Open-Label, Phase II Trial of Isatuximab for Patients With Refractory Immune Cytopenias After Allogeneic Hematopoietic Cell Transplantation

Inclusion Criteria: * Age ≥ 18 years (There are no dosing/AE data for isatuximab in children). * Disease for which patient underwent an allo-HCT is in documented remission. * Patients must have previously had documented primary neutrophil and platelet engraftment, defined as: * Neutrophil engraftment: the first of 3 successive days with an absolute neutrophil count of ≥500/μL after post-transplantation nadir. * Platelet engraftment: the first of 3 consecutive days with a platelet count of 20,000/μL or higher in the absence of platelet transfusion for 7 consecutive days. * Patients must be at least 45 days post allogeneic HCT to enroll. * Patients must be diagnosed with IC(s) based on the following criteria: o For AIHA: Positive (abnormal) DAT test and decreasing hemoglobin of ≥2 g/dL from a stable baseline (i.e., from the patients typical hemoglobin value prior to AIHA) and at least grade 2 (i.e., hemoglobin \<10 g/dL) due to evidence of hemolytic anemia with ≥2 of the following tests: increased reticulocyte count (\>ULN), increased lactate dehydrogenase (LDH) (\>ULN), decreased haptoglobin (\<LLN), increased unconjugated bilirubin (\>ULN). * DAT negative AIHA may be included providing exclusion of alternative etiology of hemolytic anemia. * For ITP: decreasing thrombocytopenia from baseline (i.e., from the patients typical platelet count prior to ITP) and platelet count ≤30 K/µL or requiring platelet transfusions in the absence of other causes of thrombocytopenia…