PDCD1 and colitis: But patients who used anti–PD-1/L1 drugs before the initial colitis episode had a higher risk of recurrent colitis; those who used anti–CTLA-4 at the time of ICI readministration had a higher risk of recurrence than those who used anti–PD-1/L1 and had a shorter time interval, which may be attributed to anti–CTLA-4 induced stronger Th17 memory in colitis than anti-PD/1, although no difference in severity was noted by Abu-Sbeih et al.