SpringWorks Releases Long-Term Efficacy and Safety Results from DeFi Trial of Ogsiveo
SpringWorks Therapeutics announced that long-term efficacy and safety data from the Phase 3 DeFi trial of Ogsiveo, an oral gamma secretase inhibitor for the treatment of adults with progressing desmoid tumors who require systemic treatment, were published in the Journal of Clinical Oncology. The long-term follow-up data from DeFi, which was a global, randomized, multicenter, double-blind, placebo-controlled trial, were previously presented at the 2024 Connective Tissue Oncology Society Meeting. The new results published in JCO utilized a December 2024 data cutoff date and showed that longer-term treatment with OGSIVEO was associated with further reductions in tumor size, an increase in objective response rate with additional partial responses and complete responses, sustained improvement in patient reported outcomes, and a consistent safety profile compared to the April 2022 data cut off utilized for the primary analysis of the trial. In the Phase 3 DeFi trial primary analysis, which was previously published in the New England Journal of Medicine, Ogsiveo showed significant improvement versus placebo in progression-free survival, objective response rate and patient-reported outcomes in adult patients with progressing desmoid tumors. In the JCO publication, long-term efficacy and safety were evaluated in patients randomized to Ogsiveo and followed through the final data-cutoff date of December 2024. The median duration of Ogsiveo treatment in these patients was 33.6 months. Objective response rates improved with long-term Ogsiveo treatment. While ORR was 34.3% in year 1, it increased to 45.7% in patients who received Ogsiveo for up to four years, with three additional complete responses and three additional partial responses since the primary analysis and yielding 24 PRs and 8 CRs in total. The median best percent reduction from baseline in target tumor size by RECIST 1.1 with continuous Ogsiveo treatment was -32.3% at year one and -75.8% for patients completing at least four years of treatment. Improvements in patient-reported outcomes of pain, desmoid tumor-specific symptom severity, desmoid tumor-specific physical functioning, global health status/quality of life and role functioning occurred early and were sustained with up to 45 months of treatment with Ogsiveo. Overall, the incidence and severity of frequently reported treatment emergent adverse events decreased through years two, three and four of treatment. The most common adverse events reported in patients receiving Ogsiveo were diarrhea, ovarian toxicity, rash, nausea, fatigue, stomatitis, headache, abdominal pain, cough, alopecia, upper respiratory tract infection, and dyspnea.