Marinus Pharmaceuticals Inc., of Branford, Conn., announced the start of a proof-of-concept clinical trial of its lead candidate ganaxolone for the treatment of post-traumatic stress disorder (PTSD). The company said that ganaxolone modulates inhibitory GABA-A receptors, possibly at a specific neurosteroid recognition site. Neurosteroid levels have been implicated in both the severity and treatment outcome in PTSD patients. The trial will take place in the U.S. and is expected to enroll about 120 PTSD patients.