Dyne Therapeutics today announced the initiation of the company’s Phase 3 FORZETTO trial of zeleciment rostudirsen (z-rostudirsen, DYNE-251), in individuals living with Duchenne who are amenable to exon 51 skipping. Z-rostudiresen is an investigational exon skipping therapy bound to an antigen-binding fragment (Fab) to help the therapy reach the muscle cells for those amenable to exon 51 skipping.

About the FORZETTO Trial

FORZETTO is a global, randomized, placebo-controlled, double-blind, confirmatory Phase 3 trial designed to further demonstrate the potential of z-rostudirsen to enable functional improvement by assessing multiple measures of mobility, lung health, and patient-reported outcomes.

The primary endpoint is the change from baseline in time to rise (TTR) velocity, a clinically meaningful measure of muscle strength and motor coordination, at Week 73. Secondary endpoints include changes from baseline in stride velocity 95th centile (SV95C), North Star Ambulatory Assessment (NSAA) total score, 10-meter walk/run (10MWR) velocity, four-stair climb (4SC) velocity and forced vital capacity percent predicted (FVC%p), as well as additional functional and patient-reported outcome measures.

According to Dyne, the trial will enroll approximately 90 ambulatory male participants 4 to 18 years of age who will be randomized 1:1 to receive 20 mg/kg of z-rostudirsen or placebo intravenously every four weeks. Following the 72-week double-blind placebo-controlled treatment period, participants will be eligible to enroll in a 96-week open-label long-term extension. The first FORZETTO trial site is activated and open to enrollment. 

Dyne notes that the company plans to submit its Biologics License Application (BLA) for Accelerated Approval in the U.S. later this quarter based on results of the DELIVER trial of z-rostudirsen. FORZETTO is intended to serve as a confirmatory trial to support the potential conversion of Accelerated Approval to traditional approval in the U.S.

What This Means for the Community

Today’s announcement from Dyne marks another important step forward for the Duchenne community, particularly for individuals amenable to exon 51 skipping. As the Phase 3 FORZETTO trial begins, individuals and families can stay informed by monitoring ClinicalTrials.gov and PPMD’s website, including our Explore Clinical Trials tool, for additional information about study sites, eligibility and enrollment, and timelines.

Families are also encouraged to speak with their neuromuscular care team about what this news may mean for them personally, or schedule 1:1 time with PPMD’s genetics team through PPMD For You (“Genetics, Clinical Trials, & The Duchenne Registry”).

Read Dyne’s press release here.