Alkermes plc announced that it has submitted a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for ALKS 5461, a once-daily, oral investigational medicine with a novel mechanism of action for the adjunctive treatment of major depressive disorder (MDD). The NDA submission is based on a comprehensive clinical efficacy and safety package with data from more than 30 clinical trials and more than 1,500 patients with MDD. Throughout the clinical development program, ALKS 5461 demonstrated a consistent profile of antidepressant activity, safety and tolerability in the adjunctive treatment of MDD. ALKS 5461 was granted Fast Track status by the FDA in October 2013 for the adjunctive treatment of MDD in patients with an inadequate response to standard antidepressant therapies.