Friday, November 21, 1997
Researchers discover new drug to treat cancer
CANCER: Heartburn is associated with rare type of upper-stomach
tumors
By Kathryn Combs
Daily Bruin Staff
For the first time anywhere, researchers at UCLA are using an
experimental drug to treat a rare type of cancer associated with
heartburn.
Adenocarcinoma, a type of cancer, affects the lower portion of
the esophagus and the upper stomach. It occurs most often in
middle-aged and older white males.
Currently, only a few patients have been given the drug, called
CPT-11. In order to determine the efficacy of CPT-11, researchers
will test approximately 30 patients.
"There are only about 5,000 cases (of this cancer, while) tens
of millions of Americans have heartburn," said Dr. Randolph Hecht,
a member of UCLA’s Jonsson Comprehensive Cancer Center.
"It’s not the most common cancer. (However) it is the most
rapidly increasing cancer in the United States," he said.
Ten years ago, adenocarcinoma accounted for less than 5 percent
of esophageal cancer. Today, it accounts for 50 percent, Hecht
said.
CPT-11 has been used in the past to treat both colon and stomach
cancer.
In fact, CPT-11, also known as irinotecan, is the first new drug
to be approved by the FDA in the last 40 years for the treatment of
colon cancer, according to Hecht.
"This drug is a derivative of a drug that comes from a Chinese
tree," he said. "It was one of the first of the new class of drugs
that inhibit the way that DNA replicates."
The drug limits the activity of cancerous cells by preventing
DNA from uncoiling. For cancerous cells to replicate, the DNA must
uncoil in order to copy itself and divide.
"It inhibits the enzyme topoisomerase," said Dr. Mark Pegram, an
assistant professor in the department of hematology and oncology.
"This is the enzyme involved in the coiling and uncoiling of DNA
during replication."
"If you treat a cancerous cell with the drug, it won’t be able
to synthesize DNA appropriately and it won’t be able to divide,"
Pegram said. "Hopefully, the tumor cells will die after the
treatment."
While treatment already exists for adenocarcinoma, researchers
hope the new drug will fight the cancer more effectively.
"While it may not cure cancer, it may end up giving us more
weapons in fighting this type of cancer," Hecht said. "This
(cancer) is becoming more of a public health problem."
"We do have some treatments, but they are not as good," Hecht
said. He stressed that due to the unique location of the cancer, it
limits the number of methods that doctors can derive to fight
it.
Traditional treatment includes removal of the cancer,
chemotherapy, or a combination of these processes. This particular
form of cancer, however, spreads quickly and often wraps itself
around vital organs that cannot be partially or entirely removed,
Hecht said.
Side effects of CPT-11 are also more manageable, said
Pegram.
"It’s a cancer for which there is no cure (and) the drug has
unique side effects compared to conventional chemotherapy," Pegram
said. He explained that some patients suffer diarrhea, stomach
cramps, hair loss and vomiting after taking the drug, but these
symptoms are less severe than those from other treatments.
"It’s really pretty well tolerated when you monitor the patient
closely and make the proper adjustments," he said.
Research like this plays an important role in making the most
current treatments available to cancer patients, said Judith
Gasson, director of the Jonsson Comprehensive Cancer Center.
"We are very hopeful that since it has shown positive results in
colon cancer, that (CPT-11) will also be of a similar use in
esophageal and stomach cancer," Gasson said.
"We’ve been very proactive in getting the new drug and testing
it in a variety of different cancers.