Longer Survival With Colorectal Cancer Drugs
Some Patients Living Longer, but Jury Is Still Out on Effectiveness
June 2, 2004 -- Findings from the largest studies to date of two new colorectal cancer treatments are encouraging, but more research is needed to understand how these therapies can best be used, experts tell WebMD.
The studies involved the cancer fighting medicine Eloxatin, approved in 2002, and Avastin -- a monoclonal antibody designed to starve tumors of their blood supply. Both drugs appear to improve survival time -- free of cancer -- in patients with colorectal cancer when added to standard treatments. Both studies are reported in the June 3 issue of The New England Journal of Medicine.
"The bottom line is that for the first time in decades we have new treatments for colorectal cancer and people are living longer," Robert Mayer, MD, of the Dana-Farber Cancer Institute in Boston, tells WebMD. "The challenge for those of us who treat this disease is to keep doing the research needed to find the most effective ways to use these drugs."
In the multicenter Avastin trial, paid for by manufacturer Genentech and first reported at a major cancer conference a year ago, roughly 800 patients with advanced colorectal cancer were treated with either the standard chemotherapy or standard chemotherapy and Avastin.
The average survival time for the patients treated with standard chemotherapy alone was 15.6 months, compared with 20.3 months for those also treated with Avastin.
Avastin is the first member of a class of drugs that is said to work by preventing the formation of new blood vessels needed for tumor growth. The hope is that these therapies, known as angiogenesis inhibitors, will one day be used in the treatment of a wide range of cancers.
While Mayer called the Avastin trial "extremely encouraging," he explains that there is, as yet, no direct proof that the drug works by shutting off a tumor's blood supply.
"Much has been written about (Avastin) in the pages of financial and mass-media publications because of its perceived unique mechanism of activity," Mayer wrote in an editorial accompanying the two studies.
"Such publicity has led to unrealistically high expectations. Patients need to be informed that (Avastin) does not cure metastatic colorectal cancer and that there is no evidence as yet that the antibody has antitumor activity when administered as a single agent for this disease."
He also noted that the survival advantage comes at a steep price: The cost for 10 months of therapy can top $50,000.
But study co-author Fairooz Kabbinavar, MD, of the UCLA Jonsson Cancer Center, tells WebMD that many of his patients with advanced cancer have lived much longer than a few extra months after beginning treatment with Avastin. He says one of his patients is still alive after six years.
"There is definitely promise for long-term survival with this drug," he says. "In cancer therapy improving survival time without increasing toxicity is the Holy Grail, and this drug seems to have achieved both."
American Cancer Society colorectal cancer spokesman Len Lichenfeld, MD, says studies are needed to determine if Avastin can benefit patients with less advanced disease.