Calithera Biosciences, Inc., a clinical-stage bio-pharmaceutical company, focuses on the discovery and development of small molecule drugs directed against tumor metabolism and tumor immunology targets for the treatment of cancer in the United States. Its lead product candidate is CB-839, an inhibitor of glutaminase, which is in Phase II clinical trial to treat solid tumors. The company also offers INCB001158, an oral inhibitor of arginase that is in Phase I/II clinical trial for the treatment of hematology and oncology. The company is also developing CB-280, an oral arginase inhibitor that is in Phase 1b clinical trial for the treatment of cystic fibrosis and chronic airway infection; and CB-708, an orally administered small molecule inhibitor of CD73, as well as CB-668, an inhibitor of the enzyme IL4I1. It has a license agreement with Mars, Inc. to develop and commercialize Symbioscience's portfolio of arginase inhibitors for use in human healthcare. The company also has clinical trial collaboration with Pfizer to evaluate Pfizer's PARP inhibitor talazoparib and CDK4/6 inhibitor palbociclib, each in combination with telaglenasta. In addition, it has a collaboration and license agreement with Incyte Corporation for the research, development, and commercialization of INCB001158, a small molecule arginase inhibitor for the treatment of hematology and oncology. Calithera Biosciences, Inc. was incorporated in 2010 and is headquartered in South San Francisco, California.