A multiyear follow-on study examining safety, immunity, and clinical outcomes for sargramostim therapy in Parkinson’s disease

Abstract Safety, biomarker, and motor outcomes in Parkinson’s disease (PD) were evaluated during extended sargramostim (Leukine®, granulocyte-macrophage colony-stimulating factor) therapy. Hematologic, metabolic, regulatory T cell (Treg) numbers and function, motor, and behavioral functions were scored in five PD patients during a 5-day on, 2-day off sargramostim regimen administered at 3 µg/kg/dose over the 33-month study. Adverse events for sargramostim included injection site reactions, increased total white cell counts, and bone pain. Treg numbers and functional improvements were sustained throughout the study. After 24 months on treatment regimen, drug use was discontinued for three months, and followed by an additional six months of treatment. No significant changes in adverse events were discernible after treatment pause or re-initiation; however, UPDRS scores increased during the pause and decreased after initiation of treatment. Taken together, the data affirmed long-term safety, Treg functional stability, and clinical stability of sargramostim in the PD population. Confirmation requiring larger numbers of enrolled patients is planned in a phase II evaluation.