A Case of Tyrosine Kinase Inhibitor-Induced Bone Marrow Aplasia That Was Successfully Treated with Allogeneic Hematopoietic Stem Cell Transplantation.

Here, we present a rare case of tyrosine kinase inhibitor (TKI)-induced bone marrow aplasia. A 58-year-old man presented with leukocytosis and was diagnosed with chronic myeloid leukemia. He was initially treated with imatinib for 6 years and abruptly discontinued treatment by himself. He was administered dasatinib 5 years after treatment interruption, and presented with pancytopenia 6 months after dasatinib initiation. Bone marrow biopsy revealed severe hypocellularity without blasts. Dasatinib was discontinued, and he recovered from pancytopenia 3 months later; however, BCR-ABL1 was positive for almost all white blood cells in the peripheral blood. We retreated with ponatinib, but pancytopenia developed again. The clinical course indicated TKI-induced bone marrow aplasia. Therefore, ponatinib was discontinued and the patient received an allogeneic hematopoietic stem cell transplantation from a haploidentical daughter using post-transplant cyclophosphamide. He had a major molecular response and had normal complete blood counts and bone marrow 1 year after transplantation.