BT-001 is an oncolytic virus developed with Transgene’s Invir.IO™ platform, engineered to encode both a Treg-depleting human recombinant anti-CTLA-4 antibody generated by BioInvent’s proprietary n-CoDeR/F.I.R.S.T platforms, and the human GM-CSF cytokine.
The use of an oncolytic virus to deliver the anti-CTLA-4 locally and selectively in the tumor microenvironment allows high intratumoral concentrations, eliciting a stronger and more effective antitumor response. By reducing systemic exposure to a very low level, this local therapeutic activity furthermore allows to increase the safety and tolerability profile of the anti-CTLA-4 antibody.
BT-001 is an oncolytic virus armed with BioInvent’s anti-CTLA-4 antibody releasing anti-CTLA-4 locally in the tumor
STATUS
Clinical phase 1/2a study (NCT04725331) ongoing
In July 2025, it was announced that BioInvent and Transgene will jointly present a poster on updated data from the Phase 1 part of the Phase 1/2a study of BT-001 at the European Society for Medical Oncology (ESMO) Annual Meeting held in Berlin, Germany, from October 17 to 21, 2025. The title of the abstract is “Updated clinical results of BT-001, an oncolytic virus expressing an anti-CTLA-4 mAb, administered in combination with pembrolizumab in patients with advanced solid tumors”.
At ESMO 2024, a poster was presented (Initial clinical results of BT-001, an oncolytic virus expressing an anti-CTLA4 mAb, administered as single agent and in combination with pembrolizumab in patients with advanced solid tumors) with data showing that BT-001 induced tumor reduction in patients who did not respond to prior anti-PD(L)-1 therapy, both as monotherapy and in combination with MSD’s (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 treatment pembrolizumab.
Preliminary translational data indicate that BT-001 replicates in the tumor without being detectable in blood. BT-001 was shown
as monotherapy, or in combination with pembrolizumab, to be well tolerated and showed first signs of efficacy with clinical response in 2/6 refractory patients, when given in combination with pembrolizumab. Treatment with BT-001 converted “cold” tumors into
“hot” ones, and induced T-cell infiltration, a higher M1/M2 ratio, as well as PD(L)-1 expression in the tumor microenvironment.
STUDY DESIGN
The Phase 1/2a study is a multicenter, open label, dose escalation trial evaluating BT-001 as a single agent and in combination with pembrolizumab (anti-PD-1 treatment). The Phase 1 study is divided into two parts. In part A, patients with metastatic/advanced tumors received single agent, intra-tumoral administrations of BT-001. Part B is exploring intra-tumoral injections of BT-001 in combination with pembrolizumab.
Phase 2a will evaluate the combination regimen in several patient cohorts with selected tumor types. These expansion cohorts will offer the possibility of exploring the activity of this approach to treat other malignancies not traditionally addressed with this type of treatment.
Read more about the ongoing Phase 1/2a study
Evaluation of BT-001 alone and in combination with pembrolizumab
OUT-LICENSING AND PARTNERING
In June 2022, BioInvent and Transgene announced a clinical trial collaboration and supply agreement with MSD, a tradename of
Merck & Co., Inc., Rahway, NJ., USA, to evaluate the oncolytic virus BT-001 in combination with MSD’s anti-PD-1 therapy KEYTRUDA® (pembrolizumab) in a Phase 1/2a clinical trial for the treatment of patients with solid tumors.
Since 2017, BioInvent and Transgene have been collaborating to develop the drug candidate BT-001, which encodes both a differentiated and proprietary CTLA-4 antibody and the cytokine GM-CSF. The research and development costs as well as revenue and royalties are shared 50:50