['Neuromyelitis optica (NMO) is a relapsing autoimmune disease targeting the spinal cord and optic nerve leading to paralysis and blindness. Current treatment for acute NMO attacks is immunosuppression with high-dose corticosteroids and/or plasmapheresis. Preclinical animal studies suggest that bevacizumab might be beneficial in limiting the extent of inflammation during a NMO relapse by reducing the disruption of the blood-brain barrier.', 'We carried out an open-label phase 1b safety and proof-of-concept trial in 10 participants with NMO immunoglobulin G seropositive NMO, NMO spectrum disease and those at high risk for developing NMO/NMO spectrum disease who presented with an acute attack of transverse myelitis, optic neuritis or brainstem inflammation. In addition to treating with 1 g of daily intravenous methylprednisolone, we infused 10 mg/kg of bevacizumab intravenously on day 1 of treatment. The primary outcome measure was safety and the secondary outcome measure was efficacy.', 'Of the 10 participants enrolled, five presented with acute transverse myelitis, four with acute optic neuritis and one with a brainstem lesion. Bevacizumab was safe in all 10 participants, with only one serious adverse event within the 90-day follow up that was not attributed to the medication. Three patients recovered to pre-attack neurological function or better, and no patients required escalation to plasmapheresis.'] Is bevacizumab safe in acute relapses of neuromyelitis optica?