Shares of Sarepta Therapeutics (SRPT Quick QuoteSRPT - Free Report) rose 35% on Wednesday after the company announced early clinical data on two experimental siRNA therapies, which were acquired last year as part of a licensing deal with Arrowhead Pharmaceuticals.

Sarepta unveiled the first clinical results from two ongoing phase I/II studies — one evaluating SRP-1001 for facioscapulohumeral muscular dystrophy type I (FSHD1) and another evaluating SRP-1003 for myotonic dystrophy type I (DM1). The data showed that both drugs achieved high muscle concentrations without dose-limiting toxicity in patients with FSHD1 or DM1.

More Details on SRPT’s Phase I/II Studies

Early clinical data on both studies showed that after a single dose, SRP-1001 and SRP-1003 supported the reduction of the target protein (or mRNA). The initial data also demonstrated dose-dependent muscle delivery, early biomarker activity and favorable safety profiles.

With regard to SRP-1001, data showed that a single dose achieved significantly higher muscle siRNA levels versus prior approaches and led to robust pharmacodynamic effects, including more than 90% suppression of DUX4-regulated gene expression and a 33% reduction in creatine kinase levels.

As far as SRP-1003 is concerned, early data showed initial dose-dependent plasma exposure and early signs of target engagement, with cohort 1 demonstrating more than 50% placebo-adjusted reduction in DMPK mRNA. Muscle concentration data remain limited but are expected to expand with additional samples.

Sarepta noted that both treatments were generally well-tolerated in study participants. Although the company did observe mild-to-moderate adverse events, they were not dose-dependent.

These findings support the potential of the αvβ6 integrin-targeted siRNA platform to improve muscle delivery and overcome key limitations of RNA therapies, thus transforming the treatment for these rare genetic disorders. The company intends to provide updated data on both candidates in the second half of 2026.

FSHD1 is a rare genetic disorder caused by abnormal activation of the DUX4 gene, leading to progressive muscle weakness in individuals. Approximately 16,000 people in the United States have been affected by facioscapulohumeral muscular dystrophy, with no approved treatment currently available.

DM1 is the most common adult-onset muscular dystrophy, caused by a DMPK gene repeat expansion, leading to a progressive, multisystem disorder including muscle weakness, respiratory issues and cardiac abnormalities. Approximately 40,000 individuals in the United States are diagnosed with DM1. At present, there is no approved therapy for the disease.

Despite the data being early-stage, SRPT stock witnessed an upside, likely due to the treatment potential of both investigational drugs.

Year to date, Sarepta Therapeutics’ shares have risen 5.7% compared with the industry’s 1.9% growth.

Image Source: Zacks Investment Research

SRPT’s Deal With Arrowhead

Sarepta closed an exclusive global licensing and collaboration agreement with Arrowhead Pharmaceuticals in February 2025. The Arrowhead deal added therapies that expand the company’s pipeline across the central nervous system and rare pulmonary disorders.

As part of the deal, Sarepta acquired exclusive rights to seven siRNA programs, including four programs being evaluated in separate phase I/II studies — SRP-1001 in FSHD, SRP-1002 in idiopathic pulmonary fibrosis, SRP-1003 in DM1 and SRP-1004 in spinocerebellar ataxia 2.

Sarepta also intends to start dosing patients in the phase I/II study on SRP-1005, an investigational Huntington’s Disease therapy, in the second quarter of 2026. It expects to report proof-of-biology data from the study in the first half of 2027.

Sarepta Therapeutics’ Zacks Rank & Stocks to Consider

SRPT currently carries a Zacks Rank #3 (Hold).                                                     

Some better-ranked stocks in the biotech sector are Catalyst Pharmaceuticals (CPRX Quick QuoteCPRX - Free Report) ,ADMA Biologics (ADMA Quick QuoteADMA - Free Report)  and Inovio Pharmaceuticals (INO Quick QuoteINO - Free Report) . While CPRX sports a Zacks Rank #1 (Strong Buy), ADMA and INO carry a Zacks Rank #2 (Buy) each at present. You can see the complete list of today’s Zacks #1 Rank stocks here.

Over the past 60 days, estimates for Catalyst Pharmaceuticals’ 2026 earnings per share (EPS) have risen from $2.55 to $2.87. CPRX shares have gained 21.7% over the past six months.

Catalyst Pharmaceuticals’ earnings beat estimates in each of the trailing four quarters, with the average surprise being 35.19%.

Over the past 60 days, estimates for ADMA Biologics’ 2026 EPS have increased from 85 cents to 96 cents. ADMA shares have lost 34.5% over the past six months.

ADMA Biologics’ earnings beat estimates in one of the trailing three quarters, matched once and missed on the remaining occasion, with the average negative surprise being 1.79%.

Over the past 60 days, estimates for Inovio Pharmaceuticals’ 2026 loss per share have narrowed from $1.26 to $1.12. INO shares have plunged 36.9% over the past six months.

Inovio Pharmaceuticals’ earnings beat estimates in each of the trailing four quarters, with the average surprise being 57.94%.