COPENHAGEN—Lipid-specific IgM bands contribute to identify JCV-positive patients at lower risk of progressive multifocal leukoencephalopathy (PML) during natalizumab treatment, according to a report presented at the 29th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS).
Lipid-specific IgM bands are associated with a suboptimal response to interferon beta in patients with MS. Consequently, many patients treated with natalizumab show these antibodies in their CSF. Luisa Maria Villar, PhD, from the Multiple Sclerosis Unit, Department of Immunology, Ramón y Cajal University Hospital, Madrid, and colleagues sought to determine whether PML risk may change in patients with and without these antibodies. The researchers conducted a multicenter study that included 307 patients with MS treated with natalizumab in 20 European hospitals. Anti-JC antibodies were measured in serum by a two-step enzyme-linked immunosorbent assay (ELISA). Lipid-specific IgM bands were measured by isoelectrofocusing and affinity blot in paired serum and CSF samples. Previous treatments with immunosuppressant drugs and treatment duration were recorded.
Nineteen patients developed PML during natalizumab treatment. Only one of them had lipid-specific IgM bands. However, 194 of the 288 patients (67.3%) who did not develop PML had these antibodies. The researchers then analyzed the risk of PML and observed a protective effect of lipid-specific IgM bands (odds ratio, 36.8). As described previously, the absence of anti-JC antibodies also showed a protective effect (odds ratio, 19.4).
To study the effect of the combination of the two variables, Dr. Villar and colleagues further classified anti-JC–positive patients according to lipid-specific IgM bands status. The researchers found that 65% had lipid-specific IgM bands, and 35% (47 patients) lacked these antibodies (anti-JC–positive, lipid-specific IgM band–negative). Seventeen patients of this group developed PML. When PML risk was analyzed, no differences were found between anti-JC–negative patients and anti-JC–positive, lipid-specific IgM band–positive ones. In contrast, the researchers found clear differences between these groups and anti-JC–positive, lipid-specific IgM band–negative patients, which accounted for 90% of PML cases (odds ratio, 59.8).
—Glenn S. Williams
Vice President/Group Editor