5 questions about… chronic myeloid leukemia (CML)

1. What is Chronic Myeloid Leukemia?

“Chronic myeloid leukemia (CML) is a cancer of the blood and bone marrow. White blood cells have started to proliferate. These cells accumulate in the bone marrow and can disrupt the production of other blood cells. These leukemia cells also move into the bloodstream, causing way too many white blood cells enter the blood, which can lead to ‘syrupy’ blood, which can cause all kinds of complaints.

The white blood cells also accumulate in the spleen, causing it to enlarge greatly. If there is a shortage of red blood cells and platelets due to displacement in the bone marrow, you get anemia and an increased risk of bleeding.

CML develops slowly. Many people don’t notice it for a long time. In the early stages, CML is often found accidentally during a blood test. The symptoms that can develop in CML are not unique and are common to many other blood cancers, including anemia, an increased risk of bleeding, unexplained bruising, a swollen spleen that causes discomfort, bone pain, unexplained weight loss and excessive sweating. “

2. What is the cause?

“It is estimated that 200 to 300 Dutch people are diagnosed with CML every year. It is more common in people over 50 and more often in men than in women.

Chronic myeloid leukemia is not hereditary. What causes it is unknown. However, it is more common among people who have been exposed to radioactive radiation, such as among survivors of the Chernobyl nuclear disaster and the atomic bomb attack on Hiroshima.

In most patients with CML, an abnormal chromosome is found, the so-called Philadelphia chromosome. This chromosome creates a protein (BCR-ABL) that is responsible for the abnormal development and rapid growth of white blood cells in CML.”

3. How is CML treated?

“CML always passes from a chronic phase into an acute phase that cannot be treated well. Without treatment, patients therefore die after a few weeks to a few years. Fortunately, the current treatments ensure that the life expectancy for the majority of patients is very high. More than 95 percent of people with the condition are now long-term survivors, as doctors prevent the disease from progressing to an acute stage.

Although several treatments are possible, the primary treatment for CML is tyrosine kinase inhibitors. For example, imatinib, nilotinib or dasatinib. These are pills that inhibit the BCR-ABL protein that is responsible for the leukemia. In almost all patients – especially while the disease is still in the chronic phase – these agents ensure a rapid recovery of blood values. The treatment usually has some side effects, but most patients can lead a more or less normal life.

It also appears that after a period of one to five years of treatment, hardly any abnormal cells can be detected in many patients. We currently advise patients with CML to take these inhibitors for life.

Despite these good results, resistance to this medication occurs in a low percentage of patients. It may then help to switch to another inhibitor. We are also currently investigating even more potent inhibitors of the abnormal protein. Depending on the age and condition of the patient, a stem cell transplant can be chosen in the event of permanent resistance.”

4. Can CML Patients Get Pregnant?

“Under certain conditions, patients can become pregnant. The disease itself or the treatment (with the exception of the stem cell transplant) does not cause infertility. We do not recommend pregnancy while taking the inhibitors, because there is an increased risk of birth defects.”

5. What does new research offer?

“To combat resistance, we are conducting research into even more potent drugs. In addition, we hope that some of the patients will be able to stop taking inhibitors with these drugs after a number of years. It seems that this is indeed possible in some of the patients that responds very well to treatment.”