Generic MS therapies show greater variability in disease biomarkers

Generic medications are expected to be equivalent to their brand-name counterparts — but a new study found that generic versions of certain treatments for multiple sclerosis (MS) were linked to greater variability in disease biomarkers than the original drugs.

“We identified differences in circulating protein biomarker variability between brand and generic [MS therapies], including biomarkers aligned with the known mechanism of action of these molecules,” researchers wrote.

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Clinical impact of biomarker differences remains unclear

The study did not assess clinical outcomes such as relapse rates or disability progression, so it remains unclear whether the biomarker differences translate into worse clinical outcomes for people taking generic medications. The findings nevertheless raise questions about whether biological differences between generic and brand-name formulations could affect treatment consistency and warrant further study.

The work was led by scientists at the University of Texas Southwestern Medical Center. According to a news release from the center, the results “raise important questions about whether biological differences between generic and brand-name medications could affect treatment consistency.”

The findings also “underscore the need for further research to determine whether these biomarker differences translate into meaningful variations in patient outcomes and treatment effectiveness,” the center said.

The study, “Comparative multi-analyte serum protein differences between generic and brand-name dimethyl fumarate, fingolimod, and teriflunomide in multiple sclerosis,” was published in Clinical Immunology.

There are more than 20 disease-modifying therapies approved for MS, and some are available as lower-cost generics. Generic drugs are approved based on evidence that they are bioequivalent to their brand-name counterparts, although their formulations can differ. Health insurance policies frequently require people taking a brand-name therapy to switch to a generic alternative, while people starting treatment may be required to try a generic before the brand-name product is covered.

The new findings suggest that some generic MS treatments may have more variable biological effects than their branded counterparts, raising questions about policies that require generic use or switching.

Study compared generic and branded MS treatments

Researchers specifically focused on generic versions of three MS treatments: teriflunomide, sold by Sanofi as Aubagio; fingolimod, sold by Novartis as Gilenya; and dimethyl fumarate, sold by Biogen as Tecfidera. The analysis included 1,124 people with relapsing-remitting MS who were taking these therapies or branded comparator treatments.

Across all three drug types, results showed greater overall variability in biomarkers related to MS disease activity among people taking generic versions. For example, CXCL9, a signaling molecule involved in inflammatory immune activity, was more variable in the generic groups for all three treatments.

The researchers said greater biomarker variability may reflect differences in drug exposure and less consistent disease control. The researchers discussed differences in formulation and treatment adherence as possible contributors to the biomarker variability.

However, the researchers noted several limitations, including the retrospective design and the lack of clinical and imaging outcome data. They said the lack of clinical and imaging outcomes makes it difficult to determine the clinical significance of the biomarker differences and stressed that further study is needed.

“As the use of generic therapies expands and recognition grows regarding variability in generic drug quality, biomarker-based measures of disease activity may become increasingly important for treatment optimization and patient safety,” the team concluded.

The study received no financial support. Several authors disclosed relationships with Biogen, Sanofi, Novartis, and Octave Bioscience; the Octave MS disease activity test was used in the analysis.