Data from the recent ASCO conference on a phase II study of cabozantinib (XL184) in patients with advanced solid tumors, including prostate cancer, demonstrates that the investigational treatment has activity in both bone and soft tissue. This study evaluated the efficacy and safety of cabozantinib compared to placebo in 9 different solid tumor types including breast, lung, ovarian, and prostate.

The data was presented as an abstract, “Activity of cabozantinib (XL184) in soft tissue and bone: Results of a phase II randomized discontinuation trial (RDT) in patients (pts) with advanced solid tumors” (J Clin Oncol 29: 2011

[suppl; abstr 3010]).

All patients in the study had progressive disease including bone metastases. The most common side effects were fatigue, hand-foot syndrome, and hypertension.

In prostate cancer patients, an “unprecedented bone scan improvement” was observed. Based upon these results, Exelixis, the company that is developing cabozantinib will expand the prostate cancer cohorts for this trial and also plans to initiate the first pivotal trial in prostate cancer by the end of this year. There was no data presented on life extension.

Joel T Nowak, M.A., M.S.W.