Announcement on Voluntary Disclosure of Subsidiary YKYY013 Injection Obtained Clinical Trial Approval from the National Medical Products Administration

Securities code: 688658 Securities abbreviation: Yuekang Pharmaceutical Announcement number: 2025-046

Yuekang Pharmaceutical Group Co., Ltd.

The company's board of directors and all directors guarantee that the contents of this announcement do not contain any false records, misleading statements or major omissions, and assume legal responsibility for the authenticity, accuracy and completeness of its contents in accordance with the law.

Beijing Yuekang Kechuang Pharmaceutical Technology Co., Ltd. (hereinafter referred to as "Yuekang Kechuang") and Hangzhou Tianlong Pharmaceutical Co., Ltd. (hereinafter referred to as "Hangzhou Tianlong"), subsidiaries of Yuekang Pharmaceutical Group Co., Ltd. (hereinafter referred to as the "Company"), have recently obtained the "Drug Clinical Trial Approval Notice" approved and issued by the National Medical Products Administration (hereinafter referred to as "NMPA") for YKYY013 injection for the treatment of chronic hepatitis B virus infection. The company will conduct Phase I clinical trials of this product. The relevant information is now announced as follows:

1. Main contents of clinical approval documents:

1. Drug name: YKYY013 injection

2. Acceptance number: CXHL2500882

3. Notice number: 2025LP02896

4. Application indication: chronic hepatitis B virus infection

5. Applicants: Beijing Yuekang Kechuang Pharmaceutical Technology Co., Ltd., Hangzhou Tianlong Pharmaceutical Co., Ltd.

6. Application stage: clinical trial

7. Approval conclusion: According to the "Drug Administration Law of the People's Republic of China" and relevant regulations, after review, the YKYY013 injection clinical trial application accepted on August 22, 2025 complies with the relevant requirements for drug registration, and it is agreed to carry out clinical trials of chronic hepatitis B virus infection with this product.

2. Other conditions of drugs

YKYY013 injection is a chemically synthesized double-stranded siRNA drug independently developed by Yuekang Science and Technology and Hangzhou Tianlong coupled with N-acetylgalactosamine (GalNAc) ligand. It effectively silences the messenger RNA (mRNA) transcribed by the HBV genome through RNA interference, thereby inhibiting the production of hepatitis B pathogenic proteins and inhibiting The replication of HBV creates conditions for host immune reconstruction, and ultimately achieves functional cure of hepatitis B. It is intended to be used clinically for the treatment of chronic hepatitis B virus infection.

Preclinical research results show that YKYY013 injection shows significant HBV virus inhibitory activity in vivo and in vitro, and shows a wide range of inhibitory effects on ten HBV genotypes (A–J). In vivo pharmacodynamic test results in AAV-HBV-transfected mice (types B, C and D) and HBVA-type transgenic mice showed that YKYY013 injection could significantly reduce the levels of HBV DNA, HBsAg, HBeAg and other viral markers in experimental mice after single and multiple administrations, and showed an obvious dose-dependent effect relationship; in the AAV-HBV transfected mouse test, varying degrees of HBV DNA and HBV DNA were observed in each dose group. The phenomenon of HBsAg clearance is accompanied by the production of anti-S antigen antibodies (HBsAb). In repeated dose toxicity tests in SD rats and cynomolgus monkeys, both showed good safety and tolerability.

This product has also recently received a letter from the U.S. Food and Drug Administration (hereinafter referred to as "FDA") approving the clinical trial of YKYY013 injection for the treatment of chronic hepatitis B virus infection (Study May Proceed Letter, IND number: 177486). For details, please refer to the "Announcement of Yuekang Pharmaceutical Group Co., Ltd. on the Voluntary Disclosure of Subsidiary YKYY013 Injection Obtained FDA Clinical Trial Approval" (Announcement Number: 2025-040).

3. Risk warning

1. The new drug clinical trial application approved by NMPA is a phased result of the company's new drug research and development, and is an important reflection of the company's new drug research and development capabilities. However, due to the characteristics of high technology, high risk, and high added value of pharmaceutical products, the cycle from drug development, clinical trials, approval to production is long, many links are involved, and the risks are high. There are many uncertainties in drug review and approval time, approval results and subsequent research processes, research results, and future product market competition. The approval of the NMPA for this clinical trial application will not have a significant impact on the company's recent performance.

2. According to drug research and development experience, there are certain risks in clinical trial research. The progress and results of clinical trials are easily affected by (including but not limited to) trial protocols, subject recruitment, safety and effectiveness of clinical trials, etc., and the research and development situation is highly uncertain. Investors are kindly requested to make prudent decisions and pay attention to preventing investment risks.

The company will actively promote the research and development and registration progress of the above-mentioned drugs and fulfill its information disclosure obligations in accordance with the law. Announcement is hereby made.

Board of Directors of Yuekang Pharmaceutical Group Co., Ltd.

November 6, 2025