Form 8-K

8-K — Transcode Therapeutics, Inc.

Accession: 0001104659-26-111170

Filed: 2026-09-28

Period: 2026-09-28

CIK: 0001829635

SIC: 2834 (PHARMACEUTICAL PREPARATIONS)

Item: Other Events

Item: Financial Statements and Exhibits

Documents

8-K — tm2626237d1_8k.htm (Primary)

EX-99.1 — EXHIBIT 99.1 (tm2626237d1_ex99-1.htm)

GRAPHIC (tm2626237d1_ex99-1img01.jpg)

XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K — FORM 8-K

8-K (Primary)

Filename: tm2626237d1_8k.htm · Sequence: 1

false

0001829635

2026-09-28

iso4217:USD

xbrli:shares

iso4217:USD

xbrli:shares

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):

September 28, 2026

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.

Liberty Square, #2382

Boston, Massachusetts

02109

(Address

of principal executive offices, including zip code)

(857)

837-3099

(Registrant’s

telephone number, including area code)

Not Applicable

(Former Name or Former Address, if Changed

Since Last 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)

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR

240.14d-2(b))

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR

240.13e-4(c))

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 September 28, 2026, TransCode Therapeutics,

Inc. (“TransCode”) issued a press release announcing updated clinical data from its Phase 1a dose clinical trial of TTX-MC138.

A copy of this press release is attached hereto as Exhibit 99.1 and incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.

Description

99.1

Press Release, dated September 28, 2026

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: September 28, 2026

By:

/s/ Philippe P.

Calais

Philippe P. Calais

Chief Executive Officer

EX-99.1 — EXHIBIT 99.1

EX-99.1

Filename: tm2626237d1_ex99-1.htm · Sequence: 2

Exhibit 99.1

TransCode Reports

Continued Disease Stabilization and Extended Treatment Duration with TTX-MC138 in Ongoing Phase 1a Clinical Trial Follow-Up

Updated clinical

data reinforces evidence of antitumor activity in heavily pretreated patients with advanced solid tumors

· In the 14 efficacy-evaluable patients:

o 71.4% stable disease rate

o 57.1% of patients had disease control through three months of therapy

o 36.7% maintained disease control through six months of therapy

o Three efficacy-evaluable patients remain progression-free at one year

· Exploratory blood RNA-sequencing showed treatment-associated antitumor immune

activation and biological features associated with stable disease.

· The primary endpoint of the study was met

o No dose-limiting toxicities were reported across the evaluated dose levels

BOSTON, MA, September 28, 2026 – TransCode Therapeutics, Inc.

(NASDAQ: RNAZ), a clinical stage company pioneering immuno-oncology and RNA-based therapeutics for the treatment of high risk and advanced

cancers, today announced updated clinical data from its Phase 1a clinical trial of TTX-MC138, its novel anti-miR-10b therapeutic candidate,

in patients with relapsed or refractory, unresectable locally advanced, or metastatic solid tumors.

At the data cutoff date of September 1, 2026, 10 of 14 efficacy-evaluable

patients, or 71.4%, achieved stable disease as their best overall response by investigator assessment. In the context of a first-in-human,

dose-escalation study enrolling patients with advanced, heavily pretreated cancers,

the Company believes the consistency, breadth, and durability of disease

control observed thus far are promising and warrant continued clinical evaluation.

The disease control rate was 57.1% (95% confidence interval, 28.9% to 82.3%) at Cycle 3 Day 1 and 35.7% (95% confidence interval, 12.8%

to 64.9%) at Cycle 6 Day 1.

The durability of responses was also notable. Six of 14 efficacy-evaluable

patients were progression-free at three months, three of 14 at six months, and three of 14 at nine and 12 months. Together, these findings

show that the efficacy signal was not limited to a single assessment and included prolonged disease control in a subset of patients.

As of the September 1, 2026, a total 98 doses have been administered.

In this pre-specified data snapshot, TTX-MC138 demonstrated an acceptable tolerability profile in subjects with advanced solid tumors.

No dose-limiting toxicities were reported, no treatment-emergent adverse events led to treatment discontinuation, including the highest

evaluated dose level of 4.8 mg/kg. Of note, administration of TTX-MC138 for over a year was well tolerated and not associated with any

dose-limiting toxicities.

