Accession Therapeutics doses first patient in Phase 1 clinical trial of TROCEPT-01 (ATTR-01), a novel cancer immunotherapy

OXFORD, England, Nov. 17, 2025 /PRNewswire/ -- Accession Therapeutics Limited, a biopharmaceutical company developing next generation cancer immunotherapies, today announced it has dosed the first patient in its Phase I clinical trial evaluating TROCEPT-01 (ATTR-01), the company's lead drug candidate from its proprietary TROCEPT platform technology. The patient has now completed the cycle of treatment. This milestone marks a major step forward in the development of a potentially transformative treatment for solid tumours.

TROCEPT-01 (ATTR-01) is a first-in-class, tumour-activated viral immunotherapy that, following systemic delivery, is designed to selectively generate a clinically validated checkpoint inhibitor within tumours. This approach, targeting αvβ6 integrin on epithelial tumours, optimises efficacy while minimising damage to healthy tissue. Preclinical studies have demonstrated strong anti-tumour activity across multiple solid tumour models, supporting its potential as a targeted therapy for aggressive cancers.

The ATTEST trial is an open label, dose-escalation and dose expansion study (https://www.isrctn.com/ISRCTN38972074) designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of TROCEPT-01 (ATTR-01) in patients with advanced carcinomas who have had at least one prior treatment course. The trial is being conducted at leading clinical sites across the UK. Additional trial sites will be activated as the study progresses, including in Spain where there is established expertise in the treatment of solid tumours.

Professor Adel Samson, Professor of Cancer Medicine and Immunotherapy at Leeds University School of Medicine and lead Investigator in the ATTEST study, said:
"As a clinician, I am very excited about the potential of TROCEPT-01 (ATTR-01) and the TROCEPT platform to increase clinical response rates through high tumour-localised production of anti-cancer drugs. This program is targeted at solid tumours where there is significant need for better treatment outcomes".

Bent Jakobsen, PhD FMedSci, CEO of Accession Therapeutics, said:
"Dosing the first patient in our TROCEPT-01 clinical trial is a pivotal moment for Accession Therapeutics and a testament to the dedication of our team and collaborators. In TROCEPT, we have created a unique, highly versatile platform that enables novel drugs to be made inside cancer cells. The platform gives us multiple opportunities to generate valuable products to transform outcomes for cancer patients. TROCEPT-01 (ATTR-01) has the potential to expand the indications where checkpoint inhibitors have been successful."

Professor Hardev Pandha, FRCP, FRACP, PhD, Medical Director of Accession Therapeutics, added:
"TROCEPT-01 (ATTR-01) represents a novel approach to target hard-to-treat cancers, and we are excited to advance this promising therapy into clinical development. We anticipate the clinical data will show that the virus gets to the tumours when given systemically, and that the drug is produced within the tumours. Our goal in the ATTEST study is to establish a strong safety profile while identifying early signals of efficacy to benefit patients with limited treatment options."

For more information about the study, please visit our website, the UK Clinical Study Registry (ISRCTN) or the US National Institutes of Health database of clinical research studies.

For more information, please contact:
Victoria Foster Mitchell
[email protected]

Stephanie Bewick - Chief Business Officer
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About Accession Therapeutics Limited

Accession Therapeutics is a clinical-stage biopharmaceutical company developing a novel class of tumour-targeted immunotherapies through its proprietary TROCEPT platform. The company is advancing a pipeline of first-in-class therapies designed to transform cancer treatment by enabling localised production of therapeutic proteins within tumours while minimising systemic exposure, potentially offering superior efficacy and safety profiles to existing immuno-oncology approaches. The potential of TROCEPT is illustrated in the animation here.

Since inception in 2021, the Company has raised USD $70 million to advance its TROCEPT technology and programmes.

For more information, visit www.accessiontherapeutics.com.

About TROCEPT-01 (ATTR-01)

The Company's lead investigational therapy utilises the company's proprietary TROCEPT platform to deliver a genetically encoded immune checkpoint inhibitor (anti-PD-L1) directly to tumour cells. This innovative approach enables cancer cells to locally produce and secrete therapeutic proteins within the tumour microenvironment, creating a potent anti-tumour response while minimising systemic exposure. Unlike conventional immunotherapies administered systemically, TROCEPT-01's tumour-targeted mechanism has demonstrated in preclinical studies the potential to enhance drug concentration at the tumour site compared to healthy tissues, significantly improving the therapeutic window. The therapy is designed to overcome limitations of current checkpoint inhibitors by increasing response rates in immunologically "cold" tumours and reducing off-target immune-related adverse events. Administered intravenously, TROCEPT-01 represents a promising new modality in cancer treatment, with potential applications across multiple solid tumour types.

SOURCE Accession Therapeutics