Remission of early persistent cladribine-induced neutropenia after filgrastim therapy in a patient with Relapsing - Remitting Multiple Sclerosis

Background: Cladribine tablets were recently approved for the treatment of Relapsing-Remitting Multiple Sclerosis (RRMS), reducing B cells and T cells, followed by reconstitution of the adaptive immune system, with transient and mild effects on the innate one. Cladribine is also the standard first-line and subsequent treatment for Hairy-Cell Leukemia (HCL), frequently complicated by neutropenic fever. Recombinant human Granulocyte Colony-Stimulating Factor (G-CSF; Filgrastim) has been proved to reduce neutropenia by increasing neutrophil count. Case report: To the best of our knowledge, we report the first case of early and persistent high grade non febrile neutropenia after oral cladribine therapy in a 49-year-old RR-MS patient, successfully treated with Filgrastim. Conclusions: This report suggests that in selected cases, cladribine requires early monitoring of blood sample as it may be responsible for early neutropenia, requiring specific treatment.