Exelixis has moved its orally bioavailable small molecule inhibitor XL880 into Phase II testing in patients with papillary renal cell carcinoma. XL880 is a small-molecule inhibitor of the receptor tyrosine kinases (RTKs) involved in tumor cell growth, migration and angiogenesis, including MET and VEGFR.

A multicenter, open-label Phase II study of the compound 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.

Secondary objectives are to assess progression-free survival, overall survival and duration of response, and to continue characterizing the pharmacokinetic and pharmacodynamic profiles of XL880. Subsequent Phase II trials will be carried out for head and neck and gastric cancer.