Leflutrozole (developmental code names BGS-649, CGP-47645) is an aromatase inhibitor which is under development by Mereo BioPharma and Novartis for the treatment of hypogonadism in men.[1] It was also under investigation for the treatment of endometriosis, but development for this indication was discontinued.[1] As of December 2017, leflutrozole is in phase IIclinical trials for hypogonadism.[1]