Pazopanib as Second-line Antiangiogenic Treatment in Metastatic Renal Cell Carcinoma After Tyrosine Kinase Inhibitor (TKI) Failure: A Phase 2 Trial Exploring Immune-related Biomarkers for Testing in the Post-immunotherapy/TKI Era

Pazopanib is an oral angiogenesis tyrosine kinase inhibitor (TKI) recommended in metastatic renal cell carcinoma (mRCC) for treatment-naïve patients or those experiencing cytokine failure. We conducted a phase 2, open-label, single-arm study in ten Spanish centres among mRCC patients whose disease progressed on first-line TKI. Patients received pazopanib until disease progression, death, or unacceptable toxicity. Twenty-seven patients were included (median age 62yr, 51.9% male). The objective overall response rate was 14.8% (95% confidence interval [CI] 1.4-28.2%). Median progression-free survival was 6.7mo (95% CI 3.7-11.2) and median overall survival was 20.6mo (95% CI 12.6-27.4). Lower circulating levels of IL-10 (p=0.002) were observed in responding patients at 8 wk after treatment. The median pazopanib treatment duration was 6.0mo (range 1.0-47.0). Most patients (48.1%) had mild or moderate adverse events (AEs), while 44.4% had severe AEs. Pazopanib was clinically active and well tolerated as a second-line treatment in mRCC patients after TKI failure, and circulating IL-10 levels could predict response. PATIENT SUMMARY: Pazopanib could be used as a second-line therapy for the treatment of metastatic renal cell carcinoma after failure of tyrosine kinase inhibitor (TKI) therapy when drugs such as nivolumab and cabozantinib are not available. Now that immunotherapy plus antiangiogenic therapy is a first-line option, IL-10 levels deserve further exploration as a potential predictor of response to sequential TKI-TKI therapy.