8-K - RNAZ - Equibles

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 13, 2025

TRANSCODE

THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Delaware	001-40363	81-1065054
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

TransCode

Therapeutics, Inc.

6Liberty Square

, #2382

Boston**, Massachusetts**

02109

(Addressof principal executive offices, including zip code)

(857

)

837-3099

(Registrant’stelephone number, including area code)

Not Applicable

(Former Name or Former Address, if Changed SinceLast Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
¨	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
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¨	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR<br> 240.14d-2(b))
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¨	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR<br> 240.13e-4(c))
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Securities registered or to be registered pursuant to Section 12(b) of the Act.

Title of each class	Trading symbol(s)	Name of each exchange on which registered
Common Stock, par value $0.0001 per share	RNAZ	The Nasdaq Capital Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company x

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 8.01 Other Events.

On October 14, 2025, TransCode Therapeutics, Inc. (“TransCode”) issued a press release announcing completion of its Phase 1a clinical trial with TTX-MC138. A copy of this press release is attached hereto as Exhibit 99.1 and incorporated herein by reference. A copy of the related poster is attached hereto as Exhibit 99.2 and incorporated herein by reference.

Note Regarding Forward-Looking Statements

This Current Report on Form 8-K contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, including, without limitation, statements concerning the timing, conduct and results of TransCode’s Phase 1a clinical trial, TransCode’s Phase 2a clinical trial, and TransCode’s Phase 2 clinical trial, statements about microRNAs and their involvement in cancer, and statements concerning the therapeutic potential of TransCode's TTX-MC138 and other therapeutic candidates. Any forward-looking statements in this Current Report on Form 8-K are based on management's current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: the risks associated with drug discovery and development; the risk that the results of clinical trials will not be consistent with TransCode's preclinical studies or expectations or with results from previous clinical trials; risks associated with the conduct of clinical trials; risks associated with TransCode's financial condition and its need to obtain additional funding to support its business activities, including TransCode's ability to continue as a going concern; risks associated with the timing and outcome of TransCode's planned regulatory submissions; risks associated with obtaining, maintaining and protecting intellectual property; risks associated with TransCode's ability to enforce its patents against infringers and defend its patent portfolio against challenges from third parties; risks of competition from other companies developing products for similar uses; risks associated with TransCode's dependence on third parties; and risks associated with geopolitical events and pandemics, including the COVID-19 coronavirus and military actions. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause TransCode's actual results to differ from those contained in or implied by the forward-looking statements, see the section entitled "Risk Factors" in TransCode's Annual Report on Form 10-K for the year ended December 31, 2024, as well as discussions of potential risks, uncertainties and other important factors in any subsequent TransCode filings with the Securities and Exchange Commission. Forward-looking statements reflect TransCode’s analysis only on their stated date; TransCode undertakes no duty to update this information unless required by law.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.	Description
99.1	Press Release, dated October 14, 2025
99.2	Poster, dated October 13, 2025
104	Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	TransCode Therapeutics, Inc.
Date: October 14, 2025	By:	/s/ Philippe Calais
		Philippe Calais
		Chief Executive Officer

Exhibit 99.1

TransCode Therapeutics presents preliminary data from its completed Phase 1a study with TTX-MC138 in metastatic disease at ESMO

·	Safety<br> primary endpoint achieved
·	Median treatment<br> duration of 4 months with a range of 2 to 12 months and three patients remain on trial
·	RECIST data with<br> apparent stable disease lasting over 4 months in 44% of patients (7 out of 16)
·	Safety and durability<br> profile consistent with known mechanism of action
·	Early signals<br> support advancement to a Phase 2a clinical trial with established treatment dose

BOSTON, October 14, 2025 - TransCode Therapeutics, Inc. (NASDAQ: RNAZ) announces completion of Phase 1a clinical trial with TTX-MC138, an investigational inhibitor of microRNA-10b, or miR-10b. By meeting its primary safety endpoint and defining a recommended Phase 2 dose, TTX-MC138 is moving forward into the next stage of clinical evaluation to assess its efficacy across selected metastatic diseases and for multiple indications.

Primary objectives of the trial focused on safety, tolerability, pharmacokinetics (“PK”) and establishment of a Phase 2 dose (RP2D). A total of sixteen patients were treated across four escalating dose levels. No significant treatment-related safety events or dose limiting toxicities were observed.

