enGene (NASDAQ: ENGN) stock suffered an 83% plunge this past week that reflects just how competitive the field is among drug candidates for nonmuscle invasive bladder cancer (NMIBC)—and how questions over clinical data are enough to send investors scurrying to sell their shares. enGene shares cratered 81% Thursday from $8.85 to $1.72, then fell another 13% Friday, reaching a 52-week low as it finished the week at $1.50. The sharp falloff followed enGene reporting updated data from its Phase II LEGEND trial (NCT04752722) assessing its nonviral gene therapy candidate detalimogene voraplasmid in high-risk, Bacillus Calmette-Guérin (BCG)-unresponsive NMIBC patients with carcinoma in situ (CIS) with or without concomitant papillary disease (CIS±papillary). The data showed a drop in response rates from a November 2025 readout, falling short of company and Wall Street expectations. As of the April 21 data cutoff, 67 of 124 evaluable patients treated with detalimogene (formerly EG-70) achieved a 54% complete response (CR) at any time, a rate that fell to 43% (52 of 121 evaluable patients) CR rate at six months. That compares with the 63% CR at any time and 62% CR rate at six months shown for the first 62 patients assessed, as announced by enGene in November 2025. Also, detalimogene showed a nine-month CR rate of 32.7%, which fell to 13.3% at 12 months after treatment. Engene said it will present its data at the American Urological Association Annual Meeting (AUA 2026), set for May 15–18 in Washington, DC. “While durability outcomes to date are not…
