VOLUNTARY ANNOUNCEMENT - PHASE I/II CLINICAL TRIAL DATA OF SYS6010 IN COMBINATION WITH ENLONSTOBART FOR THE TREATMENT OF SYSTEMIC TREATMENT-NAIVE, ACTIONABLE GENOMIC ALTERATION-NEGATIVE ADVANCED NSCLC ORALLY PRESENTED AT THE 2026 WORLD CONFERENCE ON LUNG CANCER (WCLC)

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 I/II CLINICAL TRIAL DATA OF SYS6010 IN COMBINATION WIT H ENLONSTOBART FOR THE TREATMENT OF SYSTEMIC TREATMENT-NAIV E, ACTIONABLE GENOMIC ALTERATION-NEGATIVE ADVANCED NSCLC OR ALLY PRESENTED AT THE 2026 WORLD CONFERENCE ON LUNG CANCER (WCLC) 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 orally presented the Phase I/II clinical trial (the ‘‘Study ’’) data of SYS6010 in combination with Enlonstobart for the treatment of systemic treatment-naive, actionable genomi c alteration-negative advanced non-small cell lung cancer ( ‘‘NSCLC ’’) at the 2026 World Conference on Lung Cancer (WCLC) hosted by the International Association for the Study of Lung Cancer (IAS LC). OVERVIEW OF THE STUDY The Study is a multi-centre Phase I/II clinical trial (ChiCT R2400089402) led by Professor Zhou Caicun from Shanghai East Hospital, aiming to evaluate the safety, tolerability, pharmacokinetic profile and preliminary efficacy of SYS6010 in combination with Enlons tobart Injection (a programmed cell death protein-1 (PD-1) inhibitor), with or without chemotherapy , in patients with epidermal growth factor receptor ( ‘‘EGFR ’’) and anaplastic lymphoma kinase (ALK) wild-type advanced N SCLC and other advanced solid tumours. At this conference, the Group announced the results of the ra ndomised controlled trial from the Study regarding SYS6010 in combination with Enlonstobart Inject ion for the treatment of systemic treatment- naive, actionable genomic alteration-negative advanced N SCLC. The Study evaluated two dosing regimens: SYS6010 at 4.2 mg/kg in combination with Enlonsto bart at 360 mg administered once every 3 weeks (Arm 1); and SYS6010 at 3.6 mg/kg in combination with E nlonstobart at 240 mg administered once every 2 weeks (Arm 2). – 1 – As at 13 July 2026, a total of 123 participants were enrolled a nd received treatment under the aforementioned two dosing regimens, comprising 62 in Arm 1 a nd 61 in Arm 2. The median follow-up time was 10.8 months. The relevant safety and efficacy data a re as follows: . In terms of safety, the safety profile of both dosing regimen s of SYS6010 in combination with Enlonstobart was generally manageable. The incidences of G rade 3 and above treatment-related adverse events were 51.6% (Arm 1) and 52.5% (Arm 2), respecti vely, while the incidences of treatment-related adverse events leading to treatment dis continuation were 9.7% (Arm 1) and 8.2% (Arm 2), respectively. . In terms of efficacy, both regimens demonstrated prelimina ry efficacy in the study population. Among them, the benefits were more prominent in patients wit h non-squamous cell carcinoma and high expression of programmed death-ligand 1 ( ‘‘PD-L1 ’’), and efficacy was observed in both squamous and non-squamous cell carcinoma patients with hig h PD-L1 expression. The confirmed objective response rate (ORR) of the overall population and each subgroup is shown in the table below: Arm 1 Arm 2 Overall population 58.9% 49.2% Non-squamous cell carcinoma patients 64.1% 56.1% PD-L1 positive (tumour proportion score ( ‘‘TPS’’) ≥1%) patients 58.5% 63.2% PD-L1 high expression (TPS ≥ 50%) patients 77.8% 82.4% Squamous cell carcinoma patients with high PD-L1 expressio n 71.4% 60.0% Non-squamous cell carcinoma patients with high PD-L1 expression 81.8% 91.7% Currently, the combination therapy of SYS6010 and Enlonsto bart Injection has entered Phase III clinical trials, and the Group intends to develop it for the f irst-line treatment of PD-L1 positive locally advanced or metastatic NSCLC (NCT07633873). ABOUT SYS6010 SYS6010 is an antibody-drug conjugate (ADC) targeting EGFR independently developed by the Group, which is composed of a humanised anti-EGFR monoclonal antib ody conjugated to a topoisomerase I inhibitor payload via a cleavable linker. SYS6010 specific ally binds to EGFR on the surface of tumour cells and releases the cytotoxic payload intracellularly u pon internalisation, thereby exerting anti- tumour effects. Given the widespread high expression of EGF R in various solid tumours, SYS6010 has broad development prospects, and the Group has made strateg ic layouts in multiple solid tumour fields. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 14 September 2026 – 2 – 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. – 3 –

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