The U.S. FDA granted a breakthrough therapy designation to Tonix Pharmaceuticals Holding Corp.'s TNX-102 SL to treat posttraumatic stress disorder, or PTSD.

The company plans to start enrolling patients in a phase 3 study of the drug in the first quarter of 2017 after receiving FDA agreement on the study design and interim analysis plan.

TNX-102 SL is an investigational new drug and has not been approved for any indication.