The C3-CD4 subset, mainly from tumor tissues, exhibits high accessibility to genes such as IL7R and IL2, linked to memory-like and/or effector-like fates, and shows increased accessibility to follicular helper T cells (TFH)-specific genes like IL21. The C12-CD4 subset, also predominantly from tumor tissues, is associated with high chromatin accessibility of tumor-infiltrating Treg markers, including tumor necrosis factor receptor superfamily (TNFRSF)18, ICOS, and CTLA4 [313]. Here, ICOS is linked to neoplasm.