Figure 1.

The mechanism of tumor antigen processing, presentation on MHC class I, and improving efficacy of ICI therapy. (A) DNA mutations occurred and synthesized proteins in the tumor cells. (B) The proteins are processed into smaller peptides, displayed by major histocompatibility complex (MHC) class I molecules via APC cells, and recognized by CD8+ T effector cells as neoantigens. (C) Tumors expressing higher numbers of neoantigens are more likely to induce a significantly greater number of T cells, while tumor cells inhibit T-cell function through immune checkpoints, such as PD-L1. (D) ICI therapy blocks immune checkpoint suppression, reactivates T-cell function, and kills tumor cells. APC, antigen-presenting cell; ICI, immune checkpoint inhibitor; MHC, major histocompatibility complex; PD-L1, programmed cell death ligand 1; PD-1, programmed death receptor 1; TCR, T-cell receptors.