Lymphocyte recovery after fingolimod discontinuation in patients with MS

OBJECTIVE: To investigate the dynamics of immune cells recovery after treatment discontinuation of fingolimod in real-life clinical practice, we analyzed the course of lymphocyte reconstitution and its potential influencing factors in patients with multiple sclerosis (MS). METHODS: We analyzed leukocyte, lymphocyte, and granulocyte counts of 58 patients at 3, 6, and 12 months after fingolimod cessation and the following parameters as potential risk factors for a prolonged lymphopenia up to 12 months: age; sex; Expanded Disability Status Scale, and disease duration at the time of fingolimod start; type and number of previous immunomodulatory treatments; fingolimod treatment duration; lymphocyte count at baseline before fingolimod, at fingolimod stop, and at the time of therapy switch; time interval between fingolimod cessation and new treatment initiation; type of the follow-up immunomodulatory treatment; and corticosteroid administration after fingolimod cessation. RESULTS: All patients showed a drop of the lymphocyte count under fingolimod with no relevant leukopenia or neutropenia. One year after discontinuation, still 22% of the patients were lymphopenic and 54% of them did not reach 80% of the baseline lymphocyte value. Low lymphocyte counts before fingolimod start, under fingolimod, and at therapy switch, successive treatment with rituximab, and pretreatment with mitoxantrone were significantly associated with a prolonged immune cell recovery. CONCLUSIONS: Prolonged lymphopenia after fingolimod cessation exists in a subgroup of patients with MS and should be considered in clinical practice, particularly when changing treatment regimens.