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Introduction to CML

Summary & Participants

Chronic myeloid leukemia is a form of cancer that typically occurs in adults over the age of 40. Here's what you need to know about this disease.

Medically Reviewed On: July 18, 2008

Webcast Transcript

ANNOUNCER: About 4,500 people are diagnosed with chronic myeloid leukemia or CML in the United States each year and over 20,000 people are estimated to be living with the disease. This cancer of the white blood cells usually occurs in adults over the age of 40.

GWEN NICHOLS, MD: What we think is the initial or the most important cause of CML is what we call a translocation, or a criss-crossing, of two pieces of genetic material, one on chromosome 9 and one on chromosome 22, that during the division of the cells, these two chromosomes criss-cross, break, and fuse to each other. And in doing so, they create a gene that wasn't there before.

ANNOUNCER: The new gene is made up of two parts and is called BCR-ABL. BCR-ABL creates an abnormal enzyme or protein, a type called a tyrosine kinase. The abnormal kinase signals a biochemical pathway which leads to the uncontrolled production of white blood cells.

ERIC FELDMAN, MD: It's what we call a signal transducer, a signal transduction protein, meaning that it signals to the cell to grow, and if it's constantly in the "on" phase, the cell can constantly grow. It's as if a light switch got turned on and there's no turning it off.

ANNOUNCER: There are three phases of CML.

WILLIAM G. WIERDA, MD, PhD: The chronic phase is the more indolent phase of the disease where the cells are dividing and proliferating, but they're not aggressive. As time goes on, the disease can become more aggressive patients will have a higher number of immature cells and, oftentimes, will have new chromosome abnormalities, not just the Philadelphia chromosome abnormalities. And then patients can progress to the blast crisis that is more of an acute leukemia and a very aggressive type of disease, and is typically fatal.

ANNOUNCER: 85% of patients are in the chronic phase of CML when they are diagnosed. The standard treatment is imatinib, also known as gleevec. This targeted therapy works by binding to the BCR-ABL enzyme, at a particular site on the molecule.

GWEN NICHOLS, MD: Within the kinase, there is an energy center which is called the ATP binding site, and this is critical for the kinase's activity. The molecule, being imatinib, specifically fits into that binding site, and in doing so keeps the kinase, or the enzyme, from being active.

ANNOUNCER: Side effects of imatinib are generally mild.

NEIL SHAH, MD, PhD: Some of the more common side effects include some nausea. Some patients can develop bothersome muscle cramps.

WILLIAM G. WIERDA, MD, PhD: Imatinib can cause rash. It can cause elevation in the liver enzymes, inflammation in the liver. It can cause weight gain and edema, swelling and fluid retention.

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