Sarepta Announces First Clinical Data from siRNA Pipeline Targeting FSHD1 and DM1

Sarepta Therapeutics has reported its first clinical data from two investigational siRNA programs targeting rare neuromuscular disorders, marking a significant development in RNA-based therapeutics. The update, released on March 25, 2026, outlines early findings from Phase 1/2 dose-escalation studies evaluating SRP-1001 for facioscapulohumeral muscular dystrophy type 1 (FSHD1) and SRP-1003 for myotonic dystrophy type 1 (DM1).

The preliminary data indicated dose-dependent muscle exposure and early biomarker activity for both candidates, alongside favorable tolerability profiles. Most adverse events observed during the trials were reported as mild to moderate and showed no clear dose-related pattern, suggesting an acceptable safety profile at this stage of development. Additionally, proof-of-concept findings demonstrated that a single dose of each therapy was capable of reducing, or knocking down, the targeted protein or mRNA, highlighting the potential effectiveness of the approach.

The therapies are built on a proprietary delivery platform that utilizes αvβ6 integrin targeting to enhance the uptake of small interfering RNA (siRNA) into muscle tissue. This approach is designed to address a longstanding limitation in RNA therapeutics, where rapid degradation of the drug often prevents it from reaching target cells. By improving cellular delivery and tissue penetration, the platform aims to enable higher dosing and more sustained therapeutic effects.

Both FSHD1 and DM1 are rare genetic disorders driven by the overexpression of toxic proteins or mRNA, making them suitable candidates for RNA-targeted interventions. The early-stage results suggest that targeted siRNA therapies could offer a differentiated treatment approach compared to existing options, potentially addressing unmet clinical needs in these conditions.

Company leadership indicated that the observed increases in plasma and muscle drug exposure across both clinical and preclinical studies reinforce confidence in the delivery platform’s mechanism. The findings also support continued development and further clinical evaluation to determine long-term efficacy and safety outcomes.

The announcement underscores growing momentum in RNA-based drug development, particularly for rare diseases where traditional therapeutic approaches have shown limited success. Advances in delivery technologies are increasingly enabling more precise targeting of disease-causing genetic material, expanding the scope of potential treatments.

According to Precedence Research, the mRNA therapeutics market size accounted for USD 20.83 billion in 2025 and is predicted to increase from USD 22.30 billion in 2026 to approximately USD 45.40 billion by 2035, expanding at a CAGR of 8.1% from 2026 to 2035 as advancements in RNA-targeted therapies and improved delivery platforms drive innovation in genetic medicine.

A recent report by Precedence Research highlights that the mRNA therapeutics market is benefiting from increasing research in rare genetic disorders, growing clinical success of RNA-based drugs, and rising investment in next-generation delivery technologies for enhanced efficacy and safety.