A combination of olanzapine and the opioid receptor antagonist samidorphan (OLZ/SAM) has been approved in the United States for the treatment of adults with schizophrenia or adults with bipolar I disorder. In a phase 3 study in adults with schizophrenia (ENLIGHTEN-2), OLZ/SAM treatment was associated with significantly less weight gain compared with olanzapine. Prespecified subgroup analyses explored the consistency of the weight mitigation effect of OLZ/SAM vs olanzapine across demographic subgroups in ENLIGHTEN-2.

The multicenter, randomized, double-blind ENLIGHTEN-2 study (NCT02694328) included outpatients aged 18–55 years with a diagnosis of schizophrenia based on DSM-5 criteria, a body mass index (BMI) of 18 to 30 kg/m2, and stable body weight (self-reported change ≤5% for ≥3 months before study entry). Patients were randomized 1:1 to receive OLZ/SAM or olanzapine for 24 weeks. Co-primary endpoints (previously reported) were percent change in body weight and proportion of patients with at least 10% weight gain from baseline at week 24. Prespecified exploratory subgroup analyses by sex, age, self-reported race, and baseline BMI were conducted.

At week 24, treatment with OLZ/SAM resulted in numerically less percent weight gain than with olanzapine across all subgroups evaluated. The proportion of patients with at least 10% weight gain was smaller in each subgroup treated with OLZ/SAM vs olanzapine.

In these exploratory subgroup analyses from the ENLIGHTEN-2 study, weight-mitigating effects of OLZ/SAM vs olanzapine were observed consistently across patient subgroups and were in line with results from the overall study population.