enGene reported updated Phase II LEGEND trial data for its nonviral gene therapy detalimogene voraplasmid in high-risk, BCG-unresponsive nonmuscle invasive bladder cancer with carcinoma in situ (CIS±papillary). Investors reacted sharply after the company showed complete response (CR) rates slipping versus the earlier November 2025 readout. For the April 21 data cutoff, enGene said 67 of 124 evaluable patients achieved a 54% CR at any time, with the six-month CR rate falling to 43% (52 of 121). At nine months the CR rate was 32.7%, dropping to 13.3% by 12 months—below earlier cohorts assessed. The company said the dataset is preliminary and plans continued engagement with the FDA, including review of statistical analysis plans and potential BLA filing paths. enGene also plans further longer-term durability results for Cohort 1 in the second half of the year and intends to present details at the American Urological Association (AUA) Annual Meeting 2026. The stock selloff underscored how quickly updated efficacy/durability data can reset expectations in crowded NMIBC development pipelines.