PDCD1 and neoplasm: For evaluating immunity memory following triple treatment with anti-SIRPα + HRT + anti-PD-1, 10 full responders were re-challenged using 5 × 106 (i.e., 5 fold the cell count of the first challenge) MC38 cells in the other flank 70 days following the first tumor inoculation, while 8 untreated naive mice served as controls.