New CABOSUN Data Show Better PFS With Cabozantinib in mRCC

The significantly better PFS compared with sunitinib supports cabozantinib as initial therapy for patients with advanced RCC of intermediate or poor risk.

Updated results from the phase II CABOSUN trial showed cabozantinib significantly prolonged progression-free survival (PFS) per independent review committee compared with sunitinib as first-line therapy for advanced renal cell carcinoma (RCC) of poor or intermediate risk.

Previously available results from CABOSUN showed improved investigator-assessed PFS, with a median PFS of 8.2 months for cabozantinib compared with 5.6 months for sunitinib (P = .012).

“The independent assessment confirms the investigator-assessed results for PFS and supports that cabozantinib is a potential treatment option as initial therapy for patients with advanced RCC of intermediate or poor risk,” Toni K. Choueiri, MD, of Dana-Farber Cancer Institute, and colleagues wrote in the European Journal of Cancer.

In the trial, 157 treatment-naive patients with advanced RCC of intermediate or poor risk were randomly assigned to cabozantinib at 60-mg daily or sunitinib at 50-mg daily with 4 weeks on and 2 weeks off. Review by independent committee showed a significant improvement in PFS with cabozantinib. The median PFS was 8.6 months for cabozantinib compared with 5.3 months for sunitinib (hazard ratio [HR], 0.48; 95% CI, 0.31–0.74; P = .0008).

“The observed improvement in PFS with cabozantinib compared with sunitinib may be due, in part, to inhibition of MET and AXL by cabozantinib in addition to VEGF receptors,” the researchers wrote. “Subgroup analyses of PFS based on MET expression level favored cabozantinib over sunitinib (HR < 1) regardless of MET status.”

The overall response rate (ORR) was doubled with cabozantinib compared with sunitinib (20% vs 9%).

“Although the ORR with cabozantinib was higher when assessed by the investigator, the disease control rate with cabozantinib was similar by both assessments, indicating a shift from confirmed partial response to stable disease in the IRC assessment,” the researchers explained.

The updated overall survival (OS) results included an additional 9.5 months of follow-up. After a median follow-up of almost 3 years, the median OS was 26.6 months in those assigned to cabozantinib, compared with 21.2 months with sunitinib (HR = 0.80; 95% CI, 0.53–1.21).

Adverse events of any grade and of grade 3 or 4 were similar between the treatment groups.