The biopharma Vistagen (Nasdaq:VTGN) has agreed to acquire privately-held Pherin Pharmaceuticals for roughly 12.4 million shares of Vistagen stock. It will sweeten the deal with “a nominal amount of cash,” the company said in a press release. The deal is subject to customary closing conditions. In October 2018, South San Francisco, California–based Vistagen announced that…