If the cancer cells are born, our immune cells held in our body only can kill them. But the cancer cell makes a substance named PD-1 to stop the activity of our immune system. So we can’t kill the cancer cells and beaten by them. Japanese doctor Tasuku Honjo (Kyoto University) discovered the substance PD-1 which is able to nullify our immune system. The medicine to combine the PD-1 and to rob the function of the PD-1 is manufactured and used for cancer patients. The name of the medicine is Opdivo. It is still very expensive, but many severe patients are recovered.