ENNITUO (ANBENITAMAB INJECTION) RECEIVES MARKETING AUTHORISATION FROM NMPA

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 ENNITUO ( 恩尼妥®) (ANBENITAMAB INJECTION) RECEIVES MARKETING AUTHORISATION FROM NMPA The Board of Directors (the ‘‘Board ’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company ’’, together with its subsidiaries, the ‘‘Group ’’) is pleased to announce that Anbenitamab Injection (brand name: Ennituo ( 恩尼妥®)) (the ‘‘Product ’’), co-developed by Shanghai JMT-BIO Technology Co., Ltd., a subsidiary of the Company, and Jiangsu Alphamab Biop harmaceuticals Co., Ltd., has received marketing authorisation from the National Medical Product s Administration of the People ’s Republic of China ( ‘‘NMPA ’’). The Product is a recombinant humanised bispecific antibody (IgG1 type) targeting human epidermal growth factor receptor 2 ( ‘‘HER2 ’’). The approved indication is for the use of the Product in combination with chemotherapy for the treatment of adult pa tients with locally advanced or metastatic HER2-positive gastric or gastroesophageal junction adeno carcinoma who have received at least one prior treatment regimen containing trastuzumab (the ‘‘Indication ’’). This approval is mainly based on a pivotal Phase II/III clini cal trial (KC-WISE), which enrolled patients with HER2-positive gastric or gastroesophageal j unction adenocarcinoma who had failed at least one prior line of therapy. The study results demonstra ted that compared with standard chemotherapy, the Product in combination with chemotherap y significantly prolonged progression-free survival (PFS) (7.1 months vs 2.7 months, hazard ratio ( ‘‘HR’’) = 0.25, representing a 75% reduction in the risk of disease progression or death) and overall surviv al (OS) (19.6 months vs 11.5 months, HR = 0.29, representing a 71% reduction in the risk of death). The trends of benefit were consistent across all patient subgroups. Consistent trends of benefit were also o bserved in terms of both objective response rate (ORR) and duration of response (DOR), with a favourable safety profile. – 1 – The Indication is the first approved indication for the Prod uct. In addition, a Phase III clinical study of the Product in combination with the Group ’s self-developed docetaxel for injection (albumin-bound) (‘‘HB1801 ’’) for the neoadjuvant treatment of HER2-positive early or lo cally advanced breast cancer also met its pre-specified primary endpoint of total pathol ogical complete response (tpCR) rate in March 2026, with statistically and clinically significant results. The results of the pivotal registrational Phase III clinical study of the Product in combination with H B1801 as first-line treatment for HER2- positive breast cancer are expected to be announced this yea r. By Order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 29 May 2026 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, Mr. WANG Huaiy u, Dr. LI Chunlei, Dr. YAO Bing, Mr. CAI Xin, Mr. CHEN Weiping, Mr. QU Zhiyong and Mr. ZHANG Yiw ei as Executive Directors; and Mr. WANG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, Mr. LAW Cheuk Kin Stephen and Ms. LI Quan as Independent Non-executive Dir ectors. – 2 –

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