X0202 SCHEDULE 13D/A 0001104659-25-100081 0001297567 XXXXXXXX LIVE 2 Common Stock 07/17/2026 false 0001829635 89357L501 TransCode Therapeutics, Inc.

6 Liberty Square #2382 Boston MA 02109

Cindy Chiu (852) 2126 1212 CK Life Sciences Int'l., (Holdings) Inc. 7th Fl, Cheung Kong Center, 2 Queen's Rd Central Hong Kong K3 - Steven Y Li (212) 277-4000 Freshfields US LLP 3 World Trade Center, 175 Greenwich St. New York NY 10007 Y DEFJ, LLC b WC N DE 83285.00 0.00 83285.00 0.00 83285.00 N 8.8 OO Note to Row 7, 9, and 11: The reported amount consists of 83,285 shares of common stock, $0.0001 par value per share ("Common Stock") of TransCode Therapeutics, Inc. (the "Company"), held directly by DEFJ, LLC. The reported amount excludes (i) 11,813,859 shares of Common Stock issuable upon conversion of 1,181.3859 shares of Series A Non-Voting Convertible Preferred Stock, par value $0.0001 per share ("Series A Preferred Stock"), and (ii) 2,237,337 shares of Common Stock issuable upon conversion of 223.7337 shares of Series B Non-Voting Convertible Preferred Stock, par value $0.0001 per share ("Series B Preferred Stock" and, together with the Series A Preferred Stock, the "Preferred Stock"). Note to Row 13: Based on 950,302 shares of Common Stock outstanding as of May 12, 2026 as disclosed in the Company's Quarterly Report on Form 10-Q filed with the SEC on May 15, 2026. 0001297567 N CK Life Sciences Int'l., (Holdings) Inc. b AF N E9 83285.00 0.00 83285.00 0.00 83285.00 N 8.8 CO HC Note to Row 7, 9, and 11: The reported amount consists of 83,285 shares of Common Stock, held directly by DEFJ, LLC. The reported amount excludes (i) 11,813,859 shares of Common Stock issuable upon conversion of 1,181.3859 shares of Series A Preferred Stock, and (ii) 2,237,337 shares of Common Stock issuable upon conversion of 223.7337 shares of Series B Preferred Stock. Note to Row 13: Based on 950,302 shares of Common Stock outstanding as of May 12, 2026 as disclosed in the Company's Quarterly Report on Form 10-Q filed with the SEC on May 15, 2026. Common Stock TransCode Therapeutics, Inc. 6 Liberty Square #2382 Boston MA 02109 This Amendment No.2 ("Amendment No.2") supplements and amends the Schedule 13D filed on October 16, 2025 (the "Original Statement") as amended by Amendment No. 1, filed on October 28, 2025 ("Amendment No. 1" and, together with the Original Statement and this Amendment No. 2, the "Schedule 13D") which relates to the Common Stock of the Company. Unless specifically amended hereby, the disclosures set forth in the Schedule 13D remain unchanged. Capitalized terms used but not otherwise defined herein have the meanings given to them in the Schedule 13D. Item 4 of the Original Schedule 13D is hereby amended by adding the below disclosure following the last paragraph: On July 17, 2026, DEFJ submitted an irrevocable conversion notice (the "Conversion Notice") to the Company providing that, contingent upon Company stockholder approval of Proposals 1 and 2 set forth in the Company's proxy statement filed with the SEC on June 2, 2026 for its 2026 annual meeting, DEFJ will, on the third business day following approval of Proposals 1 and 2, convert 21.6755 shares of Series B Preferred Stock into 216,755 shares of Common Stock, such that DEFJ will hold approximately 9.99% of the Company's outstanding Common Stock as of such date. DEFJ, LLC /s/ Yu Ying Choi, Alan Abel 07/17/2026 CK Life Sciences Int'l., (Holdings) Inc. /s/ Yu Ying Choi, Alan Abel 07/17/2026