A comparison of natalizumab and ocrelizumab on disease progression in multiple sclerosis

Objective: No direct comparisons of the effect of natalizumab and ocrelizumab on progression independent of relapse activity (PIRA) and relapse-associated worsening (RAW) events are currently available. We aimed to compare the risk of achieving first 6 months confirmed PIRA and RAW events and irreversible Expanded Disability Status Scale (EDSS) 4.0 and 6.0 in a cohort of naïve patients treated with natalizumab or ocrelizumab from the Italian Multiple Sclerosis Register. Methods: Patients with a first visit within 1 year from onset, treated with natalizumab or ocrelizumab, and ≥3 visits were extracted. Pairwise propensity score-matched analyses were performed. Risk of reaching the first PIRA, RAW, and EDSS 4.0 and 6.0 events were estimated using multivariable Cox proportional hazards models. Kaplan-Meier curves were used to show cumulative probabilities of reaching outcomes. Results: In total, 770 subjects were included (natalizumab = 568; ocrelizumab = 212) and the propensity score-matching retrieved 195 pairs. No RAW events were found in natalizumab group and only 1 was reported in ocrelizumab group. A first PIRA event was reached by 23 natalizumab and 25 ocrelizumab exposed patients; 7 natalizumab- and 10 ocrelizumab-treated patients obtained an irreversible EDSS 4.0, while 13 natalizumab- and 15 ocrelizumab-treated patients reached an irreversible EDSS 6.0. No differences between the two groups were found in the risk (HR, 95%CI) of reaching a first PIRA (1.04, 0.59-1.84; p = 0.88) event, an irreversible EDSS 4.0 (1.23, 0.57-2.66; p = 0.60) and 6.0 (0.93, 0.32-2.68; p = 0.89). Interpretation: Both medications strongly suppress RAW events and, in the short term, the risk of achieving PIRA events, EDSS 4.0 and 6.0 milestones is not significantly different.