Once-per-cycle pegfilgrastim (Neulasta) for the management of chemotherapy-induced neutropenia.

Filgrastim (r-metHuG-CSF) was approved in the United States in 1991 for use in decreasing the incidence of infection, as manifested by febrile neutropenia, in patients with nonmyeloid malignancies treated with myelosuppressive chemotherapy. Colony-stimulating factors such as filgrastim are a significant advance in the supportive care of patients with cancer. However, because of its short half-life, filgrastim requires daily dosing by injection to maintain its effects on the bone marrow. Pegfilgrastim (Neulasta; Amgen, Thousand Oaks, CA) is a longer-acting, self-regulating form of filgrastim created by the covalent linkage of a 20-kd polyethylene glycol molecule to the N-terminal of the filgrastim molecule. The molecular characteristics of pegfilgrastim result in a longer terminal half-life, making once-per-chemotherapy-cycle administration possible. The results from two randomized double-blind phase III clinical trials in patients with breast cancer treated with myelosuppressive chemotherapy showed that a single dose of pegfilgrastim provides neutrophil support comparable with that provided by an average of 11 daily injections of filgrastim. Pegfilgrastim has also been shown to be comparable to filgrastim in reducing neutropenic complications in patients treated with chemotherapy for lymphoma. Data from three clinical trials have been presented: a randomized controlled trial in elderly patients treated with CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone) for relapsed or refractory non-Hodgkin's lymphoma; a randomized controlled trial in patients treated with ESHAP (etoposide/methylprednisolone/cisplatin/cytarabine) for relapsed or refractory lymphoma; and a study in patients with newly diagnosed non-Hodgkin's lymphoma. The safety profile of pegfilgrastim is comparable to that of filgrastim in the clinical settings studied to date. The once-per-cycle administration of pegfilgrastim may improve patient quality of life because it is less disruptive to patients and caregivers, and increase adherence because no doses are missed, thus further advancing the management of chemotherapy-induced neutropenia and its consequences.