Exelixis, Inc. is a biopharmaceutical company. The Company is engaged in developing small molecule therapies for the treatment of cancer. It focuses on the development and commercialization of cabozantinib, an inhibitor of multiple receptor tyrosine kinases, in various tumor indications. Cabozantinib is indicated for the treatment of progressive, metastatic medullary thyroid cancer, and is sold under the brand name COMETRIQ. It is evaluating Cabozantinib in a development program, which consists of over 45 clinical trials, across multiple indications, including pivotal studies in advanced renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC). Its other products are Cobimetinib and XL888. Cobimetinib is a potent, selective inhibitor of MEK, a kinase that is a component of the RAS/RAF/MEK/ERK pathway. XL888 is a small molecule oral inhibitor of Heat Shock Protein 90 (HSP90), a molecular chaperone protein that affects the activity and stability of a range of regulatory proteins.