Preclinical and clinical efficacy of kappa opioid receptor antagonists for depression: A systematic review.

Background: Approximately 30 % of persons with Major Depressive Disorder (MDD) inadequately respond to conventional antidepressants. Kappa opioid receptor (KOR) antagonists, aticaprant and navacaprant, are in development as treatments for MDD. Herein, we aim to comprehensively evaluate the safety, efficacy and pharmacology of aticaprant and navacaprant for MDD.

Methods: We performed a systematic review of primary research investigating aticaprant and navacaprant on PubMed, OVID, and Scopus databases from inception to April 2024. Studies that reported on the pharmacological profile and/or safety and efficacy of aticaprant and navacaprant were included.

Results: Navacaprant monotherapy and aticaprant adjunctive therapy are in development for MDD. Navacaprant exhibits 300-fold selectivity for the KOR compared to the mu-opioid receptor, while aticaprant exhibits 30-fold selectivity. At clinically-relevant doses, navacaprant and aticaprant occupy 87-95 % and 73-94 % of KORs, respectively. Clinical trials of the foregoing agents (navacaprant as monotherapy and actiprant as adjunctive therapy) reported significant improvement in depressive symptoms and may clinically benefit measures of anhedonia. Both agents appear well-tolerated, with most adverse events mild and no known safety concerns.

Limitations: Aticaprant and navacaprant treatment for MDD are in early stages of clinical trials and results from Phase 3 pivotal trials are not yet available.

Conclusions: Kappa opioid receptor antagonists may serve as mechanistically-novel treatments for MDD and persons who inadequately respond to index conventional antidepressants. Anhedonia is debilitating and insufficiently treated with conventional antidepressants. Future research vistas should establish the efficacy and safety of KORAs in phase 3 studies in both acute and maintenance paradigms.