Ocrelizumab (OCR) is an alternative therapy for relapsing-remitting multiple sclerosis (RRMS) patients with an increased risk of natalizumab (NTZ) associated progressive multifocal leukoencephalopathy (PML). We developed a switch protocol for PML surveillance and prevention of rebound disease activity.
To evaluate clinical, radiological and biochemical markers in patients switching from NTZ to OCR using the locally developed switch protocol of the MS Center Amsterdam.
All patients with previous NTZ and current OCR treatment were selected from an ongoing observational cohort study with regular collection of blood samples in the Amsterdam University Medical Center (UMC) MS Biobank. Reasons for therapy switch were discriminated between patients with (indirect switchers) and without (direct switchers) use of other disease modifying treatment (DMT) during interval. Clinical, biochemical and radiological endpoints were prospectively collected from first NTZ to last OCR infusion. Serum neurofilament light (sNfL) was analyzed in direct switchers, using baseline and last follow-up samples during NTZ treatment and samples taken before every OCR infusion.
Forty-one patients with current OCR and previous NTZ treatment were included with a median follow-up of 7.7 years. Twenty-eight patients switched directly, of which 21 due to PML risk. Three direct switchers suffered from a relapse, of which 1 patient showed evidence of disease activity on brain Magnetic Resonance Imaging (MRI). Two other male patients were diagnosed with carry-over PML with favorable outcomes. Before OCR became available, 13 patients switched from NTZ to other DMT due to PML risk but eventually escalated to OCR because of disease activity, progression or adverse events. Among these indirect switchers, 4 patients showed evidence of clinical or radiological disease activity. Excluding carry-over PML, OCR treatment maintained or established complete disease activity suppression in 84% of patients. Clinical measures of disability showed no significant changes. Mean sNfL significantly decreased during NTZ treatment and remained stable during OCR treatment.
A stringent protocol can contribute to an effective switch from NTZ to OCR in RRMS. In this observational cohort study of direct and indirect switchers, disease activity suppression was maintained or established in 84% with concurrent stability of clinical measures and sNfL.