VOLUNTARY ANNOUNCEMENT - SYS6010 GRANTED ANOTHER BREAKTHROUGH THERAPY DESIGNATION IN CHINA FOR THE TREATMENT OF PATIENTS WITH LOCALLY ADVANCED OR METASTATIC ESOPHAGEAL SQUAMOUS CELL CARCINOMA

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CSPC PHARMACEUTICAL GROUP LIMITED (Incorporated in Hong Kong with limited liability) (Stock Code: 1093) ʮ ̡ VOLUNTARY ANNOUNCEMENT SYS6010 GRANTED ANOTHER BREAKTHROUGH THERAPY DESIGNATION IN CHINA FOR THE TREATMENT OF PATIENTS WITH LOCALLY ADVANCED OR METASTATIC ESOPHAGEAL SQUAMOUS CELL CARCINOMA The Board of Directors (the ‘‘Board ’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company ’’, together with its subsidiaries, the ‘‘Group ’’) is pleased to announce that SYS6010 (a humanised monoclonal antibody drug conjugate targeting EGFR) (the ‘‘Product ’’), independently developed by the Group, has recently been granted another Breakthrough Ther apy Designation by the National Medical Products Administration ( ‘‘NMPA ’’) of the People ’s Republic of China. The proposed indication is for use as a monotherapy in patients with locally advanced or met astatic esophageal squamous cell carcinoma who have failed prior treatment with platinum-ba sed chemotherapy and immunotherapy (the ‘‘Indication ’’). According to GLOBOCAN 2022 published by the International A gency for Research on Cancer (IARC), esophageal cancer is a highly prevalent gastrointe stinal malignancy globally, among which esophageal squamous cell carcinoma is the predominant path ological subtype, accounting for more than 90% of cases in high-incidence regions such as China. China h as a high incidence of esophageal squamous cell carcinoma, and the disease burden is extremel y heavy. Furthermore, data on the burden of malignant tumours in China in 2022 released by the Nationa l Cancer Center showed that esophageal squamous cell carcinoma ranks seventh in incidence among al l malignancies in China, with up to 224,000 new cases and approximately 188,000 deaths annuall y. Both new cases and deaths account for approximately half of the global total. At present, platinum-based chemotherapy in combination wi th immunotherapy has become the first-line standard treatment for advanced esophageal squamous cell c arcinoma. Nevertheless, subsequent treatment options remain limited for relapsed or refractor y patients who have failed this regimen. These patients rely solely on traditional chemotherapeutic agen ts such as docetaxel and irinotecan, which yield a relatively low overall objective response rate (ORR ) and a relatively short median overall survival (mOS). The efficacy is limited and the prognosis is poor, representing a substantial unmet clinical need. – 1 – Clinical studies of the Product for the Indication have demo nstrated breakthrough efficacy. Compared to the existing standard treatment for relapsed esophageal cancer, it is expected to bring more significant clinical benefits, coupled with a favourable s afety profile and relatively clear clinical advantages. At this stage, the Group has officially initiat ed and is fully accelerating the progress of the Phase III confirmatory clinical study of the Product for the indication of esophageal squamous cell carcinoma; meanwhile, multiple Phase III clinical studies for various solid tumour indications, including the first-line treatment of non-small cell lung c ancer, the second-line treatment of non-small cell lung cancer, and the second-line and beyond treatment o f breast cancer, are also being conducted simultaneously. Previously, the Product was granted Break through Therapy Designation by the NMPA in January 2025 for the indication of EGFR-mutant resistant non-small cell lung cancer. The granting of Breakthrough Therapy Designation to the Pro duct for the indication of esophageal squamous cell carcinoma will help accelerate the overall cl inical development and regulatory review and approval process across multiple solid tumour indicati ons, expediting market launch. This will provide a novel and highly effective treatment option for pa tients with advanced tumours, while continuously optimising the Group ’s pipeline layout in the therapeutic area of oncology, and consolidating and enhancing the Group ’s differentiated R&D capabilities and competitive market advantages in the field of antibody-drug conjugates. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 11 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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