Piper Jaffray analyst Edward Tenthoff downgraded Sarepta Therapeutics to Neutral from Overweight saying the FDA briefing documents were worse than expected. The FDA's analysis of dystrophin production of only 0.9% of normal was worse than expected and "directly questions" the approvability of eteplirsen, Tenthoff tells investors in a research note. The analyst believes the likelihood of eteplirsen approval is diminished and removed the drug from his model. This cut his price target for Sarepta shares to $15 from $48. The stock is trading down 56%, or $17.85, to $13.77 in morning trading.