Efficacy of immune checkpoint inhibitors is dependent on the immunological properties of the tumor microenvironment (TME)21 and to some extent, changes in circulating immune cells may reflect changes in tumors in situ.22 In a recent feasibility study of locally advanced PC combining IRE followed by nivolumab,13 peripheral effector memory T cell numbers increased, while no differences at day 90 in CD4, naive or-central memory T cells were found. Here, CD4 is linked to neoplasm.