About two years after she first started taking Gleevec, and about six months after the dose was increased, the woman reported that she was having irregular menstrual cycles and then her periods ceased altogether.
Doctors confirmed premature ovarian failure. While it's not possible to definitively prove that Gleevec caused premature menopause, Christopoulos said that based on the timing, the lack of other causes, and the drugs' mode of action, it's the most likely culprit.
Gleevec works by targeting tyrosine kinases, which are proteins that are very active in cancer cells. However, these proteins are also expressed by the ovaries.
"There are about 60 tyrosine kinases. Can Gleevec be so specific that it only interacts with one of the 60? This drug is pretty good at targeting and hitting the bull's-eye, but it's not perfect," said Dr. Bart Kamen, chief medical officer of the Leukemia & Lymphoma Society.
"Is it worth that risk? You better believe it," Kamen said. "The side effects of Gleevec compared to what else we do in cancer treatment is mild. It has a wonderful risk-to-benefit ratio."
"The advantages of this drug clearly outweigh the disadvantages," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La.
Brooks also pointed out that most women with CML are long past their reproductive years. According to the American Cancer Society, the average age of CML diagnosis is about 67.
While most women are already counseled about the risks to their fertility before undergoing any cancer treatment, Christopoulos said that women of reproductive age receiving Gleevec should know that they shouldn't become pregnant while taking the drug, and they may want to freeze some of their eggs before treatment.
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