The idea of using a man’s own
immune system to fight cancer has intrigued scientists for years. It makes
perfect sense: The body is supposed to attack harmful invaders, and it
does a great job protecting us from most of the germs, viruses, and disease-causing
agents we encounter throughout our lives. It even fends off most cancer
for decades.
But this idea, called cancer immunotherapy,
has not progressed as successfully as scientists had hoped it would. One
major hindrance may be a well-meaning but misguided group of cells called
regulatory T cells,which shut off the body’s immune response.
Prostate cancer is not the only disease
enabled by these cells: “The presence of regulatory T cells has
been clearly shown in breast and ovarian cancer,” says Charles Drake,
M.D., Ph.D., assistant professor of oncology. Drake has been named the
Phyllis and Brian L. Harvey scholar from The Patrick C. Walsh Prostate
Cancer Research Fund to figure out “how common regulatory T cells
are in prostate cancer, and whether the presence of these cells predicts
how well, or how poorly, a man with prostate cancer will do.
Drake and colleagues, using a mouse
model of prostate cancer, have been able to isolate regulatory T cells
from prostate tumors. His next step will be to characterize these cells,
“with the eventual goal of blocking their function so that immunotherapy
for prostate cancer will be more successful.” Earlier experiments
have provided some clues about how these regulatory cells work, he adds.
“They seem to depend on a substance known as transforming growth
factorbeta (TGF-β).” Drake will determine whether blocking
TGF-β will help immunotherapy for prostate cancer work more effectively.
All of this work, in turn, “should provide new insights into the
role of regulatory T cells in prostate cancer, and help us to design combination
immunotherapy strategies that will be more successful in treating patients.”
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