Charles River Laboratories has acquired KWS BioTest, a CRO specializing in in vitro and in vivo discovery testing services for immuno-oncology, inflammatory, and infectious diseases, for approximately $20 million.    The acquisition expands Charles River’s discovery services with additional tools in the growing therapeutic research areas of oncology and immunology. The transaction also includes a potential additional payment of as much as $4 million based on future performance.   James C. Fo...