Leukemia Chronic Myelogenous Stem Cell Transplant

A stem cell transplant, also known as “stem cell therapy” or a “bone marrow transplant,” can cure chronic myelogenous leukemia. The goal of other CML treatments is to achieve remission, a state where levels of leukemia cells are too low to be detected diagnostically. However, remission carries the risk of relapse if leukemia cells return.

High doses of chemotherapy and radiation therapy can eradicate leukemia cells. Unfortunately, chemotherapy doses required to kill cancer cells also kill healthy bone marrow. Without bone marrow, the body stops producing new blood cells and can no longer transport oxygen or stop bleeding. In addition, white blood cells that fight infection can’t be produced.

A stem cell transplant allows the use of otherwise deadly doses of chemotherapy and replaces diseased bone marrow with healthy cells.

Types of Stem Cell Therapy

Types of stem cell therapy include:

  • Bone marrow transplants
  • Peripheral blood stem cell transplants
  • Umbilical cord stem cell transplants.

Each procedure harvests stem cells from a different source, either directly from bone marrow, from circulating blood, or from stem cells present in umbilical cord blood.

How Stem Cells Work - Stem Cell Transplants for CML

Bone Marrow Transplant Donors

A bone marrow transplant requires stem cells that closely match the recipient’s stem cells. Stem cells carry proteins called HLA antigens on their surfaces. Stem cell therapy uses stem cells that have HLA antigens that closely match the patient’s own HLA antigens.

An “autologous stem cell transplant” harvests stem cells from the patient while leukemia is in remission. Harvested stem cells are treated to remove surviving leukemia cells and then returned to the patient’s body.

If CML is not in remission, healthy stem cells must come from a donor, a process known as an “allogenic stem cell transplant.” Donors may be close relatives or complete strangers.

Stem Cell Transplant Treatment

Before a stem cell transplant, the patient undergoes high-dose chemotherapy to kill all leukemia cells. Chemotherapy may be combined with radiation therapy. Patients are monitored for signs of infection, bleeding and other complications.

Donated stem cells are delivered into the blood intravenously. The new stem cells make their way to the bone marrow, where they begin to produce more stem cells and blood cells, a process called “engraftment.” It can take two to four weeks for engraftment to begin after a stem cell transplant.

Complications of Bone Marrow Transplant

A bone marrow transplant has serious risks. The immune system does not fully recover for several months after an allogenic transplant, and it can take up to two years for the immune system to recover from an autologous transplant.

Potential long-term complications of stem cell therapy include cataracts, infertility and secondary cancers. Major organs, including the heart, lungs and kidneys, may be damaged by stem cell transplant complications.

Graft-versus-host disease (GVHD) may occur if white blood cells produced by donated stem cells mistake the host body for an invader. The new blood cells then attack the host’s cells. GVHD ranges in severity from mild to life-threatening symptoms and can occur very soon after or years following a bone marrow transplant.

Resources

American Cancer Society. (2010). Bone marrow and peripheral blood stem cell transplant. Retrieved September 27, 2010, from http://www.cancer.org/Treatment/TreatmentsandSideEffects/
TreatmentTypes/BoneMarrowandPeripheralBloodStemCellTransplant/stem-cell-transplant-what-are-stem-cells.

Leukemia and Lymphoma Society. (2006). Blood and marrow stem cell transplantation. Retrieved September 27, 2010, from http://www.leukemia-lymphoma.org/all_page.adp?item_id=5965.

Mayo Clinic Staff. (2010). Stem cell transplant. Retrieved September 27, 2010, from http://www.mayoclinic.com/health/stem-cell-transplant/MY00089.

National Cancer Institute. (2008). Bone marrow transplantation and peripheral blood stem cell transplantation. Retrieved September 27, 2010, from http://www.cancer.gov/cancertopics/factsheet/Therapy/bone-marrow-transplant.