Abstract
With the Nobel Prize in Physiology or Medicine in 2018, cancer immunotherapy is attracting more attention than ever before and is strongly expected to develop in the future. Immune checkpoint inhibitors were developed as drugs with a completely different mechanism from conventional chemotherapy for cancer patients, and their therapeutic effects were characterized not only by tumor shrinkage but also by long-term survival of cancer patients, which had a strong impact on cancer treatment. On the other hand, as a result of numerous clinical trials, it was found that the efficacy of immune checkpoint inhibitors alone is only about 10-30%. Currently, more than 2,500 clinical trials of combined cancer immunotherapy with immune checkpoint inhibitors are being conducted with the hope of further improving therapeutic efficacy. Another new cancer immunotherapy, Chimeric Antigen Receptor (CAR) gene transfer T-cell therapy, has been approved for B-cell hematopoietic tumors. In this article, we will outline the future prospects of cancer immunotherapy developed in this way, especially from the viewpoint of "strategies for ineffective cancer".