The Phase 3 SunRISE-2 study tested a new bladder drug-delivery system, Gem-iDRS, combined with the immunotherapy drug cetrelimab, in patients with muscle-invasive bladder cancer (MIBC) who did not undergo bladder removal. Gem-iDRS releases chemotherapy directly into the bladder over several weeks, while the control group received standard chemoradiotherapy (CRT), which combines radiation with systemic chemotherapy.
The trial was stopped early because the experimental treatment did not outperform standard CRT. At 12 months, bladder-intact event-free survival was 65.5% with Gem-iDRS versus 79.9% with CRT. Objective response rates and overall survival were also lower in the experimental arm, showing no clear advantage over the current standard.
Despite missing the primary goal, the Gem-iDRS group had a 50.7% complete response rate without full-body chemotherapy, highlighting the potential of localized therapy. Most side effects were mild urinary issues. Overall, for high-risk MIBC, chemoradiotherapy remains the gold standard for patients aiming to preserve their bladder.