Cabozantinib in Patients with Advanced Renal Cell Carcinoma Primary Refractory to First-line Immunocombinations or Tyrosine Kinase Inhibitors

Background: A subset of patients with metastatic renal cell carcinoma (mRCC), deemed as primary refractory, shows progressive disease as the best response to first-line therapy even when treated with novel immune-based combos. Objective: We aimed to assess the outcome of patients treated with second-line cabozantinib for mRCC primary refractory to first-line therapy defined as Response Evaluation Criteria in Solid Tumors (RECIST) progression in the computed tomography scan as the best response to the upfront treatment. Design, setting, and participants: We retrospectively collected data from 11 worldwide centers. Outcome measurements and statistical analysis: Overall survival (OS) and progression-free survival (PFS) were analyzed using Kaplan-Meier curves. Cox proportional models were used at univariate and multivariate analyses. Results and limitations: We collected data from 108 patients with mRCC primary refractory to pembrolizumab plus axitinib (17%), nivolumab plus ipilimumab (36%), or tyrosine kinase inhibitors (TKIs; 31% sunitinib and 16% pazopanib). The median OS with cabozantinib was 9.11 mo, and it was 8.84 and 9.11 mo in patients primary refractory to immunocombinations and TKIs, respectively (p = 0.952). A significant difference was found between patients primary refractory to pembrolizumab plus axitinib (OS not reached) and those primary refractory to nivolumab plus ipilimumab (median OS 8.12 mo, p = 0.024). The median PFS with cabozantinib was 7.30 mo, without significant differences between patients primary refractory to immunocombinations and those primary refractory to TKIs (6.90 vs 7.59 mo, p = 0.435) or between patients primary refractory to pembrolizumab plus axitinib and those primary refractory to nivolumab plus ipilimumab (7.92 and 6.02, p = 0.509). Investigator-assessed overall response rates were 21% and 12% in patients primary refractory to first-line immunocombinations and TKIs, respectively, with a clinical benefit of 48% in the overall population. Conclusions: Our data show that cabozantinib is active in primary refractory mRCC patients regardless of which treatment is received as first-line therapy. Systemic options and prognosis of primary refractory patients with mRCC, particularly those treated with novel immune-based combos, are among the major challenges that we need to face in this field. Patient summary: Patients primary refractory to first-line therapy are characterized by a poor prognosis. Herein, we aimed to assess the outcome of patients treated with second-line cabozantinib for metastatic renal cell carcinoma (mRCC) primary refractory to first-line therapy. Our results suggest that cabozantinib is active in primary refractory mRCC patients.