Bristol-Myers Squibb Company and Calithera Biosciences , Inc. , a clinical stage biotechnology company focused on discovering and developing novel small molecule drugs directed against tumor metabolism and tumor immunology targets for the treatment of cancer, today announced a clinical trial collaboration to evaluate Bristol-Myers Squibb’s Opdivo in combination with Calithera’s CB-839 in patients with clear cell renal cell carcinoma . CB-839 is an orally administered glutaminase inhibitor currently in Phase 1/2 clinical studies.