Notably, serum levels of IL-35 in patients diagnosed with CRC disease positively correlated with the number of circulating FoxP3 Treg cells in the peripheral blood [99], which may indicate, beyond the fact that Treg cells are considered the main source of IL-35, that IL-35 is involved in the CRC-associated induction of peripheral Treg cells and thus in the initiation of tumor immune escape mechanisms. Here, FOXP3 is linked to neoplasm.