X0202 SCHEDULE 13D/A 0001104659-25-100081 0001297567 XXXXXXXX LIVE 3 Common Stock 07/23/2026 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 300040.00 0.00 300040.00 0.00 300040.00 N 9.9 OO Note to Row 7, 9, and 11: The reported amount consists of 300,040 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) 2,020,582 shares of Common Stock issuable upon conversion of 202.0582 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 3,017,306 shares of Common Stock to be outstanding as of July 23, 2026 following the conversion of certain convertible securities of the Company, as disclosed in the Company's Supplement dated July 17, 2026, to its Proxy Statement dated June 2, 2026. 0001297567 N CK Life Sciences Int'l., (Holdings) Inc. b AF N E9 300040.00 0.00 300040.00 0.00 300040.00 N 9.9 CO HC Note to Row 7, 9, and 11: The reported amount consists of 300,040 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) 2,020,582 shares of Common Stock issuable upon conversion of 202.0582 shares of Series B Preferred Stock. Note to Row 13: Based on 3,017,306 shares of Common Stock to be outstanding as of July 23, 2026 following the conversion of certain convertible securities of the Company, as disclosed in the Company's Supplement dated July 17, 2026, to its Proxy Statement dated June 2, 2026. Common Stock TransCode Therapeutics, Inc. 6 Liberty Square #2382 Boston MA 02109 This Amendment No. 3 ("Amendment No. 3") 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 Amendment No. 2, filed on July 17, 2026 ("Amendment No. 2" and, together with the Original Statement, Amendment No. 1 and this Amendment No. 3, the "Schedule 13D") which relates to the Common Stock of the Company. Item 4 of Schedule 13D is hereby amended by replacing the last paragraph of Item 4 with the following: 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 (the "Conversion") 21.6755 shares of Series B Preferred Stock into 216,755 shares of Common Stock (the "Conversion Shares"), such that DEFJ will hold approximately 9.9% of the Company's outstanding Common Stock as of such date. The Conversion was implemented and the Conversion Shares were issued to DEFJ on July 23, 2026. The Reporting Persons each beneficially own an aggregate of 300,040 shares of Common Stock which represent approximately 9.9% of the outstanding shares of Common Stock, based on an aggregate of 3,017,306 shares of Common Stock outstanding as of July 23, 2026. 1. Sole power to vote or direct vote: 300,040 2. Shared power to vote or direct vote: 0 3. Sole power to dispose or direct the disposition: 300,040 4. Shared power to dispose or direct the disposition: 0 Other than the Conversion discussed above, the Reporting Persons have not effected any transactions in the Common Stock during the past 60 days. Not applicable. Not applicable. DEFJ, LLC /s/ Yu Ying Choi, Alan Abel 07/23/2026 CK Life Sciences Int'l., (Holdings) Inc. /s/ Yu Ying Choi, Alan Abel 07/23/2026