RNA-based therapeutics developer AVI BioPharma has initiated patient dosing in a Phase II study of Eteplirsen, an exon-skipping therapeutic candidate for the treatment of Duchenne muscular dystrophy.

Eteplirsen uses AVI’s phosphorodiamidate morpholino oligomer-based chemistry and proprietary exon-skipping technology to bypass exon 51 of the dystrophin gene, restoring its ability to make a shorter, but still functional, form of dystrophin from mRNA.

The 12-patient, placebo-controlled study is being conducted at Nationwide Children’s Hospital in Columbus, Ohio, US, to evaluate the efficacy and safety of Eteplirsen in Duchenne muscular dystrophy patients over 24 weeks of dosing.

The efficacy endpoints include biochemical markers in muscle biopsies, such as the production of the dystrophin protein and markers of immune-inflammatory response, as well as clinical outcomes to measure muscle strength, function and degree of ambulation.

AVI CEO and president Chris Garabedian said the Phase II study will evaluate Eteplirsen at higher doses and over a longer duration of treatment, which will help the company understand the potential disease-modifying effects and safety of the drug as a chronically-administered therapy.

“We expect data from this study around the end of the second quarter of 2012, which will guide our design for a pivotal study,” Garabedian added.