What is the recommended use and dosage of Filgrastim (Granulocyte-Colony Stimulating Factor, G-CSF) for patients at high risk of febrile neutropenia due to chemotherapy?

From the Guidelines

Filgrastim (G-CSF) is recommended for patients at high risk of febrile neutropenia from chemotherapy at a standard dose of 5 mcg/kg/day subcutaneously, starting 24-72 hours after completion of chemotherapy and continuing until the absolute neutrophil count (ANC) recovers to ≥1,000-1,500/mm³, as supported by the most recent and highest quality study 1.

Key Considerations

• The medication works by stimulating bone marrow to produce neutrophils, thereby reducing the duration and severity of neutropenia.
• Patients are considered high-risk if they have a ≥20% risk of febrile neutropenia based on their chemotherapy regimen, age >65 years, prior chemotherapy or radiation, poor performance status, or other comorbidities.
• Patients should be monitored for bone pain (a common side effect), and rare but serious complications like splenic rupture or acute respiratory distress syndrome.
• Self-administration training should be provided if the medication will be used at home.
• Filgrastim should be stored refrigerated but allowed to reach room temperature before injection to minimize injection site discomfort.

Administration and Dosage

• The recommended dose is 5 mcg/kg/day, with the dose rounded to the nearest vial size by institution-defined weight limits, as stated in 1 and supported by 1.
• The subcutaneous route is preferred for administration.
• Treatment should continue until the ANC recovers to normal or near-normal levels by laboratory standards.

Guidelines and Recommendations

• The American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) have guidelines that support the use of G-CSF for the prevention of febrile neutropenia in patients at high risk, as mentioned in 1 and 1.
• The European Organisation for Research and Treatment of Cancer (EORTC) also has guidelines for the use of G-CSF in patients receiving chemotherapy, as noted in 1 and 1.

From the FDA Drug Label

The safety and efficacy of filgrastim to decrease the incidence of infection, as manifested by febrile neutropenia, in patients with nonmyeloid malignancies receiving myelosuppressive anti-cancer drugs were established in a randomized, double-blind, placebo-controlled trial conducted in patients with small cell lung cancer (Study 1) In Study 1, patients received up to 6 cycles of intravenous chemotherapy including intravenous cyclophosphamide and doxorubicin on day 1; and etoposide on days 1,2, and 3 of 21 day cycles. Patients were randomized to receive filgrastim (n=99) at a dose of 230 mcg/m2 (4 to 8 mcg/kg/day) or placebo (n=111) Treatment with filgrastim resulted in a clinically and statistically significant reduction in the incidence of infection, as manifested by febrile neutropenia, 40% for filgrastim-treated patients and 76% for placebo-treated patients (p < 0. 001)

The recommended use and dosage of Filgrastim for patients at high risk of febrile neutropenia due to chemotherapy is:

• Dosage: 230 mcg/m2 (4 to 8 mcg/kg/day)
• Administration: Subcutaneously daily beginning on day 4, for a maximum of 14 days
• Indication: To decrease the incidence of infection, as manifested by febrile neutropenia, in patients with nonmyeloid malignancies receiving myelosuppressive anti-cancer drugs 2

From the Research

Recommended Use and Dosage of Filgrastim

The recommended use and dosage of Filgrastim (Granulocyte-Colony Stimulating Factor, G-CSF) for patients at high risk of febrile neutropenia due to chemotherapy is as follows:

• Filgrastim is administered at a dose of 5 μg/kg/day, given as a subcutaneous injection, for up to 14 days 3.
• Alternatively, a pegylated form of filgrastim, pegfilgrastim, can be administered as a single 6 mg fixed dose per chemotherapy cycle 4, 5.
• Pegfilgrastim has an extended circulation half-life and self-regulating, patient-specific pharmacokinetics, making it possible to give the treatment as a single dose once per chemotherapy cycle 3.

Efficacy and Safety

Studies have shown that:

• A single dose of pegfilgrastim is as safe and effective as daily injections of filgrastim in patients treated with myelosuppressive chemotherapy 4, 6.
• Pegfilgrastim may have a lower incidence of febrile neutropenia compared to filgrastim 5.
• However, one study found that pegfilgrastim administered on the same day as dose-dense adjuvant chemotherapy for breast cancer was associated with a higher incidence of febrile neutropenia compared to conventional growth factor support with filgrastim 7.

Administration

• Filgrastim should be initiated 24 hours after completing chemotherapy 5.
• Pegfilgrastim can be administered as a single dose per chemotherapy cycle, and its sustained duration of action makes it possible to give the treatment as a single dose once per cycle 3, 4.