Stem Cell Transplantation

Allogeneic stem cell transplantation has been used to treat and sometimes cure chronic myelomonocytic leukemia (CMML) patients. However, because of the high, sometimes life-threatening risks associated with stem cell transplantation, doctors rarely use it in elderly patients or patients in poor health.

Allogeneic transplantation involves transferring stem cells from a healthy person (the donor) to the patient. The procedure follows high-intensity chemotherapy, potent drugs that must be toxic enough to kill leukemic cells. Unfortunately, the drugs also take aim at normal stem cells in the bone marrow.

The main reasons for doing an allogeneic stem cell transplant are to:

  • Kill the CMML cells with strong doses of chemotherapy
  • Start a new supply of red blood cells, white blood cells and platelets with help from the transplanted donor stem cells

Stem cell transplantation after high-dose chemotherapy helps restore bone marrow function and blood cell production.

Most CMML patients aren't eligible for this therapy. It's used for only a small number of younger patients who:

  • Have advanced CMML
  • Don't respond to or are no longer responding to other treatment
  • Have a matched donor

Graft-Versus-Host Disease

A serious risk of allogeneic stem cell transplantation is graft-versus-host disease (GVHD), which develops if the donor's immune cells attack the patient's normal tissue. GVHD's effects can range from minor to life threatening.

Even though there's no specific age cutoff for stem cell transplantation, older adults are more likely to develop GVHD as well as have existing medical conditions that may complicate the procedure. They may also have a lower tolerance for the high-intensity chemotherapy conditioning treatment needed before the transplant.

Reduced-Intensity Allogeneic Stem Cell Transplantation

If you can't tolerate allogeneic transplantation with high-intensity chemotherapy, you may be eligible for reduced-intensity stem cell transplantation (sometimes called nonmyeloablative transplant). This type of transplant is a modified version of allogeneic transplantation.

To prepare for the transplant, you undergo less-intense conditioning treatment compared with a standard allogeneic transplant. The chemotherapy destroys most cancer cells with a standard transplant. Reduced-intensity conditioning doesn't destroy many cancer cells, but instead relies on the donor's immune cells to fight the disease. This attack is called the graft-versus-leukemia effect.

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