Breast cancer vaccine may prevent recurrence
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A vaccine using a protein that is a biological “marker” for breast cancer, called HER2/neu, prompts a specific immune response and may prevent recurrence of the disease in certain patients who have become disease-free after treatment for breast cancer, according to researchers.
“While our results are preliminary,” lead investigator Dr. George E. Peoples told Reuters Health, “we are encouraged that this type of trial, evaluating cancer prevention as opposed to cancer treatment, will ultimately reveal the power, and appropriate future use, of cancer vaccines.”
In the Journal of Clinical Oncology, Peoples of Walter Reed Army Medical Center, Washington, DC and colleagues explain that E75 is a part of the HER2/neu protein that is seen in many breast cancers. “Our clinical trials are investigating E75 mixed with (a cell growth factor) as a simple vaccine strategy,” the researchers explain.
The team administered the vaccine to 24 patients with lymph node-positive breast cancer, while 29 lymph node-positive breast cancer patients acted as a comparison group.
Vaccinated patients showed an expansion of white blood cells that specifically attacked E75 and destroyed breast tumor cells that expressed HER2/neu.
At 22 months follow-up, the only two deaths that had occurred were in women in the comparison. Disease-free survival was 85.7 percent in the vaccinated group and 59.8 percent in comparison group. Corresponding recurrence rates were 8 percent and 21 percent.
Peoples pointed out that the “reduction in recurrences in our vaccinated breast cancer patients is similar to the recent reports using Herceptin—trastuzumab—a monoclonal antibody, that targets the same HER2/neu protein as our vaccine.”
He added: “Preclinical data suggest that the two may be synergistic, and, therefore, the combination of Herceptin and our vaccine may be even more effective in preventing recurrences in high-risk breast cancer patients.”
In an accompanying editorial, Drs. Lupe G. Salazar and Mary L. Disis of the University of Washington, Seattle, call the study data “provocative,” but note that it remains to be determined which patients might benefit most from vaccination.
SOURCE: Journal of Clinical Oncology, October 20, 2005.
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