mGlu₅ negative allosteric modulators: a patent review (2013 - 2016)

Introduction: The pursuit of small molecule mGlu₅ NAMs as treatments for a variety of psychiatric and neurodegenerative disorders has developed into a mature field. In addition to extensive preclinical studies, multiple compounds have advanced into clinical trials with the most advanced studies occurring in patients with FXS, PD-LID, and MDD. Areas covered: This review begins with an update of the clinical activity with mGlu₅ NAMs, and then moves into a summary of patent applications filed since 2013. The summaries are organized into three separate sections: (1) inventions centered on improvements to existing clinical compounds; (2) new small molecules that maintain the prototypical disubstituted alkyne chemotype found in many mGlu₅ NAM compounds; and (3) new small molecules that are not from a disubstituted alkyne chemotype. Expert opinion: It is a critical moment for mGlu₅ NAM research as recent reports from clinical trials have included some significant disappointments that have blunted prior optimism. Still, research in this area remains active, and recent years have added several more attractive small molecules to this field. There is now an arsenal of diverse chemotypes available to continue to probe this target in the hopes that a drug may yet emerge.