Aticaprant, a kappa opioid receptor antagonist, and the recovered 'interest and pleasure' in the concept of major depressive disorder.

Lack of positive mood and anhedonia probably are the most specific depressive symptoms. Anhedonia is a multifaceted concept: the clinical language describes anticipatory/consummatory anhedonia and sensory/social anhedonia while the cognitive neuroscience language describes readiness for reward, energy expenditure to attain reward, updating reward presence and value. Mounting evidence supports the potential of kappa-opioid receptor (KOR) antagonists as novel pharmacotherapies for major depressive disorder : aticaprant is a potent, selective, short-acting KOR antagonist. The fast-fail approach evaluated the impact of aticaprant on the brain circuitry hypothesized to mediate anhedonia and significantly increased fMRI activation in the ventral striatal activation during reward anticipation as compared to placebo; the aticaprant induced changes in the self-reported psychological measures of anhedonia were rather inconsistent. The recently reported results of a phase 2a randomized, double-blind, placebo-controlled trial investigating the efficacy and safety of aticaprant, co-administered to an oral SSRI/SNRI antidepressant in depressed patients who had an inadequate response to 1 or 2 antidepressants. The improvement from baseline favoured the co-administration of aticaprant over the co-administration of placebo at all time points (during 6 weeks), and this was confirmed by higher response rates with aticaprant. A mid-split of patients with higher or lower than median anhedonia also showed that the patients with higher baseline anhedonia had the largest decrease on the MADRS. Tolerability and safety were reassuring. These promising results of the co-administration of aticaprant to an SSRI/SNRI in depressed patients with prominent anhedonia support he further investigation of aticaprant in larger trials.