Drug Combo Extends Colon Cancer Survival
Avastin plus three other agents effective against advanced disease
THURSDAY, Jan. 27, 2005 (HealthDayNews) -- The results of a multi-center trial involving a quartet of drugs may bring fresh hope to patients battling advanced colorectal cancer, researchers reported Thursday.
Adding Avastin -- a drug that starves tumors of their blood supply -- to an already proven regimen of three other medications extended the lives of patients in a Phase III clinical trial by 17 percent. That is powerful news because additional research reported Thursday confirmed that the three-drug regimen continues to be successful in beating back cancer with diminishing side effects over time.
The addition of Avastin "is another tool in the arsenal," said Dr. Bruce J. Giantonio, a cancer researcher at the Abramson Cancer Center of the University of Pennsylvania in Philadelphia. "It really argues in support of using this drug with chemotherapy in patients with metastatic colorectal cancer."
Giantonio announced the results of the ongoing trial at a press conference held as part of the 2005 Gastrointestinal Cancers Symposium in Hollywood, Fla.
Cancers of the colon and rectum are the third leading cancer killer of both men and women in the United States, claiming more than 55,000 lives each year, according to the American Cancer Society. While colon cancer can be beaten if detected early, it's much harder to treat if caught late, especially if it has spread to other body sites.
The four-drug combo builds on the success of a special three-drug combo, called the FOLFOX4 regimen, which recently was found to be effective in extending patient survival. Another study presented Thursday at the conference confirmed that the three-drug regimen -- oxaliplatin, leucovorin, and fluorouracil -- kept more than 84 percent of patients diagnosed with stage II or III cancers alive four years after the onset of treatment.
"We were concerned, however, about cumulative neuropathy [nerve damage] due to oxaliplatin," said FOLFOX4 study lead researcher Dr. Aimery de Gramont, of Saint-Antoine Hospital in Paris.
But long-term results of trials with 2,246 colorectal cancer patients suggest that "after just a year of follow-up, most patients have recovered from this neuropathy," de Gramont added, with only a small percentage of patients experiencing functional impairment linked to the chemotherapy regimen.
Noting the continued success of the FOLFOX4 trial, Giantonio's team of researchers had wondered if adding a fourth drug, the angiogenesis inhibitor Avastin (bevacizumab), might improve outcomes even more.
Drugs like Avastin, which was approved by the Food and Drug Administration in February 2004 for colorectal cancer that had spread, work by interrupting angiogenesis -- the growth of new blood vessels that tumors need to survive.
"Avastin binds to a molecule called vascular endothelial growth factor (VEGF), which is a very potent mediator of angiogenesis," Giantonio explained. "It may have other [anti-cancer] pathways, too."
Giantonio's study involved almost 600 patients with advanced-stage colorectal cancer who had previously been treated with other forms of chemotherapy. The researchers had half the patients take FOLFOX4 alone, while the other half received FOLFOX4 in combination with Avastin, for a period of more than two years.
The Avastin/FOLFOX4 group experienced a median survival 17 percent greater than the FOLFOX4 group, Giantonio said.
Certain side effects, especially the nerve damage seen in de Gramont's trial, also appeared in patients taking the Avastin/FOLFOX4 combo, Giantonio said. However, he remains optimistic that this neuropathy will recede in most patients as treatment continues.
The Philadelphia researcher is hopeful median survival will increase as the trial goes on, too.
"Right now, moving from one-year to two-year survival is a very real possibility," he said.
The American Cancer Society has more on the detection and treatment of colorectal cancer.