TTX-MC138 was administered to 16 patients (77 total doses to date) with positive pharmacodynamic effects over all four administered dose range levels. Currently three patients remain on trial receiving TTX-MC138. The median treatment duration was four months. Importantly, the duration of treatment for all patients ranged from two to 12 cycles, indicative of tolerability and disease control. Forty-four per cent or seven out of sixteen patients were classified as having stable disease lasting 4 months or longer. Preliminary data in 16 patients showed positive pharmacodynamic effects over a wide dose range, consistent with preclinical models and TransCode’s Phase 0 clinical trial. Of note, one patient diagnosed with thyroid cancer and historic evidence of an increase in thyroglobulin levels, demonstrated a reversal of the trend during treatment and presented at the most recent measurement with undetectable thyroglobulin levels.

Study investigator William McKean, MD, PhD (The START Center for Cancer Research) stated, “The clinical benefit we are observing in patients treated with TTX-MC138 is compelling given the pre-clinical data and length of time the drug remains in the tumor cells”.

Data analysis and monitoring are ongoing. A final clinical study report, scientific presentations and publications are planned.

The treatment response, safety and durability profile provides the basis for TransCode’s decision to proceed with the TTX-MC138 program in a Phase 2a clinical trial. TransCode’s Daniel Vlock, MD, Consulting Clinician noted “the observed safety profile, coupled with the durability of TTX-MC138's anti-tumor effects, is particularly encouraging. These findings are consistent with the drug's mechanism of action and provide a basis for a more rigorous efficacy evaluation. This positions us to potentially intervene earlier in the patient’s disease, offering a new therapeutic option for patients at risk of developing metastatic disease."

Further information about the trial is available at www.clinicaltrials.gov NCT Identifier: (NCT06260774).

Preliminary data to be presented in a poster session at ESMO Congress October 17-21, 2025, taking place in Berlin, Germany. (FPN: 983P)

About TTX-MC138

TTX-MC138 is a first-in-class therapeutic candidate designed to inhibit microRNA-10b, or miR-10b, a microRNA widely believed to be critical to the emergence and progression of many metastatic cancers. TransCode’s Phase 0 clinical trial produced evidence of delivery of a radiolabeled version of TTX-MC138 to metastatic lesions and pharmacodynamic activity, even at a microdose of the drug candidate, suggesting a broad therapeutic window for TTX-MC138.

About TransCode Therapeutics

TransCode Therapeutics is an immuno-oncology and targeted cancer therapy company with a focus on treating advanced malignancy. The company’s lead therapeutic candidate, TTX-MC138, is focused on treating metastatic tumors that overexpress microRNA-10b, a unique, well-documented biomarker of metastasis. In addition, TransCode has a portfolio of other first-in-class therapeutic candidates designed to mobilize the immune system to recognize and destroy cancer cells.

TransCode Therapeutics, Inc.•6 Liberty Square #2382•Boston, MA 02109

Forward-Looking Statements

This release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including, without limitation, statements concerning the timing, conduct and results of TransCode’s Phase 1a clinical trial, TransCode’s Phase 2 clinical trial, and TransCode’s Phase 2a clinical trial, statements about microRNAs and their involvement in cancer, and statements concerning the therapeutic potential of TransCode’s TTX-MC138 and other therapeutic candidates. Any forward-looking statements in this press release are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: the risks associated with drug discovery and development; the risk that the results of clinical trials will not be consistent with TransCode’s preclinical studies or expectations or with results from previous clinical trials; risks associated with the conduct of clinical trials; risks associated with TransCode’s financial condition and its need to obtain additional funding to support its business activities, including TransCode’s ability to continue as a going concern; risks associated with the timing and outcome of TransCode’s planned regulatory submissions; risks associated with obtaining, maintaining and protecting intellectual property; risks associated with TransCode’s ability to enforce its patents against infringers and defend its patent portfolio against challenges from third parties; risks of competition from other companies developing products for similar uses; risks associated with TransCode’s dependence on third parties; and risks associated with geopolitical events and pandemics, including the COVID-19 coronavirus and military actions. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause TransCode’s actual results to differ from those contained in or implied by the forward-looking statements, see the section entitled “Risk Factors” in TransCode’s Annual Report on Form 10-K for the year ended December 31, 2024, as well as discussions of potential risks, uncertainties and other important factors in any subsequent TransCode filings with the Securities and Exchange Commission. All information in this press release is as of the date of this release; TransCode undertakes no duty to update this information unless required by law.

