How many doses of Zarxio (filgrastim) should a patient with severe neutropenia receive?

Management of Severe Neutropenia with Zarxio (Filgrastim) in a Pancreatic Cancer Patient

For a pancreatic cancer patient with severe neutropenia (WBC 1.0, ANC 0.37) receiving gemcitabine and nab-paclitaxel (Abraxane), Zarxio (filgrastim) should be administered at 5 μg/kg/day subcutaneously daily until the ANC recovers to at least 1,000/mm³.

Dosing Recommendation

• Administer Zarxio (filgrastim) at 5 μg/kg/day subcutaneously 1, 2
• Begin administration immediately (patient already has severe neutropenia) 2
• Continue daily administration until ANC recovers to at least 1,000/mm³ 1
• Do not continue administration to achieve an ANC >10,000/mm³, as this is unnecessary 1

Rationale for Treatment

• The patient has severe neutropenia with an ANC of 0.37 × 10⁹/L, which puts them at high risk for infection 1
• Filgrastim is strongly recommended for patients with chemotherapy-induced neutropenia to reduce the risk of infection and potentially shorten hospitalization 1, 3
• The gemcitabine and nab-paclitaxel regimen for pancreatic cancer is known to cause myelosuppression, and growth factor support is appropriate in this setting 4

Administration Considerations

• Subcutaneous injection is the preferred route of administration for outpatient management 2
• Inject in the outer area of upper arms, abdomen, thighs, or upper outer areas of the buttock 2
• Monitor complete blood counts regularly to assess response to treatment 2

Expected Response

• Neutrophil recovery typically begins within 1-2 days after initiation of filgrastim therapy 2, 5
• The duration of severe neutropenia is expected to be reduced to approximately 1-2 days with filgrastim treatment 5
• Most patients achieve ANC recovery within 7-10 days of filgrastim administration 5

Important Precautions

• Do not administer filgrastim within 24 hours before or after chemotherapy administration 2
• If the patient is receiving radiation therapy to the chest, filgrastim is contraindicated due to increased risk of complications 1
• Monitor for potential side effects including bone pain, which is common but usually diminishes within the first few weeks of treatment 1

Follow-up Recommendations

• Monitor complete blood counts daily during filgrastim administration to track neutrophil recovery 2
• Consider antibiotic prophylaxis if neutropenia is expected to be prolonged 1
• Once ANC recovers to >1,000/mm³, discontinue filgrastim 1
• Assess the patient for signs of infection throughout the treatment period 4