VOLUNTARY ANNOUNCEMENT - SYS6043 GRANTED BREAKTHROUGH THERAPY DESIGNATION IN CHINA FOR THE TREATMENT OF PLATINUM-RESISTANT OVARIAN CANCER, PRIMARY PERITONEAL CARCINOMA AND FALLOPIAN TUBE CANCER

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 SYS6043 GRANTED BREAKTHROUGH THERAPY DESIGNATION IN CHINA FOR THE TREATMENT OF PLATINUM-RESISTANT OVARIAN CA NCER, PRIMARY PERITONEAL CARCINOMA AND FALLOPIAN TUBE CANCER The Board of Directors (the ‘‘Board ’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company ’’, together with its subsidiaries, the ‘‘Group ’’) is pleased to announce that SYS6043 (the ‘‘Product ’’), a humanised monoclonal antibody-drug conjugate targeting B 7-H3 independently developed by the Group, has been granted Breakthrough Therapy Designation b y the National Medical Products Administration of the People ’s Republic of China. The proposed indication is for the treat ment of platinum-resistant ovarian cancer, primary peritoneal ca rcinoma and fallopian tube cancer as a monotherapy (the ‘‘Indication ’’). Ovarian cancer is a gynaecological malignancy with a high cl inical incidence. In 2022, 324,398 people globally were diagnosed with ovarian cancer. Over 70% of pat ients are already at an advanced stage upon initial diagnosis, with a five-year survival rate of on ly about 40%. Clinically, 70% –80% of patients with advanced ovarian cancer experience disease p rogression after receiving platinum-based chemotherapy, leaving extremely limited subsequent treat ment options. Current clinical treatments mainly shift to non-platinum chemotherapy regimens; howev er, the objective response rate (ORR) of such mono-chemotherapy is only 10% –15% with a duration of response (DOR) of only 3 to 4 months, and a median overall survival (OS) for patients of only about 12 months. Therefore, there remains a substantial unmet clinical treatment need in the field of pl atinum-resistant ovarian cancer. Clinical research data of the Product for the treatment of pl atinum-resistant ovarian cancer, primary peritoneal carcinoma and fallopian tube cancer showed that , compared with non-platinum mono- chemotherapy and mirvetuximab soravtansine treatment reg imens, the Product demonstrated more durable anti-tumour capability, doubling the progression -free survival (PFS) of patients, while maintaining a favourable overall safety profile. Currentl y, the Group has officially initiated a Phase III confirmatory clinical trial of the Product for the Indicati on to fully advance the R&D and – 1 – commercialisation processes. In addition, clinical trial s of the Product for the first-line and second-line treatment of small cell lung cancer, as well as breast cancer and various other solid tumours, are also being conducted simultaneously, steadily advancing the R& D strategy across multiple tumour types. The granting of Breakthrough Therapy Designation for the Pr oduct will effectively accelerate its clinical development and regulatory review and approval pr ocesses across various indications, promote the early approval and market launch of this innovative drug , and provide a novel and high-quality treatment option for patients with advanced gynaecologica l malignancies. Meanwhile, this will further enrich the Group ’s R&D pipeline of oncology drugs, continuously strengthen t he Group ’s differentiated R&D advantages and core market competitiveness in the field of antibody-drug conjugates (ADC), and facilitate the Group ’s continuous exploration and development of innovative onc ology drugs. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 2 July 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, 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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