** Shares of Insmed INSM.O fall 5.9% to $128.99 premarket

** The drugmaker reports Q1 sales of $98.1 million for lung disease treatment Arikayce, missing analysts' average expectation of $105.4 million - per LSEG data

** INSM says it continues to evaluate the potential effect of evolving U.S. policies, which will then impact international launch timing for its other lung disease treatment Brinsupri

** Co's quarterly revenue of $306 million beats analysts' estimate of $303 million

** Up to last close, stock down 21.2% YTD