Proteinuria with first-line therapy of metastatic renal cell cancer

Background: Vascular endothelial growth factor receptor inhibitors, mammalian target of rapamycin inhibitors, and tyrosine kinase inhibitors are approved for metastatic renal cell cancer. Proteinuria can occur, but there is limited data regarding the incidence, monitoring, and management in metastatic renal cell cancer patients. Objective: Our primary objective was to describe the incidence and severity of proteinuria in metastatic renal cell cancer patients treated in the first-line setting with pazopanib, bevacizumab, or everolimus. Methods: We conducted a retrospective review of patients with metastatic renal cell cancer enrolled from January 2011-April 2013 in a phase II trial. Baseline and toxicity data were extracted from the electronic medical record. Descriptive statistics were used. Results: In all, 129 patients were eligible for analysis. The overall incidence of proteinuria was 81%, with most events being Grade 1 or 2. The incidence of proteinuria was 80% (n = 35) for pazopanib, 64% (n = 25) for bevacizumab, and 96% (n = 44) for everolimus. At peak proteinuria, 80% (n = 28), 64% (n = 16), and 80% (n = 35) of patients on pazopanib, bevacizumab, and everolimus, respectively, were managed with continued monitoring at the same dose. The overall incidence of Grades 3 and 4 events was 24% (n = 6) and found in the bevacizumab group. Conclusion: A high incidence of proteinuria with minor severity within each class was demonstrated. It may be reasonable to continue therapy at the same dose for Grade 1 or 2 proteinuria. Treatment modification or discontinuation of therapy may be warranted with Grade 3 or 4 proteinuria.