Lumateperone Monotherapy in Bipolar Depression Falls Short on Efficacy

Key Takeaways

• Neither lumateperone 28 mg nor 42 mg showed significant improvement over placebo on the primary MADRS endpoint at Day 43.
• The key secondary endpoint of time to first sustained response also did not differ meaningfully from placebo for either dose.
• Both doses were described as generally safe and well tolerated, with low extrapyramidal symptom risk and minimal changes in weight, prolactin, and cardiometabolic or endocrine measures.

In this phase 3 randomized, double-blind, placebo-controlled trial, lumateperone monotherapy did not separate from placebo in adults with bipolar I or II disorder during a major depressive episode. At 42 mg, the least-squares mean difference versus placebo on depressive symptoms was -1.0 over 6 weeks. Even with the negative efficacy result, both lumateperone doses were described as generally safe and well tolerated.

This phase 3 study enrolled adults aged 18 to 75 years with bipolar I or bipolar II disorder who were experiencing a major depressive episode. Participants were randomized 1:1:1 to 6 weeks of lumateperone 28 mg, lumateperone 42 mg, or placebo, with 183, 185, and 186 patients in the respective groups. The primary endpoint was change from baseline to Day 43 in the Montgomery-Åsberg Depression Rating Scale, while the key secondary endpoint was time to first sustained response. Sustained response was defined as at least a 50% reduction from baseline in MADRS total score.

Neither lumateperone dose achieved significant improvement versus placebo on the primary endpoint, with P values above 0.05 for the primary comparisons in MADRS Total score. The least-squares mean differences versus placebo were 0.9 for 28 mg and -1.0 for 42 mg by Day 43. Time to first sustained response also did not improve, with hazard ratios versus placebo of 1.00 for 28 mg and 0.93 for 42 mg. The authors indicated that a high placebo response may have contributed to the absence of an efficacy signal.

Both doses were described as generally safe and well tolerated, with low extrapyramidal symptom risk during the 6-week treatment period. Changes in weight, prolactin, and cardiometabolic or endocrine parameters were minimal. These short-term safety findings accompanied the negative efficacy results.

Overall, the 6-week study did not meet the primary efficacy endpoint or the key secondary sustained-response endpoint for lumateperone 28 mg or 42 mg in bipolar depression. Both dose levels were described as generally well tolerated in adults with bipolar I or II disorder. The trial ended with negative efficacy findings alongside a favorable short-term tolerability summary.