Cabozantinib showed significant improvements in progression-free survival and objective response rate over standard-of-care sunitinib in a phase II clinical trial of adults with metastatic renal cell carcinoma, according to a report published in the Journal of Clinical Oncology.
As a first-line therapy for patients with poor- to intermediate-risk renal cell carcinoma (RCC), cabozantinib improved progression-free survival by approximately 3 months, corresponding to a 34% reduction in the rate of disease progression or death. This is the first study in this patient population in which another agent demonstrated “notable and clinically meaningful” superiority over sunitinib, which has been an established standard of care for more than 10 years, wrote Toni K. Choueiri, MD, director of the Kidney Cancer Center, Dana-Farber Cancer Institute, Boston, and his associates.
In the open-label study, participants were randomly assigned to receive daily oral cabozantinib (79 patients) or daily oral sunitinib (78 patients) in 6-week cycles until disease progressed, intolerance developed, or patients withdrew from treatment. A total of 36% had bone metastases at baseline, an indicator of poor prognosis.
The primary endpoint – median duration of progression-free survival or time to death from any cause – was 8.2 months with cabozantinib and 5.6 months with sunitinib (adjusted hazard ratio, 0.66). Analyses of patient subgroups defined by disease severity consistently favored cabozantinib. Reductions in target lesion size, as measured by CT or MRI, were observed in 87% of the cabozantinib group, compared with 44% of the sunitinib group, the investigators reported (J Clin Oncol. 2016 Nov 14. doi: 10.1200/JCO.2016.70.7398).
Preliminary data showed that overall survival was 30.3 months with cabozantinib and 21.8 months with sunitinib. This represents a 20% decrease in mortality with cabozantinib.
The median number of treatment cycles was greater in the cabozantinib group (five cycles) than in the sunitinib group (two cycles), and corresponded to median treatment durations of 6.9 months and 2.8 months, respectively. Rates of treatment discontinuation due to adverse events were similar between the two study groups, as were the rates of adverse events of any grade, adverse events of grade 3 or 4, and adverse events of grade 5.
These findings indicate that cabozantinib may represent a new treatment option for previously untreated poor- or intermediate-risk metastatic RCC, Dr. Choueiri and his associates wrote.
The study was supported by the National Institutes of Health and Exelixis, which provided the cabozantinib. Dr. Choueiri and many of his associates reported ties to numerous industry sources.