Vitamin D and Immunogenicity of IFNβ in Multiple Sclerosis Patients: A Case-Control Study (P3.355)

We investigate whether 25-OH-vitamin D serum levels in IFNβ-treated multiple sclerosis patients are associated with anti-drug antibodies (ADA) occurrence. 10-30[percnt] of IFNβ-treated multiple sclerosis patients develop ADA, ultimately leading to treatment failure. In a retrospective study on a German cohort of multiple sclerosis patients who were tested for ADA in a central laboratory, we observed higher ADA positivity in patients who had been started on IFNβ therapy in April. Here we explore the hypothesis that this observation may be accounted for by low serum vitamin D levels. 142 ADA+ were matched to 142 ADA- patients for sex, age, type of IFNβ and time of serum sampling since start of therapy. 25-OH-vitamin D was analyzed with the Roche Elecsys assay in one serum sample per patient taken after one year of therapy. Factors associated with vitamin D levels were tested with linear regression, the association of vitamin D with ADA with paired t-tests and conditional logistic regression. Age, month of serum sampling and type of IFNβ were significantly associated with vitamin D levels: IFNβ-1a i.m. displayed a mean increase of 7.7 ng/ml vitamin D compared to IFNβ-1b s.c. and samples drawn in October-November displayed an increase of 8.1 ng/ml vitamin D compared to April-May. No significant difference in vitamin D levels was observed between ADA+ and ADA- patients. We confirmed lowest seasonal vitamin D levels in April-May. We did not observe a difference in vitamin D levels between ADA+ and ADA-; study limitations may have contributed to these results: a difference in vitamin D levels at baseline might not be detectable in samples at 12 months of therapy, masked by IFNβ effects and/or presence of ADA. A prospective study is planned measuring vitamin D in baseline samples of treatment naive patients and taking into account other determinants of vitamin D levels. Disclosure: Dr. Hassler has nothing to disclose. Dr. Hermsen has nothing to disclose. Dr. Bachelet has nothing to disclose. Dr. Hess has nothing to disclose. Dr. Ingenhoven has nothing to disclose. Dr. Mbogning has nothing to disclose. Dr. Doennes has received personal compensation for activities with Scicross AB as an employee. Dr. Fogdell-Hahn has received research support from Biogen Idec, Dr. Deisenhammer has received research support from Biogen Idec. Dr. Davidson has received personal compensation for activities with GlaxoSmithKline as an employee. Dr. Davidson holds stock in GlaxoSmithKline. Dr. Boege has nothing to disclose. Dr. Hartung has received personal compensation for activities with from Bayer, Biogen, GeNeuro, Genzyme as speaker, committee member, consultant. Dr. Kieseier holds stock and/or stock options in Biogen, which sponsored research in which Dr. Kieseier was involved as an investigator. Dr. Broet has nothing to disclose. Dr. Warnke has received personal compensation in an editorial capacity for CML Multiple Sclerosis.