A "checkpoint inhibitor" is "curing" former US president Jimmy Carter of his cancer.
The 3 hotcakes in cancer immunotherapy currently are Keytruda (Pembrolizumab), Opdivo (Nivolumab) and Yervoy (Ipilimumab). The latter blocks CTLA4 (cytotoxic T-lymphocyte-associated protein) on activated T-cells, thereby preventing winding-down of their fight against enemy cells (germs, cancer). The first 2 block PD-1 (programmed cell death), preventing activated T-cells from committing suicide after they have decimated the "enemies". The downside to these anti-cancer boosters is that they may trigger autoimmune diseases. In this way, oncologists generate work for rheumatologists!