The drugs block the action of a substance released by tumors called vascular endothelial growth factor, or VEGF. VEGF binds to certain cells to stimulate new blood vessel formation.
“They work by curbing the growth of new blood vessels to tumors,” thereby depriving them of the nutrient-rich blood they need to grow, he tells WebMD.
Bajorin moderated a news conference at which the new research was discussed here at the annual meeting of the American Society of Clinical Oncology.
Avastin Fights Kidney Cancer
The study included 649 people who had surgery to remove their tumors. Those who took Avastin in addition to standard interferon treatment remained alive without worsening of their disease nearly twice as long as those given interferon alone.
“Adding Avastin resulted in a striking improvement” in the time it started for the cancer to grow, slowing it from 5.4 months to 10.2 months, says researcher Bernard Escudier, MD, head of the immunotherapy unit at the Gustave Roussy Institute in Villejuif, France.
Also, tumors shrank or stopped growing in 31% of patients taking Avastin vs. 12% of those on interferon alone.
The most common side effects were fatigue and weakness.
Avastin was the first of the new kind of cancer therapies that work by cutting off the blood to a tumor from the growth of new blood vessels -- a process called angiogenesis.
Experimental Agent Combats Thyroid Tumors
In a second study, tumors shrank or stopped growing in nearly three-fourths of people with advanced thyroid cancer given the experimental anti-angiogenesis drug axitinib.
The study included 60 people given an axitinib pill twice a day. More than 18 months after the study began, nearly two-thirds of them are still alive without evidence of progressive disease, says researcher Ezra Cohen, MD, assistant professor of medicine at the University of Chicago.
Though there was no comparison group in the study, “the natural history of the disease is such that a far greater percentage would have progressed had they not been given axitinib,” Cohen says.
Cohen says standard treatment for the 30,000 Americans who develop thyroid cancer is surgery or radiation therapy. Though this cures a large percentage of patients, there are few options for those who do not respond, he tells WebMD.
“Axitinib and other VEGF inhibitors represent an exciting new front in the treatment of advanced thyroid cancer,” he says. “As recently as three years ago we had very little to offer these patients, and now we’re seeing response rates at a level we’ve never seen with chemotherapy.”
Anti-Angiogenesis Drug Fights Ovarian Cancer
A third study looked at women with advanced ovarian cancer that had returned and was resistant to the traditional chemotherapy drugs used to treat it. All the women were given the experimental anti-angiogenesis drug VEGF-Trap.
Researcher William P. Tew, MD, an assistant attending physician in the department of medicine at Memorial Sloan-Kettering Cancer Center, tells WebMD that anti-angiogenesis drugs can be particularly helpful in ovarian cancer because it is highly dependent on blood vessel growth in order to spread.
Preliminary results in the first 162 women show that tumors shrank in 8% of them, and tumors stopped growing for at least one month in 85% of the women. Thirty weeks into the study, 4% of women still show no signs of tumor growth.
While that might not sound like much, Bajorin notes that there is no approved treatment option for these patients.
Additionally, the drug relieved excess fluid in the space between the tissues lining the abdomen and abdominal organs. This is a huge problem in advanced ovarian cancer, which occurs in nearly one-third of women.
“We’re looking at women who have failed all known therapies and provided a drug that is well tolerated and improves their quality of life,” he tells WebMD.
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