MABPHARM-B - VOLUNTARY ANNOUNCEMENT APPROVAL FROM THE NATIONAL MEDICAL PRODUCTS ADMINISTRATION ON THE NEW DRUG APPLICATION (NDA) OF OUR PIPELINE PRODUCT, CMAB807X (DENOSUMAB INJECTION)

Mabpharm Limited

邁博葯業有限公司

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 2181)

VOLUNTARY ANNOUNCEMENT

APPROVAL FROM THE NATIONAL MEDICAL PRODUCTS

ADMINISTRATION ON THE NEW DRUG APPLICATION (NDA)

OF OUR PIPELINE PRODUCT, CMAB807X 類舒® (DENOSUMAB INJECTION)

A. INTRODUCTION

This announcement is made by Mabpharm Limited (the "Company" or "Mabpharm", together with its subsidiaries, the "Group"), on a voluntary basis to inform the shareholders and potential investors of the Company about the latest business updates of the Group.

The board of directors (the "Board") of the Company is pleased to announce that the new drug application ("NDA") of CMAB807X 類舒® (denosumab injection), a pipeline product of the Company, was recently approved by the National Medical Products Administration of the People's Republic of China ("NMPA") for the treatment of (i) patients with bone metastases from solid tumors or multiple myeloma, to delay or reduce the risk of bone-related events (pathological fractures, spinal cord compression, radiotherapy to the bone or bone surgery) and (ii) giant cell tumor of bone that is inoperable or where surgical resection would result in severe functional impairment, including adult patients and adolescents who have reached skeletal maturity (defined as having at least one mature long bone and a body weight of ≥45 kg).

B. BASIC INFORMATION OF THE DRUG

Generic name of the drug: Denosumab Injection

Dosage form: Injection

Specification: 120mg/1.7ml/vial (penicillin vial)

Drug manufacturer: Taizhou Mabtech Pharmaceutical Limited* (泰州邁博太科藥

業有限公司)

Drug approval number: Guo Yao Zhun Zi (國藥准字) S20260046

C. ABOUT CMAB807X 類舒® (DENOSUMAB INJECTION)

CMAB807X 類舒® (denosumab injection) is a human immunoglobulin G2 ("IgG2") monoclonal antibody with affinity and specificity for human RANKL (receptor activator of nuclear factor kappa-B ligand), which is a transmembrane or soluble protein essential for the formation, function, and survival of osteoclasts, the cells responsible for bone resorption. CMAB807X 類舒® prevents RANKL from activating its receptor, RANK, on the surface of osteoclasts and their precursors. Prevention of the RANKL/RANK interaction inhibits osteoclast formation, function, and survival, thereby decreasing bone resorption and increasing bone mass and strength in both cortical and trabecular bones.

The increased osteoclast activity stimulated by RANKL is the medium of bone pathology in solid tumors with bone metastases. Similarly, giant cell tumor of bone is composed of stromal cells expressing RANKL and osteoclast-like giant cells expressing RANK receptor. RANK receptor signaling promotes osteolysis and tumor growth. CMAB807X 類舒® (denosumab injection) prevents RANKL from activating osteoclasts, their precursors and receptor RANK on the surface of osteoclast-like giant cells.

D. IMPACT ON THE COMPANY

CMAB807X 類舒® (denosumab injection) is an alternative specification of CMAB807 普博力® (denosumab injection), the fourth product of Mabpharm approved for marketing. The Company will work closely with its partners to rapidly facilitate the inclusion of CMAB807X 類舒® (denosumab injection) into the national medical insurance program of the People's Republic of China and expand its market channels, achieving quick market penetration and sales growth. CMAB807X類舒® (denosumab injection) is expected to become a cornerstone underpinning the Company's pharmaceutical revenue and profit growth. The Company has also initiated overseas marketing and registration activities for CMAB807X 類舒® (denosumab injection), and expects it to deliver strong sales performance in international markets as well.

Mabpharm focuses on the development of monoclonal antibodies and has an experienced research and development team with core members who have more than 22 years of experience in this area, and have led three major projects under the "863" Program, also called the State High-Tech Development Plan, among other national-level scientific research projects.

Mabpharm possesses strong in-house capabilities in pharmaceutical research, manufacturing, pre-clinical and clinical development. We promote the global commercialization of drugs developed by us through business cooperation with leading and progressive domestic and overseas enterprises engaged in sales of pharmaceutical products. Mabpharm's product pipeline currently includes several monoclonal antibody drugs, and in addition to CMAB807X 類舒® (denosumab injection), CMAB807 普博力® (denosumab injection), CMAB009 恩立妥® (cetuximab β injection), CMAB008 類停® (infliximab for injection) and CMAB007 奧邁舒® (omalizumab α for injection) of Mabpharm have also been approved for marketing by the NMPA.

The solid equipment, technology and quality foundation we have in the field of antibody drug preparation will enable us to possess an excellent competitive advantage in future exclusive negotiation under the national medical insurance program of the People's Republic of China and potential centralized procurement negotiations.

Cautionary Statement required by Rule 18A.05 of the Rules Governing the Listing of Securities on

The Stock Exchange of Hong Kong Limited: We cannot guarantee that we will be able to successfully commercialize CMAB807X 類舒® (denosumab injection).

Shareholders and potential investors of the Company are advised to exercise due care when dealing in the shares of the Company.

By Order of the Board

Mabpharm Limited Jiao Shuge

Chairman

Hong Kong, June 24, 2026