In a phase II clinical trial, olaparib (a type of targeted therapy known as a PARP inhibitor) delayed cancer progression—but did not improve overall survival—when given after chemotherapy to women with relapsed, platinum-sensitive, serous ovarian cancer. These results were published in the New England Journal of Medicine.
Ovarian cancer has the highest mortality rate of all gynecologic cancers. It is the fifth leading cause of cancer death among U.S. women, with roughly 22,000 new cases and 15,000 deaths predicted for 2012.
Targeted therapies are anticancer drugs that interfere with specific pathways involved in cancer cell growth or survival. Some targeted therapies block growth signals from reaching cancer cells, others reduce the blood supply to cancer cells, and still others stimulate the immune system to recognize and attack the cancer cell. Depending on the specific “target,” targeted therapies may slow cancer cell growth or increase cancer cell death.
Olaparib is an investigational targeted drug called a PARP inhibitor. The PARP enzyme plays a role in DNA repair, including the repair of DNA damage from chemotherapy. Drugs that inhibit this enzyme may contribute to cancer cell death and increased sensitivity to chemotherapy. Cancers that have a DNA repair deficiency are thought to be particularly likely to respond to PARP inhibitors, and up to half of high-grade serous ovarian cancers may fall into this category.
To assess the safety and efficacy of olaparib in ovarian cancer, researchers conducted a Phase II clinical trial of 265 women with relapsed, platinum-sensitive, serous ovarian cancer. After treatment with chemotherapy, women were assigned to further treatment (maintenance therapy) with either olaparib or a placebo.
- Women in the olaparib group remained free of cancer progression longer than women in the placebo group: median progression-free survival was 8.4 months in the olaparib group and 4.8 months in the placebo group.
- Although it’s still too early for the final analysis of overall survival, overall survival at the time of this interim analysis was similar in the two study groups.
- Side effects that were more common in the olaparib group included nausea, fatigue, vomiting, and anemia.
The results of this study suggest that olaparib is active against relapsed, platinum-sensitive, serous ovarian cancer. Olaparib delayed cancer progression, but still has not been shown to improve overall survival. Results based on longer follow-up will provide better information about whether olaparib affects overall survival.
Reference: Ledermann J, Harter P, Gourley C et al. Olaparib maintenance therapy in platinum-sensitive relapsed ovarian cancer. New England Journal of Medicine. Early online publication March 27, 2012.
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