New Drug Reduces Hereditary Ovarian, Breast Cancers

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Women with advanced hereditary ovarian cancer or hereditary breast cancer may get some help from a new investigational drug. Two separate phase II trials showed that the new drug, Olaparib, can reduce the size of hereditary ovarian and breast tumors.

Hereditary Ovarian and Breast Cancers

Although approximately 90 percent of ovarian cancers occur by chance, 10 percent occur in women who have mutations of the BRCA1 and BRCA2 genes. Women who carry these genes have a greater than 15-fold risk of ovarian cancer compared with noncarriers. While the lifetime risk for ovarian cancer in the general population is 1.3 percent, it ranges from 10 to 60 percent among gene carriers.

According to estimates of lifetime risk of breast cancer, about 12 percent of women in the general population will develop the disease during their lives compared with about 60 percent of women who have inherited a mutation of BRCA1 or BRCA2. That means women with a mutated gene are about five times more likely to develop breast cancer than women who do not have the mutations.

New Drug Trials
A group of international researchers conducted a phase II trial of Olaparib in women who have hereditary ovarian cancer, while Cedars-Sinai Medical Center researchers evaluated the drug in another phase II trial in women with hereditary breast cancer. In both trials the women had BRCA gene mutations, and the women in both trials responded similarly well.

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Among the 57 women in the ovarian cancer trial, 33 percent had a significant reduction in the size of their tumors, and in a few women the tumors disappeared completely. Side effects from olaparib were mild and included nausea, anemia, and fatigue.

Olaparib is not chemotherapy; it is a poly ADP ribose polymerase (PARP) inhibitor, which means this anticancer drug interferes with certain pathways that are associated with cancer growth or survival. Drugs that inhibit the PARP enzyme appear to promote cancer cell death and increase their vulnerability to chemotherapy.

William Audeh, MD, an oncologist at Cedars-Sinai’s Samuel Oschin Comprehensive Cancer Institute and the first author on the ovarian cancer study, noted that “These two studies suggest that it is the underlying genetic weakness of a cancer, not the organ of origin, that is the key to selecting effective therapy.”

Audeh also pointed out that studies of PARP inhibitors “represent a major change in the approach to treating cancer that will be reflected in future clinical trials.” Although these two studies evaluated Olaparib’s impact in patients who were known to have genetic mutations, scientists hope this new drug, and others like it, will be effective in treating the underlying genetic defects not only in ovarian and breast cancers, but in other types of cancer as well.

SOURCES:
Cedars-Sinai Medical Center
National Cancer Institute

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