May 12, 2001 (San Francisco) -- A new type of cancer drug, one that doesn't kill the tumor cells but instead attacks the ability of cells to grow and multiply, is offering new treatment options for patients who ran out of options using traditional treatment.
For example, when 121 patients with colorectal cancer that didn't respond to standard chemotherapy were given one of these new drugs in combination with a standard chemotherapy agent, "22.5% of them had a major response," says cancer researcher Leonard Saltz, MD.
"This doesn't mean we have a cure," says Saltz. But he tells WebMD that the new findings "mean we have a new weapon, and now we have to figure out how to use it." Saltz presented findings from the colorectal cancer patient study at the American Society of Clinical Oncologists meeting here on Saturday.
The "weapon" is an experimental, genetically engineered drug called IMC-C225 or cetuximab, which is a monoclonal antibody that hones in on a receptor on the surface of the cancer cell. This receptor tells the cell when to grow or multiply. Blocking this receptor weakens the cell and makes it more susceptible to attack by chemotherapy drugs, which are designed to kill cells.
Tumors shrank by at least 50% in 27 patients who were treated with cetuximab and the standard chemotherapy agent, irinotecan, also called CPT-11, says Saltz. In seven other patients the disease stabilized. "Remember, these were all patients who had not only failed therapy but in whom the disease was progressing."
Saltz tells WebMD that this same drug may also prove effective in pancreatic cancer or head and neck cancer. Any cancer cell that tests positive for the epidermal growth factor receptor is a potential target for cetuximab, he says.
Frank G. Haluska, MD, PhD, assistant professor of medicine at Harvard Medical School, tells WebMD that the patients in Saltz' study had the most difficult type of colorectal cancer. "These patients already failed treatment with both of the traditional chemotherapy drugs," he says. "This is really treatment for resistant disease."
Haluska likens this type of colorectal cancer to dandelions. "If you have dandelions in your lawn and you treat the lawn with a weed killer, you kill about 90% of the dandelions. The ones that are left are resistant," he says. "Next spring, the whole lawn is filled with dandelions again, but these dandelions are all resistant to the weed killer because they are the offspring of last year's resistant dandelions, that's the way it is with these cancers."
So the fact that there was a response when the patients were given cetuximab "is very exciting." Haluska says the drug may have an even greater effect if it was given earlier in treatment "before the patients have developed resistant cancers."
Saltz says he has started a new study that tests the drug as a first-line treatment for colorectal cancer. Patients will be given irinotecan and cetuximab.
Saltz says that ImClone Systems Inc. of New York, the manufacturer of the drug, plans to submit the drug for FDA approval next month. He says the drug is scheduled for "fast-track review", which is the same process that the FDA used in approving Gleevec last week. That drug, approved to treat a type of leukemia, set a new record for FDA approval.