A drug that has been used to treat thousands of leukemia patients may carry serious heart risks, say researchers.
Gleevec is designed to specifically target and prevent cancer cells from multiplying in patients with chronic myleogenous leukemia (CML) and some types of stomach cancer, but in laboratory tests, the drug has been shown to also destroy heart cells.
This finding is a big surprise," said Dr. Thomas Force, lead researcher and professor of medicine at Jefferson Medical College of Thomas Jefferson University, Pennsylvania.
In CML patients, a specific enzyme, Abelson tyrosine kinase (ABL) protein, becomes overactive and turns healthy blood cells cancerous, and they begin to multiply out of control. Gleevec works by targeting ABL and turning it off, so the cancer can no longer grow.
Researchers were prompted to study the heart risks of Gleevec after 10 patients with CML developed severe congestive heart failure while taking the drug. Researchers then looked at the impact of Gleevec on live mice and human heart cells. The results of the study are published in Nature Medicine.
In these tests, the study discovered that while ABL is to blame for CML, it is also necessary for the maintenance of healthy heart muscle. So, by turning off ABL, Gleevec can cause damage to the heart.
"While the cancer is treated effectively, there will be some percentage of patients who could experience significant left ventricular dysfunction and even heart failure from this," said Force.
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Unfortunately, there seems to be no way of knowing which patients will have a cardiac problem while on Gleevec. But even with this warning, Force still thinks that this drug is an important tool in our cancer-fighting arsenal. As with all drugs, doctors need to be aware of the potential risks involved when writing a prescription.
"Gleevec is a wonderful drug, and patients with these diseases need to be on it," he said.
