Dublin, Ireland-based Alkermes has kicked off a second Phase III trail of its investigational antipsychotic ALKS 3831, testing the drug’s effect on weight against that of olanzapine (Lilly’s Zyprexa).

ALKS 3831 is an investigational, novel, oral atypical antipsychotic drug candidate designed to be a broad-spectrum treatment for schizophrenia.

The ENLIGHTEN-2 trial will assess the drug’s weight gain profile in patients with schizophrenia over a six-month treatment period compared to olanzapine, an established atypical antipsychotic agent with proven efficacy but also metabolic liabilities, including significant weight gain. 

Safety and tolerability will also be evaluated in the study. All participants in the double-blind portion of the study will be eligible to take part in an open-label safety study for an additional 12 months, to assess safety and long-term tolerability of the drug.

Phase II trial data released last year showed that ALKS 3831 was equivalent to olanzapine in efficacy, but caused less weight gain; those taking Alkermes’ drug had a 37% lower mean weight gain than those taking olanzapine at week 12, but this was 51% lower gain in a pre-specified subset of patients who had put on weight during the one-week olanzapine lead-in. 

"There is a clear and compelling clinical rationale for developing an antipsychotic with the efficacy of olanzapine and a safety profile that addresses the substantial negative health impact of weight gain and metabolic consequences associated with olanzapine," said Elliot Ehrich, the firm’s chief medical officer.