6541 Tanvex-KY

Release Date: June 26, 2026 Statement Date: June 25, 2026 Statement Time: 5:54:12 Company Code: 6541 Company Name: Tanvex-KY Subject: Announcement on behalf of its key subsidiary, Tanvex BioPharma USA, Inc., regarding the receipt of a Complete Response Letter (CRL) from the U.S. FDA for its biosimilar product TX05 (Herceptin biosimilar), due to inspection issues at a downstream fill-finish manufacturing facility. Applicable Clause: Clause 51 Event Date: June 24, 2026

Details: 1. Event Date: June 24, 2026 2. Company Name: Tanvex BioPharma USA, Inc. 3. Relationship with Company (enter 'Company' or 'Subsidiary'): Subsidiary 4. Cross-shareholding Ratio: The Company holds 100% of the subsidiary. 5. Reason for Occurrence: Tanvex BioPharma USA, Inc. (hereinafter referred to as 'Tanvex US'), a subsidiary of the Company, received a Complete Response Letter (CRL) from the U.S. Food and Drug Administration (FDA) on June 23, 2026 (U.S. time) regarding its Biologics License Application (BLA) for TX05, a biosimilar of Herceptin. 6. Response Measures: None. 7. Other Matters to be Disclosed (if the subject of the event or resolution is a publicly listed company or above, this material information also qualifies under Article 7, Paragraph 9 of the Enforcement Rules of the Securities Trading Act as a matter having significant impact on shareholders' rights or securities prices): (1) Name or Code of New Drug: Recombinant protein biosimilar TX05 (Herceptin biosimilar). (2) Indications: Same as the reference drug Herceptin; currently includes breast cancer as the primary indication, as well as gastric cancer. (3) All Planned Development Stages: Not applicable. (4) Current Development Stage: A. Application submission / Approval granted / Approval denied / Results of human clinical trials (including interim analysis) / Other significant events affecting new drug development: Except for issues requiring corrective actions by the downstream manufacturer, the FDA did not raise any concerns regarding the drug substance manufactured by Tanvex US in this CRL. B. Risks and response measures faced by the company when failing to obtain approval from the competent authority, clinical trial results not reaching statistical significance, or other significant events affecting drug development: Tanvex US is currently actively discussing corrective actions with the downstream manufacturer and plans to submit a response to the FDA by the end of July. C. Future business direction upon approval, statistically significant clinical trial results, or other significant events: Not applicable. D. Cumulative R&D expenses incurred: Not disclosed, in consideration of potential future international collaborations for the TX05 product and protection of trade secrets, to safeguard the interests of the company and investors. (5) Next Development Stage to be Conducted: Tanvex US will continue collaborating with the downstream manufacturer to complete the BLA review process. A. Expected Completion Time: Subject to regulatory review timelines. B. Expected Obligations: Not applicable. (6) Market Status: According to data from IQVIA, a leading international pharmaceutical statistics agency, as of March 2026, the U.S. market sales of Herceptin and other biosimilar products over the past year totaled approximately USD 1 billion. Multiple treatment options exist for breast cancer, including biologic drugs such as Perjeta, Enhertu, and Kadcyla. (7) Drug development involves long timelines, high investment costs, regulatory reviews, and no guarantee of success, which may expose investors to risks. Investors should carefully assess and make prudent investment decisions.