response, best reduction in tumor volume, patient-reported outcomes, and safety and tolerability. RINGSIDE includes an open-label extension phase, which is ongoing.

About Desmoid Tumors

Desmoid tumors (also known as aggressive fibromatosis or desmoid-type fibromatosis) are aggressive non-metastatic soft tissue tumors that are prone to recurrence. Approximately 1,000-1,650 people are diagnosed with desmoid tumors each year in the United States, and there are approximately 10,000-11,000 actively managed patients. Those affected face debilitating pain, deformity and, in some cases, life-threatening organ damage. The chronic pain and physical limitations associated with desmoid tumors lead to a high clinical burden and impaired quality of life. Although desmoid tumors are not considered cancerous, they often require systemic treatment to prevent permanent disability and alleviate disease burden.

About Varegacestat

Varegacestat (formerly AL102) is an investigational, oral, once-daily gamma secretase inhibitor. In December 2025, Immunome reported positive topline results for the Phase 3 RINGSIDE trial of varegacestat in adults with progressing desmoid tumors. Immunome's NDA for varegacestat was accepted by the FDA in July 2026 (PDUFA target action date of April 28, 2027) and the Company plans to submit a Marketing Authorization Application to the European Medicines Agency for varegacestat by the end of 2026.

About Immunome, Inc.

Immunome is a clinical-stage targeted oncology company committed to developing first-in-class and best-in-class targeted cancer therapies. We are advancing an innovative portfolio of therapeutics, supported by a leadership team with deep experience in the design, development, and commercialization of cutting-edge therapies, including antibody-drug conjugates. Our pipeline includes varegacestat, an investigational gamma secretase inhibitor for which an NDA has been accepted by the U.S. FDA; IM-1021, a clinical-stage ROR1 ADC; IM-1617, a clinical-stage solid tumor ADC; and IM-3050, an IND-cleared FAP-targeted radiotherapy. We are also advancing a broad portfolio of early-stage ADCs pursuing undisclosed solid tumor targets.

Cautionary Statement Regarding Forward-Looking Statements

Statements in this press release that are not purely historical in nature are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. We use words such as "could," "believe," "potential," "look forward," "plans," "committed" and similar expressions to identify these forward-looking statements. These forward-looking statements include statements regarding the potential of varegacestat, including its therapeutic benefits, its ability to provide a meaningful new oral treatment option and regulatory outcomes; the FDA's review of the NDA for varegacestat; Immunome's plans for submission of a marketing authorization application to the EMA and for the continued advancement of varegacestat; and other statements regarding management's intentions, plans, beliefs, expectations or forecasts for the future.

These forward-looking statements are based on Immunome's current expectations and involve assumptions that may never materialize or may prove to be incorrect; consequently, actual results may differ materially from those expressed or implied due to a number of factors, including risks related to regulatory review of the NDA for varegacestat and Immunome's planned submission to the EMA, such as potential delays or failure to obtain regulatory approval; risks related to the safety profile of varegacestat; risks related to the labeling and commercialization of varegacestat, if approved; Immunome's ability to grow and advance its pipeline and execute on its business plan; and other risks and uncertainties included under the caption "Risk Factors" in Immunome's Quarterly Report on Form 10-Q for the quarter ended March 31, 2026, filed with the Securities and Exchange Commission on May 12, 2026.

These documents can also be accessed on Immunome's website at www.immunome.com by clicking on the link "Financials" under the "Investors" tab. The forward-looking statements included in this press release are made only as of the date of this press release. Except as required by law, Immunome assumes no obligation and does not intend to update any forward-looking statements included in this press release.

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Investor Contact:

Max Rosett

Chief Financial Officer, Immunome

[email protected]