Cantor Fitzgerald analyst William Tanner believes the future of Alkermes depression drug ALKS 5461 could be a "major" share catalyst in 2018. A successful outcome in the review of ALKS 5461 is critical to the stock's out-year performance, Tanner tells investors in a research note. The analyst thinks Alkermes' hiring of an additional 200 sales reps in 2018 "seems aggressive" given uncertainty about approval, but admits they could be shifted to Vivitrol/Aristada. Tanner lowered his price target for Alkermes shares to $50 from $53 and keeps a Neutral rating on the name.