Comparative multi-analyte serum protein differences between generic and brand-name dimethyl fumarate, fingolimod, and teriflunomide in multiple sclerosis.

Multiple sclerosis (MS) is treated with branded or generic disease modifying therapies (DMTs), with increasing concern for the composition and quality of off-patent products. Our objective was to evaluate differences in disease-specific biomarkers, a potential indicator of suboptimal therapeutic exposure, between individuals treated with branded and generic DMTs. We compared biomarker variability in MS individuals (n = 1124) treated with generic or brand-name fumarates (diroximel fumarate, dimethyl fumarate (DMF)), fingolimod, and teriflunomide. In the generic DMF group, higher coefficients of variation (COV) for CXCL9, CCL20, and TNFSF13B were observed, with a paradoxically lower variability for CXCL13. Higher COVs for CXCL9 were observed with generic fingolimod and for CXCL9 and CXCL13 with generic teriflunomide when compared to brand. Additionally, all generic DMTs demonstrated higher multi-variable variability index values across 18 proteins associated with MS disease activity. Greater biomarker variability with generic formulations may reflect differences in therapeutic exposure and less consistent disease control.