Transgene: BT-001 tested before surgery in localized rectal cancer
Candidate BT-001, whose first clinical trials involved treatment-resistant metastatic cancers, is now being evaluated at an earlier stage of the disease, before surgery. Transgene announced this in a press release published on November 5, 2026, regarding a study conducted at the initiative of Danish investigators.
A Phase 1 study before surgery in localized pMMR rectal cancer
The Phase 1 OV-PRIME-R study is conducted by Bispebjerg and Frederiksberg Hospital (University of Copenhagen), in Denmark, as an investigator-initiated trial supported by Transgene. It combines BT-001, an armed oncolytic virus injected directly into the tumor, with pembrolizumab, an anti-PD-1 therapy administered intravenously.
Eligible patients have localized rectal cancer with pMMR status. According to the press release, this population represents approximately 95% of rectal cancer cases, which to date show limited response to immunotherapy used alone.
The combination is administered as neoadjuvant treatment, before standard surgery, in order to assess its safety, tolerability and efficacy. It recalls that neoadjuvant (chemo)radiotherapy leads to a complete response in fewer than 30% of patients, that some still develop distant recurrences, and that adjuvant options remain limited.
A candidate co-developed with BioInvent
BT-001 is jointly developed by Transgene and BioInvent. Derived from Transgene's Invir.IO platform, it is designed to express BioInvent's GM-CSF cytokine and anti-CTLA-4 monoclonal antibody, with the aim of inducing an antitumor immune response while limiting systemic exposure and the associated adverse effects.
For the principal investigator, Professor Henry G. Smith, the combination “will strengthen the immune response and improve patients' future by reducing the risk of relapse or even decreasing the need for surgery”. Emmanuelle Dochy, Transgene's Medical Affairs Director, highlights tolerability already observed, which she describes as “excellent”.
The first clinical trials cited by the company involved patients with treatment-resistant metastatic cancers. The multicenter, open-label Phase I/IIa study (NCT04725331) evaluated BT-001 alone or combined with pembrolizumab in patients with advanced solid tumors.
OV-PRIME-R has only just treated its first patient, and Transgene reminds, in its forward-looking statements, that there is no guarantee that the results of previous trials will be predictive of those of the ongoing clinical trials.
