PDCD1 and neoplasm: Recently, several studies have reported that therapies targeting CCR8+ Tregs show high efficacy in the treatment of colon cancer, non-small cell lung cancer, and melanoma; these findings highlight the efficacy and safety of targeting CCR8 for the depletion of tumour-promoting Tregs in combination with anti-PD1 therapy (Campbell et al., 2021; Van et al., 2021; Kidani et al., 2022).