Immunome files FDA application for varegacestat in desmoid tumors: full analysis
Immunome has submitted a new drug application to the US FDA for varegacestat for adults with progressing desmoid tumors, marking the company’s move from late-stage development into regulatory review. The April 29, 2026 submission is supported by data from the phase 3 RINGSIDE trial, which the company says met its primary endpoint and all key secondary endpoints. (nasdaq.com)
The filing comes in a disease area that changed materially in late 2023, when the FDA approved SpringWorks Therapeutics’ nirogacestat, branded Ogsiveo, as the first approved treatment for adults with progressing desmoid tumors who require systemic treatment. That approval helped validate gamma secretase inhibition as a therapeutic strategy in desmoid disease, which is rare, non-metastatic, but often locally aggressive and associated with pain, functional impairment, and recurrent disease after surgery. (fda.gov)
In RINGSIDE, varegacestat was tested as a once-daily oral therapy in 156 adults with progressing desmoid tumors in a global, randomized, double-blind, placebo-controlled study that included an ongoing open-label extension. According to Immunome and OncLive’s summary of the dataset, varegacestat cut the risk of progression or death by 84% versus placebo, with a hazard ratio of 0.16. Confirmed objective response rate was 56% with varegacestat versus 9% with placebo, and an exploratory analysis showed a median best tumor volume change of -83% with the drug versus +11% with placebo. (investors.immunome.com)
Safety will likely stay central in any review and eventual market positioning. Immunome has described varegacestat as generally well tolerated, with adverse events consistent with the gamma secretase inhibitor class. The most common adverse events in the treatment arm were diarrhea, fatigue, rash, nausea, and cough, and most were grade 1 or 2. The company’s January 2026 investor presentation also noted ovarian toxicity in 55.6% of premenopausal women in the study, a notable point in a class where reproductive health counseling already matters. (investors.immunome.com)
Outside the company, early expert commentary has framed varegacestat as a potentially meaningful addition rather than a first-in-class breakthrough. OncLive reported in February that Rashmi Chugh, MD, discussed unmet needs in desmoid tumors, the biologic rationale for gamma secretase inhibition, and the potential role of varegacestat in the treatment paradigm based on RINGSIDE. Patient advocacy group The Desmoid Tumor Research Foundation also highlighted the submission as a milestone and pointed readers to the standard FDA filing and review process now underway. (onclive.com)
Why it matters: For veterinary professionals, especially those who follow translational oncology, this story is less about direct clinical application in animal patients and more about how rare, locally aggressive soft-tissue tumors are being managed with increasingly targeted systemic therapies. The desmoid field now appears to be moving from a single approved gamma secretase inhibitor toward potential within-class competition, which may influence future thinking on treatment sequencing, adverse-event management, quality-of-life endpoints, and long-term monitoring. It also reinforces how drug development in rare tumors is leaning more heavily on patient-reported outcomes and functional benefit, not just radiographic response. (fda.gov)
What to watch: First, the FDA must decide whether to accept the application for filing, a step that typically happens within about 60 days of submission. If accepted, varegacestat would move into a full review that often runs roughly 6 to 10 months, with updated RINGSIDE data also expected to surface at the 2026 ASCO Annual Meeting. The bigger question is whether the FDA sees varegacestat as sufficiently differentiated in efficacy, dosing, tolerability, or patient experience to carve out a clear place alongside an already approved class competitor. (dtrf.org)