Clinical trials are currently being conducted on a monoclonal antibody that targets the molecule PD1, and the results obtained thus far are quite hopeful for cases of refractory HL. PD1 is found on the surface of the T lymphoctes accompanying the tumor. When activated, PD1 causes the patient's immune system not to recognize the tumor cell as foreign, so the immune system does not attack the cell. By using anti-PD1 antibodies we change this dynamic and "awaken" the T-lymphocytes in the patient's immune system so that they recognize the tumor cells as foreign and help eliminate them.