For more information and partneringopportunities, please contact:

TransCode Therapeutics, Inc.

Tania Montgomery, VP of Business Development

tania.montgomery@transcodetherapeutics.com

TransCode Therapeutics, Inc.• 6 Liberty Square #2382 • Boston, MA 02109

Exhibit 99.2

BACKGROUND TransCode Therapeutics, Inc. is developing TTX-MC138, an antisense oligonucleotide (ASO) therapeutic targeting miR-10b, a critical driver of metastatic disease progression. Several in vivo preclinical studies with TTX-MC138 have successfully demonstrated its delivery to metastatic lesions, its activity against metastatic cancers of multiple tissue origins, and its capacity to elicit disease regression and long-term overall survival (1-3). In a Phase 0 clinical study in a patient with metastatic breast cancer, accumulation of TTX-MC138 in metastatic lesions was demonstrated. TTX-MC138 is currently being evaluated in a Phase 1a Multicenter, Open-Label, Dose-Escalation and Expansion Study in Subjects with Advanced Solid Tumors (NCT06260774). A total of sixteen patients were treated across four escalating dose levels. Primary objectives of the study focused on the safety, tolerability, PK and establishment of a Phase 2 dose (RP2D). Data from the dose-escalation phase only are presented in this poster. OBJECTIVES ENDPOINTS Primary Objectives Primary Endpoint Evaluate safety and tolerability of TTX-MC138 to determine the MTD and select an RP2D (or doses) Incidence of TEAEs Secondary Objectives Secondary Endpoints Evaluate anti-tumor activity of TTX-MC138 ORR, DCR, DoR, PFS, OS Characterize the PK profile of TTX-MC138 PK parameters versus time data: AUCt , AUCinf , AUCTAU , AI, Cmax , Tmax , t1/2 , Vss, and CLT. Note: Dose expansion phase objectives and endpoints are not presented (Dose expansion phase has not been initiated); dose escalation phase objectives and endpoints without data to present are not presented. TTX-MC138 a microRNA-10b (miR-10b) inhibitor, was evaluated in an ongoing Phase 1a Multicenter, Open-Label, Dose-Escalation and Expansion Study in Subjects with Advanced Solid Tumors. PURPOSE KEY INCLUSION KEY EXCLUSION • Histologically or cytologically confirmed diagnosis of relapsed/ refractory metastatic or locally advanced solid tumor with failed standard therapy. • Measurable or evaluable disease per RECIST version 1.1 • ECOG PS of 0 or 1 • Adequate organ function per protocol definitions • Anticancer therapy (not immunotherapy/Ab therapies) ≤ 14 days or 5 half-lives before study drug • Prior antibody therapy ≤ 28 days before study drug • History of second primary malignancy diagnosed or required active therapy within past year. • Clinically significant, uncontrolled cardiovascular disease • Symptomatic CNS metastases or primary CNS tumor associated with progressive neurologic symptoms or requires ongoing corticosteroids to control CNS disease Phase 1a Clinical Study of a First-in-Class Antisense Oligonucleotide (TTX-MC138) Therapeutic against Advanced Solid Tumors – Interim Results Siqing Fu 1 ; William B. McKean 2 ; Douglas Orr 3 ; Alex Spira 4 ; Daniel Vlock 5 ; Susan Duggan 5 ; Lisa Fortin 5 ; Zdravka Medarova 5 1The University of Texas MD Anderson Cancer Center, Houston Texas, 2START Center for Cancer Research, Salt Lake City, UT, 3Sarah Cannon research Institute at Mary Crowley, Dallas Texas, 4NEXT Oncology Viginia, Fairfax, VA, 5TransCode Therapeutics Inc., Boston, MA METHODS RESULTS No significant treatment related safety events or dose limiting toxicities were observed. To date, seventy-seven doses of TTX-MC138 have been administered. The median treatment duration was four months. Importantly, the duration of treatment for all patients ranged from two to twelve cycles indicative of durability, tolerability, and disease control. Three patients remain on study. One thyroid cancer patient with historic evidence