Leading gainers Monday morning included Cytokinetics (CYTK) - Get Report , whose shares rallied about 7% premarket after Needham upgraded the late-stage biopharma company to a Strong Buy with a $22 per share upside. Among other things, Needham analyst Chad Messer wrote that Cytokinetics' "Phase III VITALITY-ALS study of tirasemtiv in amyotrophic lateral sclerosis (ALS) is expected to read out by year end". He added that after a recent royalty financing, the company encompassed more than $230 million in pro forma cash, more than enough to launch tirasemtiv. 

Shares of small-cap biotech Artana Therapeutics (PETX) - Get Report  tumbled about 9.7% premarket after disclosing in a regulatory filing that Entyce, an in-development treatment for dogs that have lost their desire to eat, would not be commercially available until the forth quarter. Entyce was approved by the FDA's Center for Veterinary Medicine in May 2016. 

Bluebird Bio (BLUE) - Get Report shares fell about 4.5% after Roth Capital downgraded the clinical-stage company to Neutral. The company on Friday posted a loss of $2.07 per share over its latest quarter, falling short of analysts' consensus estimates. 

Other pre-market winners included Sorrento Therapeutics (SRNE) - Get Report , up about 6.9%, and Immunomedics (IMMU) - Get Report , which climbed about 5.9%. Meanwhile, Keryx Biopharmaceuticals (KERX) - Get Report fell about 2.6%, while Regeneron (REGN) - Get Report retreated about 1.6%.