Clinical utility of routine proteinuria evaluation in treatment decisions of patients receiving bevacizumab for metastatic solid tumors.

Background: Bevacizumab is an anti-vascular endothelial growth factor monoclonal antibody approved for use in treatment of patients with metastatic breast, colorectal, and non-small cell lung cancer. In the pivotal Phase 3 clinical trials, grades 3-4 proteinuria occurred in <5% of patients. The manufacturer recommends monitoring for the development of proteinuria but does not provide specific recommendations, except to discontinue treatment if the patient develops nephrotic syndrome.

Objective: To determine the incidence and severity of elevated proteinuria and the frequency of changes in bevacizumab administration due to elevated proteinuria; secondary objectives included analysis of the cost of routine proteinuria monitoring and the relationship of proteinuria with other patient comorbidities such as diabetes, hypertension, chronic kidney disease, and viral hepatitis.

Methods: A retrospective chart review was performed at the University of Washington Medical Center, a large academic teaching hospital, and its affiliated ambulatory clinics at the Seattle Cancer Care Alliance. Patients treated with bevacizumab and seen in the breast, lung, and gastrointestinal cancer clinics from June 1, 2005, to November 30, 2007, were included in the study.

Results: A total of 243 patients were included in the analysis. Only 1.6% of these patients developed grades 3-4 proteinuria. All 4 of these patients had a history of hypertension, 2 of these patients had prior chronic kidney disease, and 3 patients had prior viral hepatitis. Elevated proteinuria affected treatment decisions in 2% of patients. Over $130,000 was charged to patients for monitoring of proteinuria.

Conclusions: These results demonstrate that the development of grades 3-4 proteinuria with bevacizumab is rare and affects treatment decisions in few patients with metastatic solid tumor. Furthermore, routine proteinuria monitoring is associated with high cost and may not be required before each administration.