Blood platelets help disguise cancer from the immune system by suppressing T cells, report scientists at the Medical University of South Carolina (MUSC) in the May 5, 2017 issue of Science Immunology. In extensive preclinical tests, a promising T cell therapy more successfully boosted immunity against melanoma when common antiplatelet drugs such as aspirin were added.
Zihai Li, M.D., Ph.D., senior author on the article, is chair of the MUSC Department of Microbiology and Immunology, the program leader for the Cancer Immunology Research Program at MUSC Hollings Cancer Center, and the SmartState Sally Abney Rose Chair in Stem Cell Biology & Therapy. Li studies how tumors hide themselves from the immune system.
Li’s team found that platelets release a molecule that suppresses the activity of cancer-fighting T cells. That molecule, unsurprisingly, was TGF-beta, which has been recognized for decades for its role in cancer growth.
Dr. Stegall’s Comments: One of the lab findings we see in advanced cancer is an increased platelet count. Platelets are sticky, and help blood clots to form. Research has also shown us that platelets help cancer cells hide from the body’s immune system. Thus, an anti-platelet therapy such as aspirin can be used off-label for cancer purposes. We know from other studies that aspirin confers a survival benefit in cancer patients. As a result, I often include aspirin as part of my anti-cancer “cocktail” of treatments since it has a significant upside with little to no downside.