Regulatory T cells (Tregs), as an important mechanism for regulating homeostasis of the immune system and the immune tolerance of the body, play crucial roles in the regulation of tumour immunity and constitute a current research hotspot in the field, primarily as potential targets (Supplementary Table 1) that can inhibit the activation and differentiation of CD4+ helper T cells and CD8+ cytotoxic T cells to induce reactivity against autologous and tumour-expressed antigens [1–3]. Here, CD4 is linked to neoplasm.