VOLUNTARY ANNOUNCEMENT - PHASE III CLINICAL TRIAL OF SYS6010 IN COMBINATION WITH ENLONSTOBART FOR THE ADJUVANT TREATMENT OF RESECTED STAGE II-IIIB NON-SMALL CELL LUNG CANCER WITH ACTIONABLE GENOMIC ALTERATION-NEGATIVE STATUS AND WITHOUT ACHIEVING MPR OFFICIALLY INITIATED IN CHINA

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 PHASE III CLINICAL TRIAL OF SYS 6010 IN COMBINATION WITH ENLONSTOBART FOR THE ADJUVANT TREATMENT OF RESECTED STAGE II-IIIB NON-SMALL CELL LUNG CANCER WITH ACTIONABLE GENOMIC ALTERATION-NEGATIVE STATUS AND WITHOUT ACHIEVING MPR OFFICIALLY INITIATED IN CHINA The Board of Directors (the ‘‘Board ’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company ’’, together with its subsidiaries, the ‘‘Group ’’) is pleased to announce that the Group has officially initiated a randomised, controlled, open-label Phase III c linical trial (SYS 6010 –015) in China to evaluate the safety and efficacy of SYS 6010 in combination w ith a PD-1 monoclonal antibody (Enlonstobart) versus a PD-(L)-1 monoclonal antibody in th e adjuvant treatment of patients with completely resected stage II-III B non-small cell lung canc er who have no actionable genomic alterations and have not achieved MPR, with the enrolment of the first participant expected to be completed in July 2026. SYS 6010 is an antibody-drug conjugate (ADC) targeting the e pidermal growth factor receptor (‘‘EGFR ’’) developed by the Group, which is composed of a humanised ant i-EGFR monoclonal antibody conjugated to a topoisomerase I inhibitor payload via a cleavable linker. This drug specifically binds to EGFR on the surface of tumour cells and releases the c ytotoxic payload intracellularly upon internalisation, thereby exerting anti-tumour effects. E nlonstobart Injection (recombinant fully human anti-PD-1 monoclonal antibody injection) is a humanised Ig G4 variant monoclonal antibody targeting programmed cell death protein-1 (PD-1), which is indicated for the treatment of malignant tumours in various human organs and tissues. – 1 – SYS 6010 –015 is a randomised, open-label, multi-centre, Phase III cl inical trial aimed at evaluating the safety and efficacy of SYS 6010 in combination with Enlonsto bart as an adjuvant treatment for patients with completely resected stage II-III B non-small cell lung cancer who have no actionable genomic alterations and have not achieved MPR. Previously, the Grou p received an opinion from the Center for Drug Evaluation of the National Medical Products Administr ation of the People ’s Republic of China in June 2026, granting approval to conduct this clinical trial . Currently, the recruitment and screening of subjects are actively underway. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 30 June 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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