Goals of CML Therapy
In the chronic phase of CML the goals of drug therapy are to (1) return the levels of blood cells to normal, and (2) kill all the cells that have BCR-ABL cancer gene.
In accelerated phase or blast crisis phase, the goal of CML drug therapy is to (1) kill all the cells that have the BCR-ABL cancer gene or (2) return the disease to the chronic phase.
Oral CML Therapy
It is important to get treatment in a center where doctors are experienced in the care of CML patients. In chronic phase CML, treatment usually returns the level of blood cells to normal. The spleen shrinks towards normal size and patients do not have infections or unusual bleeding.
CML patients begin treatment with a drug called Gleevec® (Imatinib). This drug has been FDA approved since 2001. For some patients, Gleevec keeps CML under control for as long as they take it. Some patients taking Gleevec have strong side effects or the drug does not work for them. Patients who do not respond to the usual dose of Gleevec may require a higher dose. For other patients there are two newer drugs called Sprycel® (Dasatinib) and Tasigna® (Nilotinib). These drugs also block the BCR-ABL cancer gene. They work in different ways than Gleevec. All three of these drugs are taken by mouth.
Most patients being treated for chronic phase CML can go about their day-to-day activities. With drug treatment most patients are symptom free for very long periods and are said to be in remission.
However, patients are not cured of CML with drug treatment. They need to be checked carefully for any signs that CML is returning (called a relapse). They need regular health check-ups, including blood tests.
CML is likely to return if the drug treatment is stopped. The disease may also return if the drug treatment stops working (this is called drug resistance). There are other drug treatments that may be used for patients who develop resistance to a specific drug.
Some patients have very high white blood cell counts at the time their CML is discovered. This can reduce blood flow to the brain, lungs and other places in the body. Patients can have the white cells removed by a machine in a process called leukapheresis. A drug called hydroxyurea (Hydrea®) may also be used to decrease the white blood cell count. After the white blood cell count drops, then the Gleevec can be started.
Immunotherapy uses the patient’s immune system to fight the cancer. Medications like interferon are given to boost the body’s natural defenses against cancer. Interferon can reduce the white blood cell count and sometimes decrease the number of cells that have the Ph chromosome. It is given by daily injections under the skin and cases flu-like symptoms such as fever, chills, and loss of appetite Over time this drug causes fatigue and memory changes. Once used as a primary treatment for CML, Gleevec is now used first because it is more effective and has fewer side effects.
Bone Marrow (hematopoietic stem cell) Transplant
Bone marrow transplant involves killing the cancer cells and the damaged immune system and replacing it with normal transplanted stem cells from a healthy donor that will grow into and restore the body’s blood cells. CML patients may receive an allogeneic transplant – cells from a related or unrelated donor. CML patients cannot use their own stem cells for transplant. The results of transplant are best if the transplant is performed while the patient is in the chronic phase.
Fred Hutchinson Cancer Research Center, an SCCA parent organization, in 1998 published the results of a research study that showed that CML patients who received a bone marrow transplant from a tissue-type (HLA) matched unrelated donor could expect about the same five-year survival rate as patients with matched related donors. Since then, Hutchinson Center researchers have led the way in improving the treatment of CML.
Allogeneic stem cell bone marrow transplantation can be a high-risk treatment, but it is the only treatment that can cure CML. Gleevec or other drugs can control CML in many patients for a long time, but transplant is the only way to cure the patient. The time to consider transplant may be when Gleevec is no longer working to control CML or the side effects of the treatment are too great.
To be considered for a bone marrow transplant at the Fred Hutchinson Cancer Research Center (SCCA), it is best to talk to the pediatric attending physician either in person or by phone. The attending physician can be reached at (206)-288-1024.
Accelerated Phase or Blast Crisis Phase Treatment
The goal in treating accelerated or blast crisis phase CML is to kill all cells that contain the BCR-ABL gene or return the patient’s disease to the chronic phase.
Gleevec and for Sprycel (dasatinib) are important treatments for accelerated or blast crisis phase of CML. Stem cell transplant is another important for certain patients.