Cabozantinib as a novel therapy for renal cell carcinoma.

Cabozantinib/XL184 (Exelexis, Inc.) has demonstrated remarkable responses in kidney cancer. Preclinical results revealed VEGF, KIT and MET inhibition in a variety of solid tumors such as thyroid, ovarian, renal, lung, liver and prostate cancers. A phase II trial demonstrated efficacy in renal cancer with a 28 % objective response rate, stable disease rate of 62 % and median progression free survival of 14.7 months. Predominant toxicities of fatigue and diarrhea were noted. Dramatic responses in bone metastases (three of four patients) make the agent especially valuable for palliation in a disease, where presence of bone metastases is a predictor of worse survival. Cabozantinib is an emerging novel agent with promising activity in advanced kidney cancer. Randomized trials are planned in comparison with standard VEGF inhibitor therapy. Defining the role of MET overexpression would help patient selection and enrich and enhance the future evaluation of this targeted novel agent.