Cancer Research UK and Sosei Heptares sign agreement to advance cancer immunotherapy candidate into clinical trials

• HTL0039732 is a novel EP4 antagonist with potential to treat a wide range of cancers in combination with other immunotherapies

Tokyo, Japan, London and Cambridge, UK, 22 July 2022 – Sosei Group Corporation (“the Company”; TSE: 4565), an international biopharmaceutical company and world-leader in GPCR¹-focused structure-based drug design (SBDD) and development, and Cancer Research UK, the world’s largest private funder of cancer research, today announce the signing of an agreement to bring Sosei Heptares’ cancer immunotherapy drug candidate into a first-in-human trial.

Under the Clinical Trial and Licence Agreement (CTLA), Cancer Research UK’s Centre for Drug Development will sponsor, design and execute a Phase I/IIa clinical trial of HTL0039732², a novel selective EP4 antagonist.

Sosei Heptares will be responsible for CTA enabling activities, including GLP toxicology, IMP manufacture¹ and other necessary pre-clinical studies in preparation for the opening of the clinical trial. Sosei Heptares holds a licence to the results generated under the trial to continue the clinical development and commercialisation of HTL0039732.

HTL0039732 has been proposed for a range of cancers including microsatellite stable³ colorectal, gastroesophageal, head and neck and castrate resistant prostate cancer.

Many people with these types of cancer have missed out on the benefits that common immunotherapies, such as PD1/L1 checkpoint inhibitors⁴, have brought to other cancer types. The hope is that this trial could find that HTL0039732 is an effective immunotherapy for these under-served patient populations.

HTL0039732 is a type of immunotherapy known as an EP4 antagonist, which means it selectively binds and blocks a specific type of prostaglandin receptor⁵ called EP4. Prostaglandin E2 (PGE2) mediated signalling through EP4 can trigger cancer cells to evade the immune system and can also influence tumour cell growth. Therefore, blocking this type of receptor may improve patient survival, especially if used in combination with another immunotherapy.

The Director of Cancer Research UK’s Centre for Drug Development, Dr Nigel Blackburn, said: “People with these cancer types have, to date, largely missed out on some of the remarkable advances in the field of immunotherapy.

"We are therefore thrilled to be partnering with Sosei Heptares to bring their novel immunotherapy candidate into human trials. The hope is that with more trials like this, all cancer patients will eventually be able to benefit from this potentially life-saving form of cancer treatment.”

Matt Barnes, President of Heptares Therapeutics and Head of UK R&D, commented: “We are extremely pleased to collaborate with Cancer Research UK to advance HTL0039732 into Phase I/IIa clinical trials and take a step towards bringing new treatments to cancer patients.

“HTL0039732 was rationally designed using our highly productive SBDD platform specifically for this type of immunotherapy approach and as such we believe it offers the potential to be a best-in-class EP4 antagonist agent.”