Stem cell mobilisation
In preparation for HDT and autologous SCT, patients must first have an adequate amount of haematopoietic stem cells in the blood for collection. Normally the levels of stem cells in blood are very low so to collect enough for a transplant, it is necessary for patients to undergo treatment to stimulate the migration of stem cells from the bone marrow into the peripheral blood. This process is known as stem cell mobilisation.
Growth factor
Mobilisation is achieved by injection of a synthetic form of the growth factor, granulocyte-colony stimulating factor (G-CSF) which promotes the proliferation and maturation of the stem cells before their release into peripheral blood.
G-CSF is given as a subcutaneous injection over several days prior to collection of the stem cells. The injections are given in the outpatient clinic or patients can self-inject at home either once or twice daily, depending on the dose prescribed. Those administering at home rely on high quality education and teaching provided by their nursing team.
Possible side effects of G-CSF treatment include redness around the injection site, headache, fever, nausea, bruising/bleeding gums. Pain can be a major side effect of G-CSF, particularly in younger people and males where bone marrow is often more dense. It is important that the nurse educates the patient of theses side effects and ways to manage the pain for example taking painkillers.
Chemotherapy
Although it is possible to mobilise stem cells using G-CSF alone, a cycle of chemotherapy drug is often given before the G-CSF injections. Chemotherapy temporarily reduces the number of stem cells in the bone marrow. When the bone marrow recovers, it goes into stem cell proliferation ‘over-drive’ and with the addition of G-CSF, it is usually much easier to collect the required number of stem cells. High-dose cyclophosphamide given intravenously a few days before G-CSF is most commonly used. For some patients, the side effects associated with this higher dose, such as nausea, may be more apparent than those with the oral induction chemotherapy. Although these side effects are usually temporary and should resolve quickly, nurses should provide patients with instructions to contact staff if this becomes distressing. Additional anti-emetics can also be given.
G-CSF is given consecutively over the course of five to seven days when used alone, or over approximately 10 days when used after chemotherapy.
For some patients a sufficient number of stem cells cannot be collected by mobilisation using G-CSF. In such situations patients may benefit from the drug plerixafor (Mozobil®) which, when given alongside G-CSF, can significantly enhance the release of stem cells from the bone marrow.
Mozobil is now routinely commissioned on the NHS for ‘rescue’ use in myeloma patients who have failed to harvest sufficient stem cells to proceed to transplantation using the standard regimen of chemotherapy and G-CSF. The most common side effects of using Mozobil include: diarrhoea, nausea, dizziness, headache, pain in the joints and redness around the injection site.