A randomised study and an extension study of brexpiprazole in patients with borderline personality disorder.

Objective: No drugs are currently approved for the treatment of borderline personality disorder (BPD). These studies (a randomised study and its open-label extension) aimed to evaluate the efficacy, safety and tolerability of brexpiprazole for the treatment of BPD.

Methods: The Phase 2, multicentre, randomised, double-blind, placebo-controlled, parallel-group study enrolled adult outpatients with BPD. After a 1-week placebo run-in, patients were randomised 1:1 to brexpiprazole 2-3 mg/day (flexible dose) or placebo for 11 weeks. The primary endpoint was change in Zanarini Rating Scale for BPD total score from randomisation (Week 1) to Week 10 (timing of randomisation and endpoint blinded to investigators and patients). The Phase 2/3, multicentre, open-label extension study enrolled patients who completed the randomised study; all patients received brexpiprazole 2-3 mg/day (flexible dose) for 12 weeks. Safety assessments included treatment-emergent adverse events (TEAEs).

Results: Brexpiprazole was not statistically significantly different from placebo on the primary endpoint of the randomised study (N = 324 randomised; N = 110 analysed per treatment group; least squares mean difference -1.02; 95% confidence limits -2.75, 0.70; p = 0.24). Numerical efficacy advantages for brexpiprazole were observed at other time points. The most common TEAE in the randomised study was akathisia (brexpiprazole, 14.0%; placebo, 1.2%); data from the open-label study (N = 199 analysed) suggested that TEAEs were transient.

Conclusion: The primary endpoint of the randomised study was not met. Further research on brexpiprazole in BPD is warranted based on possible efficacy signals at other time points and its safety profile.ClinicalTrials.gov identifiers: NCT04100096, NCT04186403. Funding: Otsuka, Lundbeck.