Hematopoietic Growth Factors
Key Points
- Hematopoietic growth factors stimulate the bone marrow to produce specific blood cell lineages, used to prevent or treat cytopenia from chemotherapy or chronic disease.
- G-CSF agents (filgrastim, pegfilgrastim) stimulate neutrophil production — used to reduce neutropenic fever and infection risk.
- ESAs (epoetin alfa, darbepoetin alfa) stimulate red blood cell production — used to treat chemotherapy-induced anemia or CKD anemia.
- Bone pain is a common side effect of G-CSF — caused by bone marrow expansion; treat with acetaminophen or NSAIDs.
- ESAs carry black box warnings for cardiovascular risk when used to target hemoglobin >11 g/dL.
Drug Class Overview
Hematopoietic growth factors are recombinant cytokines that mimic natural bone marrow stimulating proteins:
| Category | Drugs | Target Cell | Primary Use |
|---|---|---|---|
| Myeloid CSF (G-CSF) | Filgrastim (Neupogen), pegfilgrastim (Neulasta) | Neutrophils | Post-chemotherapy neutropenia, febrile neutropenia prevention |
| ESA | Epoetin alfa (Epogen, Procrit), darbepoetin alfa (Aranesp) | Red blood cells | Chemotherapy-induced anemia, CKD anemia |
| Thrombopoietic | Eltrombopag, romiplostim | Platelets | Immune thrombocytopenia (ITP) |
Granulocyte Colony-Stimulating Factors (G-CSF)
Filgrastim (Neupogen) and Pegfilgrastim (Neulasta)
Mechanism: Bind to G-CSF receptors on bone marrow progenitor cells → stimulate production and differentiation of neutrophils.
Indications:
- Prevention of chemotherapy-induced febrile neutropenia (ANC <1.5 cells/µL + fever ≥100.4°F)
- Mobilization of stem cells for collection prior to bone marrow transplant
- Aplastic anemia and severe congenital neutropenia (filgrastim)
Administration:
- Filgrastim: subcutaneous injection daily (start 24-72 hours AFTER last chemotherapy dose)
- Pegfilgrastim: single subcutaneous injection per chemotherapy cycle — longer-acting (pegylated form)
- Do NOT administer within 24 hours before or after chemotherapy — bone marrow stimulation may increase sensitivity to chemotherapy toxicity
Key Adverse Effects of G-CSF
| Adverse Effect | Mechanism | Nursing Action |
|---|---|---|
| Bone pain | Bone marrow expansion → bone pressure | Acetaminophen or NSAIDs; reassure patient this is expected |
| Splenomegaly | Increased marrow activity | Rare; educate on left-side pain as warning sign |
| Leukocytosis | Excess WBC production | Monitor CBC; hold if WBC >100,000/µL |
| Fever | Cytokine release | Differentiate from febrile neutropenia |
Erythropoiesis-Stimulating Agents (ESA)
Epoetin Alfa (Epogen, Procrit) and Darbepoetin Alfa (Aranesp)
Mechanism: Stimulate erythropoietin receptors on red blood cell precursors → increase RBC production.
Indications:
- Anemia associated with chemotherapy in non-myeloid cancers
- Anemia of chronic kidney disease (CKD) — when dialysis-dependent
- Anemia from zidovudine (AZT) therapy in HIV patients
Administration:
- Epoetin alfa: subcutaneous or IV injection, 3 times weekly
- Darbepoetin alfa: less frequent dosing (weekly to every 3 weeks) — longer half-life
Black Box Warnings for ESAs
- Cardiovascular risk: ESAs increase risk of MI, stroke, thrombosis, and death when Hgb target >11 g/dL. Use the lowest dose to avoid RBC transfusion. Do not target Hgb to “normal” levels.
- Tumor progression: ESAs may stimulate erythropoietin receptors on some tumors — not indicated for cure; use only for symptom palliation in cancer.
- Shortened survival: Observed in some cancer trials — use only per FDA-approved indications.
Nursing Assessment
NCLEX Focus
Monitor CBC during G-CSF therapy — assess ANC (absolute neutrophil count) and WBC. For ESAs, monitor Hgb and Hct regularly; hold drug if Hgb rises more than 1 g/dL in any 2-week period.
- Assess complete blood count (CBC) before each dose and periodically during therapy
- For G-CSF: assess for signs of febrile neutropenia (ANC <500/µL + temp ≥100.4°F)
- For ESA: assess blood pressure — hypertension is a common adverse effect of epoetin
- Assess for bone pain — common with G-CSF; reassure patients this is an expected sign of drug working
Nursing Interventions
- Refrigerate growth factors; do NOT shake — shaking denatures the protein
- Administer subcutaneous injections using proper technique; rotate sites
- Do not administer filgrastim within 24 hours before or after chemotherapy
- Teach patients to report: bone pain (G-CSF), headache or hypertension (ESA), unusual swelling (ESA thrombosis risk)
- Monitor for rare but serious: splenic rupture (pain in left shoulder/abdomen), anaphylaxis (first dose)
- For ESA: monitor iron, folate, B12 stores — deficiency prevents adequate RBC production
Related Concepts
- leukopenia-and-neutropenia — G-CSF directly used to treat and prevent chemotherapy-induced neutropenia.
- aplastic-anemia-pancytopenia-management — Hematopoietic growth factors used in aplastic anemia management.
- anemia-overview-and-transfusion-thresholds — ESAs provide an alternative to transfusion in chronic anemia.
- kidney-disease — Epoetin alfa is the standard treatment for CKD-related anemia.
- vesicants — Growth factors are administered in the chemotherapy care context.
- cbc — CBC monitoring required throughout growth factor therapy.
Self-Check
- A patient receiving filgrastim complains of severe back and bone pain. How should the nurse respond?
- What is the maximum recommended hemoglobin target when using ESAs in cancer patients, and why?
- Why should G-CSF not be administered within 24 hours before or after chemotherapy?