 Zacks Investment Research upgraded shares of Principia Biopharma NASDAQ:PRNB from a hold rating to a buy rating in a report issued on Tuesday, Zacks.com reports. Zacks Investment Research currently has 75.00 price objective on the stock. According to Zacks, Principia Biopharma Inc. is a clinical stage biopharmaceutical company. It offers reversible covalent small molecule drugs ... 