Myeloid Growth Factors to Reduce Neutropenia & Infection in Oncology Flashcards
Myelosuppression
- Most common dose-limiting toxicity of conventional chemotherapy
- Not immediate after administration – circulating blood cells must be depleted
- Onset 7-10 days post-chemotherapy form Neutrophils
- WBC – lymphocytes, neutrophils increase infectious risks
- Anemia – often delayed
- Platelets – risk of bleeding
Neutropenia
- Neutropenia occurs quickly – WBC life 6-12 hours
- Lowest WBC (or “nadir”) typically 7-10 d after chemotherapy
- Usually recover by 21-28 days BUT may be delayed
- NEUTROPENIA increases risk of infection
Which chemotherapy are High Risk of Marrow Suppression and Neutropenia?
- Anthracyclines >/= 90 mg/m2/exposure
- Alkylators
- Antimetabolites
G-CSF
- stimulate proliferation and maturation of progenitors and release of neutrophils
- Dose-dependent leukocytosis due to neutrophil release occurring sooner (1 vs 5 days) than in unstimulated marrow
- Neutropenia still occurs but not as severe
- Shorter duration and faster time to WBC recovery (to start new RX)
How do we use G-CSF?
Primary prophylaxis to prevent febrile neutropenia with 1st cycle of chemotherapy
* 20% or higher risk of febrile neutropenia
* 10-20% risk of febrile neutropenia when risk factors
- Age 65 years or older, previous chemotherapy/radiation, pre-existing conditions, poor performance status, poor organ function
Filgrastim dosing
5 mcg/kg/dose SQ daily until post-nadir and ANC increased greater than 1000-1500 cells/mL
* Usually rounded to 300 or 480 mcg vial
* Manufacturer endpoint ANC 10,000 cells – protocols use 1000-1500 cells
PEGfilgrastim dosing
6 mg SQ x 1
Rules of Filgrastim and Pegfilgrastim
- Give no sooner than 24 hours post-chemo
- Do NOT give chemotherapy within 24 hours of last dose (for filgrastim) or within 14 days of pegfilgrastim
What are the expected allergic reactions of G-CSF?
- Anaphylaxis
- Rash
- Urticaria
- Facial edema
- Wheezing
- Dyspnea
- Tachycardia
- Hypotension
