Cyclophosphamide Pulse Therapy after Natalizumab Discontinuation for Multiple Sclerosis: a multicenter study.

Importance: Natalizumab discontinuation induces the recurrence of Multiple Sclerosis (MS) disease activity: Currently no therapeutic approach has been found able to abolish disease reactivation. Objective: To collect data from patients with MS switching from natalizumab to cyclophosphamide. Design: Retrospective multicentre study. Setting: Nine Multiple Sclerosis Centers in Italy. Participants: A total of 47 patients with clinically definite RR-MS switched to cyclophosphamide after natalizumab discontinuation. Two patients were excluded from the analysis because received less than 12 natalizumab infusions. The remaining 45 patients were subdivided into two main groups: Early Treatment (peri…