Exelixis has begun a Phase II program for XL880, an orally bioavailable small molecule inhibitor of the receptor tyrosine kinases (RTKs) involved in tumor cell growth, migration and angiogenesis including MET and VEGFR.

The multicenter, open-label Phase II study will be conducted in up to 15 clinical sites and is designed to enroll up to 34 patients with hereditary or sporadic papillary renal cell carcinoma. Primary objectives of the study are to determine best-confirmed response rate and to evaluate safety and tolerability of XL880 administered orally for five consecutive days every two weeks.