The circulating and tumor-infiltrating iNKT cells from melanoma patients showed elevated proportions of iNKTreg cells and exhibited higher levels of activation markers, NKR/NKG2 (such as NKG2A, NKG2C, and NKG2D), and ICP (particularly ICOS, TIM3, and/or LAG3) compared with the control groups. Here, ICOS is linked to melanoma.