Granulocyte-Colony Stimulating Factor (G-CSF)
G-CSF is a cytokine normally produced by the human body itself. Cytokines are proteins and peptides that allow cells to communicate with one another. They act like hormones and neurotransmitters and are involved in a variety of immunological, inflammatory, and infectious diseases. The type of G-CSF which is given as treatment is not from human beings but is safely made by genetic engineering to produce an identical substance which acts like the naturally occurring cytokine.
G-CSF stimulates the production and enhances the activity of mature neutrophils to improve their bacteria-killing function. SCN patients produce their own G-CSF, but for unknown reasons it does not produce the normal effects within the blood system so extra G-CSF is required.
The dose and frequency of injection of G-CSF varies widely. For most patients, 5-20 micrograms (mcg) per kilogram (kg) of body weight of G-CSF given as a daily subcutaneous injection is usually sufficient. Sometimes certain patients need very high doses, even up to 120/mcg/kg/day and others will require very low doses, as low as 0.01 mcg/kg/day.
For some patients with severe chronic Neutropenia the dosage frequency of G-CSF may be required less than daily, but short-term amendments may be necessary if infections occur.
G-CSF is usually administered by an injection just under the skin in areas such as the abdomen below the naval, upper outer arms, and upper outer thighs. It is possible to self-administer G-CSF depending on the age of the patient. The injection is not usually very painful but, occasionally, a stinging sensation may be experienced for a short period of time.
G-CSF treatments can be expensive, up to $4000 a month. However, it might be possible to get financial help with G-CSF supplies. Patients and families are strongly encouraged to register and investigate options that could be available with research organizations.
Effects and Side Effects
Administration of G-CSF may result in a dramatic increase in the numbers of neutrophils in the blood and is without a doubt, the most effective therapy in treating SCN. Some SCN patients receiving G-CSF report bone or muscle pain and splenomegaly (enlargement of spleen). Other side effects are infrequent but few patients have experienced some of the following:
- Thrombocytopenia (Low platelet levels)
- Injection site reactions such as rash
- Hepatomegaly (liver enlargement)
- Arthralgia (joint pain)
- Osteoporosis (reduced bone density)
- Cutaneous vasculitis (renal disease)
- Haematuria/ proteinuria (blood or serum in urine)
- Alopecia (hair loss)
- Exacerbation of some pre-existing skin disorders (e.g. psoriasis).
Bone Marrow Transplant
BMT is a treatment option for SCN. It may be considered for failure to respond to treatment, or for patients who develop leukemia or MDS in the course of their disease. BMT is a very intensive procedure, carrying serious risks and therefore it is not recommended as first choice treatment. Your physician will be able to discuss this with you.
In some conditions steroids have long been effective at increasing neutrophil counts in the blood. Steroids work by encouraging neutrophils to leave the bone marrow and enter the blood stream. However, they do not induce the production of new neutrophils in the bone marrow. They may even decrease the number of other types of white cells increasing the risk of infection.
In general, steroids have not proven useful for patients with SCN, except for very few SCN patients not responding to other therapies.