For women with advanced cases of ovarian cancer, the drug Avastin adds about four months to the time it takes for the cancer to worsen, according to a new report.
Patients treated with Avastin in addition to chemotherapy had about 14 months before their advanced ovarian cancer progressed, compared to about 10 months for those in the study who were treated with chemotherapy and a placebo.
An early analysis of the trial's results was presented in June 2010 at the meeting of the American Society of Clinical Oncology; the complete report from the trial appears today (Dec. 28) in the New England Journal of Medicine.
This was the third clinical trial to show that adding Avastin to standard chemotherapy treatments extends the time before ovarian cancers progress, said Dr. Carol Aghajanian, chief of gynecologic medical oncology service at Memorial Sloan-Kettering Cancer Center in New York City.
"This is good news for women with ovarian cancer," said Aghajanian, who was not involved in the new study.
However, women treated with Avastin did not live any longer than other women in the study, according to the report.
The European Commission approved Avastin as a treatment for ovarian cancer this month, but it is unclear whether the drug will be approved to treat this cancer in the United States, Aghajanian said.
The drug, made by pharmaceutical company Genentech, is designed to inhibit the growth of blood vessels that feed a tumor. It is currently approved to treat certain types of colon, lung, kidney and brain cancers, while the FDA recently disallowed its use for breast cancer.
Preventing cancer from worsening
The new report is based on 1,873 ovarian cancer patients who had been assigned at random to three groups. One received chemotherapy treatments along with a placebo; one received Avastin (generically known as bevacizumab) along with chemotherapy at the start of their treatment, then received only chemotherapy for the rest of their treatment; the third group received Avastin along with chemotherapy for the entirety of their treatment. The patients did not know which treatment they were receiving; neither did the doctors treating them.
The researchers measured the blood levels of a marker called CA-125 to determine whether the patients' cancers were progressing. CA-125 levels are a very early marker of worsening cancer, Aghajanian said. Levels of CA-125 begin to rise before a growing cancer is visible on a CT scan.
"They used a very conservative method of measuring progression, so we can be certain that it's meaningful," Aghajanian said.
Whether Avastin could extend patients' lives is a tricky question to try to answer with studies, Aghajanian said. At the end of this trial, for example, the patients and their doctors were told whether they had received Avastin or the placebo treatment, and it was entirely possible that those who had been on the placebo then received Avastin, she explained. Such a crossover in treatments after a study's conclusion would make it difficult to later determine whether patients who received a drug during a trial lived longer.
Avastin and breast cancer
There are important differences between the studies of Avastin as a treatment for breast cancer and the studies of its use for ovarian cancer, Aghajanian said.
In November the FDA revoked its approval of Avastin to treat breast cancer because studies showed that breast cancer patients treated with it did not live any longer, and faced significant risks of severe side effects such as small holes developing in the intestines. The drug had been cleared by the FDA in February 2008 under an "accelerated approval" process based on promising early studies, allowing Avastin to be used for breast cancer patients while Genentech did further research.
"There was not a consistent benefit seen in the breast cancer studies," Aghajanian said. By contrast, three studies of the drug's use in ovarian cancer showed a consistent benefit.
The safety of the drug as seen in the new study "was reassuring," Aghajanian said, as was the finding that patients taking the drug reported no difference in their quality of life from patients receiving the placebo.
The rate of patients who developed gastrointestinal perforations was twice as high among those who received Avastin as among those who received a placebo, but the rate was still under 3 percent.
Elevated blood pressure was seen in more patients who received Avastin throughout the study than in those who received the drug only at the beginning or not at all.
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