On October 20, 2025 Transgene (Euronext Paris: TNG), a biotech company that designs and develops virus-based immunotherapies for the treatment of cancer, and BioInvent International AB ("BioInvent") (Nasdaq Stockholm: BINV), a biotech company focused on the discovery and development of novel and first-in-class antibodies for cancer immunotherapy, reported a poster at the 2025 European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) Annual Meeting on updated clinical results and positive antitumoral activity of BT-001 in patients with advanced refractory tumors.
The data show that intra-tumoral (IT) BT-001 injection in combination with MSD’s (Merck & Co., Inc., Rahway, NJ, USA) intravenous (IV) anti-PD-1 therapy KEYTRUDA (pembrolizumab[1]), was well tolerated and showed positive local, abscopal and sustained antitumoral activity in injected and non-injected lesions.
Translational analyses reveal increased T cell chemoattractants in the blood and infiltration of activated CD8+ T cells and macrophages in tumors after treatment with BT-001 in combination with pembrolizumab. Significant tumor shrinkage (≥30% decrease in longest diameter) was observed in five of 16 injected lesions (in three patients with melanoma and one patient with sarcoma). Four patients had tumor shrinkage of non-injected lesions.
Long-lasting partial responses (PRs) were observed in a patient with melanoma resistant to anti-PD-1/anti-CTLA-4 combination therapy and in a heavily pre-treated, PD-L1 negative leiomyosarcoma patient.
These immune-mediated tumor shrinkages are consistent with the mechanistic hypothesis that BT-001, in combination with pembrolizumab, turns "cold" tumors into immunologically active ones. The overall data support further development of BT-001 across a range of solid tumors to improve responses to cancer immunotherapies.
Prof. Celeste Lebbé, Dermatologist and Venereologist, Head of Dermatology Department at Hospital Saint-Louis, Paris, commented: "Many cancer patients fail to respond to existing treatments, emphasizing the urgent need for new approaches. BT-001 represents a promising new class of immunotherapy, capable of inducing a potent local immune response through the expression of GM-CSF and an anti-CTLA-4 antibody. These clinical data provide compelling proof of concept, highlighting the relevance of this oncolytic virus in transforming cold tumors into immunologically active ones. Whether administered alone or in combination with pembrolizumab, BT-001 offers the potential to expand treatment options with a favorable safety profile across multiple tumor types."
Dr. Alessandro Riva, Chairman and CEO of Transgene, said: "We are pleased to jointly present these clinical data on BT-001 at ESMO (Free ESMO Whitepaper) 2025, demonstrating encouraging antitumor activity in patients with solid, refractory solid tumors. These updated results confirm BT-001’s mechanism of action as a single agent administered via intra-tumoral injection and show early signs of clinical benefit, including lesion shrinkage and stable disease. With a favorable safety profile – both alone and in combination with pembrolizumab – BT-001 could represent an effective option to enhance responses to immune checkpoint inhibitors (ICI) in patients with limited treatment alternatives. Together with our partner BioInvent, we will continue to explore its safety and efficacy and share further data as it becomes available."
Andres McAllister, MD, PhD, Chief Medical Officer at BioInvent, added: "By combining BT-001 with pembrolizumab, we are building upon the promising data generated by BT-001 as a single agent. Targeting the PD-1/PD-L1 pathway in addition to BT-001’s mechanism of action is expected to further stimulate and restore the patient’s immune system, which should result in improved antitumoral activity and patient outcome. We are pleased to pursue clinical development opportunities with clinicians and further demonstrate the potential of this novel oncolytic virus."
Transgene and BioInvent are co-developing BT-001, an oncolytic virus developed using Transgene’s Invir.IO platform armed to express GM-CSF and BioInvent’s full-length anti-CTLA-4 monoclonal antibody, to elicit a strong and effective anti-tumoral response in solid tumors.
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.", can be accessed at the websites for the ESMO (Free ESMO Whitepaper) conference, Transgene and BioInvent.
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(Press release, Transgene, OCT 20, 2025, https://www.bioinvent.com/en/press/transgene-and-bioinvents-armed-oncolytic-virus-bt-001-shows-positive-local-abscopal-and [SID1234656826])