Filgrastim. A reappraisal of pharmacoeconomic considerations in the prophylaxis and treatment of chemotherapy-induced neutropenia.

Neutropenia is a frequent and often dose-limiting complication of chemotherapy and is associated with considerable patient morbidity and mortality. Standard treatment in patients who become febrile includes hospitalisation and empirical antibiotic therapy. Filgrastim is a recombinant human granulocyte colony-stimulating factor (rHuG-CSF). It significantly decreases the incidence of febrile neutropenia in patients receiving standard-dose chemotherapy, and shortens the duration of febrile neutropenia in patients undergoing autologous bone marrow transplantation (BMT) or peripheral blood progenitor cell (PBPC) infusion after myeloablative chemotherapy regimens. These effects are usually associated with a decrease in hospitalisation and antibiotic requirements. The contribution of filgrastim therapy to beneficial effects on other clinically important end-points (e.g. quality of life, tumour relapse rate, and short and long term survival) remains to be accurately determined. Pharmacoeconomic data concerning the use of filgrastim as an adjunct to standard-dose chemotherapy are derived largely from the results of phase III trials. Cost analyses based on hospital charges suggest that the cost of providing filgrastim therapy can be fully recouped if the drug is used as primary prophylaxis in previously untreated patients, for whom the risk of developing febrile neutropenia is at least 40%. Reserving filgrastim for use in patients who have developed febrile neutropenia in a previous chemotherapy cycle may result in further cost savings. However, careful patient selection is required, since potential cost savings will vary depending upon the risk of hospitalisation in the absence of filgrastim treatment. Infusion of filgrastim-mobilised PBPCs is emerging as a preferred strategy in patients receiving myeloablative chemotherapy, and promising results have been obtained from cost analyses. From a pharmacoeconomic viewpoint, future research should be directed towards defining optimum dosage regimens and hence improving the cost-effective use of filgrastim. Data evaluating patient quality of life and treatment preferences would help define the cost utility of filgrastim therapy. In the meantime, available pharmacoeconomic data support the use of filgrastim as an adjunct to chemotherapy in selected clinical situations.