Cabozantinib (Cabometyx) was more effective than everolimus (Afinitor) in people with advanced renal cell carcinoma (RCC) and bone metastases, according to a subgroup analysis of the METEOR clinical trial carried out by researchers at the Gustave Roussy Institute in Villejuif, France and published in Journal of Clinical Oncology.
Progression-free survival in people with bone metastases was 7.4 months with cabozantinib versus 2.7 months with everolimus. In addition, median overall survival was also significantly longer with cabozantinib in patients with bone metastases (20 versus 12 months), as was the objective response rate (17% versus 0%). Improved progression-free survival, overall survival, and objective response rates were also found in patients on cabozantinib without bone metastases. Bone biomarkers also changed more in the cabozantinib group compared to the everolimus group, suggesting that changes were caused by the study medication.
The authors noted, “Bone metastases are associated with a poor prognosis in advanced renal cell carcinoma, and additional treatments for these patients are needed. Cabozantinib is a standard of care for previously treated patients with advanced renal cell carcinoma, with clinical benefits in progression-free survival, overall survival, and objective response rates that are observed irrespective of the presence of bone metastases. On the basis of these outcomes, cabozantinib represents a good treatment option for this difficult-to-treat patient population.”
However, experts warn that these results should be interpreted with caution, and argue that the results show that RCC patients with bone metastases do worse on everolimus, and not better on cabozantinib. Response rate and median progression-free survival on cabozantinib are identical in patients with and without bone metastases. Because everolimus patients with bone metastases do worse, the relative advantage is greater. The subgroup analyses were unplanned, and a prospective study is needed to prove the findings.