Navacaprant, a Novel and Highly Selective Kappa Opioid Receptor Antagonist, in Adults With Major Depressive Disorder: A Randomized, Double-Blind Phase 2 Clinical Trial.

Abstract

Purpose/background: This phase 2a randomized, double-blind, placebo-controlled, 8-week trial assessed the efficacy and safety of navacaprant, a highly selective kappa opioid receptor antagonist, in adults with major depressive disorder (MDD).

Methods/procedures: Participants with 17-Item Hamilton Depression Rating Scale (HAMD-17) scores of 14 to 30 were randomized 1:1 to once-daily navacaprant 80 mg or placebo (n = 102 each). The primary endpoint was HAMD-17 change from baseline (CFB) to week 8. Secondary endpoints included CFB in Snaith-Hamilton Pleasure Scale (SHAPS). No adjustment for multiple comparisons was made.

Findings/results: At week 8, HAMD-17 CFB was not statistically significantly improved with navacaprant vs placebo (least squares mean difference -1.7 [standard error, 1.08], P = 0.121; mixed-models repeated-measures) in the efficacy population. In a prespecified sensitivity analysis using last-observation-carried-forward, navacaprant statistically significantly improved HAMD-17 CFB (-2.9 [0.88], P = 0.002; -2.2 [0.98], P = 0.024) and SHAPS CFB (-2.8 [0.96], P = 0.004; -3.4 [1.10], P = 0.002) vs placebo at weeks 4 and 8. In the prespecified subgroup with moderate-to-severe MDD (baseline HAMD-17 score ≥22; n = 100), navacaprant statistically significantly improved HAMD-17 CFB at both timepoints (-3.0 [1.20], P = 0.015; -2.8 [1.33], P = 0.037) and SHAPS CFB at week 8 (-4.8 [1.35], P = 0.001) vs placebo. Most frequently reported adverse events (AEs) included headache (4.9% both) and nausea (4.9% navacaprant, 1.0% placebo); no serious AEs were reported with navacaprant.

Implications/conclusions: Although the primary endpoint was not met in the efficacy population, which included participants with mild depression, statistically significant improvements with navacaprant on depressive symptoms including anhedonia in the moderate-to-severe MDD subgroup, along with a favorable safety profile, support further study of navacaprant for the treatment of MDD.