- New Drugs Slow Spread of
Prostate Cancer
KOREN CAPOZZA, UPI Science News
SAN FRANCISCO, May 14, 2001 (United Press International
via COMTEX) -- Oncology researchers Monday said two drugs show promise in slowing the
progression of prostate cancer to the bones, a major cause of death in patients in the
late stage of the disease.
The oncologists, presenting studies at the annual meeting
of the American Society of Clinical Oncologists, said both treatment options appear to
slow the progression of cancer metastases in a patient's bones, a condition that affects
30 ++percent of men with prostate cancer and is a major cause of death. Once the cancer
invades the skeleton, it becomes painful and debilitating.
Researchers tested the drug Atrasentan on 244 patients
who were undergoing hormone treatment therapy for prostate cancer. They found that,
compared to a group of patients receiving only a placebo, patients on Atrasentan went more
than two months longer before symptoms appeared that signaled skeletal disease
progression.
In addition, tests of a cancer antigen associated with
disease progression, called PSA, showed that the drug doubled the time before PSA rapidly
increased.
Atrasentan, which is made by Abbott Laboratories, works
by blocking a pain-inducing protein from binding to the surface of prostate cancer cells.
The results are significant because the median survival
rate for patients with late-stage prostate cancer is only 12 months and there are few
treatment options for patients who have failed hormone therapy. The drug also helped
maintain the patients' quality of life, had few side effects and was well tolerated.
"The data suggests this low-toxicity pill leads to
clinical benefit and delays time before patients may need additional systemic
treatments," said Dr. Michael Carducci of Johns Hopkins University in Baltimore and
the lead study researcher. "The plan is to move this to stage three clinical
testing."
A second related study from Royal Marsden Hospital in
Sutton, England found the drug Clodronate also slowed the progression of prostate-related
bone cancer. The drug was taken orally by 311 patients with advanced prostate cancer and
appeared to deliver an overall survival benefit of seven months.
The lead author, Dr. David Dearnaley, cautioned that the
results were just under conventional statistical significance.
"Clodronate is poorly absorbed through the
stomach," he said. "We might now feel justified in giving intravenous treatment
to patients."
Dearnaley also said he suspects more significant results
will be observed if the drug dosage is increased and if treatment begins earlier.
"Most of these patients were five months into the
disease when they started therapy," he said. "Our data indicates that the
earlier they start, the more likely they were to have a benefit."
Earlier studies have shown Clodronate was able to reduce
new metastases in women with breast cancer.
Researchers said additional follow-up studies are needed
to further explore the benefits of both new drug options for prostate cancer patients.
"Dr. Carducci's and Dr. Dearnaley's work is an
example of how we can target the same mechanisms through different drug therapies,"
said Dr. Deborah Kuban of M.D. Anderson Cancer Center in Houston. "We are beginning
to target cancer cells' function on a molecular level."
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