enGene Therapeutics has reported additional interim outcomes from the pivotal cohort of its ongoing LEGEND Phase II trial assessing detalimogene voraplasmid for Bacillus Calmette-Guérin (BCG)-unresponsive non-muscle invasive bladder cancer (NMIBC).
The open-label, multi-cohort ongoing trial targets patients with high-risk BCG-unresponsive NMIBC who have carcinoma in situ (CIS), with or without accompanying papillary disease.
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NMIBC forms when cancer cells are confined to the bladder lining, appearing as surgically removable papillary growths or as flat, multifocal CIS lesions.
The study enrolled 125 patients and reported that treatment with detalimogene resulted in a 54% complete response (CR) at any time during the study, with a 43% CR rate observed at six months.
The progression rate to muscle-invasive or advanced disease was low at 3.2%.
Detalimogene was generally well tolerated, with 55% of patients experiencing treatment-related adverse events, mostly mild (Grade 1 and 2).
Response rates at first disease assessment accounted for 91% of those observed. Among responders at six months, 37 out of 44 evaluated at nine months were still in CR.
At 12 months, 13 out of 22 assessed maintained CR, with other evaluations pending. The 12-month Kaplan-Meier estimate for duration of response was 25%, and the median duration was 37.3 weeks.
Safety data showed 55% of patients had a treatment-related adverse event, mostly mild. Grade three events occurred in six patients (4.8%), and interruptions or discontinuations due to adverse events were low (2.4% each).
enGene has finished US Food and Drug Administration (FDA) manufacturing validation batches and submitted a Statistical Analysis Plan to the agency.
The company intends to share data at the American Urological Association meeting on 15 May 2026 and update following further FDA engagement later this year.
enGene president and CEO Ron Cooper said: “These updated data continue to reinforce the favourable 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. While durability outcomes to date are not what we hoped, these data are preliminary.”
In November 2025, enGene Therapeutics reported that its gene therapy for high-risk, BCG-unresponsive NMIBC achieved a 63% complete response rate in a pivotal Phase II trial.
