Efficacy and Safety of BI 1358894 in Patients With Borderline Personality Disorder: Results of a Phase 2 Randomized, Placebo-Controlled, Parallel Group Dose-Ranging Trial

Objective: To provide proof-of-concept (PoC), dose-range finding, and safety data for BI 1358894, a TRPC4/5 ion channel inhibitor, in patients with borderline personality disorder (BPD). Methods: This was a phase 2, multinational, randomized, double-blind, placebo controlled trial. Patients were randomized to oral placebo or BI 1358894 (5 mg, 25 mg, 75 mg, or 125 mg) once daily in a 2.5:1:1:1:2 ratio for 12 weeks. The primary end point was change from baseline in the Zanarini Rating Scale for BPD (ZAN BPD) total score at Week 10. Secondary end points included ≥30% ZAN-BPD reduction response from baseline at Week 10, change from baseline at Week 10 in the Difficulties in Emotion Regulation Scale-16 item total, State-Trait Anxiety Inventory-State Anxiety total, Patient Health Questionnaire-9 total, Clinical Global Impressions-Severity, and Patient Global Impression-Severity scores. Results: Of 655 enrolled patients, 390 were randomized and 323 (82.8%) completed the trial. For primary and secondary end points, no differences were observed between treatment and placebo; therefore, PoC was not established. The proportion of patients with adverse events (AEs, BI 1358894 overall vs placebo: 77.9% vs 75.0%) and serious AEs (SAEs; 10.3% vs 8.6%) was comparable between treatments. The proportion of patients with an SAE of suicidal ideation was 4.2% (BI 1358894 overall) and 6.3% (placebo). Conclusions: Although the primary end point was not met, BI 1358894 was well tolerated with no increase in self harm or suicidality. More targeted populations, alternative outcome assessments, and additional measures to minimize placebo effects should be considered for future trials. Trial Registration: ClinicalTrials.gov identifier: NCT04566601.