VOLUNTARY ANNOUNCEMENT - PHASE II CLINICAL TRIAL OF SYS6041 AS A COMBINATION THERAPY FOR THE TREATMENT OF RECURRENT OVARIAN CANCER OFFICIALLY INITIATED AT THE FIRST CENTRE IN CHINA

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 PHASE II CLINICAL TRIAL OF SYS6041 AS A COMBINATION THERAPY FOR THE TREATMENT OF RECURRENT OVARIAN CANCER OFFICIALLY INITIATED AT THE FIRST CENTRE IN CHINA The Board of Directors (the ‘‘Board ’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company ’’, together with its subsidiaries, the ‘‘Group ’’) is pleased to announce that the Phase II clinical trial of SYS6041 (the ‘‘Product ’’) developed by the Group, as a combination therapy for the tre atment of recurrent ovarian cancer, has been officially initiated at the first centre in China. The Product is an antibody-drug conjugate targeting folate receptor alpha ( ‘‘FRα’’), and its registration classification is Class 1 therapeutic biolog ical product. The antibody of the Product can specifically bind to the surface of cells expressing FR αand is internalised into the lysosomes of the cells. Within the lysosomes, the small molecule toxin, a top oisomerase I inhibitor, is released through specific cleavage by cathepsin, thereby killing tumour cel ls. Meanwhile, the Product can non- specifically eliminate surrounding tumour cells through t he bystander effect. Previously, in June 2026, the Group received the Notice of Ap proval for Clinical Trial from the National Medical Products Administration for the Phase II c linical trial of the combination therapy. This clinical trial is currently underway, aiming to evalua te the safety, tolerability and preliminary anti- tumour efficacy of different combination therapy regimens of the Product in patients with recurrent ovarian cancer. At present, the recruitment and screening o f trial subjects are actively progressing. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 31 July 2026 – 1 – As at the date of this announcement, the Board comprises Mr. C AI Dong Chen, Dr. CAI Lei, Mr. WEI Qingjie, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Dr. LI Chunlei , Dr. YAO Bing, Mr. CAI Xin, Mr. CHEN Weiping, Mr. QU Zhiyong and Mr. ZHANG Yiwei as Executive Directors; and Mr. WANG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, M r. LAW Cheuk Kin Stephen and Ms. LI Quan as Independent Non-executive Directors. – 2 –

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