FLUENT investigated immune cell subset changes in the innate and adaptive immune systems during fingolimod therapy, and their associations with efficacy and safety outcomes.
To report changes in immune cell profile, efficacy and safety of fingolimod 0.5 mg/day in adults with relapsing multiple sclerosis (RMS).
In FLUENT (NCT03257358), a prospective, 12 month, phase 4, multicenter, nonrandomized, open-label study, patients were stratified as fingolimod naive (Cohort 1) or previously treated with fingolimod 0.5 mg/day continuously for ≥2 years (Cohort 2). Primary outcome was change from Baseline to Month 12 in immune cell subsets. Secondary outcomes included Patient Determined Disease Steps (PDDS), anti-John Cunningham virus (anti-JCV) antibody status, serum neurofilament light chain (NfL) concentration, and adverse events (AEs) incidence. Data were analyzed from all patients completing Month 12 follow-up.
165 patients enrolled in Cohort 1; 217 in Cohort 2. Proportionally more patients in Cohort 1 than Cohort 2 relapsed in the year before baseline. At Baseline, patients in Cohort 1 had proportionally more naive and central memory CD4+ and CD8+ T cells and memory B cells, and proportionally fewer effector memory CD4+ and CD8+ T cells and regulatory B cells, than those in Cohort 2. At Month 12, between-cohort differences in the proportions of these lymphocyte types/subtypes were much reduced or negligible. Levels were essentially unchanged in Cohort 2, indicating reductions in naive T cells and increases in effector memory T cells and regulatory B cells in Cohort 1. Mean baseline PDDS scores were low (Cohort 1, 1.7; Cohort 2, 1.8), and changed little by Month 12. Median change from Baseline in anti-JCV antibody index was small in both cohorts. Proportions of patients with positive JCV serology remained stable at Month 12 (61% and 67% in Cohorts 1 and 2 vs 57% and 65% at Baseline). Mean serum NfL level was higher in Cohort 1 than Cohort 2 at Baseline (12.2 vs 9.6 pg/mL); levels were similar at Month 12 (8.7 vs 9.8 pg/mL), having reduced substantially in Cohort 1. Proportionally more patients in Cohort 1 than in Cohort 2 had treatment-emergent AEs (54.6% vs 44.2%), and discontinued study treatment (12.3% vs 5.5%); 5.5% of patients in each cohort reported serious AEs.
These data expand our knowledge of changes in immune cell profiles over time in patients with RMS treated with fingolimod in the short or long term.