BOSTON — enGene Therapeutics Inc. reported updated interim results from the pivotal cohort of its ongoing Phase 2 LEGEND trial evaluating detalimogene voraplasmid in patients with high-risk, BCG-unresponsive non-muscle invasive bladder cancer.
The Boston and Montreal clinical-stage genetic medicines company said patients treated with detalimogene achieved a 54% complete response rate at any time and a 43% complete response rate at six months. The data came from 125 patients with carcinoma in situ, with or without concomitant papillary disease, and were current as of April 21.
enGene said the progression rate to muscle-invasive or more advanced disease was 3.2%. The company also reported that 55% of patients experienced treatment-related adverse events, most of which were mild.
“These updated data continue to reinforce the favorable safety and tolerability profile of detalimogene and its clinical activity in a heavily pretreated, high-risk NMIBC patient population with limited therapeutic options. Importantly, the low rate of progression to muscle-invasive disease leaves patients eligible for other bladder-sparing therapies,” said Ron Cooper, president and chief executive officer of enGene. “While durability outcomes to date are not what we hoped, these data are preliminary. We are focused on evaluating the totality of the data as it evolves and plan to continue to engage with the FDA and the medical community.”
The trial’s interim analysis showed that 67 of 124 evaluable patients achieved a complete response at any time, with 91% of responses occurring at the first disease assessment. At six months, 52 of 121 evaluable patients were in complete response.
Among the 52 six-month responders, 37 of 44 patients who had a nine-month assessment remained in complete response. At 12 months, 13 of 22 patients who had an assessment remained in complete response, with additional patients still pending evaluation.
The Kaplan-Meier estimate of the 12-month duration of response was 25%, while the estimated median duration of response was 37.3 weeks.
Safety findings showed that 69 of 125 patients experienced at least one treatment-related adverse event. Among patients with any treatment-related adverse event, 91% had Grade 1 or Grade 2 events. Grade 3 or higher treatment-related adverse events were reported in six patients. Treatment-related adverse events leading to treatment interruption or discontinuation occurred in 2.4% of patients in each category.
The most common treatment-related adverse events were fatigue, dysuria, micturition urgency, pollakiuria and bladder spasm. The company said there were no Grade 5 treatment-related adverse events.
enGene said complete response rates were lower among 32 patients who had their first disease assessment after the company’s prior data analysis in October 2025. In that group, the complete response rate at any time was 39%, and the six-month complete response rate was 32%. The company said a preliminary subgroup analysis did not identify material differences in demographics or key disease characteristics, and a more detailed analysis is ongoing.
enGene said it has completed required FDA manufacturing validation batches and submitted a statistical analysis plan to the agency. The company plans further engagement with the FDA as it approaches a potential Biologics License Application filing and expects to provide an update in the second half of 2026.
The company plans to present the data at the American Urological Association meeting on May 15.
