Tumors use antioxidant enzyme to disarm cancer-fighting T cells

Researchers from the University of Cambridge and Oregon Health & Science University have identified a new mechanism that tumors use to evade the immune system. According to a study published in the journal Science, cancer cells release an antioxidant enzyme called peroxiredoxin 1 (PRDX1) into the tumor microenvironment.

This enzyme neutralizes reactive oxygen species (ROS), which were previously viewed primarily as harmful molecules that cause DNA damage. However, the study reveals that cancer-fighting T cells actually require small amounts of ROS to trigger the molecular signaling necessary for full activation. By creating an antioxidant-rich environment, tumors effectively “smother” T cells, depriving them of the signals needed to attack the cancer.

This discovery identifies what researchers call a “redox checkpoint” in antitumor immunity. The findings suggest that targeting the PRDX1 enzyme could serve as a new strategy to make resistant tumors more responsive to immunotherapy.