Sarepta Therapeutics Inc. (NASDAQ: SRPT) reported initial clinical results from Phase 1/2 studies of two siRNA treatments targeting rare neuromuscular diseases.

The company's SRP-1001 for facioscapulohumeral muscular dystrophy type 1 and SRP-1003 for myotonic dystrophy type 1 showed dose-dependent muscle exposure and early biomarker effects in ascending dose studies. Both treatments demonstrated what the company described as favorable tolerability profiles.

According to the company's statement, proof-of-concept data indicated that after a single dose, both SRP-1001 and SRP-1003 achieved reduction of target protein or mRNA. The studies showed that most adverse events were mild to moderate and were not dose dependent.

The treatments use an αvβ6 integrin-targeted delivery platform designed to overcome delivery challenges associated with siRNA therapies for genetic diseases caused by overexpression of mutant proteins or toxic mRNA.

"These preliminary clinical data show consistent dose-dependent increases in plasma and muscle drug exposures across clinical and nonclinical studies," said Louise Rodino-Klapac, President of Research & Development and Technical Operations.

FSHD affects approximately 16,000 individuals in the United States and causes progressive weakness of skeletal muscles. DM1, affecting about 40,000 individuals in the United States, is the most common form of adult-onset muscular dystrophy. Neither condition currently has approved disease-modifying treatments.

Sarepta will host an investor call on March 25, 2026, at 8:30 a.m. Eastern time to discuss the data. The company's siRNA platform includes five investigational treatments across neurodegenerative and pulmonary diseases, developed under an exclusive license with Arrowhead Pharmaceuticals.