VOLUNTARY ANNOUNCEMENT - ACCEPTANCE OF BIOLOGIC LICENSE APPLICATION OF USTEKINUMAB INJECTION

Hong Kong Exchanges and Clearing Limited and The Stock Excha nge of Hong Kong Limited take no responsibility for the contents of this announcemen t, make no representation as to its accuracy or completeness and expressly disclaim any lia bility whatsoever for any loss howsoever arising from or in reliance upon the whole or any pa rt of the contents of this announcement. CSPC PHARMACEUTICAL GROUP LIMITED (Incorporated in Hong Kong with limited liability) (Stock Code: 1093) ʮ ̡ VOLUNTARY ANNOUNCEMENT ACCEPTANCE OF BIOLOGIC LICENSE APPLICATION OF USTEKINUMAB 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 biologic license application of Ustekinumab Injection (th e ‘‘Product ’’) developed by CSPC Megalith Biopharmaceutical Co., Ltd ( 石藥集團巨石生物製藥有限公司), a subsidiary of the Company, has been accepted by the National Medical Products Administration (NMPA) of the People ’s Republic of China. The Product, a fully human IgG1 κmonoclonal antibody, is an IL-12/IL-23 p40 inhibitor. Ustekinumab binds with specificity to the p40 protein subun it of IL-12 and IL-23 with high affinity, disrupting the interaction of IL-12 and IL-23 wit h the cell-surface receptor, IL-12R b1, to disrupt IL-12 and IL-23 mediated signal transduction a nd cytokine cascades, which in turn inhibits the proliferation of keratinocytes and plays a curative effect in the treatment of psoriasis. The Product is applied as a Class 3.3 therapeutic biological product for the indication of plaque psoriasis in adults and children. The application is mainly based on a pivotal Phase III clinical trial enrolling adult patients with moderate t o severe plaque psoriasis who have not responded to, are contraindicated for, or cannot tolera te any of the systemic therapies, including cyclosporine, methotrexate (MTX), PUVA (psoral en and ultraviolet A), and acitretin capsules. The clinical trial results demonstrat ed that the Product was highly consistent with the originator drug, Stelara ®, in terms of efficacy for the treatment of subjects with moderate to severe plaque psoriasis, and had g ood safety profile. The Product has good efficacy in the treatment of plague psoriasis, with a dosing interval of once every 12 weeks during the stabilisation period, possessing a dist inct advantage in clinical application. By Order of the Board CSPC Pharmaceutical Group Limited CAI Dongchen Chairman Hong Kong, 26 November 2024 – 1 – As at the date of this announcement, the Board comprises Mr. C AI Dongchen, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Mr. PAN Weidong, Mr. WANG Huaiyu, Dr. LI Chunlei, Dr. JIANG Hao, Dr. YAO Bing and Mr. CAI Xin as executive direct ors; and Mr. WANG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, M r. LAW Cheuk Kin Stephen as independent non-executive directors. – 2 –

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