Moreover, a recent review of the largest clinical trials of ICIs (Michot et al., 2019), found that the frequency of hematological irAEs of all grades (including CRS), was higher with anti-PD-1 (4.1%) and anti-PD-L1 (4.7%) than with anti-CTLA-4 agents (0.5%, P < 0.0001). Here, CTLA4 is linked to congenital rubella syndrome.