FDA Approves New Colon Cancer Drug
Vectibix Follows Chemotherapy for Colorectal Cancer That Has Spread
Sept. 27, 2006 -- The FDA today approved a new drug called Vectibix to help
treat colorectal cancer that has spread to other parts of the body.
Vectibix is to be given by IV following standard chemotherapy treatment.
The FDA put Vectibix on its fast track for approval after the drug showed
effectiveness in slowing tumor growth, and, in some cases, reducing tumor
According to the FDA, an estimated 150,000 new cases of colon cancerwill be
diagnosed and 55,000 deaths will occur from colorectal cancer in 2006.
"Colorectal cancer is the third most common cancer and the third leading
cause of cancer mortality in the United States," says Steven Galson, MD,
MPH, in an FDA news release.
Galson directs the FDA's Center for Drug Evaluation and Research.
"This approval adds a treatment option for patients with an advanced
stage of a disease that can be life-threatening," Galson says.
About the Drug
Vectibix is a monoclonal antibody.
Antibodies are the body's natural defense against foreign substances, such
as infection or cancer cells. Monoclonal antibodies are made in a lab to target
a very specific portion of foreign substances.
Vectibix binds to a protein called epidermal growth factor receptor (EGFR),
which is found in about 70% of all colorectal cancers, according to the
Vectibix isn't the first monoclonal antibody for colorectal cancer. Another
monoclonal antibody, Erbitux, also targets EGFR in colorectal cancer.
A third monoclonal antibody, Avastin, also treats colorectal cancer. It's
believed to target a different growth factor (vascular endothelial growth
factor, or VEGF).
Erbitux was approved by the FDA on Feb. 12, 2004. The FDA approved Avastin
two weeks later.
The FDA approved Vectibix based on the results of clinical trials that
included 463 patients in Europe with metastatic colorectal cancer.
The patients had already gotten chemotherapy using three chemotherapy drugs.
Afterwards, they all got "best supportive care."
Half of the patients also got Vectibix as soon as the trial began. The rest
were allowed to take Vectibix if their tumor worsened.
On average, patients taking Vectibix lived 96 days before they died of their
before their cancer worsened, compared with 60 days for those who originally
just got best supportive care.
Overall survival was similar for both groups during the 48-week study.
"Almost everyone had progressed by 48 weeks," J. Randolph Hecht, MD,
tells WebMD. By "progressed," he means their tumors had worsened.
"But at eight weeks, the first look, 70% of the people had progressed on
best supportive care, while only 51% had progressed [with] Vectibix," Hecht
says. "That 20% or so difference persisted for awhile. By the time you get
to 32 weeks it was not a big difference."
Hecht has conducted U.S. studies of Vectibix, but he wasn't involved in the
European trial. He directs the gastrointestinal oncology program at the
University of California, Los Angeles.
In addition, tumors shrank in 8% of the patients taking Vectibix. In some
cases, those tumors shrank to less than half of their pretreatment size.
"At every time point that you looked at, if you were in the Vectibix arm
you were much less likely to have your tumor progress than if you were on the
best supportive care arm," Hecht says.
"That's another way of looking at that," says Hecht.