Investigators have identified several tumor-phagocytosis-related checkpoints, including the CD47/signal regulatory protein α (SIRPα) axis, the PD-1/PD-L1 axis, the MHC-I/leukocyte immunoglobulin-like receptor subfamily B (LILRB1) axis, and the CD24/SIGLEC10 axis. The gene discussed is PDCD1; the disease is neoplasm.