VOLUNTARY ANNOUNCEMENT - DATA FROM PHASE I CLINICAL STUDY OF SYS6002 AS MONOTHERAPY FOR THE TREATMENT OF ADVANCED CERVICAL CANCER PRESENTED AS A RAPID ORAL PRESENTATION AT THE 2026 ANNUAL GLOBAL MEETING OF THE INTERNATIONAL GYNECOLOGIC CANCER SOCIETY (IGCS 2026)

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 DATA FROM PHASE I CLINICAL STUDY OF SYS6002 AS MONOTHERAPY FOR THE TREATMENT OF ADVANCED CERVICAL CANCER PRESENTED AS A RAPID ORAL PRESENTATION AT THE 2026 ANNUAL GLOBAL MEETING OF THE INTERNATIONAL GYNECOLOGIC CANCER SOCIETY (IGCS 2026) 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 presented the data from the Phase I clinical study (the ‘‘Study ’’) of SYS6002 as monotherapy for the treatment of advanced cervical cancer as a rapid oral presentation at the 2026 Annual Global Meeting of the International Gynecologic Cancer Society (IGCS 2026). OVERVIEW OF THE STUDY The Study is a nationwide, multi-centre Phase I clinical tri al designed to evaluate the safety, tolerability, pharmacokinetic profile and preliminary ef ficacy of SYS6002 in patients with advanced solid tumours. At this meeting, the Group presented the tria l results of SYS6002 as monotherapy for the treatment of previously treated advanced cervical canc er. As at 8 May 2026, a total of 82 patients were enrolled in the Stu dy and assigned to two dose cohorts, including 39 patients in the 2.4 mg/kg once every 2 weeks ( ‘‘Q2W’’) cohort and 43 patients in the 3.6 mg/kg once every 3 weeks ( ‘‘Q3W’’) cohort, with a median follow-up of 16.1 months. The relevan t safety and efficacy data are as follows: . In terms of safety, the safety profile of the above two dose co horts was generally manageable, with treatment-related adverse events mostly being Grade 1 to 2. Among them, ocular-related adverse events were the most common, but no Grade 3 or above events occ urred, and no patient discontinued treatment due to these events. The incidence o f interstitial lung disease and non- infectious pneumonitis was low (2.4%). The incidence and se verity of treatment-related rash were both low (any grade: 20.7%; Grade 3 or above: 1.2%), and no cas es of Stevens-Johnson syndrome – 1 – or toxic epidermal necrolysis were reported. The incidence and grade of peripheral neuropathy were also low (12.2%; all Grade 1 to 2). In addition, no treatm ent-related adverse events leading to death occurred. . In terms of efficacy, both dosing regimens demonstrated pre liminary efficacy in the study population. The confirmed objective response rate (ORR) wa s 35.9% in the 2.4 mg/kg Q2W cohort and 28.6% in the 3.6 mg/kg Q3W cohort. The median duration of r esponse (DoR) for patients who achieved a confirmed response in the two cohorts was 8.2 mont hs and 10.3 months, respectively; the median progression-free survival (PFS) was 4.1 months a nd 4.3 months, respectively; and the median overall survival (OS) was 15.1 months and 11.5 months , respectively. Currently, the study of SYS6002 2.4 mg/kg Q2W regimen for the treatment of advanced cervical cancer previously treated with immunotherapy has entered a Phase I II clinical trial (NCT07230626). ABOUT SYS6002 SYS6002 is a next-generation antibody-drug conjugate (ADC ) targeting Nectin-4. By utilising enzyme- catalysed site-specific antibody conjugation technology , the drug specifically directs the potent mitotic inhibitor MMAE to Nectin-4-expressing cancer cells. In add ition, the stable linker design of SYS6002 not only facilitates the delivery of high concentrations of MMAE to the tumour but also reduces toxicity by decreasing systemic exposure to the toxin. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 8 October 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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