Biogen falls after US FDA declines to approve higher dose of co's genetic disorder drug

Shares of drugmaker Biogen BIIB.O fall 1.5% to $137.25 in extended trading

Company says the U.S. FDA has declined to approve higher dose version of its drug for a rare genetic disorder that causes progressive muscle weakness, citing the need for updated technical information in the application

The FDA has requested revisions to the Chemistry Manufacturing and Controls module in its "complete response letter," but did not identify deficiencies in the clinical data supporting the high-dose regimen — BIIB

Company plans to resubmit the application promptly based on readily available information

As of last close, stock down 8.9% YTD