CABOSEQ 3—Comparison of Cabozantinib versus Sunitinib Following First-Line Nivolumab- Ipilimumab for Metastatic Renal Cell Carcinoma: A Target Trial Emulation Using Real-World Data from the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC)

BACKGROUND AND OBJECTIVE: While the benefit of cabozantinib in metastatic renal cell carcinoma (mRCC) is well established post-tyrosine kinase inhibitor therapy, its comparative effectiveness versus sunitinib after first-line (1L) nivolumab-ipilimumab is uncertain. METHODS: A target trial emulation was designed using data from the IMDC to estimate the effect of second-line (2L) cabozantinib versus sunitinib within 18 months of discontinuing 1L nivolumab-ipilimumab on overall survival (OS). Patients diagnosed after January 1, 2017 were followed from initiation of 2L until death or last known contact. Inverse-probability of treatment weighting was used to adjust for hemoglobin, calcium, platelets, and neutrophils at 2L, Karnofsky performance score (KPS) at 2L, time from diagnosis to initiation of 2L, and response to 1L nivolumab-ipilimumab. Treatments were compared using adjusted Kaplan-Meier curves and adjusted hazard ratios (HR) from a Cox regression model. Missing data were addressed with multiple imputation by chained equations. E-values were used to assess the likelihood findings could be explained by residual confounding. KEY FINDINGS AND LIMITATIONS: A total of 120 and 121 patients who received cabozantinib or sunitinib after 1L nivolumab-ipilimumab were included. The proportion with a KPS < 80% at 2L (21% vs. 46% P = .001) and the overall response rate to first line therapy (12.7% vs. 17.9% P = .002) differed significantly between cabozantinib and sunitinib. The objective response was 27% for cabozantinib versus 20% for sunitinib with a median time to treatment failure of 8.5 (95% CI: 6.9-12.9) and 4.5 (95% CI: 3.7-5.8) months. Median OS was 21.4 (95% CI: 17.9-NA) months from initiation of cabozantinib and 10.1 (95% CI: 7.6-17.7) months for sunitinib (Adjusted HR 0.44 (95% CI: 0.22-0.86)). The E-value was 2.92, suggesting a low likelihood of findings being due to residual confounding alone. CONCLUSIONS: These data provide real-world evidence supporting cabozantinib as a second-line treatment option in mRCC following 1L nivolumab-ipilimumab.