18. Biogen

Biogen's 2015 was hindered by less-than-stellar sales of its flagship multiple sclerosis treatment Tecfidera. After three disappointing quarters in 2015, the drugmaker announced it would cut its workforce by 11% and launched a new DTC campaign for Tecfidera. More fallout came with the departure of Tony Kingsley, the company's lead commercial executive. Five months later, it named Merck primary-care ace Michael Vounatsos as its chief commercial officer. The news wasn't all sour: Tecfidera's sales surged in Q4 2015 to $785 million, beating analyst estimates of $751 million. Company execs noted that demand for the drug is stable and that growth should follow. Biogen's mid-term future success hinges on its experimental MS treatment  anti-LINGO 1, which is being studied as a possible means of repairing nerve cells affected by the disease. The drug's Phase II trial, dubbed Synergy, is expected to conclude in mid-2016. Its goal is to evaluate whether patients experience a confirmed improvement in cognitive function or disability.