“We are very excited about this discovery. Identifying new tumor antigens that elicit strong responses by the immune system is imperative for the success of tumor-specific immunotherapy,” said Dr. Finn. “If we can use a patient’s own immune system to recognize and attack existing cancer cells and prevent future tumors from developing, we are closer to finding a more effective and less toxic treatment for cancer and to possibly preventing certain types of cancer.”
In the study, cells of the immune system from healthy donors were exposed to dendritic cells generated in vitro (outside the body) that contained peptides from a breast cancer cell line. Dendritic cells are referred to as the pacemakers of the immune system – they are the first cells to recognize and process antigens. Antigens are substances that cause the immune system to make a specific immune response by producing antibodies and killer T cells. When the researchers examined the immune responses that were generated, they determined that their target was a fragment derived from cyclin B1, a protein that regulates cell growth and proliferation. They also found that cyclin B1 was over-expressed in breast and lung cancer cells, as well as squamous cell carcinomas of the head and neck, but not in normal cells, indicating that it is a tumor antigen.
According to Dr. Finn, these findings are important because very few tumor-specific antigens have been identified in epithelial tumors, which account for over 83 percent of all human tumors. “There is a need to identify and isolate the antigens for all types of tumors and use them to develop vaccines that can stimulate an immune response to attack existing cancer cells,” said Dr. Finn.
This study was funded by grants from the Department of Defense and the National Institutes of Health. Collaborators on the study include University of Pittsburgh researchers Henry Kao, Ph.D.; Thomas K. Hoffmann, M.D.; Sydney D. Finkelstein, Ph.D.; and Theresa L. Whiteside, Ph.D.; as well as researchers from the University of Virginia in Charlottesville.
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CONTACT: Clare Collins
Jocelyn Uhl
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FAX: (412) 624-3184
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UhlJH@msx.upmc.edu
Journal
Journal of Experimental Medicine