AKESO - VOLUNTARY ANNOUNCEMENT - NEW DRUG APPLICATION FOR (GUMOKIMAB, AK111) HAS BEEN APPROVED BY NMPA

Akeso, Inc.

康方生物科技（開曼）有限公司

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 9926))

VOLUNTARY ANNOUNCEMENT

NEW DRUG APPLICATION FOR 奇佑康® (GUMOKIMAB, AK111)

HAS BEEN APPROVED BY NMPA

This announcement is made by Akeso, Inc. (the 'Company', together with its subsidiaries, the 'Group') on a voluntary basis to inform the shareholders and potential investors of the Company about the latest business development of the Group.

The board of directors (the 'Board') of the Company is pleased to announce that 奇佑康® (gumokimab, AK111) has received approval from the National Medical Products Administration of the People's Republic of China ('NMPA') for the treatment of moderate-to-severe plaque psoriasis.

The approval of gumokimab for the treatment of moderate-to-severe plaque psoriasis is based on one pivotal Phase III clinical study (AK111–301) and three supportive studies.

Gumokimab: Rapid and Potent, Sustained Complete Clearance, Safe and Convenient

Rapid and potent at 12 weeks: The PASI75 response rate at 12 weeks was 94.6%, and the PASI100 response rate (complete clearance of lesions) was 47.7% (as compared to 28.6% for comparable drugs targeting the same receptor);

Sustained complete clearance at 52 weeks: The PASI75 response rate (long-term efficacy endpoint) at 52 weeks was nearly 100%, and the PASI100 response rate (complete clearance of lesions) was 68.9% (as compared to 39.2% for comparable drugs targeting the same receptor);

Good safety profile: The incidence of Treatment-Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs), infections/infestations were numerically among the lowest rates of TEAEs, SAEs, and infections/infestations reported in pivotal trials of IL-17inhibitors.

Convenient to use: One injection per dose, totaling 17 injections per year (as compared to 34 injections for comparable drugs targeting the same receptor).

奇佑康® (Gumokimab, AK111)

Gumokimab is a novel humanized monoclonal antibody targeting IL-17 (interleukin-17), independently developed by the Company, intended for the treatment of autoimmune diseases such as psoriasis and ankylosing spondylitis.

Currently, Phase III clinical trials for the registration of gumokimab for the treatment of moderate-to-severe plaque psoriasis and ankylosing spondylitis have met all efficacy endpoints. Based on these results, gumokimab has been approved for the treatment of moderate-to-severe plaque psoriasis, and the new drug application for the treatment of active ankylosing spondylitis is currently under review by the Center for Drug Evaluation of the NMPA.

By order of the Board

Akeso, Inc.

Dr. XIA Yu

Chairwoman and executive director

Hong Kong, June 12, 2026