CStone Pharmaceuticals — Earnings Release 2025

Feb 2, 2026

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The forward-looking statements made in this announcement relate only to the events or information as of the date on which the statements are made in this announcement. Except as required by law, we undertake no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise, after the date on which the statements are made or to reflect the occurrence of unanticipated events. You should read this announcement completely and with the understanding that our actual future results or performance may be materially different from what we expect. In this announcement, statements of, or references to, our intentions or those of any of our directors and/or our Company are made as of the date of this announcement. Any of these intentions may alter in light of future development.

CStone Pharmaceuticals

基石藥業

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 2616)

DATE OF BOARD MEETING AND NOTICE OF KEY BUSINESS UPDATES

The board (the "Board") of directors (the "Directors") of CStone Pharmaceuticals (the "Company") hereby announces that a meeting of the Board will be held on Thursday, March 26, 2026, for the purposes of, among other matters, considering and approving the annual results of the Company and its subsidiaries for the year ended December 31, 2025 and its publication.

Following the Board meeting, the Company will issue a voluntary announcement on March 26, 2026, and host an investor conference call on March 27, 2026. These communications will provide shareholders and potential investors with the latest business developments, including updates on the following key areas:

• CS2009 (PD-1/VEGF/CTLA-4 trispecific antibody): Updates on Phase I clinical data, progress of the Phase II trial, and business development (BD) advancements;
• CS5001 (ROR1 ADC): Recent clinical trial progress and development updates;
• Sugemalimab (anti-PD-L1 antibody): Updates on global commercialization progress;
• GAVRETO® (pralsetinib): Sales performance updates following its inclusion in China's National Reimbursement Drug List (NRDL), effective January 1, 2026; and
• Preclinical pipeline and Investigational New Drug (IND) plans: Development progress and plans for IND applications.

Further details regarding the agenda and arrangements for the investor conference call will be provided in due course.

By Order of the Board

CStone Pharmaceuticals

Dr. Wei Li

Chairman

Suzhou, the People's Republic of China, February 2, 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.