Transfer of myxovirus-protein-A mRNA assay for interferon-β bioactivity measurement in multiple sclerosis patients to routine laboratory practice. A 4-year experience

Background: As new biomarkers are validated and their significance in the natural history of specific diseases is established, these technologies can be rapidly transferred to clinical application. Since it has been shown that a single post-interferon-beta (IFN beta) injection measurement of myxovirus-protein-A (MxA) mRNA correlates with IFN beta bioactivity in IFN beta treated patients with multiple sclerosis (MS), we had previously validated an assay for its quantification. Methods: We introduced a real-time PCR relative quantification assay into routine clinical practice and measured MxA mRNA expression in 564 samples from 500 unselected IFN beta treated MS patients over a 4-year period. Results: We confirmed that the assay is reproducible over time, and found that the percentage of patients lacking MxA mRNA induction is comparable to that described in studies performed worldwide after patient selection by pre-screening for the presence of anti-IFN beta antibodies. Conclusions: In view of its simplicity and reproducibility, this MxA assay is an alternative to anti-IFN beta antibody determinations for use in routine clinical practice. Clin Chem Lab Med 2010;48:1235-8.