Phase 2 FORWARD-53 Trial Reports Sustained Dystrophin Expression With WVE-N531 in Duchenne Muscular Dystrophy

This article was originally published on our sister site, NeurologyLive®.

The investigational exon-skipping therapy WVE-N531 (Wave Life Sciences) produced sustained increases in dystrophin levels and early indications of functional improvement in boys with Duchenne muscular dystrophy (DMD) who are amenable to exon 53 skipping, according to 48-week findings from the phase 2 FORWARD-53 study.¹

The data were presented at the 2026 Muscular Dystrophy Association (MDA) Clinical and Scientific Conference, held March 8-11 in Orlando, Florida. In the open-label trial, treatment with the stereopure antisense oligonucleotide was associated with increased dystrophin production, reductions in biomarkers linked to muscle damage and inflammation, and improvements in several exploratory functional outcomes.

DMD is a progressive X-linked neuromuscular disease caused by mutations in the dystrophin gene that lead to absent or markedly reduced dystrophin protein. The loss of dystrophin results in ongoing muscle fiber degeneration, progressive weakness, and cardiopulmonary complications that shorten life expectancy. Therapeutic strategies designed to restore dystrophin production—including exon-skipping antisense oligonucleotides—have emerged as targeted disease-modifying approaches for specific genetic subgroups of patients.²

FORWARD-53 Trial Design and Findings

The ongoing study, led by Li Tai, MD, PhD, executive director at Wave Life Sciences, enrolled 11 boys aged 5 to 11 years with DMD eligible for exon 53 skipping. The cohort included 10 ambulatory and 1 nonambulatory participant. Patients initially received WVE-N531 at 10 mg/kg every other week, and all subsequently entered the extension phase of the trial, transitioning to monthly dosing.

At 48 weeks, investigators reported that the therapy was generally well-tolerated. Treatment-related adverse events were described as mild to moderate, and there were no serious adverse events or treatment discontinuations during the observation period.

Biochemical analyses showed sustained restoration of dystrophin over time. Muscle content–adjusted dystrophin expression measured by western blot averaged 7.8%, with levels appearing to plateau between weeks 24 and 48. Among the 8 participants evaluated during that time frame, 7 (88%) achieved mean dystrophin expression above 5%. Measurements of exon skipping using reverse transcription–polymerase chain reaction (RT-PCR) remained stable through week 48, averaging 54% between weeks 24 and 48, suggesting continued engagement of the therapy’s molecular mechanism.

Investigators also reported histologic changes in muscle tissue consistent with improved muscle health. Biopsy analyses demonstrated a shift from regenerative toward more mature muscle fibers over time. Between weeks 24 and 48, muscle fibrosis declined by 28.6% (P < .01), while median scores for muscle necrosis and inflammation decreased from 2 to 1, indicating minimal tissue damage.

Biomarkers associated with muscle injury and inflammation were also reduced. Notably, creatine kinase levels declined by approximately 50% (P < .001), and reductions in inflammatory markers interleukin-6 and monocyte chemoattractant protein-1 were observed during treatment.

Functional outcomes were assessed using multiple measures. The time-to-rise test demonstrated a mean improvement of 3.8 seconds on the investigational agent relative to natural history data, exceeding the minimal clinically important difference threshold of 1.4 seconds (P < .05). Investigators also reported improvements compared with natural history trajectories on the North Star Ambulatory Assessment as well as increases in handgrip strength from baseline.¹

Drug Background and Mechanistic Approach

WVE-N531 is an investigational stereopure antisense oligonucleotide designed to induce skipping of exon 53 in the dystrophin transcript, enabling production of a shorter but partially functional dystrophin protein. Unlike earlier exon-skipping therapies, WVE-N531 incorporates phosphoryl guanidine (PN) chemistry, which is intended to enhance molecular stability and tissue uptake.

According to investigators, the therapy appears to target both differentiated muscle fibers and muscle stem cells. Engagement of muscle stem cells could theoretically support long-term regenerative capacity, though the functional implications of this mechanism remain to be fully characterized in clinical studies.²

Interpretation and Remaining Questions

Although the findings provide encouraging molecular and histologic signals, several limitations warrant consideration. The FORWARD-53 trial is a small open-label study with only 11 participants and lacked a randomized control group. Comparisons to natural history data may provide context but cannot fully account for variability in disease progression.

Additionally, while increases in dystrophin expression and improvements in biomarkers may suggest biological activity, the relationship between dystrophin levels and long-term clinical outcomes in DMD remains incompletely defined. Larger controlled studies will be necessary to determine whether WVE-N531 can produce durable functional benefits and how it compares with currently available exon-skipping therapies targeting exon 53.

Read more coverage of the 2026 MDA Conference here.

REFERENCES
1. Tai L, Servais L, Bader M, et al. 48-Week Data from the Phase 2 Open-Label FORWARD-53 Study of WVE-N531 in Boys with Duchenne Muscular Dystrophy amenable to Exon 53 Skipping. Presented at: 2026 Duchenne Muscular Dystrophy Clinical & Scientific Conference; March 8, 2026; Orlando, Florida.
2. Aartsma-Rus A, Krieg AM. FDA approval of eteplirsen for Duchenne muscular dystrophy: the next chapter in the Eteplirsen saga. Nucleic Acid Ther. 2017;27(1):1-3.