Basimglurant for treatment of major depressive disorder: a novel negative allosteric modulator of metabotropic glutamate receptor 5

Introduction: Metabotropic glutamate receptor 5 (mGlu5) negative allosteric modulators (NAM) such as 2-Methyl-6-(phenylethynyl) pyridine (MPEP) and 3-((2-Methyl-1,3-thiazol-4-yl) ethynyl) pyridine (MTEP) can produce antidepressant-like effects; an example being the forced swim test in rodents. It is therefore of high interest that a new mGlu5 NAM called basimglurant (RO4917523, RG7090) was recently introduced for clinical development in depression. Areas covered: The current article reports on the preclinical and clinical work with basimglurant which strongly supports its use for treatment of depression. The authors cover the pharmacodynamics, pharmacokinetics and safety and tolerability features of basimglurant together with its clinical efficacy in a clinical type II trial. Expert opinion: The antidepressant activity of basimglurant may be related to a preferential reduction of mGlu5 receptor signaling in distinct populations of cortical limbic GABA interneurons causing disinhibition of discrete glutamate neuronal networks in brain circuits of mood and emotion. Basimglurant's removal of mGlu5 receptor induced inhibition of D2 receptor signaling in A2A-D2-mGlu5 heteroreceptor complexes of ventral striato-pallidal GABA neurons mediating anti-reward may also play a role. Basimglurant is a highly promising antidepressant drug now in clinical development for depression. However, further clinical trials are highly warranted.