SUNDAY, Aug. 21, 2011 (HealthDay News) -- An experimental drug that's shown promise against ovarian cancer caused by mutations in the BRCA1 or BRCA2 genes may also be effective against ovarian cancer not caused by those gene mutations, according to a new study.
Olaparib blocks the activity of a protein called poly ADP ribose polymerase (PARP). Both PARP and BRCA proteins are involved in DNA repair. Clinical trials of olaparib in patients with BRCA 1 and 2 mutations have yielded promising results, the study authors noted.
In the new study, Canadian researchers say they're the first to show that olaparib reduces tumor size in patients with non-hereditary (sporadic) ovarian cancer, which is much more common than BRCA-mutated ovarian cancers.
The phase 2 trial included 65 ovarian cancer patients who received 400 milligrams of olaparib twice daily for four weeks. Measurable tumor shrinkage was seen in 41 percent of patients with BRCA mutations and in 24 percent of those without BRCA mutations, the researchers said.
The study was published online Aug. 21 in The Lancet Oncology.
Side effects were described as mild and included fatigue, nausea, vomiting and decreased appetite, study lead author Karen Gelmon, of the B.C. Cancer Agency in Vancouver, and colleagues said in a news release from the journal.
"This finding not only suggests new therapeutic possibilities for women with this aggressive type of ovarian cancer, but also importantly confirms the hypothesis that subpopulations of patients with common sporadic tumors can be targeted effectively with PARP inhibitor therapy," Dr. Melinda Telli, of Stanford University School of Medicine, wrote in an accompanying editorial.
Another expert agreed. Dr. Stephanie V. Blank is an assistant professor in clinical gynecologic oncology at NYU School of Medicine. She said: "It is extremely exciting that an agent as promising as olaparib can be effective in a broader group of women than had been expected. The next challenge will lie in getting our hands on the drug, which at present is only available for patients on clinical trials."
The American Cancer Society outlines the risk factors for ovarian cancer.