CTLA4 and anemia (phenotype): Our previous study showed that different anti-human CTLA-4 show drastically different irAE.33 Thus, while Ipilimumab+anti-PD-1 treatment induces severe growth retardation, death, anemia and multi-organ inflammation, anti-PD-1 combination with HL12 or HL32 caused no growth retardation, anemia nor death, and minimal leukocyte infiltration to organs.33 Since Tremelimumab was also found to have strong irAE in the clinic,37 we generated an IgG1 variant of Tremelimumab (TremeIgG1) to enable evaluation of CITE along with irAE in vivo.