For instance, breast cancer patients exhibit greater numbers of circulating FOXP3+ T cells compared to healthy volunteers [43], a particularly immunosuppressive subpopulation of FOXP3hi/CD45RA-Tregs which closely resembles an intratumoural, both in their expression of CD39, CTLA-4, TIGIT and CCR8 and their clonal diversity [34]. Here, CTLA4 is linked to breast cancer.