VOLUNTARY ANNOUNCEMENT - HUTCHMED Highlights Publication of Phase III ESLIM-01 Results in The Lancet Haematology

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement.HUTCHMED (China) Limited 和黄医药（中国）有限公司 (?ncorporated in the Cayman ?slands with limited liability) (Stock Code: ??) VOLUNTARY ANNOUNCEMENT HUTCHMED Highlights Publication of Phase III ESLIM-01 Results in The Lancet Haematology — Publication shows treatment demonstrated durable response rate of 48.4% vs. 0% with placebo — — Presentations at EHA showcased subgroup analyses demonstrating consistent benefits regardless of prior lines of therapies or prior TPO/TPO-RA1 exposure — — Data supported regulatory submission in China accepted in January 2024 — HUTCHMED (China) Limited (“HUTCHMED”) today announces that results from ESL?M-01 HUTCHMED’s Phase ??? trial of sovleplenib (HMPL-523) in adult patients with primary immune thrombocytopenia (“?TP”) in China were published in The Lancet Haematology. Additional details and subgroup results of the study were also presented on June 14 at the European Hematology Association (“EHA”) 2024 Hybrid Congress as an oral and two poster presentations.Sovleplenib is a novel selective oral inhibitor targeting spleen tyrosine kinase (“Syk”) for the treatment of hematological malignancies and immune diseases. Syk is a component in Fc receptor (“FcR”) and B-cell receptor signaling pathway. ?TP is a complex autoimmune bleeding disorder leading to a reduced platelet level in the peripheral blood. ?TP can also impact on patients’ quality of life due to fatigue restrictions on activities and anxiety. The ESL?M-01 trial results published by The Lancet Haematology suggest that sovleplenib could be a potential treatment option for patients with ?TP who received at least one prior therapy.ESL?M-01 is a 2:1 randomized double-blind Phase ??? study conducted in 188 adult patients with primary ?TP who had received at least one previous anti-?TP treatment (NCT05029635). The study demonstrated a clinically meaningful early and sustained durable platelet response in patients with primary ?TP with a tolerable safety profile and improvement in quality of life. The primary endpoint was met with durable response rate of 48.4% (61/126) with sovleplenib compared to zero with placebo (p<0.0001) which was consistent across most pre-defined subgroups. ?n addition overall response rates were 68.3% at 0–12 weeks and 70.6% at 0–24 weeks with sovleplenib compared to 14.5% and 16.1% with placebo (p<0.0001). The median time to response was 8 days with sovleplenib compared to 30 days with placebo.Further post-hoc subgroup analysis of the study demonstrated consistent clinical benefits across ?TP patients regardless of prior lines of ?TP therapies or prior TPO/TPO-RA exposure including TPO/TPO-RA treatment types and number of prior regimens. Most patients were heavily pretreated with a median of four prior lines of ?TP therapy. ?n patients who received four or more prior lines of therapy the durable response rate was 47.7% with sovleplenib compared to 0% with placebo (p<0.0001). ?n addition a majority of the patients had received prior TPO/TPO-RA. 74.6% of patients in the sovleplenib group had received prior treatment with TPO/TPO-RA and analysis in this subgroup also demonstrated a significantly higher durable response rate of 46.8% with sovleplenib compared to zero with placebo (p<0.0001). 1The safety profile of sovleplenib in ESL?M-01 was consistent with previously reported studies. The majority of treatment-emergent adverse events (“TEAEs”) were mild or moderate in severity (grade 1 or 2). Grade 3 or above TEAEs were reported in 25.4% of patients with sovleplenib and 24.2% with placebo. Sovleplenib also significantly improved quality of life in physical functioning and energy/fatigue (p<0.05).2 The China National Medical Products Administration (“NMPA”) granted Breakthrough Therapy designation for this indication and accepted the New Drug Application (“NDA”) for review with Priority Review in January 2024. A dose-finding study in the U.S. is being planned (NCT06291415). HUTCHMED also initiated the registration stage of the Phase ??/??? clinical trial of sovleplenib in adult patients with warm antibody autoimmune hemolytic anemia (“wA?HA”) in China in March 2024 (NCT05535933). HUTCHMED retains all rights to sovleplenib worldwide.About ITP ?TP is an autoimmune disorder characterized by immunologic destruction of platelets and decreased platelet production.Patients with ?TP are at increased risk of excessive bleeding and bruising.3 ?TP is also associated with fatigue (reported in up to 39% of adults with ?TP) and impaired quality of life.45 678 The incidence of primary ?TP in adults is 3.3/100000 adults per year with a prevalence of 9.5 per 100000 adults.9 Based on this prevalence rate approximately 110000 patients are estimated to be living with primary ?TP in China in addition to 56000 patients in the U.S. Germany France ?taly Spain UK and Japan. ?t has been estimated that as many as 145000 patients are living with chronic ?TP in major pharmaceutical markets excluding China.10 Adult ?TP is a heterogeneous disease that can persist for years even with best available care and treatments are infrequently curative. Despite availability of several treatments with differing mechanisms of action chronicity of disease continues to be a problem. Many patients develop resistance to treatment and thereby are prone to relapse.11 Thus there remains a significant population of patients who have limited sensitivity to currently available agents and are in need of new treatments.As platelet destruction in ?TP is mediated by