Prevention of rebound effect after natalizumab withdrawal in multiple sclerosis. Study of two high-dose methylprednisolone schedules.

Background: Natalizumab (NTZ) is a disease-modifying treatment (DMT) in multiple sclerosis (MS) whose discontinuation can produce a "rebound effect", consisting of severe clinical deterioration and/or evidence of disease reactivation on magnetic resonance imaging (MRI).

Objective: To analyze the efficacy of two treatment schedules with intravenous methylprednisolone (IVMP) administered during the washout period of natalizumab (i.e., before starting another DMT) in preventing the rebound phenomenon.

Methods: Five-year retrospective study of NTZ withdrawals after at least 24 uninterrupted doses. Two IVMP schedules were tested. In schedule 1 (3-month washout), 1, 2, and 3 g of IVMP were administered on the first, second, and third month respectively. In schedule 2 (2-month washout), 1 and 2 g of IVMP were administered on the first and second month respectively. A new DMT was started 10 days after the end of each schedule. Rebound was defined as at least one clinical relapse plus rebound activity on MRI (>5 gadolinium-enhanced lesions and a number of new/T2-enhanced and/or gadolinium-enhanced lesions greater than before initiation of NTZ) during washout or at 6 months after new DMT initiation (6M-DMT). Clinical and MRI evaluations were performed at 3, 6, 12, and 24 months after initiation of the new DMT.

Results: Fifty patients (68% women) were included, with a mean (SD) age of 37.76 (10.88) years and pre-NTZ annualized relapse rate (ARR) of 1.78 (1.04). During NTZ therapy, mean Expanded Disability Status Scale (EDSS) score was 3.7 (1.73) and ARR was 0.23 (0.39). The ARR (mean of both schedules) was 0.1 (0.71) during washout and 0.32 (0.84) at 6M-DMT. Rebound was observed in 10% of cases (n = 5), with no significant clinical or radiological differences (p>0.05) between the two IVMP schedules. Rebound was observed in younger patients and was associated with new MRI lesions and higher ARR at 3M-DMT and 6M-DMT respectively, with no difference in EDSS after 2 years of follow-up. Neither the ARR before NTZ initiation nor the choice of new DMT after NTZ discontinuation was associated with development of rebound effect.

Conclusions: Both IVMP schedules were well tolerated during NTZ washout and rebound was observed in only 10% of cases. In our experience, administration of IVMP during NTZ washout could reduce the possibility of a rebound effect.