[Successful treatment of post-allogeneic hematopoietic transplant immune thrombocytopenia with eltrombopag].

A 44-year-old woman in the first remission phase of mixed-phenotype acute leukemia (T-lymphoid and myeloid lineages) suddenly exhibited thrombocytopenia (1.1×104 /µl) with generalized petechiae approximately 150 days after bone marrow transplantation (BMT) from a one-locus (HLA-B) mismatched unrelated donor. Until then, the donor bone marrow had smoothly engrafted, and the platelet count had promptly normalized. Despite extensively searching for the triggering agent such as GVHD, graft failure, relapsed leukemia, or adverse drug effects, it could not be determined. Suspecting immune thrombocytopenia secondary to BMT, prednisolone (1 mg/kg/2 days) therapy was initiated, but its effects were unsatisfactory. Next, eltrombopag, a thrombopoietin receptor agonist (TPO-RA), was administered, which exhibited a marked effect on thrombocytopenia, resulting in the withdrawal of prednisolone. Even though the efficacy of eltrombopag against immune thrombocytopenia is well established, limited studies have reported the efficacy and safety of eltrombopag against immune thrombocytopenia after allogeneic stem cell transplantation. Herein we report a case in which thrombocytopenia occurred late after transplantation but was successfully treated with a TPO-RA. In addition, we discuss suspected causative mechanisms and review the literature.