SATURDAY, June 1 (HealthDay News) -- Women with advanced ovarian cancer stayed in remission almost six months longer when they were treated with the targeted drug pazopanib (Votrient), new German research says.
"Our findings show that we finally have a drug that can maintain control over ovarian cancer growth achieved through initial treatments," study author Dr. Andreas du Bois, a professor of gynecologic oncology at Kliniken Essen-Mitte in Essen, said in a statement. "If pazopanib is approved for ovarian cancer, many patients will experience longer disease-free and chemotherapy-free periods. During this time, the patient keeps control over the disease, instead of the disease having control over patient's life."
The results were to be presented Saturday at the American Society of Clinical Oncology annual meeting, in Chicago. Research presented at medical meetings is considered preliminary until published in a peer-reviewed journal.
However, other cancer experts warned against placing too much hope in these early findings.
"I would say that it is intriguing, but I think it's important for the public to know this is not a home run," said Dr. Karen Lu, a professor of gynecologic oncology at the University of Texas MD Anderson Cancer Center, in Houston. "This is an incremental step in the right direction. There did not seem to be a survival advantage. It does increase by 5.6 months, on average, the amount of time a woman does not need to be on chemotherapy, but in terms of prolonging survival or increasing the rate of cure, it doesn't reach that standard."
Advanced ovarian cancer is an aggressive disease with a cure rate of only 20 percent to 25 percent, according to background information in the study. It is often referred to as a "silent killer" because it usually is not detected until it has progressed into its later stages. Two of every three patients with advanced ovarian cancer experience a relapse following successful initial treatment with surgery and chemotherapy.
"Ovarian cancer is a difficult disease to treat," explained Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society. "We don't have effective screening, and women present with more advanced disease."
No targeted therapies are currently approved in the United States for maintenance treatment of ovarian cancer, although bevacizumab (Avastin) is registered for use alongside traditional chemotherapy.
Pazopanib, which is taken in pill form, works by blocking the growth of tumors and their blood vessels. The U.S. Food and Drug Administration has already approved its use for the treatment of kidney cancer and soft tissue sarcoma. The drug's maker, GlaxoSmithKline, funded this latest research.
In the study, 940 patients with stage III or IV ovarian cancer received either pazopanib or a placebo daily for 24 months. All patients already had gone through surgery and chemotherapy that successfully prevented the disease from worsening.
Researchers found that the pazopanib group experienced a median 17.9 months before their cancer symptoms returned, compared with 12.3 months for patients taking the placebo.
There are drawbacks. For one, Votrient is a costly drug. Online pharmacies charge around $1,900 for 30 200-milligram tablets of the medication.
Also, one of every four ovarian cancer patients taking pazopanib reported unpleasant side effects, including hypertension, diarrhea, nausea, headache and fatigue.
"If they were having horrible diarrhea or nausea while they were on it, that five months will look a lot less attractive than if there were minimal side effects," Lu noted.
Lichtenfeld said more research is needed to determine if maintenance treatment with pazopanib will improve overall survival. Researchers also need to look into whether using pazopanib alongside chemotherapy will produce even better results.
"We just don't know if this is going to translate into a meaningful improvement of survival for these women," he said. "We really have to be cautious in determining where that new treatment fits in the overall care for these women. This may be very exciting, but we need more time and analysis to see how this fits in the treatment protocols we would use for women treated in more routine settings than a clinical trial."
Research also needs to determine whether there are certain types of patients who would respond more favorably to pazopanib, Lu added.
"Can we identify a subgroup of patients who will have a good response and will have a prolonged period where they can be off of chemotherapy?" she said. "For all biologic agents, that's an important area of research, to identify markers that will tell us which patients will have that benefit."
For more on ovarian cancer, go to the U.S. National Cancer Institute.
SOURCES: Karen Lu, M.D., professor, gynecologic oncology, University of Texas MD Anderson Cancer Center, Houston; Len Lichtenfeld, M.D., deputy chief medical officer, American Cancer Society; June 1, 2013, presentation, American Society of Clinical Oncology annual meeting, Chicago