Fig. 1. T-cell activating and inhibitory receptors [21]. T cells express a variety of receptors known for the ability to stimulate or inhibit the activation of their secretors. The effect of T-cell activation is determined by how much those receptors are involved. Inhibitory receptors: CTLA-4 — cytotoxic T-lymphocyte antigen 4, a negative regulator of T-cell activation; PD-1 — programmed cell death 1 receptor. PD-1 plays an important role in the negative regulation of the immune system by preventing the activation of T cells, increasing self-tolerance and reducing autoimmunity; TIM — Т-cell immunoglobulin mucin protein BTLA or B- and T-lymphocyte attenuator — an antigen that attenuates B- and T-cell functions; it participates in the regulation of T cells in the immune response. It is encoded by the BTLA gene. BTLA is expressed following T-cell activation and stays on the surface of Th1, but not Th2 cells. VISTA — V-domain Ig suppressor of T-cell activation; LAG-3 (CD223) — lymphocyteactivation gene. Activating receptors: CD28 — a co-stimulatory receptor; OX40 — a co-stimulatory receptor; GITR — a glucocorticoid-induced TNF receptor; CD137 — a co-stimulatory receptor; CD27 — a co-stimulatory receptor; HVEM — a membrane protein from a superfamily of tumor necrosis factor receptors 14 (TNFRSF14) and a herpes virus entry mediator

Fig. 2. The mechanism of neoantigen recognition and immune checkpoint blockade [42]. Anti-PD-1, anti-PDL-1 and anti-CTLA-4-antibodies block signaling pathways, facilitating neoantigen recognition and T cell activation. CD4⁺ — T cells expressing cluster of differentiation antigen 4 (CD4); recognizes MHC class II antigens; CD28 — T cells expressing cluster of differentiation antigen 28; CTLA-4 — antigen 4 associated with cytotoxic T lymphocytes; IFN — interferon; PD-L1 — programmed deathligand 1; PD-1 — programmed cell death 1 receptor; pMHC — peptide-major histocompatibility complex receptor complementary to TCR; TCR — a T-cell receptor