AVI tanks after positive PhIIb fails to improve outcomes for DMD

Looking to make a comeback, Bothell, WA-based AVI Biopharma--an RNA company--heralded the news that its lead therapy hit the primary endpoint in a Phase IIb study, increasing levels of dystrophin in a tiny trial for Duchenne muscular dystrophy. But when investors took a closer look and saw that the boys did not experience a significant improvement in walking ability, AVI's shares ($AVII) plunged about 25%.

Investigators noted that the small group of boys treated with eteplirsen benefited from a spike in levels of the protein, which is associated with muscle function. Raising levels of dystrophin is a key target for a number of developers trying to treat DMD, based on the logical theory that if you improve dystrophin levels a developer can have a positive impact on symptoms of the rare disease. AVI's drug uses an exon-skipping approach to skip exon 51 in the dystrophin gene, restoring its function. And the investigators noted the improvement of dystrophin after 24 weeks of treatment.

"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 principal investigator Jerry Mendell. "We anticipate that these levels of dystrophin could lead to significant clinical benefit if maintained over a longer course of treatment."

But clinicians didn't see a comparable improvement in the 6-minute walk test used to gauge the expected improvement. The company added that "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." 

Prosensa is also developing an exon 51 skipping approach to DMD. And PTC Therapeutics has experienced its own problems in the DMD field.

Late last fall AVI announced a restructuring that cost the jobs of 28% of its workforce. The restructuring was brought about as CEO Chris Garabedian responded to a string of setbacks. It also hasn't helped that the RNA field in general has been operating under a cloud in recent years, as Big Pharma dropped some high-profile partnerships. Garabedian's strategy is closely focused on the successful development of eteplirsen, with other programs in place for Ebola and the Marburg virus.

- read the press release
- here's the story from Reuters