To assess the efficacy of switching to or maintaining ocrelizumab (OCR) on disease activity and progression after 4 years of open-label extension (OLE) of the Phase III OPERA I (NCT01247324) and OPERA II (NCT01412333) trials in patients with relapsing multiple sclerosis (RMS).

The efficacy and safety of OCR in RMS were demonstrated in the 96-week controlled double-blind period (DBP) of OPERA I and OPERA II.

Patients completing the DBP either continued OCR (OCR-OCR) or switched from interferon (IFN) β-1a to OCR (IFN-OCR) when entering the OLE period. Adjusted annualized relapse rate, time to onset of 24-week confirmed disability progression (CDP24) and risk of requiring a walking aid (Expanded Disability Status Scale score ≥6.0) from the DBP baseline were analyzed.

Overall, 82.3% of patients who entered the OLE period completed OLE Year 4. Adjusted annualized relapse rate decreased year-on-year from the pre-switch year to OLE Year 4 in IFN-OCR switchers (pre-switch, 0.2; OLE Year 4, 0.04) and was maintained at low levels in OCR-OCR continuers (pre-switch, 0.13; OLE Year 4, 0.05). The rates of CDP24 were lower in OCR-OCR continuers vs IFN-OCR switchers in the pre-switch year (7.7% vs 12.0%) and at OLE Year 1 (10.1% vs 15.6%), Year 2 (13.9% vs 18.1%), Year 3 (16.2% vs 21.3%) and Year 4 (19.2% vs 23.7%); p<0.05 all comparisons. Over the DBP and OLE periods, the risk of requiring a walking aid was 44% lower (p=0.004) in OCR-OCR continuers vs IFN-OCR switchers. Safety profiles in the DBP and OLE were generally consistent.