HENLIUS - VOLUNTARY ANNOUNCEMENT -

INVESTIGATIONAL NEW DRUG APPLICATION FOR CLINICAL TRIAL OF HLXTE-HAase02 (RECOMBINANT HUMAN HYALURONIDASE INJECTION) APPROVED BY THE NATIONAL MEDICAL PRODUCTS ADMINISTRATION

Shanghai Henlius Biotech, Inc. 上海復宏漢霖生物技術股份有限公司

(a joint stock company incorporated in the People's Republic of China with limited liability) (Stock Code: 2696)

VOLUNTARY ANNOUNCEMENT

INVESTIGATIONAL NEW DRUG APPLICATION FOR CLINICAL TRIAL OF HLXTE-HAase02 (RECOMBINANT HUMAN

HYALURONIDASE INJECTION) APPROVED BY THE NATIONAL MEDICAL PRODUCTS ADMINISTRATION

A. INTRODUCTION

This announcement is made by Shanghai Henlius Biotech, Inc. (the "Company") on a voluntary basis to inform the shareholders and potential investors of the Company about the latest business development of the Company.

The board of directors of the Company (the "Board") is pleased to announce that, recently, the investigational new drug (IND) application for a phase 1 clinical trial of HLXTE-HAase02 (recombinant human hyaluronidase injection) ("HLXTE-HAase02") independently developed by the Company was approved by the National Medical Products Administration (NMPA). The Company intends to commence the relevant clinical trial in Chinese Mainland (excluding Hong Kong, Macau and Taiwan regions of China) when the conditions are met.

B. ABOUT HLXTE-HAase02

HLXTE-HAase02 is a novel recombinant human hyaluronidase (rHuPH20) independently developed by the Company, intended to facilitate the diffusion and absorption of drugs administered via subcutaneous injection or subcutaneous infusion. Under physiological

conditions, HLXTE-HAase02 can locally and reversibly depolymerize subcutaneous hyaluronic acid with specificity, increasing the administration volume in subcutaneous tissue, enhancing the dispersion and permeability of drugs within the subcutaneous tissue, thereby improving the bioavailability of the drugs and enhancing patient convenience for subcutaneous drug administration. HLXTE-HAase02 is intended for the development of subcutaneous drug products, aiding these drugs in achieving more effective subcutaneous delivery. Non-clinical studies have shown that HLXTE-HAase02 exhibits enzyme activity comparable to that of marketed recombinant human hyaluronidase products.

C. MARKET CONDITION

As at the date of this announcement, approximately 10 rHuPH20-containing co-medication regimens has been approved for marketing globally, covering fields such as tumours, autoimmunity, immunodeficiency and neurological diseases.

WARNING STATEMENT WITH REFERENCE TO THE REQUIREMENTS UNDER RULE 18A.05 OF THE RULES GOVERNING THE LISTING OF SECURITIES ON THE STOCK EXCHANGE OF HONG KONG LIMITED: The Company cannot guarantee the successful development and commercialization of HLXTE-HAase02. Shareholders and potential investors of the Company are advised to exercise caution when dealing in the shares of the Company.

On behalf of the Board Shanghai Henlius Biotech, Inc. Wenjie Zhang

Chairman

Hong Kong, 31 March 2026