VOLUNTARY ANNOUNCEMENT - PHASE III CLINICAL STUDY OF SYS6010 FOR EGFR-MUTATED LOCALLY ADVANCED OR METASTATIC NSCLC FOLLOWING FAILURE OF EGFR TKI THERAPY MEETS PRE-SPECIFIED PRIMARY ENDPOINT

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 STUDY OF SYS6010 FOR EGFR-MUTATED LOCALL Y ADVANCED OR METASTATIC NSCLC FOLLOWING FAILURE OF EGFR TKI THERAPY MEETS PRE-SPECIFIED PRIMARY ENDPOINT 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 (the ‘‘Product ’’) developed by the Group has recently met the pre-specified pr imary endpoint of progression-free survival ( ‘‘PFS’’), as reviewed and assessed by the Independent Data Monitori ng Committee (‘‘IDMC ’’), in its Phase III clinical study ( ‘‘SYNSTAR-01 ’’) evaluating the Product as a monotherapy versus platinum-based chemotherapy for epidermal growth f actor receptor ( ‘‘EGFR ’’)-mutated locally advanced or metastatic non-small cell lung cancer ( ‘‘NSCLC ’’) following the failure of EGFR tyrosine kinase inhibitor ( ‘‘TKI’’) therapy. The study data demonstrated that the PFS of the Pro duct was significantly superior to existing treatment regimens, wi th the efficacy difference being statistically significant and clinically meaningful, and the overall saf ety profile of the Product was favourable. The Product is an EGFR-targeting antibody-drug conjugate ( ADC) developed by the Group, comprising a humanised anti-EGFR monoclonal antibody conjugated to a t opoisomerase I inhibitor payload via a cleavable linker. The Product specifically binds to EGFR re ceptors on the surface of tumour cells and, upon internalisation, releases the cytotoxic payload intr acellularly, thereby exerting its anti-tumour pharmacological effects. Lung cancer ranks first in both in cidence and mortality among malignancies in the Chinese Mainland, with approximately 1.176 million new cases in 2024. NSCLC accounts for approximately 85% of lung cancer cases, among which EGFR-mu tated patients account for approximately 40 –50%. At present, EGFR TKIs are the standard first-line treat ment regimen for patients with EGFR-mutated advanced NSCLC. However, patie nts inevitably develop resistance following EGFR TKI therapy, and the efficacy of post-resist ance treatment regimens is limited. If successfully approved for marketing, the Product will prov ide a new treatment option for patients, demonstrating high clinical application value and commerc ialisation prospects. – 1 – SYNSTAR-01 is a randomised, open-label, multi-centre Phas e III clinical study designed to evaluate the efficacy and safety of the Product versus platinum-base d chemotherapy in participants with EGFR- mutated locally advanced or metastatic NSCLC following the failure of EGFR TKI therapy. Its primary endpoint is PFS as assessed by the Independent Review Commit tee (IRC). Currently, the study has successfully met its pre-specifie d primary endpoint and achieved positive results. Statistical analysis data confirmed that in the pr e-specified interim analysis, the Product demonstrated a statistically significant and clinically m eaningful improvement in PFS compared with platinum-based chemotherapy and showed a trend of benefit i n overall survival (OS). By Order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 26 August 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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