VOLUNTARY ANNOUNCEMENT - SYS6010 GRANTED ANOTHER BREAKTHROUGH THERAPY DESIGNATION BY THE NMPA IN CHINA FOR THE TREATMENT OF PATIENTS WITH RECURRENT OR METASTATIC HEAD AND NECK SQUAMOUS CELL CARCINOMA

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 SYS6010 GRANTED ANOTHER BREAKTHROUGH THERAPY DESIGNATION BY THE NMPA IN CHINA FOR THE TREATMENT OF PATIENTS WITH RECURREN T OR METASTATIC HEAD AND NECK SQUAMOUS CELL CARCINOMA 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 been granted another Br eakthrough Therapy Designation by the National Medical Products Administration ( ‘‘NMPA ’’) of the People ’s Republic of China, for the proposed indication of recurrent or metastatic head and nec k squamous cell carcinoma (‘‘R/M HNSCC ’’) in patients who have failed prior immunotherapy and platin um-based chemotherapy. The Product is an epidermal growth factor receptor ( ‘‘EGFR ’’)-targeting antibody-drug conjugate (ADC) developed by the Group, which is conjugated from a huma nised anti-EGFR monoclonal antibody with a topoisomerase I inhibitor as the payload via a cleavable linker. The Product can specifically bind to EGFR on the surface of tumour cells, and upon internalisation, release the cytotoxic payload intracellularly, thereby exerting its anti-tumou r effects. Head and neck squamous cell carcinoma ( ‘‘HNSCC ’’) is a malignant epithelial tumour arising from the oral cavity, oropharynx, hypopharynx, and larynx. Accordi ng to the global cancer statistics reported in GLOBOCAN 2024, released by the International Agency for Res earch on Cancer (IARC) of the World Health Organization (WHO), there are approximately 845,00 0 new cases and 392,000 deaths globally each year, while in China the corresponding figures are abou t 87,000 new cases and 48,000 deaths annually. This indicates that this tumour type is highly mal ignant and clinically challenging to treat, with a 5-year overall survival rate of only 40% to 50%. HNSCC i s a severe and life-threatening disease. Despite the availability of standard treatment re gimens, therapeutic efficacy remains limited, resulting in poor patient prognosis. – 1 – The Product has demonstrated a significant improvement in t he objective response rate (ORR) in patients with R/M HNSCC who have failed prior immunotherapy and platinum-based chemotherapy, with durable clinical responses achieved. The Product demo nstrates outstanding clinical value and, upon approval for marketing, is expected to provide patient s with a better treatment option, possessing favourable market potential. Currently, a pivotal Phase II I clinical trial of the Product as a monotherapy for the treatment of R/M HNSCC following failure of immunoth erapy and platinum-based chemotherapy is underway. Previously, the Product had been granted two Breakthrough T herapy Designations by the NMPA (excluding the current one), with the proposed indications being: monotherapy for EGFR mutation- positive advanced non-small cell lung cancer (NSCLC) after failure of EGFR TKIs and platinum-based chemotherapy; and unresectable locally advanced or metast atic esophageal squamous cell carcinoma in patients who have failed prior first-line treatment with pl atinum-based chemotherapy and immune checkpoint inhibitors (ICIs). By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 1 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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