Dyne Therapeutics reports Q3 2026 financial results

Item 2.02 Results of Operations and Financial Condition.

On [November 5], 2026, Dyne Therapeutics, Inc. (the "Company") issued a press release announcing the Company's financial results for the quarter ended September 30, 2026.¹ A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The information in this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any filing by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filling.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.

Description

99.1

104

Press Release issued by Dyne Therapeutics, Inc. on November 5, 2026

Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.²

DYNE THERAPEUTICS, INC.

Date: November 5, 2026

By:

/s/ John G. Cox

Name:

John G. Cox

Title:

President and Chief Executive Officer

Dyne Therapeutics Reports Third Quarter 2026 Financial Results and Recent Business Highlights

- Topline data from ACHIEVE registrational expansion cohort (REC) planned for Q1 2027 -

- Preclinical data presented at NMSG support the ongoing development of four investigational therapies for DMD amenable to skipping of exons 44, 45, 53, or 55 -

WALTHAM, Mass., November 5, 2026 – Dyne Therapeutics, Inc. (Nasdaq: DYN), a clinical-stage company focused on delivering functional improvement for people living with genetically driven neuromuscular diseases, today reported financial results for the third quarter of 2026 and recent business highlights.

"As we work toward potential commercialization, we are investing across multiple programs with the goal of unlocking the full value of our FORCE TM platform," said John Cox, president and chief executive officer of Dyne. "This includes preparations for the potential U.S. launch of z-rostudirsen for exon 51 DMD, if approved, and topline data from the registrational expansion cohort of the ACHIEVE trial for z-basivarsen in DM1, both expected in the first quarter of 2027. At the same time, we are advancing HARMONIA, the only Phase 3 clinical trial in DM1 currently enrolling participants and progressing four preclinical DMD programs that have the potential to expand our reach to over one third of individuals living with Duchenne."

Zeleciment rostudirsen (z-rostudirsen, also known as DYNE-251) in DMD (Duchenne muscular dystrophy)

Key milestones for z-rostudirsen

• Dyne's BLA is under priority review by the FDA with a Prescription Drug User Fee Act (PDUFA) target action date of January 21, 2027.

• Dyne continues to expect a potential U.S. launch of z-rostudirsen in Q1 2027, assuming approval is received on the anticipated timeline.

• The ongoing confirmatory Phase 3 FORZETTO trial of z-rostudirsen is intended to support conversion of Accelerated Approval, if granted, to traditional approval in the U.S. and to support ex-U.S. marketing applications.

• In addition to z-rostudirsen, Dyne is advancing four development candidates (DYNE-244, DYNE-245, DYNE-253 and DYNE-255) for the potential treatment of DMD amenable to skipping of exons 44, 45, 53, and 55, respectively. Preclinical data supporting the ongoing development of these investigational therapies was recently presented at the 27 th Annual Neuromuscular Study Group (NMSG) Scientific Meeting.

1

Zeleciment basivarsen (z-basivarsen, also known as DYNE-101) in DM1 (myotonic dystrophy type 1)

Additional one-year clinical data from Phase 1/2 ACHIEVE trial

• Dyne presented additional one-year efficacy data from the multiple ascending dose (MAD) portion of the ongoing Phase 1/2 ACHIEVE clinical trial of z-basivarsen at the 31 st Annual International Congress of the World Muscle Society (WMS) and the 2026 Annual Meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM).

• Data from a pooled dose group of participants initially enrolled in the MAD portion of ACHIEVE showed functional improvement versus baseline, versus placebo and versus a matched natural history cohort across multiple measures at 12 months.

Key milestones for z-basivarsen

• Topline data from the ACHIEVE REC are planned for Q1 2027 to support a potential BLA submission for U.S. Accelerated Approval in Q3 2027.

o Dyne intends to use data from the REC and from the already enrolled participants in the MAD and ongoing long-term extension portions of the ACHIEVE trial to support this potential BLA submission.

• Dyne expects a potential U.S. launch of z-basivarsen in H1 2028, assuming the FDA grants Priority Review and approval is received on the anticipated timeline.

• The ongoing confirmatory Phase 3 HARMONIA trial of z-basivarsen is intended to support conversion of Accelerated Approval, if granted, to traditional approval in the U.S. and to support ex-U.S. marketing applications.

Third Quarter Financial Results

Cash position : Cash, cash equivalents and marketable securities were $1.134 billion as of September 30, 2026.³ The Company expects that its cash, cash equivalents and marketable securities as of September 30, 2026, will be sufficient to fund its operations into the second quarter of 2028.

Research and development (R&D) expenses: R&D expenses were $161.7 million for the three months ended September 30, 2026 compared to $97.2 million for the three months ended September 30, 2025.⁴ The increase in R&D expense was primarily due to increased manufacturing activity for z-rostudirsen and higher clinical trial costs related to conducting the ongoing FORZETTO and HARMONIA Phase 3 trials for z-rostudirsen and z-basivarsen, respectively.

General and administrative (G&A) expenses: G&A expenses were $35.3 million for the three months ended September 30, 2026 compared to $16.7 million for the three months ended September 30, 2025.⁵ The increase in G&A expenses was primarily due to pre