JUNSHI BIO - OVERSEAS REGULATORY ANNOUNCEMENT - SHANGHAI JUNSHI BIOSCIENCES CO., LTD.* ANNOUNCEMENT ON THE CONVENING OF THE 2025 ANNUAL RESULTS BRIEFING

SHANGHAI JUNSHI BIOSCIENCES CO., LTD.* 上海君實生物醫藥科技股份有限公司 (a joint stock company incorporated in the People's Republic of China with limited liability) (Stock code: 1877) OVERSEAS REGULATORY ANNOUNCEMENT This announcement is made pursuant to Rule 13.10B of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited. Reference is made to the "Shanghai Junshi Biosciences Co., Ltd.* Announcement on the Convening of the 2025 Annual Results Briefing" published by Shanghai Junshi Biosciences Co., Ltd.* on the website of the Shanghai Stock Exchange, for reference purpose only. By order of the Board Shanghai Junshi Biosciences Co., Ltd.* Mr. Xiong Jun Chairman Shanghai, the PRC, 20 March 2026