PDCD1 and cancer: The interaction of Gal-9 with PD-1 and TIM-3 regulates T cell death, making these promising targets for cancer immunotherapy.314 The activity of the TIM-3/Gal-9 checkpoint can be modulated in two ways: (i) blockage of TIM-3 with monoclonal antibodies or small molecules and (ii) blockage of Gal-9.315 Three monoclonal antibodies to TIM-3 are already in clinical trials for the treatment of solid tumours.