On November 5, 2026 Transgene (Euronext Paris: TNG), a biotech company that designs and develops virus-based immunotherapies for the treatment of cancer and Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Denmark, reported that the first patient with proficient mismatch repair (pMMR) rectal cancer has successfully been dosed in the Phase 1 OV-PRIME-R 2 trial. The investigator-sponsored trial is evaluating BT-001, an armed oncolytic virus administered via intratumoral injection which will be followed by intravenous pembrolizumab3 . This population, which represents approximately 95% of rectal cancer cases, has to date shown poor response to immunotherapy alone.

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Henry G. Smith, PhD, Associate Professor and consultant surgeon at Abdominal Center K, Bispebjerg and Frederiksberg Hospital University of Copenhagen and Principal Investigator, commented: "We are excited to launch this investigator-sponsored trial, which explores an innovative approach to treating rectal cancer in patients with proficient mismatch repair status. By combining BT-001, an armed oncolytic virus, with anti-PD-1 therapy, in patients with localized disease, we aim to enhance the immune response and potentially improve outcomes for patients by reducing the risks of relapse or even reducing the number who need surgery at all. This study represents an important step toward more effective and less toxic treatment strategies for this underserved population."

"We are proud to support this investigator-sponsored trial in collaboration with the University of Copenhagen, evaluating BT-001 in patients with rectal cancer at high risk of relapse and severe toxicities from standard of care," added Emmanuelle Dochy, MD, Chief Medical Officer of Transgene. "BT-001 has already demonstrated excellent tolerability and the ability to transform "cold" tumors into biologically active ones. This study aims to further validate its potential to improve outcomes and quality of life for cancer patients."

While neoadjuvant (chemo)-radiotherapy can reduce recurrence and enable organ preservation in some patients with rectal cancer, fewer than 30% achieve a complete response and some patients still develop distant recurrences. Current adjuvant options are also limited, highlighting the need for effective, well-tolerated treatments that can prevent relapse without compromising quality of life.

The aim of this study is to investigate the safety, tolerability, and efficacy of neoadjuvant treatment with BT-001 combined with an anti-PD-1 antibody prior to standard surgery in patients with primary, localized rectal cancer.

Transgene and BioInvent are co-developing BT-001, developed using Transgene’s Invir.IO platform armed to express GM-CSF and BioInvent’s full-length anti-CTLA-4 monoclonal antibody, to trigger a strong anti-tumor immunity while minimizing systemic exposure.

With the ability to induce both local and systemic anti-tumor immune responses (see press release), BT-001 is a prime candidate to remodel the pMMR rectal cancer tumor microenvironment and enhance immune checkpoint inhibition without adding significant treatment-related toxicity, as evidenced by early clinical trials of BT-001 in patients with treatment-resistant metastatic cancers.

(Press release, Transgene, NOV 5, 2026, View Source [SID1234674329])