Immunome Announces Detailed Phase 3 RINGSIDE Data for Varegacestat in Adults with Progressing Desmoid Tumors at the 2026 ASCO Annual Meeting

Key Takeaways

• Varegacestat cut progression risk by 84% in Phase 3 RINGSIDE trial.
• Objective response rate reached 56% versus 9% for placebo.
• Pain scores improved by over 2 points by week 4, clinically significant.
• Most adverse events were mild; 20% discontinued due to side effects.
• NDA filed with FDA; EMA filing planned by end‑2026.

Pulse Analysis

Desmoid tumors, though non‑metastatic, impose a heavy clinical burden because they grow aggressively, cause chronic pain, and often recur after surgery. Historically, treatment options have been limited to surgery, hormonal therapy, or non‑specific chemotherapy, each with modest efficacy and significant toxicity. The emergence of a targeted gamma secretase inhibitor marks a shift toward mechanism‑driven therapy, and Immunome’s RINGSIDE trial provides the most robust data to date, underscoring the unmet need for a disease‑modifying oral agent.

The RINGSIDE trial enrolled 156 adults with progressive disease and demonstrated a statistically significant 84% reduction in the hazard of progression or death (HR 0.16, p < 0.0001). Varegacestat achieved a 56% confirmed objective response rate, far surpassing the 9% seen with placebo, and reduced tumor volume by an average of 109.6 mm³ at week 24. Equally compelling, patients reported a mean drop of 2.24 points in worst‑pain intensity by week 12, with a clinically meaningful improvement evident as early as week 4. Subgroup analyses showed consistent benefits regardless of tumor location, baseline size, age, or prior systemic therapy, suggesting broad applicability across the desmoid population.

Regulatory momentum is strong: an NDA was filed with the FDA in April 2026, and Immunome plans an EMA submission by year‑end. The safety profile appears manageable; 95% of adverse events were grade 1‑2, though dose reductions were required in 80% of patients and 20% discontinued due to toxicity. If approved, varegacestat could capture a U.S. market of roughly 10,000‑11,000 active patients, providing Immunome with a revenue engine that supports further pipeline development. The data also set a new benchmark for future trials in this niche, potentially reshaping treatment algorithms for aggressive fibromatosis.