New monoclonal option for metastatic colorectal cancer

November 6, 2006

A diagnosis of metastatic colorectal cancer is not one that a patient wants to hear. It has historically been one of the most difficult cancers to treat, associated with mediocre responses and short survival periods. According to 2006 estimates from the American Cancer Society, colorectal cancer is now the second- and third-leading cause of cancer deaths in men and women, respectively, in the United States. Now a new treatment option is available for patients with metastatic cases that are refractory or intolerant to traditional agents. Enter panitumumab (Vectibix, Amgen).

"Vectibix is a monoclonal antibody against epidermal growth factor receptor [EGFR], a receptor that is overexpressed in many cancers, including colon cancer," said Patrick J. Medina, Pharm.D., BCOP, associate professor at the University of Oklahoma College of Pharmacy. "Overexpression of EGFR results in an increase in tumor cell proliferation and a survival advantage for the tumor cells. Vectibix is the first entirely human antibody that competitively binds to EGFR and prevents the receptor from activating these signals that lead to tumor proliferation," he continued.

Not everyone will be a candidate for the new therapy, however. To assess the eligibility for treatment and potential for response, patients could use Dako's EGFR pharmDX, a diagnostic test that detects EGFR protein expression. The test was previously approved by the Food & Drug Administration for use in conjunction with cetuximab (Erbitux, Imclone/Bristol-Myers Squibb) to test for evidence of EGFR expression prior to treatment in colorectal cancer patients.

According to Amgen, panitumumab will be priced 20% lower than other anti-EGFR therapies currently on the market. To aid in the cost to patients who are uninsured or underinsured, the company has developed the Amgen Oncology Assistance program, which will provide a cap on out-of-pocket expenses. For more information, pharmacists can visit the Amgen Web site at http://www.amgen.com/.

"The survival of metastatic colon cancer has increased dramatically over the past 10 years, requiring additional effective agents to prolong the survival of these patients while not adversely affecting their quality of life. Vectibix is a well-tolerated and effective medication that will provide clinicians another choice in treating this devastating disease," Medina concluded.

TIPS TO REMEMBER Vectibix