BOTHELL, WA, Apr 02, 2012 (MARKETWIRE via COMTEX) --AVI BioPharma, Inc. (NASDAQ: AVII), a developer of RNA-based therapeutics, today announced that treatment with eteplirsen met the primary efficacy endpoint in a randomized, double-blind, placebo-controlled Phase IIb study in boys with Duchenne muscular dystrophy (DMD). Eteplirsen administered once weekly at 30mg/kg over 24 weeks resulted in a statistically significant (p ≤ 0.002) increase in novel dystrophin (22.5% dystrophin-positive fibers as a percentage of normal) compared to no increase in the placebo group.

"This study represents a major advance in the field of DMD research as the results indicate that eteplirsen is producing consistent levels of dystrophin, which is the essential protein that these patients need," said Jerry Mendell, M.D., Director of the Centers for Gene Therapy and Muscular Dystrophy at Nationwide Children's Hospital and principal investigator of the Phase IIb study. Dr. Mendell added, "We anticipate that these levels of dystrophin could lead to significant clinical benefit if maintained over a longer course of treatment."

In the study, a shorter duration of eteplirsen treatment, 12 weeks, did not show a significant increase in novel dystrophin (0.79% dystrophin-positive fibers as a percentage of normal; p-value NS), despite administration of the drug at a higher dose (50mg/kg once weekly). This finding suggests that a longer duration of dosing is required before meaningful levels of dystrophin are produced. There were no significant improvements in clinical outcomes in the treated groups compared to placebo. Performance on the 6-minute walk test and other outcome measures were generally stable across most of the patients, including the placebo patients, suggesting that a longer period of observation will be required to demonstrate clinical effects of eteplirsen versus a placebo control.

Eteplirsen was well tolerated at both dose levels through 24 weeks of treatment. There were no treatment-related adverse events, no serious adverse events, and no treatment discontinuations related to eteplirsen. Furthermore, no treatment related changes were detected on any safety laboratory parameters, including several biomarkers for renal function.

"We are very encouraged by the results of this first placebo-controlled study investigating exon-skipping technology in DMD," said Chris Garabedian, President and CEO of AVI BioPharma. "Eteplirsen represents the first drug candidate for DMD to demonstrate the production of novel dystrophin in a robust and consistent manner and these study results support advancing eteplirsen into a pivotal study."