Zai Lab Limited — Board/Management Information 2026

Mar 5, 2026

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.

Zai Lab Limited

再鼎醫藥有限公司*

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 9688)

RE-DESIGNATION OF A DIRECTOR

This announcement is made by Zai Lab Limited (the "Company") pursuant to Rule 13.51(2) of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited (the "Listing Rules").

The board of directors of the Company (the "Board") announces that Mr. Leon O. Moulder, Jr. ("Mr. Moulder"), an independent director, has been redesignated as a director with effect from the date of this announcement.

Mr. Leon O. Moulder, Jr., aged 68, is a member of the Research and Development Committee and the Commercial Committee of the Board. He brings to the Board significant operational and senior management experience in the biopharmaceutical industry as well as extensive experience as a director on public and private boards in the industry. Mr. Moulder is Founder and Managing Member of Tellus Bio Ventures, LLC, a life sciences investment fund. In addition to serving on the Board, he has also served on other public company boards, including as a member of the board of directors of Dianthus Therapeutics, Inc. (Nasdaq), and he serves on the boards of several Tellus portfolio companies. Mr. Moulder is also Founder, Chief Executive Officer, and Chairman of the board of directors of Zenas BioPharma (Nasdaq), a clinical-stage global biopharmaceutical company focused on the development and commercialization of immunology-based therapies. Previously, he served as Chairman of the Board of Directors of Trevana, Inc. He also co-founded and served as Chief Executive Officer and a member of the board of directors of TESARO, Inc. (Nasdaq), a fully-integrated Boston based oncology-focused biopharmaceutical company with operations in North America and Europe, until its acquisition by GlaxoSmithKline. Prior to that, he served as President, Chief Executive Officer, and Vice Chairman of the board of directors of Abraxis BioScience, Inc. (Nasdaq), prior to its eventual acquisition by Celgene Corporation. He also served as Vice Chairman of Eisai Corporation of North America following Eisai's acquisition of MGI PHARMA, where he served in various roles, including as President, Chief Executive Officer, and member of the board of directors; President and Chief Operating Officer; and Executive Vice President. Mr. Moulder began his career as a clinical pharmacist followed by a seventeen-year career at predecessor companies of Sanofi, beginning with Marion Laboratories. Mr. Moulder is a Temple University Trustee, a Council Member for the University of Chicago Booth School of Business and the Polsky Center for Entrepreneurship and Innovation, and Board Member

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of the Fox Chase Cancer Center.

Mr. Moulder received an MBA from The University of Chicago Booth School of Business and a B.S. in Pharmacy from Temple University.

Mr. Moulder is entitled to receive compensation from the Company in accordance with the non-employee director compensation policy (the “Compensation Policy”) of the Company, including (i) an annual cash retainer of $50,000 for his service on the Board, (ii) an additional annual cash retainer of $7,500 for his service as a member of the Commercial Committee, and (iii) an additional annual cash retainer of $10,000 for his service as a member of the Research and Development Committee. Furthermore, he is entitled to receive equity compensation each year pursuant to the Compensation Policy, subject to his continued service as a member of the Board.

Save as disclosed above, as at the date of this announcement, (i) Mr. Moulder does not hold any other position in the Company or its subsidiaries; (ii) Mr. Moulder does not hold any other directorships in any other public companies the securities of which are listed on any securities market in Hong Kong or overseas in the last three years; (iii) Mr. Moulder does not possess any other major appointment or professional qualifications; (iv) except for the restricted shares covering a total of 72,602 American Depositary Shares, Mr. Moulder does not, and is not deemed to have any interests or short positions in any shares, underlying shares or debentures of the Company or any of its associated corporations within the meaning of Part XV of the Securities and Futures Ordinance (Chapter 571 of the Laws of Hong Kong); and (v) Mr. Moulder does not have any relationship with any directors, senior management, substantial shareholders (as defined under the Listing Rules) or controlling shareholders (as defined under the Listing Rules) of the Company.

So far as the directors of the Company are aware, save as disclosed above, there is no other information which is disclosable pursuant to any of the requirements under Rule 13.51(2)(h) to (v) of the Listing Rules, and there is no other matter relating to the redesignation of Mr. Moulder that needs to be brought to the attention of the shareholders of the Company.

Mr. Moulder has not entered into any service contract with the Company which is not determinable by the Company within one year without payment of compensation (other than statutory compensations). He has not been appointed for any specified length or proposed length of service with the Company but shall hold office until the next annual general meeting of the Company and be eligible for re-election in accordance with the articles of association of the Company.

By order of the Board

Zai Lab Limited

Samantha Du

Director, Chairperson and Chief Executive Officer

Hong Kong, March 5, 2026

As at the date of this announcement, the board of directors of the Company comprises Dr. Samantha Du and Mr. Leon O. Moulder, Jr. as directors, and Dr. John Diekman, Dr. Richard Gaynor, Ms. Nisa Leung, Mr. William Lis, Mr. Scott W. Morrison, Mr. Michel Vounatsos and Mr. Peter Wirth as independent directors.

• For identification only