Syk-dependent phagocytosis of FcγR-bound platelets Syk inhibition represents a promising approach to management of ?TP.12 About Sovleplenib Sovleplenib is a novel selective inhibitor of Syk for once daily oral administration. Syk a non-receptor tyrosine kinase is a major component in B-cell receptor and FcR signaling and is an established target for the treatment of multiple subtypes of B-cell lymphomas and autoimmune disorders.Sovleplenib is currently under clinical investigation and its safety and efficacy have not been approved by any regulatory authority.HUTCHMED retains all rights to sovleplenib worldwide. ?n addition to ?TP sovleplenib is also being studied in warm antibody autoimmune hemolytic anemia (NCT05535933) and indolent non-Hodgkin’s lymphoma (NCT03779113).About HUTCHMED HUTCHMED (Nasdaq/A?M:HCM; HKEX:13) is an innovative commercial-stage biopharmaceutical company. ?t is committed to the discovery global development and commercialization of targeted therapies and immunotherapies for the treatment of cancer and immunological diseases. ?t has approximately 5000 personnel across all its companies at the center of which is a team of about 1800 in oncology/immunology. Since inception it has focused on bringing cancer drug candidates from in-house discovery to patients around the world with its first three oncology medicines marketed in China the first of which is also marketed in the U.S. For more information please visit: www.hutch-med.com or follow us on Linked?n. 2Forward-Looking Statements This announcement 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 HUTCHMED’s current expectations regarding future events including its expectations regarding the therapeutic potential of sovleplenib for the treatment of patients with ?TP and the further development of sovleplenib in this and other indications. Forward- looking statements involve risks and uncertainties. Such risks and uncertainties include among other things assumptions regarding the timing and outcome of clinical studies and the sufficiency of clinical data to support NDA approval of sovleplenib for the treatment of patients with ?TP or other indications in China or other jurisdictions its potential to gain approvals from regulatory authorities on an expedited basis or at all the safety profile of sovleplenib HUTCHMED’s ability to fund implement and complete its further clinical development and commercialization plans for sovleplenib and the timing of these events. 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 these and other risks see HUTCHMED’s filings with the U.S. Securities and Exchange Commission The Stock Exchange of Hong Kong Limited and on A?M. HUTCHMED undertakes no obligation to update or revise the information contained in this announcement whether as a result of new information future events or circumstances or otherwise.Medical Information This announcement contains information about products that may not be available in all countries or may be available under different trademarks for different indications in different dosages or in different strengths. Nothing contained herein should be considered a solicitation promotion or advertisement for any prescription drugs including the ones under development. 1 TPO = Thrombopoietin; TPO-RAs = Thrombopoietin receptor agonists. 2 Hu Y et al. Efficacy and safety of the Syk inhibitor sovleplenib (HMPL-523) in adult patients with primary immune thrombocytopenia in China (ESL?M-01): a randomized double-blind placebo-controlled phase 3 study [published online ahead of print 2024 Jun 14]. Lancet Haematol. 2024. 3 Zufferey A et al. Pathogenesis and Therapeutic Mechanisms in ?mmune Thrombocytopenia (?TP). J. Clin. Med. 2017 6(2) 16. 4 McMillan R et al. Self-reported health-related quality of life in adults with chronic immune thrombocytopenic purpura. Am J Hematol. 2008 Feb;83(2):150-4. 5 Snyder CF et al. Health-related quality of life of immune thrombocytopenic purpura patients: results from a web-based survey. Curr Med Res Opin. 2008 Oct;24(10):2767-76. 6 Doobaree ?U et al. Thromboembolism in adults with primary immune thrombocytopenia: a systematic literature review and meta-analysis. Eur J Haematol. 2016 Oct;97(4):321-30. 7 Sarpatwari A et al. Thromboembolic events among adult patients with primary immune thrombocytopenia in the United Kingdom General Practice Research Database. Haematologica. 2010 Jul;95(7):1167-75. 8 Sarpatwari A et al. Health-related lifestyle in adults and children with primary immune thrombocytopenia (?TP). Br J Haematol. 2010 Oct;151(2):189- 91. 9 Lambert MP Gernsheimer TB. Clinical updates in adult immune thrombocytopenia. Blood. 2017 May 25;129(21):2829-2835. 10 Clarivate Landscape & Forecast for ?mmune Thrombocytopenic Purpura 2018. 11 Provan D et al. Updated international consensus report on the investigation and management of primary immune thrombocytopenia. Blood Adv. 2019;3(22):3780-3817. 12 Crowley MT et al. A critical role for Syk in signal transduction and phagocytosis mediated by Fcγ receptors on macrophages. J. Exp. Med. 186(7) 1027– 1039(1997). 3By Order of the Board Edith Shih Non-executive Director and Company Secretary Hong Kong June 17 2024 As at the date of this announcement the Directors of the Company are: Chairman and Non-executive Director: Non-executive Directors: Dr Dan ELDAR Ms Edith SH?H Ms Ling YANG Executive Directors: Dr Weiguo SU Independent Non-executive Directors: (Chief Executive Officer and Mr Paul Rutherford CARTER Chief Scientific Officer) (Senior ?ndependent Director) Mr CHENG Chig Fung Johnny Dr Renu BHAT?A (Chief Financial Officer) Mr Graeme Allan JACK Professor MOK Shu Kam Tony 4