Chronic Myelogenous Leukemia

Treatment

When patients with CML are first diagnosed, they may have no symptoms, mild symptoms or, occasionally, severe symptoms. If left untreated or minimally treated, CML can remain stable (chronic phase) for several years, but eventually the disease transforms into either acute lymphocytic leukemia or acute myelogenous leukemia (known as blast phase). When CML becomes acute it can sometimes be controlled for a time, but eventually it becomes untreatable and the patient can die.

Effective CML treatments have been developed in recent years which offer new hope to patients. Mayo Clinic offers treatments for chronic myelogenous leukemia including established drug regimens, bone marrow transplantation and experimental therapies.

Effective Drugs

In 1961, a researcher in Philadelphia discovered that a portion of chromosome 9 can exchange material with chromosome 22, causing a gene known as "abl" from chromosome 9 to locate next to the "bcr" gene on chromosome 22. This abnormal gene — known as bcr-abl or the Philadelphia chromosome — produces an abnormal protein, known as tyrosine kinase, that causes excessive production of white blood cells.

Researchers have developed a drug called Gleevec® that binds to the bcr-abl protein and prevents it from causing cells to grow and divide. These bcr-abl protein-containing cells then die, allowing normal cells in the bone marrow and blood to grow. This drug treatment is available at Mayo Clinic.

For CML cases that are resistant to Gleevec® other options such as Interferon, Cytarabine, and chemotherapy pills can be substituted. These drugs can often control a patient's blood counts, but less often affect the presence of the bcr-abl gene and protein.

Bone Marrow Transplant

Patients who do not experience success with drug treatments or some younger patients may be candidates for allogeneic bone marrow transplantation. In this treatment, the patient is treated with chemotherapy and/or radiation therapy to kill the leukemia cells, then infused with normal hematopoietic stems cells from a donor to repopulate the patient's bone marrow. The immune system components contained in the donor's bone marrow and blood are also given to the patient. Cells from the donor's immune system then attack the leukemia as if it were an infection.

Bone marrow transplantation is highly effective in treating CML, but it can cause severe side effects, including internal organ damage, infection and an immune reaction against the donor cells known as graft-versus-host disease.

Experimental Therapy

Some patients may quality for a newer experimental allogeneic transplant being tested at Mayo known as non-myeloablative transplant. This treatment uses less intensive chemotherapy and radiation and has fewer side effects.