CTLA4 and autoimmune thrombocytopenic purpura: The second highest incidence of hematologic irAEs was immune thrombocytopenia (ITP), although it does vary dramatically by geography One study (57 patients) determined i) patient origin as predominantly from North America (53%) followed by and Asia (33%) then Europe (14%); ii) the underlying diseases remained most common in melanoma and NSCLC; iii) 65% were treated with anti-PD-1 monoclonal antibody alone (Davis et al., 2019), 16% with anti-CTLA-4 monoclonal antibody alone, 18% with a combination of both, and 2% with anti-PD-L1 monoclonal antibody alone (Calvo, 2019).