The patient is taking part in a phase 1/2a trial with the immunotherapy drug HTL0039732 for advanced solid tumors. Sosei Heptares’ drug works by blocking signalling through a specific type of prostaglandin receptor – the E2 (PGE2)-type prostanoid receptor 4 (EP4).
Sosei Group Corporation, the world-leader in GPCR-focused structure-based drug design (SBDD) and development, and Cancer Research UK, the world’s largest independent funder of cancer research have been working together on the trial evaluating Sosei Heptares’ orally available small molecule cancer immunotherapy drug HTL0039732 for advanced solid tumors.
HTL0039732 works by blocking signalling through a specific type of prostaglandin receptor, the prostaglandin E2 (PGE2)-type prostanoid receptor 4 (EP4). In cancer, PGE2 acts in the tumor microenvironment to trigger cancer cells to evade the immune system. Targeting EP4 to block the effects of PGE2 increases the ability of the immune system to detect and control cancer cells and makes HTL0039732 a potential candidate to treat patients with cancers that generally do not respond well to current immunotherapies.
Cancers not responding to current immunotherapies
These include microsatellite stable colorectal, gastroesophageal, head and neck, and castrate-resistant prostate cancer. Positive results from the trial will bring effective treatment closer to these underserved patient populations.
Approximately 80–85% of colorectal cancer patients are classified as ‘microsatellite stable’ (MSS), which means they have low instability in short, repeated sequences of DNA in their tumours, known as microsatellites. MSS tumours often exist in an environment that suppresses the immune system and do not respond well to immunotherapies.
Matt Barnes, president of Heptares Therapeutics and head of UK R&D, said: “We are very pleased to be collaborating with Cancer Research UK to advance HTL0039732 into clinical development. This novel oral small molecule drug candidate was rationally designed using our SBDD platform and has the potential to become a best-in-class approach to enhance the efficacy of immunotherapies used to treat many cancer patients.”
Cancer Research UK’s Centre for Drug Development (CDD) is sponsoring, designing and conducting the trial with three main objectives: to define the toxicity, tolerability and pharmacokinetics of HTL0039732, to identify the recommended dose for phase 2 studies, and to assess its antitumor activity as a monotherapy and in combination with the PD-L1 inhibitor atezolizumab.
'Desperately need more trials like this'
Nigel Blackburn, director of Cancer Research UK’s CDD, said: “We are delighted to have reached this next significant milestone in our partnership with Sosei Heptares. The fact that immunotherapy works for some patients but not others means we desperately need more trials like this to open up potentially life-saving treatment options to more people.”
Phase 2a of the trial will expand the optimal combination dose in up to four cohorts in specified cancer indications. Sosei Heptares holds a license to the results generated under the trial to continue the clinical development and commercialization of HTL0039732.
Chief investigator Bristi Basu, University of Cambridge, and co-chief investigator Debashis Sarker, King’s College London, are leading the trial. Patient recruitment has been initiated in the UK at Cambridge University Hospitals and Guy’s and St Thomas’ NHS Foundation Trusts, with additional sites across the Experimental Cancer Medicine Centre (ECMC) network to open soon.
Immnosuppresive environment
Dr. Bristi Basu, University of Cambridge, said: “We are excited to be opening a new UK clinical trial using HTL0039732 to target a protein called EP4, a member of the prostaglandin receptor family that has been implicated in creating the immunosuppressive environment which promotes tumor growth in multiple cancer types.
“By studying HTL0039732 alone and in combination with immunotherapy, we aim to understand more about how to optimize modulation of the immune system to fight cancers. We hope that this EP4-targeting approach will deliver a promising route to improving treatment options for patients with a broad range of cancers.”
The UK Medicines and Healthcare products Regulatory Agency (MHRA) has granted HTL0039732 an Innovation Passport, the first step in its Innovative and Licensing Access Pathway (ILAP), which aims to improve patient access to new medicines by reducing the time to market. The MHRA grants Innovation Passports to medicines that treat life-threatening or seriously debilitating conditions, and where there is a significant patient or public health need.
