Advances in personalized cancer immunotherapy

There are currently three major approaches to T cell-based cancer immunotherapy, namely, active vaccination, adoptive cell transfer therapy and immune checkpoint blockade. Recently, this latter approach has demonstrated remarkable clinical benefits, putting cancer immunotherapy under the spotlight. Better understanding of the dynamics of anti-tumor immune responses (the "Cancer-Immunity Cycle") is crucial for the further development of this form of treatment. Tumors employ multiple strategies to escape from anti-tumor immunity, some of which result from the selection of cancer cells with immunosuppressive activity by the process of cancer immunoediting. Apart from this selective process, anti-tumor immune responses can also be inhibited in multiple different ways which vary from patient to patient. This implies that cancer immunotherapy must be personalized to (1) identify the rate-limiting steps in any given patient, (2) identify and combine strategies to overcome these hurdles, and (3) proceed with the next round of the "Cancer-Immunity Cycle". Cancer cells have genetic alterations which can provide the immune system with targets by which to recognize and eradicate the tumor. Mutated proteins expressed exclusively in cancer cells and recognizable by the immune system are known as neoantigens. The development of next-generation sequencing technology has made it possible to determine the genetic landscape of human cancer and facilitated the utilization of genomic information to identify such candidate neoantigens in individual cancers. Future immunotherapies will need to be personalized in terms of the identification of both patient-specific immunosuppressive mechanisms and target neoantigens.