VOLUNTARY ANNOUNCEMENT - TOPLINE RESULTS OBTAINED FROM PHASE III CLINICAL TRIAL OF SECUKINUMAB INJECTION

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 TOPLINE RESULTS OBTAINED FROM PHASE III CLINICAL TRIAL OF SECUKINUMAB INJECTION 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 topline results from the Phase III equivalence clinical trial of Secukinumab Inject ion (the ‘‘Product ’’), developed by the Company ’s subsidiary, CSPC Megalith Biopharmaceutical Co., Ltd., f or the treatment of moderate to severe plaque psoriasis have been obtained. Psoriasis is an immune-mediated, chronic, inflammatory an d systemic disease. Currently, there are over 7 million patients with psoriasis in China. Fully human inte rleukin (IL)-17A ( ‘‘IL-17A ’’), primarily produced by activated T cells, is a key mediator in the pathog enesis of psoriasis. Secukinumab can specifically bind to IL-17A and block the signal transducti on of IL-17 receptors, thereby inhibiting psoriastic inflammation. The Product is a fully human IgG1 monoclonal antibody drug de veloped by the Group and is a biosimilar to Secukinumab Injection (Cosentyx ®). The approved indications of Cosentyx ® in China include plaque psoriasis in patients aged 6 years and older, psoriatic arthritis, ankylosing spondylitis, and hidradenitis suppurativa, and its efficacy and safety h ave been widely recognized. The Group has conducted the development of the Product in acc ordance with the relevant research guidelines for biosimilars and carried out a head-to-head e quivalence study versus Cosentyx ®. This study was a multi-center, randomised, double-blinded, par allel, positive-controlled Phase III equivalence clinical trial designed to demonstrate consis tency of efficacy between the Product and Cosentyx ®in patients with moderate to severe plaque psoriasis. Subje cts with moderate to severe plaque psoriasis were enrolled and randomised 1:1 to receive eithe r the investigational group (the Product) or the reference group (Cosentyx ®) in this study. Its primary endpoint was the proportion of pa tients achieving a 75% improvement from baseline in the Psoriasis A rea and Severity Index (PASI-75) at Week 12. – 1 – This pivotal study met its pre-specified primary endpoint a nd delivered positive topline results. Statistical analyses demonstrated that the Product was cli nically equivalent to Cosentyx ®, with a favorable safety profile and no new or unexpected safety sig nals observed, giving it potential to meet the long-term safety requirements for patients. Detailed d ata from this study will be presented at upcoming academic conferences and published in peer-revie wed journals. By order of the Board CSPC Pharmaceutical Group Limited CAI Dong Chen Chairman Hong Kong, 18 December 2025 As at the date of this announcement, the Board comprises Mr. C AI Dong Chen, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Mr. WANG Huaiyu, Dr. LI Chunlei, Dr. YAO Bin g, Mr. CAI Xin, Mr. CHEN Weiping and Mr. QU Zhiyong as Executive Directors; and Mr. WA NG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, Mr. LAW Cheuk Kin Steph en and Ms. LI Quan as Independent Non-executive Directors. – 2 –

The release as fetched from its publisher. irasia.com ↗