The aim of an allogeneic transplant is to give you a source of healthy bone marrow and to try to completely cure the leukaemia. In this transplant, stem cells (collected directly from the blood or from bone marrow) are donated by someone else and given to you. The most suitable donor is usually a brother or a sister whose bone marrow is a close match to your own.
Occasionally it is possible to use bone marrow from someone who is not related to you, if tests have shown their white blood cells are a good match with yours. Several organisations in the UK maintain registers of bone marrow donors including the Anthony Nolan Trust and the British Bone Marrow Registry.
In CML, an allogeneic transplant is usually carried out during the chronic phase, when the disease is stable. A transplant may be used after the blast phase has been treated and you are in remission but it would not usually be used as treatment for the blast phase.
Collecting stem cells from the blood
To collect the stem cells from the blood (known as a stem cell harvest), the donor will be given injections of a growth factor called G-CSF. This is a protein that stimulates the bone marrow to produce lots of immature, normal blood cells. These ‘spill over’ into the blood and can then be collected.
Collecting stem cells takes 3–4 hours. The donor lies down or sits in a special chair, with a drip into a vein in each arm. Blood is taken through the drip to a machine called a cell separator, where it is spun to separate out the stem cells. These are collected and frozen until needed. The blood is then given back through the vein in their other arm. The stem cell collection may be done two or three times to make sure that there are enough stem cells to be stored.
The same procedure for collecting cells may be used when you are first diagnosed, to reduce your white cell count.
Collecting stem cells from bone marrow
The procedure for collecting stem cells from the bone marrow is known as a bone marrow harvest. About a week before the bone marrow harvest the donor will have 1–2 pints of blood taken. This is given back during the bone marrow harvest procedure. The harvest is carried out under a general anaesthetic. It involves removing some marrow from inside the bones at the back and the front of the hip bones or, rarely, from the breast bone (sternum).
The doctor inserts a special needle through the skin and into the bone. The marrow is then sucked out into a syringe and put into a sterile container with various solutions to keep the cells healthy during processing and storage. The marrow is taken from a number of different places in the hip bone, usually through several small punctures which quickly heal. You are likely to have some bruising and pain for a few days afterwards. The pain can be controlled with painkillers.
Whether the stem cells are collected from the blood or from bone marrow, your doctors and nurses will make sure that you and your donor are clear about what is involved.
Don’t be afraid to ask questions about anything that you do not understand.
High-dose treatment
The first stage of the treatment destroys your own bone marrow completely. This is done with high doses of chemotherapy, often combined with radiotherapy. After this treatment the donated stem cells are given to you through a drip into the vein or through your central line.
The new marrow or stem cells, known as the graft, take a few weeks to settle in your bone marrow and produce the blood cells you need. Because of your low immunity, certain precautions will be taken to protect you from infections until your white cell count has recovered. You will be looked after in a room on your own and may be given antibiotics to help to protect you against infection. You may also be advised to be careful about what you eat, to protect you against the risk of infection from raw, undercooked or contaminated food. The hospital will give you information on how to prepare foods and which foods to avoid.
Family and friends will be asked not to visit you if they have any coughs or colds or are ill. Most hospitals or specialist centres have their own policies on how to care for you during this time and your doctor or nurse will discuss this with you beforehand.
Graft versus host disease
Your doctors and nurses will be watching you carefully, both during the transplant, and for some months afterwards, for any signs of the new marrow reacting against your own body tissue (this is called graft versus host disease – GvHD). This can occur up to six months after your transplant and can cause various problems including diarrhoea, rashes and liver damage, but it does not mean that your transplant has not worked. Your doctor will prescribe drugs to help prevent the graft reacting to your body.
White blood cells from your donor (donor lymphocyte infusion)
After an allogeneic transplant, your doctors will monitor your blood closely for any signs of remaining leukaemia cells. Having a small number of remaining leukaemia cells may be one of the reasons why CML comes back in some people after an allogeneic transplant.
One way of getting rid of these leukaemia cells may be to have treatment with white blood cells from your donor. This works by helping your immune system reject the remaining leukaemic cells (known as the graft versus leukaemia effect – GvL). The white blood cells can be collected from your donor especially for this reason, or they may be taken and stored when the stem cells are originally collected. The white cells from your donor can be given to you through an injection into a vein in your arm (intravenously). This can be carried out in the outpatient department and some people may need to have it done up to three or four times. Side effects are uncommon but you can develop graft versus host disease in the same way as after an allogeneic transplant.
