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 as a first-line treatment.
Although it's not the only type of stem cell transplantation, allogeneic stem cell transplantation is the most common type used to treat CMML. 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:
- start a new supply of red cells, white cells and platelets with help from the transplanted donor stem cells
- give strong doses of chemotherapy to kill CMML cells
Stem cell transplantation after high-dose chemotherapy helps restore marrow function and blood cell production. This gives the initial chemotherapy a chance to better do its work with less damage to your normal cells.
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 your 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 might complicate the procedure. They may also have a low 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 being used in clinical trials.
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-tumor (GVT) effect.