CD8A and neoplasm: In order to elicit effective antitumor CD8+ T cell responses, antigen presentation must be successful in two major events: First, tumor antigens are captured by antigen-presenting cells (APCs), processed into peptide fragments and presented on APCs with major histocompatibility complex class I (MHC-I) or human leukocyte antigen class I (HLA-I) to prime CD8+ T cells.