enGene’s stock plunged after updated Phase II LEGEND trial data for its nonviral gene therapy detalimogene voraplasmid in high-risk, BCG-unresponsive nonmuscle invasive bladder cancer. Updated results showed complete response rates dropping versus an earlier November 2025 readout, raising questions about durability and meeting benchmarks. As of an April 21 data cutoff, 67 of 124 evaluable patients achieved a 54% complete response (CR) at any time, falling to 43% at six months. The company also reported 32.7% CR at nine months, dropping to 13.3% at 12 months after treatment. Management said durability outcomes were preliminary and that it plans longer-term follow-up and continued engagement with the FDA regarding statistical analysis plans and potential BLA filing. Analysts warned the updates could make competition harder in a crowded NMIBC landscape.