Transgene and BioInvent International AB announced they will jointly present updated clinical data on their armed oncolytic virus BT-001 at the European Society for Medical Oncology (ESMO) Annual Meeting, taking place in Berlin, Germany, from October 17 to 21, 2025. The poster presentation will showcase results from the Phase I portion of their ongoing Phase I/IIa study in patients with advanced solid tumors.
Clinical Efficacy and Safety Profile
BT-001 has demonstrated promising early efficacy signals in the Phase I study. When administered in combination with MSD's anti-PD-1 therapy KEYTRUDA® (pembrolizumab), the treatment showed clinical responses in two out of six refractory patients, with thirteen patients evaluated in total. Notably, the therapy achieved shrinkage of both injected and non-injected lesions, suggesting systemic anti-tumor activity.
The treatment has been well tolerated both as monotherapy and in combination with pembrolizumab. BT-001 successfully converted "cold" tumors into "hot" ones, inducing T-cell infiltration and PD(L)-1 expression in the tumor microenvironment, indicating enhanced immune activation within treated tumors.
Novel Therapeutic Design
BT-001 represents an innovative approach to cancer immunotherapy, generated using Transgene's Invir.IO® platform and its patented large-capacity VVcopTK-RR- oncolytic virus. The virus has been engineered to encode both a Treg-depleting recombinant human anti-CTLA-4 antibody, developed through BioInvent's proprietary n-CoDeR®/F.I.R.S.T™ platforms, and the human GM-CSF cytokine.
This dual-armed design allows BT-001 to simultaneously deliver targeted immunomodulation through CTLA-4 blockade while stimulating immune cell recruitment and activation via GM-CSF expression directly within the tumor microenvironment.
Study Design and Development Partnership
The ongoing Phase I/IIa study (NCT04725331) is a multicenter, open-label, dose-escalation study evaluating BT-001 as a single agent and in combination with pembrolizumab. The last patient in the Phase I portion was enrolled in August 2024, marking completion of the dose-escalation phase.
BT-001 is being co-developed through a 50/50 collaboration between Transgene and BioInvent, combining Transgene's viral vector engineering expertise with BioInvent's antibody discovery capabilities. This partnership leverages both companies' proprietary platforms to create next-generation oncolytic immunotherapies.
Conference Presentation Details
The poster, titled "Updated clinical results of BT-001, an oncolytic virus expressing an anti-CTLA4 mAb, administered in combination with pembrolizumab in patients with advanced solid tumors," will be presented as abstract number 2828. The research team includes investigators C. Lebbe, R. Bahleda, E. Ezine, B. Baroudjian, M. Sakkal, E. Rowinski, A. Vinceneux, S. Champiat, K. Bidet Huang, N. Stojkowitz, H. Makhloufi, A. Sadoun, A. Ropenga, M. Semmrich, A. McAllister, M. Chisamore, and P. Cassier.
The abstract will be available on ESMO's website on October 13, 2025, at 00:05 CEST, providing the scientific community with detailed results ahead of the conference presentation.
