CStone Pharmaceuticals — Board/Management Information 2026

Feb 6, 2026

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Hong Kong Exchanges and Clearing Limited and The Stock Exchange 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 whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement.

CStone Pharmaceuticals 基石藥業

(Incorporated in the Cayman Islands with limited liability) (Stock Code: 2616)

UPDATE ON THE QUALIFICATION OF JOINT COMPANY SECRETARY AND CHANGE OF COMPANY SECRETARY AND AUTHORIZED REPRESENTATIVE

References are made to the announcements of CStone Pharmaceuticals (the "Company") dated January 18, 2023 and June 18, 2024 in relation to, among other things, the appointment of Ms. Weicong Ni ("Ms. Ni") and Ms. Mei Yee Yung ("Ms. Yung") as the joint company secretaries (each a "Joint Company Secretary", and collectively, the "Joint Company Secretaries") of the Company and the waiver (the "Waiver") granted to the Company by The Stock Exchange of Hong Kong Limited (the "Stock Exchange") from strict compliance from Rules 3.28 and 8.17 of the Rules Governing the Listing of Securities on the Stock Exchange (the "Listing Rules") for three years up to January 17, 2026.

UPDATE ON THE QUALIFICATION OF JOINT COMPANY SECRETARY AND CHANGE OF COMPANY SECRETARY

The board of directors (the "Board") of the Company is pleased to announce that the Stock Exchange has confirmed that Ms. Ni, a Joint Company Secretary, is qualified to act as the company secretary of the Company under Rule 3.28 of the Listing Rules upon expiry of the Waiver on January 17, 2026. Accordingly, Ms. Yung has resigned as a Joint Company Secretary with effect from February 6, 2026. Ms. Ni continues to serve as the sole company secretary of the Company following the resignation of Ms. Yung. Ms. Yung has confirmed that she has no disagreement with the Board and there is no matter relating to her resignation that needs to be brought to the attention of the shareholders of the Company or the Stock Exchange.

The Board would like to take this opportunity to express its gratitude to Ms. Yung for her valuable contribution to the Company during her tenure of service.

CHANGE OF AUTHORIZED REPRESENTATIVE

Ms. Yung has also resigned as an authorized representative of the Company (the "Authorized Representative") under Rule 3.05 of the Listing Rules following her resignation as the Joint Company Secretary. Ms. Ni has been appointed as an Authorized Representative in replacement of Ms. Yung with effect from February 6, 2026. Dr. Jianxin Yang, an executive director of the Company, remains as another Authorized Representative.

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PROCESS AGENT

Ms. Yung remains as the process agent of the Company in Hong Kong for the purpose of accepting service of process in Hong Kong under Part 16 of the Companies Ordinance (Chapter 622 of the Laws of Hong Kong) and for the purpose of accepting services of process and notices on the Company's behalf in Hong Kong under Rule 19.05(2) of the Listing Rules.

By order of the Board CStone Pharmaceuticals Dr. Wei Li Chairman

Hong Kong, February 6, 2026

As at the date of this announcement, the Board comprises Dr. Wei Li as Chairman and non-executive director, Dr. Jianxin Yang as executive director, Mr. Kenneth Walton Hitchner III and Mr. Edward Hu as non-executive directors, and Mr. Kenneth Howard Jarrett, Ms. Fang Xie and Ms. Catherine Yen as independent non-executive directors.