The use of growth factors to manage the hematologic side effects of PEG-interferon alfa and ribavirin.

Hematologic side effects (anemia, neutropenia, and thrombocytopenia) of combination therapy with pegylated (PEG)-interferon alfa and ribavirin are commonly encountered during antiviral therapy for chronic hepatitis C (HCV). An important consequence of these side effects is dose modification of PEG-interferon alfa, ribavirin, or both. Dose modification (including discontinuation) diminishes the efficacy of optimal treatment regimen for HCV and may have a negative impact on sustained virologic response. Additionally, fatigue associated with anemia may impair patients' quality of life. The clinical implications of neutropenia or thrombocytopenia are less clear than for anemia; nevertheless, severe infection and bleeding are uncommon. Dose adjustments effectively treat these hematologic side effects, but the resulting suboptimal dosing and potential impact on virologic response are major concerns. Recent attempts to maximize adherence to the optimal treatment regimen have used hematopoietic growth factors rather than dose adjustment to treat side effects. Research on growth factor support has focused on anemia and neutropenia. Epoetin alfa and darbepoetin alfa are erythropoietic growth factors that effectively increase hemoglobin while maintaining the optimal ribavirin dose and improving patients' quality of life. Preliminary work suggests that filgrastim, granulocyte colony stimulating factors, may be an effective treatment of interferon-induced neutropenia. Although this early work shows tremendous promise for managing hematologic side effects of combination therapy for HCV, and potentially enhancing adherence, further research is needed to clarify the efficacy, safety, and cost-effectiveness of growth factors in the management of patients with chronic HCV.