CStone Pharmaceuticals — Director's Dealing 2025

Oct 23, 2025

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CStone Pharmaceuticals

基石藥業

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 2616)

VOLUNTARY ANNOUNCEMENT INCREASE IN SHAREHOLDING BY CEO AND EXECUTIVE DIRECTOR DR. JIANXIN YANG AND SENIOR MANAGEMENT BY 1,000,000 SHARES

This announcement is made by CStone Pharmaceuticals (the "Company", together with its subsidiaries, collectively referred to as the "Group" or "CStone") on a voluntary basis to inform its shareholders and potential investors in relation to the increase in shareholding in the Company (the "Shares") by Dr. Jianxin Yang ("Dr. Yang"), the chief executive officer (the "CEO"), president of research and development and an executive director together with other members of senior management ("Senior Management") of the Company.

The Company was informed by Dr. Yang and Senior Management that they have purchased an aggregate of 1,000,000 Shares in the open market using personal funds between October 20 and 22, 2025 (the "Share Purchases"). Of this total, Dr. Yang acquired 700,000 Shares.

This recent purchase continues a pattern of strong commitment from Dr. Yang. Since assuming the role as CEO in August 2022, Dr. Yang has purchased a total of 11,501,000 Shares in the open market. Following the Share Purchases, Dr. Yang's total shareholding interest in the Company represents approximately $4.81\%$ of the total issued share capital of the Company as at the date of this announcement.

Dr. Yang and Senior Management expressed their strong confidence in the Company's long-term investment value and future growth prospects. The increase in their shareholding in the Company represents their belief in the Company's ability to maintain steady operations and to achieve rapid growth in the future. Dr. Yang and Senior Management do not rule out the possibility of further increasing their shareholding in the Company as and when appropriate.

The board of directors of the Company (the "Board") is of the view that the increase in shareholding of the Company by Dr. Yang and Senior Management signifies their long-term commitment to, and confidence towards, the future business prospects of the Company.

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About CStone

CStone (HKEX: 2616), established in late 2015, is an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, autoimmune/inflammation, and other key disease areas. Dedicated to addressing patients’ unmet medical needs in China and globally, the Company has made significant strides since its inception. To date, the Company has successfully launched 4 innovative drugs and secured approvals for 16 new drug applications covering 9 indications. The company’s pipeline is balanced by 16 promising candidates, featuring potentially first-in-class or best-in-class antibody-drug conjugates (ADCs), multispecific antibodies, immunotherapies and precision medicines. CStone also prides itself on a management team with comprehensive experiences and capabilities that span the entire drug development spectrum, from preclinical and translational research to clinical development, drug manufacturing, business development, and commercialization.

For more information about CStone, please visit: www.cstonepharma.com.

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

Suzhou, the People’s Republic of China, October 23, 2025

As at the date of this announcement, the board of directors of the Company 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. Ting Yuk Anthony Wu, Ms. Yip Betty Ho and Mr. Kenneth Howard Jarrett as independent non-executive directors.