VOLUNTARY ANNOUNCEMENT - SYH2070 INJECTION (A DOUBLE-STRANDED SMALL INTERFERING RNA DRUG) 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 SYH2070 INJECTION (A DOUBLE-STRANDED SMALL INTERFERING RN A DRUG) 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 SYH2070 Injection (a double- stranded small interfering RNA ( ‘‘siRNA ’’) drug) (the ‘‘Product ’’), a Class 1 new chemical drug independently developed by the Group, has obtained approva l from the U.S. Food and Drug Administration (FDA) to conduct clinical trials in the U.S. The Product also obtained approval from the National Medical Products Administration of the People ’s Republic of China in September 2025 to conduct clinical trials in China. The Product is an siRNA drug that achieves liver-targeted de livery through N-acetylgalactosamine (GalNAc) conjugation and targets Angiopoietin-like 3 ( ‘‘ANGPTL3 ’’) via subcutaneous administration, effectively reducing ANGPTL3 levels. Through sequence opt imization and chemical modification strategies, the Product achieves a more sustained gene sile ncing effect, making it a potential candidate as an ultra-long-lasting siRNA drug for ANGPTL3 reduction. It is indicated for the treatment of hypertriglyceridemia or mixed hyperlipidemia and has the p otential to effectively reduce the risk of elevated residual cholesterol levels. Preclinical studies showed that the Product exhibited supe rior pharmacological activity and duration of efficacy compared to similar siRNA products, and demonstra ted differentiated advantages, such as long-lasting therapeutic effects, good safety profile and high patient adherence, providing a promising clinical development value. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 9 October 2025 – 1 – As at the date of this announcement, the Board comprises Mr. C AI Dong Chen, 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. – 2 –

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