VOLUNTARY ANNOUNCEMENT - SYH2051 (SELECTIVE ATM INHIBITOR) OBTAINS CLINICAL TRIAL APPROVAL IN THE U.S.

Hong Kong Exchanges and Clearing Limited and The Stock Excha nge 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 whatsoe ver for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this ann ouncement. CSPC PHARMACEUTICAL GROUP LIMITED (Incorporated in Hong Kong with limited liability) (Stock Code: 1093) ʮ ̡ VOLUNTARY ANNOUNCEMENT SYH2051 (SELECTIVE ATM INHIBITOR) OBTAINS CLINICAL TRIAL APPROVAL IN THE U.S. The board of directors (the ‘‘Board ’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company ’’, together with its subsidiaries, the ‘‘Group ’’) is pleased to announce that SYH2051 (the ‘‘Product ’’) developed by the Group has been approved by the U.S. Food and D rug Administration (FDA) to conduct clinical trials in the U.S. The Product has also obtained app roval from the National Medical Products Administration of the People ’s Republic of China in June 2023 to conduct clinical trials in China. The Product is a Class 1 chemical drug independently develop ed by the Group. As an ATM inhibitor, the Product selectively delays the repairing of DNA double- strand breaks through targeted inhibition of phosphorylation of ATM protein kinase and its downstream si gnaling proteins CHK2 and KAP1, causing persistent DNA double-strand breaks and ATM-media ted cell cycle arrest to inhibit the proliferation of tumor cells. The indication for this appro val is advanced solid tumors. Preclinical studies demonstrated that the Product had good selectivity of ATM targets and exhibited excellent in vitro and in vivo activities, providing a promising clinica l development value. The Product has completed a Phase Ia dose escalation trial of monotherapy in advanced solid tumors in China, obtaining the safety profile and human pharmacokinetic data for monot herapy. Currently, a series of clinical trials, including combination with radiotherapy, combina tion with antibody-drug conjugate (ADC), and combination with chemotherapy, are being actively carried out. By order of the Board CSPC Pharmaceutical Group Limited CAI Dongchen Chairman Hong Kong, 13 March 2025 As at the date of this announcement, the Board comprises Mr. C AI Dongchen, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Mr. PAN Weidong, Mr. WANG Huaiyu, Dr. LI Chu nlei, Dr. YAO Bing, Mr. CAI Xin and Mr. CHEN Weiping as executive directors; and Mr. WANG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, Mr. LAW Cheuk Kin Steph en and Ms. LI Quan as independent non-executive directors.

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