In REFLEX, subcutaneous interferon β-1a (scIFNβ-1a) reduced conversion to McDonald (2005 criteria) and clinically definite (CD) multiple sclerosis (MS) versus placebo in patients with a first clinical demyelinating event. Retrospective analysis demonstrated overall results were unchanged after application of McDonald-2010 MS criteria. Revised McDonald-2017 MS criteria included presence of cerebrospinal fluid specific oligoclonal bands, symptomatic lesions, and cortical lesions. Effect of scIFNβ-1a on time to McDonald-2005 MS and CDMS, and annualised relapse rate (ARR) during REFLEX was assessed, stratified by retrospective diagnosis of patients at baseline that did/did not meet McDonald-2017 MS criteria.
During REFLEX, patients were randomised to scIFNβ-1a three times (tiw) or once weekly (qw), or placebo for 2-years. Patients in the intention-to-treat population were retrospectively stratified into McDonald-2017-positive (retrospectively met the McDonald-2010 MS criteria at baseline or had positive oligoclonal bands) and -negative subgroups. Kaplan-Meier curves estimated time to McDonald-2005 MS or CDMS by treatment group for each McDonald-2017 subgroup.
Oligoclonal band detection was optional during REFLEX and only a small number of patients were added from the McDonald-2010 analysis. Overall, 235/517 patients were McDonald-2017-positive at baseline (40 were McDonald-2010-negative but had positive oligoclonal bands). In the McDonald 2017-positive subgroup, scIFNβ-1a tiw or qw versus placebo significantly delayed time to McDonald-2005 MS (hazard ratio [HR] versus placebo: tiw,0.47;p<0.001; qw,0.58;p=0.002) and CDMS (HR versus placebo: tiw:0.46;p=0.010; qw:0.42;p=0.003). scIFNβ-1a qw and tiw significantly reduced mean ARR versus placebo in McDonald-2017-positive patients (69.1% and 59.3%;p<0.001).
Effect of scIFNβ-1a observed in McDonald-2010 patients on time to McDonald-2005 MS and CDMS was maintained in McDonald-2017-positive patients, although only a small number of patients were added after applying the 2017 criteria.
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