Stem Cell Transplant for Chronic Myeloid Leukemia

Stem cell transplant is not a common treatment for chronic myeloid leukemia (CML) today. In the past, before tyrosine kinase inhibitors (TKIs) were available, SCT was often used to treat CML. Now, TKIs are the standard treatment, and transplants are being used far less often.

Because allogeneic SCT offers the only proven chance to cure CML, doctors may still recommend a transplant for younger patients, particularly children. Transplant is more likely to be considered for those with an available matched donor, like a well-matched brother or sister.

Transplant may also be recommended if CML is not responding well to TKIs. It's also an important option for people with CML that's advancing to or diagnosed in the accelerated or blast phases.

What is a stem cell transplant?

The usual doses of chemotherapy drugs can cause serious side effects by damaging quickly dividing cells such as the bone marrow. Even though higher doses of these drugs might be better at killing leukemia cells, they're not given because the severe damage to bone marrow cells would cause lethal shortages of blood cells.

For a stem cell transplant (SCT), high doses of chemo are given to kill the leukemia cells. Sometimes the whole body also is given a low dose of radiation. This treatment kills the leukemia cells, but also damages the normal bone marrow cells. Then after these treatments, the patient receives a transplant of blood-forming stem cells to restore the bone marrow.

Blood-forming stem cells used for a transplant can come from either from blood (called a peripheral blood stem cell transplant, or PBSCT) or from the bone marrow (called a bone marrow transplant, or BMT). Bone marrow transplant was done more commonly in the past, but it has largely been replaced by PBSCT.

The 2 main types of stem cell transplants are allogeneic and autologous.

For an autologous transplant, the patient’s own stem cells are collected from the blood or bone marrow and then given back after treatment. The problem is that leukemia cells may be collected with the stem cells.

In an allogeneic transplant, the stem cells come from someone else (a donor). To lower the chance of complications, the donor needs to “match” the patient's tissue type. Often, a close relative, like a brother or sister is a good match. Less often, a matched unrelated donor may be found.

Because collecting the patient’s stem cells can also collect leukemia cells, allogeneic transplants are the main type of transplant used to treat CML. Allogeneic stem cell transplant is the only known cure for CML. Still, this type of transplant can cause severe or even life-threatening complications and side effects, and it's often not be a good option in people who are older or have other health problems.