Today, Avidity Biosciences announced new data from its EXPLORE44® and EXPLORE44-OLE
Phase 1/2 studies of del-zota in people living with Duchenne muscular dystrophy amenable to exon 44 skipping. Del-zota is designed to deliver phosphorodiamidate morpholino oligomers (PMOs) to skeletal muscle and heart tissue to specifically skip exon 44 of the dystrophin gene and enable production of near-full length dystrophin.
According to Avidity, treatment with del-zota led to an increase in dystrophin expression of approximately 25% of normal, resulting in restored total dystrophin of 58% of normal. Individuals who are amenable to exon 44 skipping may also produce low levels of dystrophin through naturally occurring skipping. Creatine kinase (CK) levels showed sustained reductions in participants out to 16 months.
Participants also showed encouraging trends across multiple functional assessments when compared with both baseline measurements and natural history data, suggesting that del-zota may help preserve or improve muscle function over time. Improvements or stability were seen across several measures, including 4-Stair climb, 10-Meter Walk/Run, Time to Rise, North Star, and Performance of the Upper Limb—marking a first in Duchenne trials.
Del-zota has continued to demonstrate a favorable long-term safety and tolerability profile, and was granted Breakthrough Therapy designation by the U.S. Food and Drug Administration (FDA) in July 2025. Avidity remains on track to submit a BLA to the FDA at year end 2025 and continues to prepare for a confirmatory study to support full global approval.
These results are promising for our community. An estimated 6% of the Duchenne population are amenable to exon 44 skipping. For the first time, we are seeing evidence that an investigational therapy may not only impact biomarkers, but also improve function in a subset of people living with Duchenne. We look forward to future updates from Avidity on del-zota’s progress.
Read Avidity’s press release here.
Read Avidity’s community letter here.
The post Avidity Biosciences Announces Positive New Data from EXPLORE44® and EXPLORE44-OLE™ Phase 1/2 Studies appeared first on Parent Project Muscular Dystrophy.