Stem cell transplant for chronic myeloid leukemia

Stem cells are found in bone marrow, blood and umbilical cords. They are basic cells that develop into different types of cells that have different jobs. For example, all our blood cells develop from blood stem cells.

A stem cell transplant replaces stem cells. It uses chemotherapy at very high doses to kill all of the cells in the bone marrow. This includes both healthy cells and leukemia cells. Sometimes whole-body radiation therapy is also given. After high-dose chemotherapy, healthy stem cells are then given to replace the ones in the bone marrow that were killed.

A stem cell transplant is not used very often for CML since targeted therapy with tyrosine kinase inhibitors (TKIs) became the standard treatment. A stem cell transplant can be a cure for CML. While TKIs can effectively control and manage the disease, a stem cell transplant removes the stem cells with the BCR-ABL gene and replaces them with healthy ones. But it is a much more difficult treatment to have.

In the chronic phase, a stem cell transplant may be offered to the very small number of people who experience the following:

• CML doesn't respond to, or stops responding to, TKIs
• TKIs cause severe side effects
• blood cell counts don't return to normal levels

In the accelerated phase or blast phase, a stem cell transplant may be offered only if treatment with TKIs moves the disease into the chronic phase or improves blood counts. This improves the chance that a stem cell transplant will be successful.

An allogeneic stem cell transplant is the type used to treat CML. With this type of transplant, the stem cells are taken from one person (the donor) and given to another person (the recipient). The donor and recipient may or may not be related. They are matched through a process called human leukocyte antigen (HLA) typing.

Before an allogeneic stem cell transplant, lymphocytes may be removed from the donor’s blood and frozen for storage.

If CML comes back after an allogeneic stem cell transplant, these lymphocytes can be thawed and given to you through an intravenous infusion, like a blood transfusion. This is called a donor lymphocyte infusion (DLI). It may stimulate your immune system and bring on a stronger immune reaction against the leukemia cells.

If there aren't frozen lymphocytes available, your healthcare team may contact your donor to ask them to donate the lymphocytes.

Side effects of a stem cell transplant will depend mainly on the type of chemotherapy drug or drug combination given, if radiation therapy was given, the type of transplant, how well matched the donor cells are to your own, and your overall health. Tell your healthcare team if you have side effects that you think are from a stem cell transplant. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Side effects of a stem cell transplant include:

• low blood cell counts, which can cause infection, bleeding and anemia
• graft-versus-host disease (GVHD)
• blockage of the small blood vessels that lead into and are inside the liver, called veno-occlusive disease (VOD)
• digestive system problems, including sore mouth and throat, loss of appetite and diarrhea
• skin problems
• pain
• fertility problems
• osteoporosis

Find out more about a stem cell transplant and side effects of a stem cell transplant. To make the decisions that are right for you, ask your healthcare team questions about stem cell transplant.