Feb. 12, 2004 -- The FDA approved Erbitux, the very drug at the heart of the Martha Stewart stock-sale controversy. This first-of-its-kind treatment is for colon cancer that has spread to other parts of the body.
Erbitux is a unique type of treatment called a monoclonal antibody and is the first such treatment for colon cancer. Antibodies are the body's natural defense against foreign substances, such as infection or cancer cells. Monoclonal antibodies are produced in a laboratory to target a very specific portion of foreign substances. Because of their precision, ideally treatment is more effective and has fewer side effects.
The FDA has approved Erbitux to treat colon cancer in combination with another colon cancer drug irinotecan, or alone if patients cannot tolerate irinotecan. Erbitux is shot into a vein.
Although treatment with Erbitux has not been shown to extend patients' lives in clinical trials, it was shown to shrink tumors in some patients and delay tumor growth, especially when used as a combination treatment.
Researchers say Erbitux works by targeting a natural protein called "epidermal growth factor receptor" (EGFR) on the surface of cancer cells, interfering with their growth.
"Erbitux is the second drug approved by the FDA that targets EGFR. The first was Iressa, approved last year for lung cancer," medical oncologist Harold Burstein, MD, PhD, tells WebMD. Burstein is a specialist on WebMD's Cancer Treatments and Advances message board and oncologist at the Breast Oncology Center at Dana-Farber Cancer Institute in Boston.
The drug has been tested in patients with tumors that contain EGFR and who failed treatment with irinotecan or other chemotherapy drugs. The combination treatment of Erbitux and irinotecan shrank tumors in 23% of patients and delayed tumor growth by approximately four months. For patients who received Erbitux alone, the tumor shrank in 11% and tumor growth was delayed by 1 1/2 months.
"While it is not clear if Erbitux helps patients live longer or better, it can shrink tumors in some patients," says Burstein.
"What is quite exciting is to see how the field of colorectal cancer treatment has evolved in recent years that clearly can provide benefit to patients. Now we need to figure out how best to use these many drugs -- alone, in combination, in sequence, and in whom. Those are good challenges to have."
The FDA first evaluated Erbitux in December 2001 after its manufacturer ImClone submitted an application for approval. The FDA rejected Erbitux in December 2001, saying that important safety and effectiveness data were missing. Prosecutors say Martha Stewart lied about unloading her ImClone shares at that time after she received inside information and then tried to obstruct an investigation.
In their new request for approval, Imclone submitted the results of a large, well-run trial that included 329 patients as well as the results of the earlier two studies. For the studies submitted in their original 2001 request for approval, ImClone successfully collected substantial amounts of missing information from hospital records and other sources.
"The FDA staff work hard to ensure doctors and patients can have confidence in the safety and effectiveness of new therapies such as Erbitux," says Mark B. McClellan, MD, PhD, in a news release. "FDA believes it is crucial for cancer patients to have many proven treatment options in their battle against this disease."
Two studies involving approximately 2,000 patients are currently underway to assess the clinical benefits of Erbitux. These studies are specifically examining the ability of Erbitux to stop the progression of colon cancer and to extend the amount of time patients survive with the disease.
Erbitux can cause serious side effects, usually during the administration of the first treatment, which may include difficulty breathing and low blood pressure. Rarely, a condition known as interstitial lung disease (ILD) has been reported; however, it is difficult to determine if Erbitux caused ILD, the FDA says. ILD occurs when the lung becomes stiff because of scarring of the tissue between the air sacs of the lungs.
Other more common side effects of Erbitux treatment are:
Colon cancer is the third most common cancer affecting men and women in the U.S., according to the CDC, and is the second leading cause of cancer-related death. Colorectal cancer is also one of the most commonly diagnosed cancers in the U.S.; approximately 147,500 new cases were diagnosed in 2003.