PARP inhibitors could aid larger ovarian cancer patient population

PARP inhibitors are a promising new class of drugs thought to be an effective weapon against ovarian cancer, among others. But scientists have asserted that no more than 15% of women with the disease--those who have two specific protein mutations--can benefit from the treatment.

That may no longer be true. Based on a new study, it turns out ovarian cancer patients with other protein mutations could also be good candidates for the drugs, scientists from the Oregon Health & Science University Knight Cancer Institute have concluded. Details are published in PLoS ONE.

Pay attention to this particular research focus, as the researchers amply point out there haven't been many new ovarian cancer treatment advances in 20 years. More studies will be needed to support their conclusion, but, if successful, a promising class of drugs could reach even more ovarian cancer patients. Ovarian cancer is particularly deadly; the institute estimates 14,000 patients die from the disease annually, and 21,000 cases are diagnosed each year.

PARP drugs, however, aren't without controversy. For example, Sanofi ($SNY) subsidiary BiPar Sciences faced a setback last year when its PARP inhibitor drug iniparib failed a Phase III trial for metastatic breast cancer. The company is exploring whether some patients can still benefit from the treatment in certain situations. AstraZeneca ($AZN) has also struggled with its drug olaparib.

Still, PARP, or poly ADP Ribose polymerase inhibitors, are considered pretty compelling because a number of cancers depend on PARP to grow. The drugs are designed to stop cancer cell enzymes from being able to repair radiation- and chemotherapy-related DNA damage. But for ovarian cancer patients, they're only being tested on those who have BRCA 1 or BRCA 2 malfunctioning proteins.

Lead study author Tanja Pejovic, a gynecologic oncologist at the institute, and others evaluated 186 patients with nonhereditary cancer. They found 41% of patients who saw the ovarian cancer recur had abnormal levels of the BRCA 1 or 2 mutations, as well as unusual levels of other proteins typically tracked. But 19.5% of patients whose cancer hadn't yet returned in three years had the same abnormal protein levels. Researchers focused on proteins in the body that are ordinarily supposed to aid in homologous recombination, a process that helps repair harmful breaks in DNA strands. These proteins are also thought to affect how long a patient survives after therapy, along with her response to the overall drug treatment.

- here's the release
- read the study

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