Immunome’s desmoid tumor drug varegacestat posts landmark Phase 3 results, setting up a potential challenge to Merck KGaA’s Ogsiveo
Immunome reported topline results from its global Phase 3 RINGSIDE trial of varegacestat, an oral gamma secretase inhibitor for desmoid tumors, a rare soft-tissue tumor.13
The trial met its primary endpoint, showing an 84% reduction in the risk of disease progression or death versus placebo (hazard ratio 0.16), indicating a major improvement in progression-free survival.13
Varegacestat achieved an objective response rate (ORR) of 56% compared with 9% for placebo, the highest response rate reported to date in this patient population on a cross-trial basis.1
Patients on varegacestat had a median best tumor volume reduction of 83%, versus an 11% increase in the placebo arm, demonstrating substantial tumor shrinkage.1
Most adverse events were grade 1–2 and consistent with the gamma secretase inhibitor class, including diarrhea, fatigue, rash, nausea, and cough, suggesting a manageable safety profile.1
Based on the strength of RINGSIDE, Immunome plans to submit a New Drug Application (NDA) in the U.S. in Q2 2026, aiming to establish varegacestat as a new standard of care for desmoid tumors.14
Desmoid tumors are rare, with an estimated 1,000–1,650 new U.S. cases annually and around 10,000–11,000 patients under active management, highlighting the significance of an effective oral therapy.13
Market commentary notes that these Phase 3 data position varegacestat as a potential best-in-class oral treatment for desmoid tumors and substantially de‑risk the program ahead of regulatory discussions.23
On a cross-trial comparison, Oncology Pipeline reports that varegacestat’s efficacy metrics appear to outperform Merck KGaA’s Ogsiveo (nirogacestat), the first approved gamma secretase inhibitor for desmoid tumors, suggesting competitive pressure for Merck’s franchise if varegacestat is approved.4
Following the data release, Immunome’s stock has surged sharply (around 20% in one report and over 100% over six months), reflecting investor expectations that varegacestat could challenge Merck KGaA’s Ogsiveo in the rare desmoid tumor market.23
Sources:
1. https://marketchameleon.com/articles/b/2025/12/15/immunome-varegacestat-landmark-phase-3-desmoid-tumor-results
2. https://www.nasdaq.com/articles/immunome-stock-surges-20-after-positive-phase-3-data-desmoid-tumor-drug
3. https://www.investing.com/news/company-news/immunomes-desmoid-tumor-drug-shows-84-reduction-in-disease-progression-93CH-4408737
4. https://www.oncologypipeline.com/apexonco/ringside-sends-immunome-towards-filing