Current Strategies for the Identification of Immunogenic Epitopes of Tumor Antigens

Peptide-based cancer immunotherapy relies on the identification of epitopes recognized by T-lymphocytes. Because of the high degree of polymorphism of human leukocyte antigens and issues of tumor escape from the immune response, the availability of a wide choice of diverse epitopes is essential for the therapist. There are a number of different approaches for identifying new class Iand class II-restricted target antigens appropriate for immunotherapy and as discussed in this volume, several of these are complimentary. The strategy of “reverse immunology,” which is presented in this chapter, is applied for prediction of tumor-associated antigens by in silico screening sequences of selected proteins for peptides with high binding affinity to different human leukocyte antigen molecules. Subsequently, these peptides are synthesized and tested experimentally. Here, we outline some of the most prominent current algorithms and methods for assessing the immunogenicity of the predicted peptides in vitro and in vivo. We also describe the complimentary approach of isolating major histocompatibility complexassociated peptides from target cells followed by sequencing using reverse phase highpressure liquid chromatography fractionation and mass spectrometric analysis. We conclude by discussing some of the potential advantages and disadvantages of these methods and problems associated with their application.