Sosei Group Corporation: Sosei Heptares Regains Full Ownership from GSK of HTL0027477, a Clinic-ready, First-in-Class Oral GPR35 Agonist for Inflammatory Bowel Disease

• GPR35 is a novel target with an established genetic association to IBD
  
• UK regulatory approval received to commence first-in-human studies
• Return of rights follows change in immunology research strategy by GSK

Tokyo, Japan and Cambridge, UK, 21 March 2024 - Sosei Group Corporation ("Sosei Heptares" or "the Company"; TSE: 4565) announces it has regained full ownership from GSK of HTL0027477 (formerly GSK4381406), a clinic-ready, highly selective, first-in-class, oral GPR35 agonist in development as a potential new treatment for Inflammatory Bowel Diseases (IBD).

GPR35 is an important orphan G protein-coupled receptor ("GPCR") with an established genetic association to IBD, for which there remains significant unmet need for millions of sufferers worldwide.

HTL0027477 was designed by Sosei Heptares using its proprietary structure-based drug design (SBDD) platform and licensed to GSK in 2020. Since then, HTL0027477 has been advanced through a joint development program, generating promising mechanistic, preclinical efficacy and safety data suggesting that it may have the potential to improve intestinal barrier function and reduce visceral pain in gastrointestinal indications such as ulcerative colitis and irritable bowel syndrome. The UK Medicines and Healthcare products Regulatory Agency ("MHRA") gave approval in mid-2023 for HTL0027477 to be investigated in first-in-human studies.

The process to regain rights to the program was initiated in late 2023 following a decision by GSK to deprioritize and discontinue its development following changes to both its immunology research strategy and immunology research leadership. The decision was not based on any scientific, preclinical or safety data related to the candidate.

Sosei Heptares regained full ownership of the HTL0027477 program including associated intellectual property licensed by Sosei Heptares to GSK, and preclinical data generated under the partnership for no upfront payment. Sosei Heptares expects to determine the optimal strategy for further clinical development of the program, which could include in-house development and re-partnering.

Matt Barnes, President of Heptares Therapeutics and Head of UK R&D, commented: "The return of the GPR35 agonist program, with its first-in-class mechanism of action and potential to address major unmet needs in IBD worldwide, is a strong addition to our growing clinical pipeline. This exciting program has already delivered highly promising preclinical data that support its potential as a new therapy for IBD and is poised to enter a Phase 1 clinical trial. This presents a clear opportunity for Sosei Heptares to further advance this program while determining the optimal path forward for further development and commercialization."

-ENDS-

About Sosei Heptares

Sosei Heptares is a fully integrated biopharmaceutical company focused on bringing life-changing medicines based on world-class science to patients globally. Our vision is to become one of Japan's global biopharmaceutical champions.

Our global business combines our world-leading GPCR-targeted StaR® technology, structure-based drug design and early development capabilities in the UK with a highly experienced clinical development capability and a commercial operation in Japan.

We are leveraging these capabilities to generate and advance a broad and deep pipeline of novel medicines across multiple therapeutic areas, including neurology, immunology, gastroenterology and inflammatory diseases. We intend to develop these opportunities for patients in Japan and globally both internally and through our partnerships with global biopharmaceutical companies and emerging technology companies.

Sosei Heptares operates from key locations in Tokyo and Osaka (Japan), London and Cambridge (UK), Basel (Switzerland) and Seoul (South Korea).

"Sosei Heptares" is the corporate brand and trademark of Sosei Group Corporation, which is listed on the Tokyo Stock Exchange (ticker: 4565). Sosei, Heptares, the logo and StaR® are trademarks of Sosei Group companies.

For more information, please visit https://soseiheptares.com/
LinkedIn: @soseiheptaresco | X: @soseiheptaresco | YouTube: @soseiheptaresco

Enquiries:

Sosei Heptares - Media and Investor Relations
Kentaro Tahara, VP Investor Relations and Corporate Strategy
Shinichiro Nishishita, VP Investor Relations, Head of Regulatory Disclosures
Maya Bennison, Communications Manager
[phone] | [phone] | [e-mail]

MEDiSTRAVA Consulting (for International Media)
Mark Swallow, Frazer Hall, Erica Hollingsworth
[phone] | [e-mail]

Forward-Looking Statements
This press release contains forward-looking statements, including statements about the discovery, development, and commercialization of products. Various risks may cause Sosei Group Corporation's actual results to differ materially from those expressed or implied by the forward-looking statements, including: adverse results in clinical development programs; failure to obtain patent protection for inventions; commercial limitations imposed by patents owned or controlled by third parties; dependence upon strategic alliance partners to develop and commercialize products and services; difficulties or delays in obtaining regulatory approvals to market products and services resulting from development efforts; the requirement for substantial funding to conduct research and development and to expand commercialization activities; and product initiatives by competitors. As a result of these factors, prospective investors are cautioned not to rely on any forward-looking statements. We disclaim any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.