Increased incidence of HLA-DR3+ individuals amongst HER2/neu expressing breast cancer patients

22215 Background: HER2/neu is a tumor associated antigen that is over-expressed in several epithelial cancers. HER2/neu-specific immunity can prevent breast cancer in animal models. Immune surveillance against HER2/neu is a potential defense mechanism against cancer and is pursued as immunotherapy of breast cancer. Prior studies demonstrated that peptides from HER2/neu display varying binding affinities to different MHC Class II DR alleles. HLA-DR3 had the lowest affinity for HER2/neu peptides suggesting that DR3+ individuals may have reduced immunosurveillance against HER2/neu and thereby be susceptible to developing HER2/neu related cancers. We hypothesized that the presence of the DR3 allele may predispose patients to develop breast cancer, and if true, might expect to find higher numbers of DR3+ individuals among BrCa patients compared to the general population. Methods: Serologic and molecular testing for HLA-DR3 was performed on 52 HER2/neu+ (IHC 1–3+) breast cancer patients. We compared clinicopath...