Cancer drug Avastin reduces progression of ovarian cancer, and perhaps death rate
The widely used cancer drug Avastin may benefit women with ovarian cancer, both those who are newly diagnosed and those in whom the disease has recurred after initial treatment, researchers reported Saturday at a Chicago meeting of the American Society of Clinical Oncology. For ovarian cancers treated early in the course of the disease, the drug reduced the risk of death. For recurrent cancers, the drug delayed progression but the improvement in survival did not quite reach statistical significance, researchers said.
Avastin, known generically as bevacizumab, is one of the most widely used cancer drugs, with annual sales worldwide of about $7 billion. The drug blocks the formation of new blood vessels that support a growing tumor, starving it of nutrients. It is currently approved for the treatment of colorectal, brain, lung, kidney and breast cancers. The Food and Drug Administration has moved to withdraw approval for breast cancer, however, because several clinical trials have shown that the drug does not reduce the risk of death, even though it delays progression of the disease.
Ovarian tumors are an unusually lethal form of cancer because they are not usually detected until they are well advanced, which makes treatment difficult. Conventional treatment involves a combination of the drugs carboplatin and paclitaxel.
About 21,880 American women are diagnosed witih ovarian cancer each year, according to the American Cancer Society, and about 13,850 die from it.
In the first study, Dr. Gunnar Kristensen of the Norwegian Radium Hospital in Oslo and his colleagues studied 1,528 women with newly diagnosed advanced ovarian cancer. Half were given six cycles of conventional treatment with carboplatin and paclitaxel and half were given the same therapy plus Avastin, and then Avastin alone for a total of 12 months. After a median follow-up of 28 months, 178 of the women in the Avastin group had died, compared with 200 in the conventional therapy group. That 15% reduction was not statistically significant, however. But in a subgroup of patients with the highest risk of recurrence, there was a 36% reduction in risk of death -- 79 deaths in the Avastin group compared with 109 in the standard therapy group. That reduction was statistically significant. Kristensen predicted that, for the entire group of women, the survival benefit is likely to become statistically significant as the women are followed for a longer period of time.
In a second study, Dr. Carol Aghajanian of the Memorial Sloan-Kettering Cancer Center in New York and her colleagues studied 488 patients who had a recurrence of ovarian cancer following an initial successful treatment. As in the other study, half received Avastin plus conventional therapy and half received only conventional therapy. Aghajanian reported that, over a follow-up period of 24 months, women receiving Avastin went a median of 12.4 months before their disease began worsening, while those receiving only conventional therapy went only 8.4 months -- a 52% improvement. The number of women who survived at 24 months was slightly higher in the Avastin group, but the imrpovement was not statistically significant.
Side effects in the two studies were similar to those observed in clinical trials for other forms of cancer, and were not deemed sufficient to prevent women from taking the drug. But one factor that might is the cost. The drug is quite expensive: a complete course of therpay could run as high as $88,000.