Initial lymphocyte count and low BMI may affect fmgolimod-induced lymphopenia

Objective: To assess whether pretreatment-lymphocyte counts, treatment before fingolimod, age, sex, or body mass index (BMI) affects the risk of fingolimod-induced lymphopenia in patients with relapsing-remitting multiple sclerosis (RRMS). Methods: Data were obtained from a German multicenter, single-arm, open-label study of patients with RRMS treated with fingolimod, and findings were validated in an independent Swedish national pharmacovigilance study. Results: Four hundred eighteen patients with RRMS from Germany and 438 patients from Sweden were included. A nadir [< or =]0.2 x 10 super(9) lymphocytes/L was reached in 15% (95% confidence interval [Cl] 12%-17%) of all 856 patients. Patients with lower starting lymphocyte counts (below 1.6 x 10 super(9)/L) and patients with BMI lower than 18.5 kg/m super(2) (women only) were at higher risk of developing lymphopenia with values [< or =]0.2 x 10 super(9)/L in the combined analysis, increasing the risk in these subgroups to 26% (95% Cl 20%-31%) or 46% (95% Cl 23%-71 %), respectively. In the German cohort, infection rates were similar in patients who developed severe lymphopenia and those who did not. Conclusions: Our findings suggest that patients with low baseline lymphocyte counts and underweight women in which fingolimod treatment will be initiated should possibly be monitored more closely.