Press release
Nov 12, 2021

Sosei Heptares Notes that its Partnered Adenosine A2a Antagonist Imaradenant (AZD4635) has been Removed from AstraZeneca’s Clinical Pipeline

Tokyo, Japan and Cambridge, UK, 12 November 2021 – Sosei Group Corporation (“the Company”; TSE: 4565) notes that in AstraZeneca’s third quarter 2021 clinical trials appendix presentation (published today and available on, the oral, small molecule adenosine A2a receptor antagonist imaradenant (AZD4635) has been removed from its clinical development pipeline as part of its ongoing pipeline prioritization. Imaradenant was discovered by Sosei Heptares and licensed to AstraZeneca in 2015.

AstraZeneca has been evaluating imaradenant in Phase 1 and 2 clinical trials as a monotherapy and in combination with Imfinzi (durvalumab) in solid tumors. In these trials, imaradenant, with or without Imfinzi, was found to be safe and well tolerated and associated with clinical benefit in some immune checkpoint-naïve patients with metastatic castrate-resistant prostate cancer (mCRPC). Imaradenant has been extensively tested in patients with a range of different solid tumor types and has been demonstrated to be safe and well tolerated at escalating doses.

Targeting the production or action of adenosine is a promising strategy for overcoming immune suppression in the tumor microenvironment, and several companies have now disclosed positive results from early clinical trials.

AstraZeneca has a diverse oncology pipeline that requires it to regularly make strategic prioritization decisions regarding projects in its portfolio. Following the removal of the imaradenant program from AstraZeneca’s clinical pipeline, Sosei Heptares will discuss with its partner AstraZeneca the next steps for the future of imaradenant, including the possibility of the Company regaining worldwide rights to the licensed program.

The event reported today has no material impact on the consolidated financial results for the fourth quarter and full year accounting period ending 31 December 2021. Should any impacts or other matters that require an announcement be identified, the Company will announce such matters promptly.

Shinichi Tamura, President and CEO of Sosei Heptares, commented: “The imaradenant clinical program has generated encouraging clinical results in cancer patients under AstraZeneca’s guidance. We respect their decision on imaradenant, as a result of a pipeline portfolio review, and we are keen to assess the possibility of regaining the worldwide rights in order to evaluate the future clinical development and/or re-licensing potential of the program, as we have successfully done so on multiple occasions. AstraZeneca is one of our longest serving partners, and we have enjoyed a highly productive collaboration with them. We look forward to the ongoing discussions about the future of imaradenant and will report the outcome in due course.”