Figure 1. Swimmer Plot (Safety Population)

“The updated efficacy findings are highly positive and clinically

meaningful for an early dose-escalation study in a heavily pretreated, heterogeneous advanced solid-tumor population,” said Daniel

Vlock, M.D., Medical Consultant for TransCode Therapeutics. “A 71% stable disease rate, disease control extending through six months,

and three patients remaining progression-free at twelve months collectively demonstrate a compelling and durable signal of antitumor activity.

Importantly, these efficacy findings were observed alongside continued tolerability and no reported dose-limiting toxicities, supporting

further evaluation of TTX-MC138.”

Post-hoc Growth Modulation Index (GMI) Analysis Further Supports

Clinical Benefit

The Growth Modulation Index (GMI) was calculated to further document

the activity of TTX-MC138. GMI compares the progression-free survival achieved on study treatment to that achieved on the patient’s

most recent prior systemic anticancer therapy. A GMI greater than 1.3 is generally considered evidence of meaningful clinical benefit.

In this analysis, 6 of 15 evaluable patients (40%) achieved a GMI greater than 1.3, indicating that treatment with TTX-MC138 resulted

in at least a 30% longer progression-free interval than that achieved with the patient’s immediately preceding therapy. Notably,

several patients demonstrated substantially greater extensions of disease control relative to prior treatment, providing additional evidence

of antitumor activity in this heavily pretreated population.

Exploratory Biomarker Findings Support Biological Activity

Exploratory RNA-sequencing analysis of peripheral blood identified

treatment-associated, target-specific immune effects without major dysregulation of the global immune landscape. The analysis showed encouraging

on-treatment increases in an antitumor cytokine signature and dose-dependent immune effects, including cytotoxic effector activity and

increased monocyte and M1-associated inflammatory activity. Patients with stable disease showed higher B-cell and monocyte fractions and

enrichment of cytotoxic, phagocytic, and Type I interferon programs compared with patients with progressive disease. These exploratory

findings provide orthogonal biological support for the clinical efficacy observations and are consistent with TTX-MC138 engaging antitumor

immune pathways. Given the small sample size, the biomarker findings are hypothesis-generating and require confirmation in larger studies.

“The alignment between the highly positive clinical disease-control findings and the exploratory transcriptomic evidence is particularly

encouraging,” said Zdravka Medarova, Ph.D., Co-founder and Chief Scientific Officer of TransCode Therapeutics. “The data show

treatment-associated activation of multiple arms of antitumor immunity and biological features that distinguish patients with stable disease

from those with progressive disease. This convergence of clinical and biomarker evidence strengthens the mechanistic rationale for targeting

miR-10b and supports advancement of TTX-MC138.”

“These updated findings substantially strengthen our confidence

in TTX-MC138,” said Philippe P. Calais, Pharm.D., Ph.D., Chairman and Chief Executive Officer of TransCode Therapeutics. “The

breadth and durability of disease control, together with an acceptable tolerability profile and supportive evidence of biological activity,

provide a strong foundation for the next stage of development. We are evaluating dose-expansion strategies designed to confirm activity

in selected cancers and molecularly defined patient populations.”

TransCode expects to incorporate the updated clinical findings into

a clinical study report addendum and to continue evaluating safety, pharmacokinetics, pharmacodynamics, and antitumor activity.

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.

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 1a first-in-human clinical trial achieved its primary safety endpoint and is

currently being evaluated in a Phase 2a clinical trial targeting ctDNA-positive colorectal cancer patients following curative-intent

treatment.

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 and Phase 2a clinical trials, statements concerning the therapeutic

potential, consistency, breadth, durability of disease control of and responses to 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. 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,

2025, as well as discussions of potential risks, uncertainties and other important factors in any subsequent TransCode filings with the

U.S. 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 except as required by applicable law.

For more information and partnering

opportunities, please contact:

TransCode Therapeutics, Inc.

Tania Montgomery, VP of Business Development

tania.montgomery@transcodetherapeutics.com

GRAPHIC

Filename: tm2626237d1_ex99-1img01.jpg · Sequence: 6

Binary file (25607 bytes)

Download tm2626237d1_ex99-1img01.jpg

XML — IDEA: XBRL DOCUMENT

XML

Filename: R1.htm · Sequence: 8

v3.26.3

Cover

Sep. 28, 2026

Cover [Abstract]

Document Type

8-K

Amendment Flag

false

Document Period End Date

Sep. 28, 2026

Entity File Number

001-40363

Entity Registrant Name

TRANSCODE

THERAPEUTICS, INC.

