Tumor-infiltrating plasma cell profiling after PD-1 blockade reveals tumor-specific antibodies

Tumor-infiltrating plasma cells were identified as a source of therapeutically relevant antibodies that recognize citrullinated antigens expressed on both cancer cells and tumor-promoting myeloid cells. The lead antibody, PC-1, isolated after PD-1 blockade, targets citrullinated epitopes shared across malignant and immunosuppressive stromal compartments. The authors demonstrated that PC-1 can be repurposed as a targeting moiety for CAR T cell therapy, providing a novel strategy to simultaneously attack tumor cells and reshape the immunosuppressive microenvironment.