Alkermes’ alks shares soared more than 30% in Friday trading after news that its experimental drug for severe depression hit its goal in a clinical trial.

The treatment, ALKS 5461, combines samidorphan and buprenorphine, a drug commonly used to treat opioid dependence. ALKS 5461 significantly reduced depression symptoms as measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) compared to placebo in a late-stage study, the company announced Thursday. That’s important because the therapy is meant for people who are already on other depression-fighting drugs but have seen little improvement in their conditions.

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

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“With these data now in hand, we will move forward rapidly to meet with the FDA to determine the appropriate next steps toward a regulatory submission for ALKS 5461, with a goal of bringing this important new medication to patients with [major depressive disorder],” he added.

But ALKS 5461 is no shoe-in for Food and Drug Administration approval. The encouraging new data comes after Alkermes released disappointing trial results for the drug from two prior phase 3 studies. The treatment failed to meet its primary goal on both of those occasions, sending Alkermes shares tanking.

 

Furthermore, the treatment wasn’t a universal success in the latest trial, either. It was only effective at a higher dose; a lower dose failed to achieve significant improvements compared to placebo.