Exelixis has initiated a Phase II trial for its XL880, an orally bioavailable small molecule inhibitor of the receptor tyrosine kinases involved in tumor cell growth.

The multicenter study will enroll up to 34 patients with hereditary or sporadic papillary renal cell carcinoma. It will evaluate safety and tolerability of XL880 administered orally for five consecutive days every two weeks. Subsequent trials will be carried out in head and neck and gastric cancer.