MONDAY, April 14 (HealthDay News) -- A new drug duo might help
prevent colorectal cancer, and the powerful new cancer drug Sutent
may slow the progression of liver cancer.
So conclude two studies presented Monday at the American
Association for Cancer Research annual meeting in San Diego.
In the first report, researchers found that a two-drug regimen
made up of low doses of difluoromethylornithine (DFMO) plus
sulindac, a non-steroidal anti-inflammatory drug (NSAID), cut the
risk of colorectal adenomas by up to 95 percent. Colorectal
adenomas are an early sign of colon cancer.
"We really think we are on track to develop a medical means to
prevent colon cancer," lead researcher Dr. Frank L. Meyskens, a
professor of medicine at the University of California, Irving, told
reporters during a Monday afternoon teleconference.
Meyskens believes the drug combo could be used for people at
high risk for colon cancer to prevent the disease from developing.
It could also be used by those who have already had colon cancer,
to help prevent its return, he said.
In the phase III trial, researchers studied 375 people with a
history of colorectal polyps. They randomly assigned patients to a
combination of DMFO and sulindac or placebo. Patients were followed
for three years.
Patients taking the combination of drugs saw a 70 percent
reduction in the risk of a new adenoma compared with patients
receiving placebo.
For people who had advanced adenomas, the risk of developing new
adenomas was reduced by 92 percent among those on the drug
combination, Meyskens said.
Moreover, patients taking the drug combination who had had large
adenomas saw a 90 percent reduction in their risk of developing new
adenomas compared with patients taking placebo.
"The real home run was that we had a 95 percent decrease in new
adenomas in those patients who had multiple adenomas," Meyskens
said. "So, 17 patients in the placebo group had more than one
adenoma, compared with only one patient in the treatment group," he
said.
The rate of risk reduction was so high that the trial's Data
Safety and Monitoring Board stopped the trial early so that
everyone could benefit, the researchers noted. In addition, there
was no difference between people getting the medications and
placebo in terms of side effects requiring hospitalization,
gastrointestinal side effects, cardiovascular side effects or
temporary hearing loss, a rare side effect of DMFO.
In the second study, the researchers showed that sunitinib
(Sutent) appears effective in slowing tumor growth and cutting the
risk of metastases in patients with hepatocellular liver cancer,
researchers report.
Sutent, a member of a family of cancer drugs that also includes
Gleevec (imatinib), has proven effective against kidney cancer and
a type of malignancy called gastrointestinal stromal tumors. Recent
studies have also linked Sutent to higher heart risks, so experts
say cancer patients and their doctors must weigh its risks and
benefits.
The new study focused on hepatocellular liver cancer.
"Hepatocellular cancer is a very challenging cancer to deal with,"
lead researcher Dr. Andrew Zhu, an assistant professor of medicine
at Harvard Medical School said during the Monday afternoon
teleconference. "It is a very common cancer worldwide, and it is
the third leading cause of cancer mortality," he said. "The cancer
most likely results from having had a hepatitis B infection."
The prognosis associated with this cancer is very poor, Zhu
noted. "The average survival is six to eight months," he said.
In the study, 34 patients with advanced liver cancer were given
Sutent daily for four weeks with two weeks off before the next
round of treatment. Sutent works by targeting receptors in cancer
cells called VEGFR2, c-Kit and FLT3. These receptors are also
present in normal cells.
The drug appears to work by controlling the growth of blood
vessels, which is how this type of liver cancer is able to spread
so rapidly.
At 12 weeks, one patient had a partial response and 17 saw their
disease stabilize. Progression-free survival lasted an average of
four months, and overall survival was 10 months, the researchers
report.
"Even though the response rate to make the tumor smaller was
observed in only one patient, 50 percent of the patients had stable
disease and are doing well," Zhu said. "Sunitinib can be safely
given, with close monitoring, to the majority of these patients,"
he said.
The treatment was well-tolerated, and there were low rates of
all blood disorders, the researchers report. Because Sutent has
been associated with increased risk of heart problems, all patients
taking Sutent -- but especially those who have risks for heart
disease -- need careful monitoring and treatment for high blood
pressure and other signs of heart problems.
In a third report, researchers from the Kimmel Cancer Center at
Thomas Jefferson University in Philadelphia found that blood
pressure-lowering drugs called angiotensin receptor blockers appear
to retard pancreatic cancer cell growth and cause malignant cells
to die.
This type of drug is able to inhibit the function of the hormone
angiotensin II in the pancreas. The same receptor is found in
pancreatic cancer cells. In laboratory experiments, the researchers
found that the drug was able to block the production of a growth
factor called VEGF, which helps spur the growth of tumor blood
vessels.
"This is really exciting because the role of this receptor has
never been known," lead researcher Dr. Hwyda Arafat said in a
prepared statement. "It's never been connected to cell division or
apoptosis. We're also now further exploring the mechanisms
involved. The exciting thing is that this receptor already has so
many available pharmaceutical blockers on the market." Ultimately,
the group hopes to be able to test these agents in human trials,
she said.
More information
For more information on cancer, visit the
American Cancer Society.