of an increase in thyroglobulin levels, demonstrated a reversal of the trend during treatment and presented at the most recent measurement with undetectable thyroglobulin levels. Forty-four per cent or seven out of the sixteen patients were noted to have stable disease lasting 4 months or longer. Abbreviations: AI: accumulation index; AUCinf : area under the curve from the time of dosing extrapolated to infinity; AUCt : area under the concentration-time curve from the time of dosing to the time of the last observation; AUCTAU : area under the curve from time zero to the end of the dosing interval; CLT: total body clearance; Cmax : maximum observed concentration; CNS: central nervous system; DCR: disease control rate; DoR: duration of response; ECOG PS: Eastern Cooperative Oncology Group performance status; MTD: maximum tolerated dose; ORR: objective response rate; OS: overall survival; PFS: progression-free survival; RECIST: Response Evaluation Criteria in Solid Tumors; RP2D: recommended Phase 2 dose; TEAE: treatment-emergent adverse event; t1/2 : terminal elimination half-life; Tmax : time of the maximum observed concentration; Vss: steady-state volume of distribution. 0.1 1 10 100 1000 10000 100000 1000000 10000000 100000000 Dose (mg/kg) AUC0-t of TTX-MC138 (ng*h/mL) Rat Human Dog Figure 2. Thyroglobulin levels in patient 103-003 with thyroid cancer. Patient with historic evidence of an increase in thyroglobulin levels, demonstrated a reversal of the trend during treatment and presented at the most recent measurement with undetectable thyroglobulin levels. 0 24 48 72 96 120 144 168 0.1 1 10 100 1000 10000 100000 Time (h) on C1D1 C2D1 C3D1 . Concentration of TTX-MC138 in Plasma (ng/mL) 0 2 4 Cohort 1 (0.8 mg/kg n=3) Cohort 2 (1.6 mg/kg, n=3) 0 2 4 Cohort 3 (3.2 mg/kg, n=7) Cohort 4 (4.8 mg/kg, n=3) Figure 1. Mean Plasma TTX-MC138 Concentration Time Profiles. Preliminary data are illustrated as mean concentrations in ng/mL for 4 treatment cohorts (0.8 mg/kg, 1.6 mg/kg, 3.2 mg/kg, and 4.8 mg/kg) in linear scale. Error bars represent standard errors of mean. Exposure increases with dose administration consistently on all cycles tested. Figure 3. Estimated Tumor Size Change in Patients Treated with TTX-MC138. Preliminary data are illustrated per patient. 1) Yigit, et al, Oncogene. 2013;32(12):1530-8. 2) Yoo, et al, Cancer Res. 2015;75:4407-15 3) Yoo, et al, Sci Rep. 2017;7:45060. REFERENCES Funding and Disclosures Contact Information Study sponsored by Transcode Therapeutics Inc. and National Cancer Institute under grant number 1R44CA295173-01 to Z.M. The presenting author has no disclosures to declare. Corresponding author email: siqingfu@mdanderson.org - Phase 1a preliminary data show apparent stable disease lasting over 4 months in 44% (7 out of 16) patients. Three patients still on study. - One thyroid cancer patient with historic evidence of an increase in thyroglobulin levels, demonstrated a reversal of the trend during treatment and presented at the most recent measurement with undetectable thyroglobulin levels. - No DLTs were reported in patients treated with TTX-MC138. A strong safety and durability profile was observed. - Preliminary PK analysis in all 16 patients showed predictable systemic exposure and positive pharmacodynamic effects over a wide dose range, consistent with preclinical models and TransCode’s Phase 0 clinical trial. CONCLUSIONS Figure 5. Estimated Change in Tumor Size in response to exposure at Cycle 1 Day 1. Preliminary data are illustrated per cohort. Figure 6. TTX-MC138 Exposure. Data are illustrated as mean exposure of TTX-MC138 in human, dog, and rat per dose level. Figure 4. Swimmer Plot of Tumor Response. Preliminary data are illustrated per patient. SD, stable disease; PD, progressive disease; IV, intravenous; Q28D, every 28 days. Data as of October 1, 2025 FPN: 983P