Management of Bevacizumab-Induced Proteinuria Using an Angiotensin Receptor Blocker (ARB) in a Neurofibromatosis Type 2 (NF-2) Patient With Vestibular Schwannoma.

Neurofibromatosis type 2 (NF-2) is a genetic condition that by definition includes bilateral vestibular schwannoma, a non-malignant lesion also known as acoustic neuroma. Patients often develop hearing impairment and hearing loss as a result of the involvement of the vestibulocochlear nerve bilaterally as well as attempts at surgical repair. A common treatment for NF-2-mediated schwannoma is the antiangiogenic agent, bevacizumab. In many cases, patients require prolonged and even lifelong treatment with bevacizumab to control schwannoma growth. However, long-term use of bevacizumab can be associated with multiple side effects including hypertension and proteinuria including nephrotic syndrome (>3g of protein excreted in the urine in 24 hours). In these situations, the challenge with discontinuing prolonged bevacizumab can be rapid tumor growth and worsening hearing loss. Pre-clinical data suggests that hearing loss can be prevented following treatment with the angiotensin receptor blocker (ARB), losartan, in an animal model of NF-2. ARBs are already established in nephrology guidelines to treat proteinuria and hypertension. Here, we present a patient with NF-2 who developed nephrotic syndrome while on bevacizumab. Attempts to discontinue bevacizumab resulted in near-immediate hearing loss. Treatment with the ARB telmisartan together with bevacizumab resulted in improved hearing, reduced proteinuria, and controlled hypertension.