What’s involved in allogeneic stem cell transplants?

Before a donor stem cell transplant, you’ll be given treatment to get you ready for your donor’s cells. This is called conditioning treatment. You will go into hospital about a week before your transplant date. You’ll be given advice about what to bring to make your stay more comfortable.

There are different ways of giving conditioning treatment and different levels of intensity (strength) of treatment. The conditioning treatment you have will depend on the type of cancer or leukaemia you have, your general health and any chemotherapy or radiotherapy treatment you’ve had in the past.

You will have a combination of chemotherapy drugs through your PICC or central line. Some people also receive radiotherapy to the whole body (total body irradiation).

One or two days after you finish your conditioning treatment a nurse will give you the donated stem cells through your central or PICC line. The stem cells travel through your blood to your bone marrow, where they’ll engraft and start to make blood cells.

Going into hospital

About a week before your transplant date, you will be admitted to hospital to start your conditioning treatment. Arrangements vary between transplant units, but you’ll usually have your own room.

Because you may have to stay in your room for a long period of time, you might want to bring special items from home to make you feel more comfortable.


The conditioning treatment

Before a donor stem cell transplant, you’ll be given treatment to get you ready for your donor’s cells. This is called conditioning treatment. During this time, the doctors may talk about days as numbers. The day of your transplant (stem cell infusion) is Day 0. The days before the transplant are counted as Day -8, Day -7, and so on, until Day 0 when you have the transplant. The days after the transplant are counted as Day +1, Day +2, and so on.

Your conditioning treatment will be completed 24–48 hours before the transplant (Day -2 or Day -1).

You will usually have several different chemotherapy drugs for your conditioning treatment. These can be given in different combinations. Some people also have radiotherapy to the whole body, which is known as total body irradiation, or TBI.

The conditioning treatment is given:

  • to prepare your immune system to accept the donor stem cells
  • to reduce the risk of your immune system attacking the donor stem cells
  • to remove any remaining cancer cells from your body.

Conditioning treatment can take up to a week. The conditioning treatment starts before the donor’s stem cells are collected. If your donor is a relative, their cells will be collected on Day -1 (the day before the transplant). If the donor is not related, their cells will be collected on Day -2 (two days before the transplant date). This is to make sure you’re ready for the transplant soon after the stem cells are available.

There are different ways of giving conditioning treatment and also different levels of intensity (strength) of treatment. The treatment you have will depend on the type of cancer or leukaemia you have, your general health and any chemotherapy or radiotherapy treatment you’ve had in the past.

Full-intensity conditioning

High-dose chemotherapy, sometimes with total body irradiation, is given to destroy your bone marrow and immune system. You are then given donor stem cells to replace your immune system and to attack any remaining cancer cells in your body.

Reduced-intensity conditioning

This uses less intense doses of chemotherapy or radiotherapy, which should mean fewer complications. Reduced-intensity conditioning weakens your immune system enough to allow the donor stem cells to grow in your bone marrow. When both your donor’s cells and your own cells are in your system, this is called mixed chimerism. The donor stem cells will gradually replace your immune system and attack any remaining cancer cells in your body.


Chemotherapy

Chemotherapy is given through your central or PICC line with plenty of fluids. The treatment is usually given over several days. You’ll be given drugs to help control any side effects.

Our section on understanding chemotherapy explains the treatment and has information on how to cope with side effects. We also have information on individual drugs and drug combinations.


Radiotherapy

Radiotherapy uses high-energy rays to destroy cancer cells. You may be given total body irradiation (TBI) as conditioning treatment before your transplant.

TBI may be given twice a day for 6–8 sessions over 3–4 days. If you’re having radiotherapy as part of a reduced-intensity regimen, only one or two low doses of TBI may be needed.

If you’re having radiotherapy, you will go to the radiotherapy department for a planning session a few days before the treatment begins. The doctor will explain what will happen during your radiotherapy, and you can ask any questions you may have.

Before each session, the radiographer will position you carefully and will make sure you’re comfortable. You’ll have to change position a few times during the session. The radiographer will explain this to you.

During the treatment, you’ll be left alone in the room, but you’ll be able to talk to the radiographer, who will be watching you from the next room. Each session lasts about 40 minutes, but the radiotherapy only takes about 10–20 minutes. You can bring some CDs to listen to during your treatment.

Radiotherapy isn’t painful, but you do have to keep still while your treatment is being given.

Many people find that they don’t have many side effects from total body irradiation. This is because the treatment gives a relatively low dose of radiation to all parts of the body. Possible side effects include tiredness, feeling sick (nausea), diarrhoea and a sore mouth.


Having the stem cells

A nurse will give you the donated stem cells through your central or PICC line  one to two days after finishing your conditioning treatment. This is like having a blood transfusion.

Fresh donor cells are usually given within 48 hours of collection. If you are having a cord blood donation, it will be brought to the unit on your transplant date, thawed and given to you through your line.

Some people have mild side effects while the stem cells are given, such as feeling sick and breathless. You’ll be closely monitored during and after having the cells.

The stem cells travel through your blood to your bone marrow, where they’ll engraft and start to make blood cells. It can be at least 10 days and up to three weeks before some of the ‘new’ blood cells are released into the blood.

You may be given growth factors by injection. This will stimulate your bone marrow to start making new blood cells more quickly. Getting growth factors can reduce how long you’re at risk of side effects.

You will have regular blood tests to measure how well your donor’s cells have engrafted. This is called chimerism.


Mixed chimerism

Chimerism is a measure of how well your donor’s cells have engrafted. You will have regular blood tests to measure the numbers of donor cells and your original cells. Your doctors might talk about this as a percentage (%). The aim is that you will get 100% (total) chimerism. This means your blood and bone marrow will be 100% the same as your donor’s.

If you develop a side effect called graft-versus-host disease (GvHD), you are more likely to have total chimerism. This is because the donor cells will have destroyed any remaining cells of your own and you will have total engraftment.

Some people will have a ‘mixed chimerism’. This is more common after reduced-intensity conditioning, when lower doses of drugs and radiation are given. This is because some of your own blood cells will survive this conditioning treatment. Mixed chimerism can improve over time but may be a sign of graft failure.

You will be carefully monitored after your transplant. If you are having immunosuppressive drugs , they may be stopped or reduced. Or you may be given treatment with donor lymphocyte infusions (DLI).

Donor lymphocyte infusions (DLI)

Lymphocytes are white blood cells and are part of the immune system. Your doctors may decide to treat you with donor lymphocytes. These will be from your original donor.

They may have been saved when cells were first collected from your donor. Otherwise, the donor may be asked to donate again. No injections are needed before this procedure. The lymphocytes are collected by a cell separator machine.

The lymphocytes are then given to you by a drip into your line. The lymphocytes should destroy any remaining cancer cells and improve your mixed chimerism. The aim is for all your bone marrow cells to be from your donor. The main risk of DLI is that you might develop GvHD. Your doctor will talk to you about any risks.


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