AVI BioPharma: Longer test needed for muscular dystrophy drug

AVI BioPharma Inc. said a study of its eteplirsen drug for boys with Duchenne muscular dystrophy (DMD) "met the primary efficacy endpoint" but added a longer study will be needed. A 12-week study "did not show a significant increase" in results, even at higher doses, and officials at the Bothell biotech said the "finding suggests that a longer duration of dosing is required ... There were no significant improvements in clinical outcomes in the treated groups compared to placebo ... suggesting that…