Antipsychotics and Weight Gain: Positive Study Results


Alkermes announced positive results from their phase 3b ENLIGHTEN-Early study.

weight gain


Alkermes recently announced positive topline results from their phase 3b study, ENLIGHTEN-Early, which evaluated the effect of Lybalvi (olanzapine and samidorphan) compared to olanzapine on body weight in 428 young adult participants aged 16 to 39 with schizophrenia, schizophreniform disorder, or bipolar I disorder who were early in their illness.

The study met its primary endpoint: Patients treated with Lybalvi experienced statistically significantly less weight gain than patients treated with olanzapine at week 12. For example, the proportion of patients who gained 10% or more of their baseline body weight at 3 months was 30.4% for olanzapine versus 21.9% for Lybalvi. Additionally, the mean change from baseline in waist circumference at 3 months was 3.90 cm for patients treated with olanzapine vs 2.99 cm for patients treated with Lybalvi.

“We’re pleased to share topline results from the ENLIGHTEN-Early study, in which Lybalvi demonstrated less mean weight gain compared to olanzapine in patients early in illness with schizophrenia, schizophreniform disorder, or bipolar I disorder. These results complement the weight gain profile of Lybalvi shown in the ENLIGHTEN-2 pivotal study and reinforce the potential of Lybalvi as a new treatment option for adults living with schizophrenia or bipolar I disorder,” said Alkermes Chief Medical Officer Craig Hopkinson, MD.1

Furthermore, treatment with Lybalvi was associated with improvements in symptoms of schizophrenia and bipolar I disorder over 3 months, measured by the Clinical Global Impression of Severity (CGI-S) scale. The mean change from baseline in CGI-S score was -0.82.

“Olanzapine is well-known as an efficacious medicine but is often not used as a first-line treatment for early-in-illness patients due, in part, to concerns about weight gain. We’re encouraged to see the positive results of this study in patients who have had less exposure to antipsychotic therapy and may be particularly susceptible to olanzapine-induced weight gain,” said Christoph Correll, MD, professor of psychiatry and molecular medicine at Hofstra Northwell School of Medicine.

The safety profile of Lybalvi was consistent with previous studies. Of the 428 participants, 63.5% receiving Lybalvi and 63.3% receiving olanzapine reported adverse events. The most common adverse events reported for the Lybalvi treatment group were weight gain, somnolence, and increased alanine aminotransferase. For the olanzapine treatment group, adverse events included weight gain, somnolence, and increased waist circumference. Serious adverse events occurred in 3.8% of Lybalvi participants and 3.7% of olanzapine participants.

Alkermes intends to submit these results to a peer-reviewed journal for publication and will present additional results at upcoming scientific meetings.


1. Alkermes announces positive topline results from ENLIGHTEN-Early phase 3b study of LYBALVI® in patients early in illness. Alkermes. News release. February 8, 2022. Accessed February 9, 2022.

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