Response of Vestibular Schwannomas in NF2-Related Schwannomatosis (NF2-SWN) to Losartan: A Case Series.

Abstract

Objective: Identify response rates of vestibular schwannomas in NF2-related Schwanomatosis to treatment with losartan alone or combined with other treatments.

Study design: Single-institution retrospective case series.

Setting: Tertiary referral center.

Patients: Twenty patients with NF2-related Schwannomatosis.

Interventions: Losartan alone, Losartan plus other therapy (bevacizumab, brigatinib, axitinib).

Main outcome measures: Volumetric progression, defined as a change in VS size >20%, in accordance with the Response Evaluation in Neurofibromatosis and Schwannomatosis (REiNS) criteria. Audiometric progression is defined as a change in hearing measures, either a 10 dB or greater increase in PTA or a 10% or greater decrease in WRS.

Results: This study included 20 patients, with 33 VSs, treated at our institution from 2014 to 2023. Losartan treatment duration ranged from 8.09 to 153.04 months (mean: 53.8, SD: 37.32). Twelve VSs were concurrently managed with antineoplastic therapy. Among 21 VSs treated with losartan alone, volumetric regression, progression, and stability were seen in 23.8%, 47.6%, and 28.6% of tumors, respectively. Among 5 VSs treated with combination losartan and bevacizumab, 40% of tumors regressed, 20% progressed, and 40% remained stable during the combination period. One tumor that progressed during bevacizumab monotherapy treatment achieved volumetric stability following combination therapy. Volumetric growth rates during bevacizumab alone did not significantly differ from growth rates following combination therapy.

Conclusions: This case series describes response rates among NF2-SWN patients treated with losartan. The potential role of losartan in modulating tumor size, either alone or in combination with bevacizumab, should be further studied through well-controlled studies. The study is limited by a small sample size.