Understanding Tumor-Antigen Presentation in the New Era of Cancer Immunotherapy

For more than a century, scientists have tried to exploit the anti-tumoral potential of the immune system to treat cancer. However, clinical success was traditionally limited. Consequently, classical anti-neoplastic treatments such as surgery, radiotherapy, and chemotherapy used to be the first line of treatment. Fortunately, this scenario is changing, particularly with the identification of immune checkpoint inhibitors. Now more than ever, it becomes essential to understand how cancer cells modulate the immune system. In this review, we summarize main mechanisms of antigen presentation in the tumor microenvironment, a main event in the establishment of anti-tumor immunity. Specifically, we focus on recent progress in mechanisms involved in tumor antigen presentation, as well as on strategies cancer cells develop to favor immune suppressive and immune tolerant enironments. In addition, we briefly discuss current therapeutic approaches to overcome tumor immune evasion.