Effectiveness of Second-Line Cabozantinib in Metastatic Clear Cell Renal Cell Carcinoma Patients After First-Line Treatment with Immune Checkpoint Inhibitor-based Combinations

Background: Cabozantinib, a tyrosine kinase inhibitor (TKI), is a prevalent second-line (2 L) therapy and was approved for use after progression on TKIs. However, the 1 L treatment setting has changed since the approval of cabozantinib monotherapy in salvage therapy settings. Objective: To assess the differential effectiveness of cabozantinib after prior progression on 1 L ipilimumab with nivolumab (IPI + NIVO) compared to programmed death receptor-1 (PD-1) or PD-1 ligand (PD-L1) inhibitors (PD1/L1i) with TKIs. Methods: Utilizing a nationwide electronic health record (EHR)-derived de-identified database, we included patients with metastatic clear cell renal cell carcinoma (mccRCC) who received 1 L treatment with an immune checkpoint inhibitor (ICI)-based combination and 2 L treatment with cabozantinib monotherapy. These patients were categorized based on the type of 1 L ICI-based combination received: IPI + NIVO vs. PD1/L1i with TKI. Real-world time to next therapy (rwTTNT) and real-world overall survival (rwOS) were summarized using Kaplan-Meier curves and compared using Cox-proportional hazard models adjusted for International mRCC Database Consortium (IMDC) risk groups. Results: Among 12,285 patients with metastatic renal cell carcinoma, 237 were eligible and included. Median rwTTNT was 8 months for the IPI + NIVO subgroup and 7.5 months for the PD1/L1i + TKI subgroup (HR 1.05, 95% CI: 0.74-1.49, p = 0.8). Median rwOS was 17 months for IPI + NIVO and 16 months for PD1/L1i + TKI subgroup (HR 0.79, 95% CI: 0.52-1.20, p = 0.3). Conclusions: Cabozantinib remains effective as a 2 L therapy for mccRCC independent of the type of prior 1 L ICI-based combination. Further research is needed to validate these findings and explore the ideal sequencing of therapies.