IMG-004 demonstrated extended half-life and durable pharmacodynamic characteristics in a Phase 1 study

SAN DIEGO,SHANGHAI and SYDNEY,April 28,2023 -- Inmagene Biopharmaceuticals ("Inmagene") today announced positive topline results from a Phase 1 study evaluating IMG-004 in healthy participants.

IMG-004 is a potent,non-covalent,reversible,and brain permeable third-generation Bruton's tyrosine kinase (BTK) inhibitor. Inmagene is developing the drug candidate to potentially treat immunological diseases.

The study was a single ascending dose design with dose levels of 30 mg to 600 mg. The objectives of the study were to evaluate the safety,pharmacokinetic,and pharmacokinetic effects of IMG-004 in healthy participants. A total of 40 participants were randomized in the study,with 30 participants receiving IMG-004 and 10 receiving placebo. Additional details can be found at clinicaltrials.gov,using identifier NCT05349097.

IMG-004 was well tolerated,with no dose-limiting or serious adverse events. It was rapidly absorbed following the oral administration with peak concentrations occurring around 2 hours post-treatment and was eliminated with a terminal half-life ranging from 26 to 37 hours. In an ex vivo basophil CD63 activation assay,IMG-004 showed robust and dose-dependent target engagement. A maximum (approximately 95%) inhibition of basophil activation was observed at a dose level as low as 100 mg,up to 600 mg. Sustained inhibition (80-90%) of basophil activation was observed at 100mg up to 600mg,for at least 72 hours post-treatment.

"BTK remains an attractive target for autoimmune diseases but many BTK inhibitors have been limited by serious safety risks due to their molecular features," commented Dr. Yufang Lu,Chief Medical Officer of Inmagene. "Designed specifically as a non-covalent,and brain permeable BTK inhibitor,IMG-004 has demonstrated a longer half-life and pharmacodynamic effect than most leading BTK inhibitors. It presents the best-in-class potential as a therapeutic candidate for autoimmune diseases."

Dr. Michael Shi,Head of R&D and Chief Medical Officer of HUTCHMED commended,"Autoimmune diseases are often chronic,requiring long-term care and monitoring. We understand and value the desire for safety,convenience and quality of life for this group of patients. Our teams are committed to the discovery and development of novel treatment options to address the high unmet medical needs."

About IMG-004

Designed specifically for inflammatory and autoimmune diseases that usually require long-term treatment,IMG-004 is potent,highly selective and brain permeable. It was originally discovered by HUTCHMED,with Inmagene assuming the development responsibility at the candidate stage. Inmagene has an exclusive option to in-license IMG-004's global rights for the treatment of immunological diseases.

About Inmagene

Inmagene is a global clinical-stage biotechnology company focused on developing novel therapeutics for immunology-related diseases. Inmagene's most advanced drug candidate is IMG-020 (izokibep),which has successfully met the protocol endpoints in global Phase 2 studies for both psoriasis and psoriatic arthritis (PsA). It has received the IND approval from China's Center for Drug Evaluation (CDE) for Phase 3 studies in plaque psoriasis. In addition,IMG-007,a monoclonal antibody (mAb) against OX40 with a silenced antibody-dependent cell-mediated cytotoxicity (ADCC) function,is entering two global Phase 2 clinical trials. IMG-004 is in Phase 1 development. Moreover,IMG-008,a long-acting mAb against IL-36 receptor (IL-36R),has been cleared by the FDA via an IND-application for Phase 1 clinical development.

Believing in "Borderless Innovation",the Inmagene team strives to integrate efficient resources worldwide to develop novel therapeutics for global patients. Based on its proprietary QuadraTek® platform,Inmagene creates and develops several novel drug candidates with global rights. Inmagene also in-licenses drug candidates and,together with its partners,carries out global development activities,including global multi-center clinical trials. Inmagene has formed strategic partnerships with multiple partners,such as HUTCHMED and Affibody AB,to develop highly innovative drug candidates. For more information,please visit: www.inmagenebio.com

About HUTCHMED

HUTCHMED is an innovative,commercial-stage,biopharmaceutical company. It is committed to the discovery and global development and commercialization of targeted therapies and immunotherapies for the treatment of cancer and immunological diseases. It has more than 4,600 personnel across all its companies,at the center of which is a team of about 1,700 in oncology/immunology. Since inception it has advanced 12 cancer drug candidates from in-house discovery into clinical studies around the world,with its first three oncology drugs now approved and marketed in China. For more information,please visit: www.hutch–med.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the U.S. Private Securities Litigation Reform Act of 1995. These forward-looking statements reflect Inmagene's and/or HUTCHMED's current expectations regarding future events,including expectations regarding the therapeutic potential of IMG-004 for the treatment of patients with immunological diseases,the further clinical development of IMG-004,expectations as to whether clinical studies of IMG-004 would meet their primary or secondary endpoints,and expectations as to the timing of the completion and the release of results from such studies. Forward-looking statements involve risks and uncertainties. Such risks and uncertainties include,among other things,assumptions regarding IMG-004's potential to successfully advance in clinical studies and to eventually gain approvals in any jurisdiction,the safety profile of IMG-004,the timing of these events,and the impact of the COVID-19 pandemic on general economic,regulatory and political conditions. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements,which speak only as of the date hereof. For further discussion of various risks applicable to HUTCHMED,see HUTCHMED's filings with the U.S. Securities and Exchange Commission,on AIM and with The Stock Exchange of Hong Kong Limited. Neither Inmagene nor HUTCHMED undertakes to update or revise the information contained in this press release,whether as a result of new information,future events or circumstances or otherwise.