Researchers test gene therapy
for advanced prostate cancer
LOS ANGELES -- May
24, 2001 (Cancer Digest) -- Researchers have shown for the first
time that injecting a gene into the tumor can affect prostate
cancer in humans. The early clinical trial proved the approach
safe and reduced the blood levels of a protein marker for cancer.
Lead author Dr. Arie
Belldegrun of the University of California at Los Angeles, said
in a press release that this early phase study suggests that
the approach represents a new option for treating men with cancer
that has spread beyond the boundaries of the prostate.
The research team published
the study in the May issue of Human Gene Therapy showing that
for the first time that injecting a gene that produces IL-2,
a hormone-like protein that stimulates the immune system, can
reduce the levels of a protein maker for cancer or PSA. Until
now, scientists believed prostate cancer to be resistant to immunotherapy.
Belldegrun said his study proves otherwise.
"Based on our
earlier studies in the laboratory, which were published in the
journal Cancer, we suspected that this approach might work in
humans," he said.
"We did not know,
however, that gene therapy and immunotherapy could be options
for patients with locally advanced prostate cancer, a high-risk
group to whom we have little to offer right now," said Belldegrun,
chief of urologic oncology at UCLA's Jonsson Cancer Center
In this study, the
researchers injected the IL-2 gene into the prostates of 24 patients
with locally advanced prostate cancer. IL-2 stimulates the immune
system to attract so-called "killer cells" called lymphocytes,
which researchers hope will seek out and destroy cancer cells,
Belldegrun said.
The injection is done
in an outpatient clinic, with no hospital stay needed. The researchers
use ultrasound to deliver the gene with great accuracy prior
to surgery or after the failure of radiation therapy.
In more than half of
the patients, the therapy resulted in reduced PSA levels, a blood
marker that signals the presence of prostate cancer. The treatment
proved to be safe and, because the therapy was injected into
the prostate and not delivered via the circulatory system, as
is chemotherapy, it resulted in few side effects, Belldegrun
said.
"We proved this
is a feasible approach for patients with locally advanced prostate
cancer," said Dr. Robert Figlin, an oncologist at UCLA's
Jonsson Cancer Center and co-author of the study.
"Because of its
location, we were able to inject into the prostate these genes
that stimulate the immune system to fight cancer. We anticipate
that, in the near future, newer and more powerful agents will
be delivered directly to the prostate via gene therapy ?
perhaps eliminating the need to remove the prostate. This is
an important new concept and a proof of principal that the technology
can work," Figlin said.
Because of the success
in this early study, five centers nationwide, including UCLA's
Jonsson Cancer Center, are now testing this treatment method
in much larger phase II studies, Belldegrun said.
For more information
on prostate cancer studies at UCLA's Jonsson Cancer Center, call
the toll-free clinical trials hotline at 888-798-0719.
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