Clinical and radiological outcomes of directed treatment transitions from Gilenya^®to generic fingolimod

Background: Gilenya^® (fingolimod), a sphingosine-1-receptor agonist, is an effective treatment for multiple sclerosis (MS). However, increased relapse activity has been observed after transitioning to generic fingolimod despite prior prolonged disease stability. Objective: To quantify the clinical and radiological impact of transitioning from Gilenya^® to generic fingolimod in people with MS (PwMS). Methods: Retrospective data were evaluated from a single tertiary MS care center. Time to magnetic resonance imaging (MRI) activity and clinical relapse was assessed during Gilenya^® and generic fingolimod treatment. Differences in absolute lymphocyte count (ALC) and side effects were also measured by treatment group. Results: The cohort included 88 PwMS (71 female; 76 White, mean age when starting Gilenya^® was 39.6 years (standard deviation (SD) = 10.6 years), and mean age when starting generic fingolimod was 46.9 years (SD = 11.2 years)). A shorter time to MRI activity (p = 0.0026) and time to relapse (p = 0.0027) was observed during generic fingolimod treatment. The ALC increased by 8.81% after generic fingolimod treatment, relative to Gilenya^® (95% CI = (2.00%, 16.08%), p = 0.01), with an intersubject variability of 1.97%. A 2.45-fold increase in side effects was observed with generic fingolimod relative to Gilenya^® (95% CI = (1.38, 4.36), p = 0.002). Conclusion: Measures of disease stability appear less optimal with generic fingolimod based on serological, clinical, and radiological measures.