Entity Central Index Key

0001829635

Entity Tax Identification Number

81-1065054

Entity Incorporation, State or Country Code

Entity Address, Address Line One

Liberty Square

Entity Address, Address Line Two

#2382

Entity Address, City or Town

Boston

Entity Address, State or Province

Entity Address, Postal Zip Code

02109

City Area Code

857

Local Phone Number

837-3099

Written Communications

false

Soliciting Material

false

Pre-commencement Tender Offer

false

Pre-commencement Issuer Tender Offer

false

Title of 12(b) Security

Common

Stock, par value $0.0001 per share

Trading Symbol

RNAZ

Security Exchange Name

NASDAQ

Entity Emerging Growth Company

true

Elected Not To Use the Extended Transition Period

false

- Definition

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

+ References

No definition available.

+ Details

Name:

dei_AmendmentFlag

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Area code of city

+ References

No definition available.

+ Details

Name:

dei_CityAreaCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Cover page.

+ References

No definition available.

+ Details

Name:

dei_CoverAbstract

Namespace Prefix:

dei_

Data Type:

xbrli:stringItemType

Balance Type:

Period Type:

duration

- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

+ References

No definition available.

+ Details

Name:

dei_DocumentPeriodEndDate

Namespace Prefix:

dei_

Data Type:

xbrli:dateItemType

Balance Type:

Period Type:

duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:

dei_DocumentType

Namespace Prefix:

dei_

Data Type:

dei:submissionTypeItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 1 such as Attn, Building Name, Street Name

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine1

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 2 such as Street or Suite number

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine2

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the City or Town

+ References

No definition available.

+ Details

Name:

dei_EntityAddressCityOrTown

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Code for the postal or zip code

+ References

No definition available.

+ Details

Name:

dei_EntityAddressPostalZipCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the state or province.

+ References

No definition available.

+ Details

Name:

dei_EntityAddressStateOrProvince

Namespace Prefix:

dei_

Data Type:

dei:stateOrProvinceItemType

Balance Type:

Period Type:

duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityCentralIndexKey

Namespace Prefix:

dei_

Data Type:

dei:centralIndexKeyItemType

Balance Type:

Period Type:

duration

- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityEmergingGrowthCompany

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Indicate if an emerging growth company has elected not to use the extended transition period for complying with any new or revised financial accounting standards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Securities Act

-Number 7A

-Section B

-Subsection 2

+ Details

Name:

dei_EntityExTransitionPeriod

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

Name:

dei_EntityFileNumber

Namespace Prefix:

dei_

Data Type:

dei:fileNumberItemType

Balance Type:

Period Type:

duration

- Definition

Two-character EDGAR code representing the state or country of incorporation.

+ References

No definition available.

+ Details

Name:

dei_EntityIncorporationStateCountryCode

Namespace Prefix:

dei_

Data Type:

dei:edgarStateCountryItemType

Balance Type:

Period Type:

duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityRegistrantName

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityTaxIdentificationNumber

Namespace Prefix:

dei_

Data Type:

dei:employerIdItemType

Balance Type:

Period Type:

duration

- Definition

Local phone number for entity.

+ References

No definition available.

+ Details

Name:

dei_LocalPhoneNumber

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 13e

-Subsection 4c

+ Details

Name:

dei_PreCommencementIssuerTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14d

-Subsection 2b

+ Details

Name:

dei_PreCommencementTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b

+ Details

Name:

dei_Security12bTitle

Namespace Prefix:

dei_

Data Type:

dei:securityTitleItemType

Balance Type:

Period Type:

duration

- Definition

Name of the Exchange on which a security is registered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection d1-1

+ Details

Name:

dei_SecurityExchangeName

Namespace Prefix:

dei_

Data Type:

dei:edgarExchangeCodeItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14a

-Subsection 12

+ Details

Name:

dei_SolicitingMaterial

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:

dei_TradingSymbol

Namespace Prefix:

dei_

Data Type:

dei:tradingSymbolItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Securities Act

-Number 230

-Section 425

+ Details

Name:

dei_WrittenCommunications

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration