New drugs called immune checkpoint inhibitors have revolutionized treatment for certain cancers, including melanoma and Hodgkin lymphoma. They are showing promise for other cancers as well. Examples of these drugs are pembrolizumab (Keytruda), atezolizumab (Tecentriq), ipilimumab (Yervoy) and nivolumab (Opdivo). These powerful drugs fight cancer by boosting the bodys own immune system. Cancer cells send out signals that block the ability of immune system cells to recognize and kill them. The new drugs inhibit these blocking signals, thus unleashing a stronger immune system response.