VOLUNTARY ANNOUNCEMENT - A DOUBLE-STRANDED SMALL INTERFERING RNA DRUG (SYH2061 INJECTION) 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 A DOUBLE-STRANDED SMALL INTERFERING RNA DRUG (SYH2061 INJE CTION) 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 a double-stranded small interfering RNA ( ‘‘siRNA ’’) drug (SYH2061 Injection) (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 October 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 complement component C5 ( ‘‘C5’’) via subcutaneous administration, effectively reducing C5 levels. Through sequence optimiza tion and chemical modification strategies, the Product achieves a more sustained gene silencing effect , representing the first independently developed, ultra-long-lasting siRNA drug that reduces C5 l evels to have entered clinical trials in China. It is indicated for the treatment of IgA nephropathy and othe r complement-mediated diseases. 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, 24 November 2025 – 1 – As at the date of this announcement, the Board comprises Mr. C AI Dong Chen, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Mr. WANG Huaiyu, Dr. LI Chunlei, Dr. YAO Bin g, Mr. CAI Xin, Mr. CHEN Weiping and Mr. QU Zhiyong as Executive Directors; and Mr. WA NG 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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