Olaparib Delays Progression of Ovarian Cancer after Initial TreatmentLong-term therapy with the targeted drug olaparib significantly improved progression-free survival among women with the most common type of ovarian cancer in a randomized, placebo-controlled phase II clinical trial. The interim findings were published online March 27 in the New England Journal of Medicine.
The trial included 265 women with relapsed, high-grade serous ovarian cancer who had responded to previous treatment with platinum-based chemotherapy. Patients were randomly assigned to receive either olaparib, a drug that blocks a DNA-repair protein called PARP, or a placebo.
Women who received olaparib experienced a median progression-free survival of 8.4 months, compared with 4.8 months for those who received the placebo. Patients in the olaparib group had a lower risk of disease progression after researchers took into account factors including BRCA gene mutation status, age, ancestry, and previous time to progression. Side effects were more common among women who received olaparib, but most of these were mild to moderate; few patients stopped therapy because of side effects.
The improvement in progression-free survival did not lead to improved overall survival. In an interim analysis, overall survival was virtually identical between the olaparib and placebo groups, at 29.7 months and 29.9 months, respectively.
Ovarian cancer usually responds to platinum-based combination chemotherapy, and if the disease returns, it may respond again to another platinum-based chemotherapy regimen. However, responses to subsequent courses of chemotherapy tend to be short-lived, explained the authors, who were led by Dr. Jonathan Ledermann of the University College London Cancer Institute.
This trial is one of several recent studies investigating whether maintenance therapy can help improve control of ovarian cancer. Researchers have found that maintenance therapy with either extended chemotherapy or the targeted agent bevacizumab may help delay cancer recurrence. Olaparib was recently found to induce tumor responses in women with recurrent, high-grade serous ovarian cancer or ovarian cancer associated with a BRCA1 or BRCA2 mutation.
The results from the current study show that “maintenance treatment with olaparib [is] associated with a significant improvement in progression-free survival among patients with platinum-sensitive, relapsed, high-grade serous ovarian cancer,” the authors wrote. Furthermore, the authors noted that 21 percent of patients were still receiving the drug at the time of writing, which “indicates that the disease is controlled for a prolonged period in some patients,” they concluded.
“This is an important gain for ovarian cancer patients,” commented Dr. Elise Kohn of NCI’s Center for Cancer Research. “The doubling in time to progression with olaparib is an exciting observation and should be the stimulus for further olaparib-based studies.”
See also: “Drug that Inhibits DNA-Repair Enzyme Shrinks Some Breast and Ovarian Tumors”