enGene Highlights Surfactant-Enhanced Bladder Cancer Therapy Data and 2027 Update Path

Key Points

• Detalimogene showed a 54% complete response rate at any time in the May interim update of enGene’s pivotal LEGEND cohort for BCG-unresponsive, high-risk NMIBC, with low rates of treatment-related dose interruption or discontinuation at 2.4% each.
• Preclinical studies indicated that adding a 0.25% polidocanol surfactant rinse substantially improved therapy delivery, producing up to ninefold higher IL-12 expression in primates and more than tenfold higher expression in mice versus detalimogene alone. The surfactant safety run-in reported no dose-limiting toxicities.
• enGene plans to pursue a biologics license application for detalimogene without the surfactant, with an updated pivotal data release expected in the fourth quarter. A six-month response update from roughly 20 patients in the surfactant cohort is targeted for mid-2027.

enGene NASDAQ: ENGN used a company webinar to outline preclinical findings for its investigational non-viral gene therapy, detalimogene voraplasmid, used with a polidocanol surfactant bladder rinse, while community urologists discussed the treatment burden facing patients with high-risk non-muscle invasive bladder cancer, or NMIBC.

Chief Executive Officer Ron Cooper said the company believes the NMIBC market will support multiple therapies as more bladder-sparing options become available. He said treatment decisions in community urology practices often require clinicians to balance efficacy, tolerability, workflow requirements and economics.

Detalimogene is being evaluated in patients with BCG-unresponsive, high-risk NMIBC with carcinoma in situ, with or without papillary disease. Cooper said the company’s May interim update from the LEGEND pivotal cohort, which studied detalimogene without a surfactant, showed a 54% complete response rate at any time. Median follow-up for all patients was 5.5 months at that point, he said.

Cooper also highlighted the treatment’s tolerability profile, reporting treatment-related adverse events resulting in dose interruption or discontinuation of 2.4%, respectively. He said enGene expects to provide an updated pivotal-cohort data release in the fourth quarter, including an estimate of 12-month durability, while noting that the durability endpoint will remain immature.

Community Urologists Describe Treatment Trade-Offs

Dr. Suzanne Merrill, a urologist at Colorado Urology, and Dr. David Cahn, the practice’s director of clinical research, presented illustrative cases intended to show the varied practical issues affecting NMIBC treatment decisions.

Merrill described an elderly patient with recurrent disease, worsening urinary symptoms and multiple comorbidities who was not a candidate for cystectomy. In that example, treatment selection was influenced by the need for less frequent dosing, improved tolerability and avoidance of post-treatment precautions associated with certain viral therapies.

Cahn described a separate case involving an active patient with recurrent high-grade disease who struggled to tolerate dwell times required for BCG and chemotherapy and requested removal of an implanted treatment device because of urinary symptoms. He said the cases demonstrate that there is no “one-size-fits-all” treatment approach for NMIBC patients.

During the question-and-answer session, Merrill said treatment decisions extend beyond efficacy and include a patient’s bladder symptoms, travel constraints and ability to tolerate therapy. Cahn said patients may potentially move through several bladder-preserving regimens as more treatment choices enter the market, though he added that not every urology practice is likely to offer every available therapy because of administration and management requirements.

Surfactant Rinse Program

enGene co-founder Anthony Cheung reviewed the rationale for combining detalimogene with a surfactant rinse. Detalimogene is a plasmid-based therapy designed to deliver DNA encoding three genes into bladder-lining cells. According to Cheung, the approach is intended to activate innate immune signaling and support localized IL-12 expression, T-cell activity and an antitumor immune response.

Cheung said the company’s earlier work indicated that increasing the dose of detalimogene did not produce a proportional increase in gene expression at higher doses. The company instead evaluated whether a surfactant could improve penetration and distribution of the therapy through the bladder lining.

The company selected polidocanol after evaluating surfactants based on performance, supply availability, manufacturing practicality and safety history, Cheung said. Polidocanol is being used at a 0.25% concentration in the bladder-rinse program. Cheung said it has prior clinical and consumer-use history at higher concentrations.

In murine models, enGene said a surfactant rinse increased localized IL-12 expression by more than tenfold and improved antitumor activity at a suboptimal detalimogene dose. In non-human primates, a five-minute polidocanol rinse followed by a 15-minute detalimogene dwell produced approximately ninefold higher mean human IL-12 expression than detalimogene alone with a 60-minute dwell, according to Cheung.

Cheung said the studies showed no systemic distribution of polidocanol in the non-human primate model and no evidence of systemic exposure to DNA or IL-12 in the murine work. He also said the clinical safety run-in for the surfactant cohort was complete with no dose-limiting toxicities observed.

Clinical and Regulatory Timing

The ongoing LEGEND surfactant cohort uses a single catheterization procedure: a five-minute rinse with 50 milliliters of 0.25% polidocanol followed by detalimogene with a 30-minute dwell time. The cohort may enroll up to 80 patients, according to the company.

enGene expects to report a six-month complete response update involving approximately 20 patients from the surfactant cohort in mid-2027. The company is also collecting exploratory urine biomarkers, including IL-12 and CXCL10, to compare biological activity in the surfactant cohort with the prior pivotal cohort.

Cooper said enGene plans to initiate a biologics license application submission for detalimogene without the surfactant based on the pivotal cohort. He said the company expects the surfactant approach, if pursued following approval of detalimogene alone, would likely be addressed through a supplemental regulatory submission.

About enGene (NASDAQ:ENGN)

enGene Holdings Inc, through its subsidiary enGene, Inc, operates as a clinical-stage biotechnology company that develops genetic medicines through the delivery of therapeutics to mucosal tissues and other organs. Its lead product candidate is EG-70 (detalimogene voraplasmid), which is a non-viral immunotherapy to treat non-muscle invasive bladder cancer patients with carcinoma-in-situ (Cis), who are unresponsive to treatment with Bacillus Calmette-Guérin. The company was founded in 2023 and is based in Saint-Laurent, Canada.

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