Masterful Antibodies: Checkpoint Blockade.

Cancer therapeutics that target the immune system rather than the cancer cell itself are becoming standard of care in a growing number of different malignancies. Although cancer immunotherapy is not a new concept, the potential importance of this class of drugs was probably not fully appreciated as recently as a decade ago when much of the focus of cancer drug discovery was on cancer cell-targeted medicines. The authors were lucky enough to be able to witness and participate in the discovery and development of ipilimumab and nivolumab, two relatively early examples of immune system-targeted drugs. The challenges associated with discovering and developing these molecules may be of historical interest and instructive for moving cancer immunotherapy forward for greater numbers of patients. Cancer Immunol Res; 5(4); 275-81. ©2017 AACR. ©2017 American Association for Cancer Research.