Strikingly, it was found that administration of the anti-PD-1 mAb unleashed activation and recruitment of central memory T cells (TCM) into draining lymph nodes and within the tumor and increased the Teff/Treg cell ratio but only if specific bacterial strains (A. muciniphila and E. hirae) were present in the intestine of the tumor-bearing mice (86). Here, PDCD1 is linked to neoplasm.