Pulse monthly steroids during an elective interruption of natalizumab: a post-marketing study.

BACKGROUND AND PURPOSE: Temporary discontinuation of natalizumab is sometimes considered as the observed risk of progressive multifocal leukoencephalopathy (PML) in patients with multiple sclerosis (MS). However, interruption of natalizumab may result in a re-start of disease activity. METHODS: In this prospective post-marketing study, 23 patients with MS treated with natalizumab elected a trial of treatment interruption (90-150 days) because of safety concerns on the risk of developing PML. To reduce the risk of disease activity return, patients received monthly intravenous (i.v.) steroid pulses before natalizumab re-start. RESULTS: Despite the steroid coverage, seven patients (30.4%) had an active scan during the natalizumab interruption period; of these, four also had a concomitant clinical exacerbation. CONCLUSIONS: Our findings suggest that i.v. steroids are not currently recommendable as drug coverage during a scheduled treatment interruption period.