SY7-7 - New Peptide-Based Cancer Vaccine: Phase I and Early Phase II Clinical Trials for Castration-Resistant Prostate Cancer

Abstract

ABSTRACT The field of cancer vaccines has moved forward dramatically since 1991, when Boon and his colleagues reported their discovery of the first tumor-associated antigen. Numerous tumor-associated antigens have been identified since that time, and some of them have been clinically tested with encouraging results in immunotherapy against patients with various types of cancer. Indeed, several immunotherapy strategies for prostate cancer, such as single-peptide-based vaccine, multiple-peptide-based vaccine, cell-based vaccine, viral vaccine, antibody-based therapy and their combination with other therapies, have been evaluated. We also reported the clinical outcome along with the safety and immune responses of the personalized peptide vaccination (PPV) alone as well as combined with other therapies. More recently, the US Food and Drug Administration (FDA) recently approved two novel immunotherapy agents, sipuleucel-T and ipilimumab, which showed a survival benefit for patients with metastatic prostate cancer and melanoma, respectively. These cancer vaccines, however, had several limitations, with regard to clinical efficacy, cost, and HLA-restriction. To overcome these limitations, new types of cancer vaccine are under basic and clinical investigation. Tumor cell heterogeneity and heterogeneity of the human immune response in different individuals suggest that polyvalent tumor vaccines will be required for optimal efficacy. We have developed a new cancer vaccine which included 20 different peptides for HLA-A2, -A24, -A3 supertype (A3, A11, A31, or A33) or -A26. Now, we are planning phase I and early phase II clinical trials for patients with castration-resistant prostate cancer. We discuss the current status of the cancer vaccine, particularly mixed peptide based vaccine, and the future direction of therapeutic cancer vaccines.