Filgrastim Use in Cancer Patients

Primary Indications

• The American Society of Clinical Oncology recommends prevention of chemotherapy-induced febrile neutropenia in patients receiving myelosuppressive chemotherapy, particularly when the risk of febrile neutropenia is ≥20% 3, 4
• The European Society for Medical Oncology suggests reduction in the duration of severe neutropenia in patients with non-myeloid malignancies receiving myelosuppressive anticancer drugs 5
• The National Comprehensive Cancer Network recommends support for dose-intensity maintenance of chemotherapy regimens to avoid dose reductions or treatment delays 1, 6

Mechanism of Action and Dosing

• Filgrastim is a recombinant human granulocyte colony-stimulating factor that stimulates the proliferation, differentiation, and function of neutrophil precursors and mature neutrophils, administered subcutaneously and works by binding to specific receptors on neutrophil precursors to promote their growth and maturation 1
• The standard dose is 5 μg/kg/day administered subcutaneously, started 1-3 days after completion of chemotherapy 5, 4

Clinical Efficacy

• The Journal of the National Comprehensive Cancer Network reports that filgrastim reduces the incidence of febrile neutropenia by approximately 50% compared to placebo in patients receiving chemotherapy 8, 9
• The Journal of the National Comprehensive Cancer Network also reports that filgrastim decreases infection-related mortality from 3.3% to 1.7% in patients receiving chemotherapy 8, 9

Clinical Decision Making

• For primary prophylaxis, the American Society of Clinical Oncology recommends using filgrastim in chemotherapy regimens with ≥20% risk of febrile neutropenia 3, 4
• The European Society for Medical Oncology suggests considering patient risk factors that increase febrile neutropenia risk, such as prior chemotherapy, abnormal hepatic/renal function, low baseline white blood cell count, and planned delivery of ≥85% of chemotherapy dose 1
• The National Comprehensive Cancer Network recommends that for patients receiving weekly chemotherapy regimens, daily G-CSFs like filgrastim may be more appropriate than long-acting formulations 4
• The National Comprehensive Cancer Network also recommends that when treating established neutropenia, filgrastim is preferred over pegfilgrastim due to its shorter half-life and ability to titrate the dose 7