VOLUNTARY ANNOUNCEMENT - PHASE III CLINICAL TRIAL OF BECOTATUG (JMT101) IN COMBINATION WITH OSIMERTINIB FOR THE FIRST-LINE TREATMENT OF LOCALLY ADVANCED OR METASTATIC NSCLC HARBOURING EGFR EXON 20 INSERTION MUTATIONS ACHIEVES POSITIVE TOPLINE RESULTS

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CSPC PHARMACEUTICAL GROUP LIMITED (Incorporated in Hong Kong with limited liability) (Stock Code: 1093) ʮ ̡ VOLUNTARY ANNOUNCEMENT PHASE III CLINICAL TRIAL OF BECOTATUG (JMT101) IN COMBINATI ON WITH OSIMERTINIB FOR THE FIRST-LINE TREATMENT OF LOCALLY ADVANCED OR METASTATIC NSCLC HARBOURING EGFR EXON 2 0 INSERTION MUTATIONS ACHIEVES POSITIVE TOPLINE RESULTS 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 Phase III clinical trial of Becotatug (JMT101) (the ‘‘Product ’’) developed by the Group, in combination with osimertinib fo r the first-line treatment of locally advanced or metastatic non -small cell lung cancer ( ‘‘NSCLC ’’) harbouring epidermal growth factor receptor ( ‘‘EGFR ’’) exon 20 insertion mutations (EGFR ex20ins), has met its primary endpoint at a pre-specified interim anal ysis, achieving positive topline results. Compared with platinum-based chemotherapy in combination with pemetrexed, the treatment regimen of the Product in combination with osimertinib significant ly prolonged the progression-free survival (‘‘PFS’’) of patients and demonstrated a trend of benefit in overall s urvival (OS). The trial is a randomised, open-label, parallel-controlle d Phase III clinical trial designed to compare the efficacy and safety of the Product in combination with osime rtinib versus platinum-based chemotherapy in combination with pemetrexed in the first-line treatment of the aforementioned patients. The primary endpoint is PFS as assessed by the Independent Review Commit tee (IRC) in accordance with the Response Evaluation Criteria in Solid Tumours (RECIST 1.1) . According to the pre-specified statistical analysis plan, as reviewed and resolved by the Independent D ata Monitoring Committee (IDMC), the PFS benefit in the treatment group of the Product in combinat ion with osimertinib met the pre-specified statistical superiority boundary for the interim analysis and was of clinical significance. In addition, this combination treatment regimen demonstrated a favoura ble safety profile. – 1 – About Becotatug (JMT101) The Product is a high-affinity, humanised monoclonal antib ody targeting EGFR. In combination with the EGFR tyrosine kinase inhibitor osimertinib, it serves a s a chemotherapy-free, dual-targeted therapy regimen, acting simultaneously on the extracellular and in tracellular EGFR signalling pathways, which reflects an innovative therapeutic approach that combines distinct mechanisms of action. Meeting the primary endpoint at the pre-specified interim analysis of t his Phase III study provides pivotal clinical evidence for this chemotherapy-free, dual-targeted combi nation therapy regimen, and is expected to offer a new, potentially superior and chemotherapy-free fi rst-line treatment option for such patients. The Group plans to present the results of this trial at upcomi ng academic conferences. Furthermore, pivotal Phase III clinical studies of the Product for indica tions such as the first-line treatment of locally advanced or metastatic non-squamous NSCLC with classical E GFR mutations, and advanced metastatic colorectal cancer that has failed at least two lines of stand ard therapies, are also ongoing. About EGFR Exon 20 Insertion Mutation (EGFR ex20ins) Non-Sm all Cell Lung Cancer Lung cancer is one of the most common malignant tumours globa lly and is also the malignant tumour with the highest incidence and mortality rates in China. NSC LC account s for approximately 85% of lung cancer, among which EGFR mutations account for the high est proportion in the Chinese NSCLC population (approximately 40 –50%), and EGFR exon 20 insertion mutation is the most common t ype of EGFR gene mutation other than classical EGFR mutations. EGF R ex20ins tumours have high mutational heterogeneity and a high proportion of brain met astasis, and often present with a higher tumour burden, resulting in a poor prognosis for patients. F or patients with locally advanced or metastatic disease, there are unmet clinical needs such as p rolonging the duration of disease control, improving long-term survival, and improving treatment tol erability. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 24 September 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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