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A new
study by Dana-Farber Cancer Institute scientists suggests it
may be possible to prevent tumors from recurring and to
eradicate metastatic growths by implanting a gel containing
immunotherapy during surgical removal of a tumor. In the
study, published online today by Science Translational
Medicine, researchers removed breast tumors from mice and
placed biodegradable gels containing an immune-stimulating
drug in the resulting empty space. The gels released the
drug, which switches on a key type of immune cell, over an
extended period of time. When researchers examined the
animals over the next several months, they found that this
approach cured a much higher proportion of mice than
delivery of the drug by other techniques. Not only did the
original tumors not recur in the breast, but metastatic
tumors in the lungs far away from the site of drug delivery
were eliminated as well. The lead researchers say the
findings, which were duplicated in mice with lung cancer and
melanoma, hold immense promise for overcoming two of the
greatest obstacles to curing cancer: the tendency of the
disease to recur in patients who have undergone surgery to
remove solid tumors and the difficulty in eradicating
distant metastases. The goal of the new approach is to
convert that immunosuppressive environment into an "immune
stimulatory" one, the lead researcher says, a condition in
which the immune system is primed for an offensive against
cancer cells. In the study, the researchers loaded a
hydrogel, a half-inch disc made of a biodegradable sugar
naturally found in the human body with drugs that activate
dendritic cells. Dendritic cells are part of the innate
immune system the body's first responders to foreign
intruders or diseased cells. The hydrogel, placed in the
spot where the tumor was removed, releases the drug over an
extended period of time, lengthening the window of
effectiveness. When the dendritic cells are activated, they
train T cells their allies in the adaptive arm of the immune
system to attack cancer cells anywhere in the body, whether
at the site of the original tumor or distant metastases. The
benefits of this approach to treatment appear to be
enduring. Three months after the mice underwent the
treatment, they didn't have a recurrence. When the lead
researcher injected fresh breast cancer cells in the side
opposite the original tumor site, the disease didn't recur
in any of the mice, as the cancer was rejected by the immune
system's memory.
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