Efficacy of the antiCD38 Monoclonal Antibody Isatuximab in the Treatment of PCRA by Major ABO Mismatch After Allogeneic Hematopoietic Stem Cell Transplantation

A quarter of allogeneic hematopoietic stem cell transplantation are performed in a situation of major ABO mismatch exposing patients to the risk of immunological pure red cell aplasia (PRCA) after transplant. PCRA after transplant is defined as anemia with low reticulocytes count (under 10 G/L) after day 60 despite good leucocytes and platelet engraftment, full donor chimerism, associated with the persistence of recipients hemagglutinins (anti-A or anti-B antibodies). Bone marrow evaluation when performed show erythroid hypoplasia. Red blood cells transfusions are necessary every two weeks until remission leading to impaired quality of life (anemia, repeated hospitalization), iron overload, and need for iron chelation therapy. Treatments currently used are inefficient (anti CD20 monoclonal antibodies, EPO, steroids, plasma exchanges, proteasome inhibitors) or at risk of severe acute GVHD (donor lymphocytes infusion). PRCA has been demonstrated to be associated with the persistence of recipient's plasma cells. Anti-CD38 monoclonal antibodies which targets plasma cells secreting hemagglutinins responsible of PCRA are a promising treatment: 6 cases reported in the literature support a rapid and sustain efficacy but a prospective randomized evaluation of its efficacy and safety in this context is necessary. The main objective of the study is to assess the efficacy of the treatment of PRCA by isatuximab after allogeneic hematopoietic stem cell transplant compared to supportive care only control group (reduction in PRCA resolution time in days)