Sosei Heptares Initiates Phase 1 Trial with Novel Small-Molecule CGRP Antagonist under Collaboration with Biohaven

Tokyo, Japan and Cambridge, UK, 23 June 2021 – Sosei Group Corporation (“the Company”; TSE: 4565) today announces that the first healthy subject has been dosed with HTL0022562 in a Phase 1 clinical study. HTL0022562 (also known as BHV3100) is a novel, small molecule CGRP* receptor antagonist discovered by Sosei Heptares and the lead compound in a portfolio of CGRP antagonists licensed to Biohaven Pharmaceutical Holding Company Ltd. (“Biohaven”, NYSE: BHVN) in December 2020 for development as new therapies for CGRP-mediated disorders.

The trial is a Phase 1, randomized, double-blind, placebo-controlled, first-in-human study to evaluate the safety, tolerability, and pharmacokinetics of a single ascending dose and multiple ascending doses of subcutaneous HTL0022562 in healthy adult subjects. The trial aims to enroll 88 subjects at a single center in the UK and is expected to complete in 2022.

Sosei Heptares has advanced HTL0022562 successfully though a preclinical development program demonstrating its promising and differentiated properties for further investigation in human trials.

Under the global collaboration and license agreement with Biohaven, Sosei Heptares will conduct the Phase 1 clinical trial itself, receiving a milestone payment for its initiation, and is also eligible for development costs for conducting the trial. Biohaven will lead all future studies and development activities and Sosei Heptares will be eligible for further milestone payments and royalties.

Although the event reported today has no significant impact on the consolidated financial results for the accounting period ending 31 December 2021, the Company considers that an important developmental milestone has been achieved with HTL0022562 becoming the tenth drug candidate overall generated from Sosei Heptares’ SBDD platform to enter clinical development, and therefore makes this announcement.

Tim Tasker, Executive Vice President and Chief Medical Officer of Sosei Heptares, said: “We are pleased to initiate this new clinical trial with HTL0022562 following the successful discovery and preclinical development work conducted by Sosei Heptares. We are also delighted at the speed of progress and the positive collaborative approach that has developed between our team and our partners at Biohaven and the confidence they have shown in our early clinical development capabilities. Together, we are committed to developing this novel differentiated agent to treat CGRP-mediated diseases with unmet need.”

*Abbreviations used: CGRP - calcitonin gene-related peptide