Complications of cancer immunotherapy

Cancer immunotherapy drugs called immune checkpoint inhibitors take the brakes off the body’s immune system, allowing it to find and attack cancer cells. One such checkpoint protein, programmed cell death protein 1 (PD-1) , has been a successful immunotherapy target. But this therapy is not effective in all patients, and scientists haven’t known why. A recent paper shows how preclinical mouse studies may be confounding researchers. A new study showed that a small sequence of amino acids, or motif, that plays a major role in the PD-1 mechanism is present in humans but not in mice. This difference makes the immune response interactions of PD-1 in mice weaker. Therefore, mice are more responsive to immunotherapy drugs. ( Sci. Immunol. 2025, DOI: 10.1126/sciimmunol.ads6295 ) “Our study suggests that, at least for the PD-1 pathway, the mouse models cannot accurately predict the human PD-1 [pathway],” says study author Enfu Hui of the