Shares in Ireland-headquartered Alkermes shot up nearly 50 percent after its experimental depression drug hit targets in a pivotal late-stage trial.

Alkermes unveiled positive topline results from FORWARD-5, the third Phase III efficacy study of its pivotal program 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 study met its prespecified primary endpoint showing treatment with ALKS 5461 significantly reduced symptoms of depression in patients with MDD compared to placebo, and the drug was also shown to be generally well tolerated, with the most common adverse events nausea, dizziness and fatigue.

Based on the data, as well as that collected to date on the efficacy and safety of ALKS 5461 for the treatment of MDD, the company said it plans meet with the US Food and Drug Administration's Division of Psychiatric Products to discuss filing strategy for the drug.

"We designed ALKS 5461 to have a novel mechanism of action for the treatment of MDD, a serious disease where new therapeutic options are highly sought after as millions of patients in the US do not respond to standard courses of antidepressant therapy," said Elliot Ehrich, chief medical officer of Alkermes.

"With the successful completion of the FORWARD-5 study and data from more than 1,500 patients to date, we have established a strong foundation of evidence of ALKS 5461's clinical utility in the adjunctive treatment of major depressive disorder".