2005). In both settings, Herceptin has been shown to decrease the recurrence rate by approximately 50%. Unfortunately, Herceptin can only be used in a minority of breast cancer patients, specifically those that over-express the HER2 protein. These results have served to fuel ongoing research into immunologic approaches to cancer treatment ranging from the administration of mAbs, such as Herceptin, to the development of anti-cancer vaccines. Advances in the understanding of the immune response to cancer have led to the genesis of other immunotherapeutic approaches as well. Specifically, the development of anti-cancer vaccines holds promise as an adjuvant and preventive therapy for breast cancer patients at high risk for recurrence after primary therapy (Khoo et al. 2006). HER2 has also been shown to be the source of multiple immunogenic peptides to include E75, GP2, and the wild type AE37 (Fisk et al. 1995, Peoples et al.