Prolonged Survival of a Refractory Acute Myeloid Leukemia Patient after a Third Hematopoietic Stem Cell Transplantation with Umbilical Cord Blood following a Second Relapse

Although hematopoietic stem cell transplantation (HSCT) has been considered to be the only way for potential cure of relapsed acute myeloid leukemia (AML), there has been no report on a third HSCT in patients with multiple relapsed AML. Here, we report a case of 53-year-old female who received a successful third allogeneic HSCT after relapse of AML following a second allogeneic HSCT. She was treated with a toxicity reduced conditioning regimen and received direct intrabone cord blood transplantation (CBT) using a single unit of 5/6 HLA-matched cord blood as a graft source. Graft-versus-host disease prophylaxis was performed with a single agent of tacrolimus to increase graft-versus-leukemia effect. She is in remission for 8 months since the direct intrabone CBT. This report highlights not only the importance of individually adjusted approach but also the need for further investigation on the role of HSCT as a treatment modality in patients with refractory or multiple relapsed AML. 1. Introduction Decisions about how to treat patients with multiple relapsed AML are often based on the individual condition of each patient at relapse because no consensus on treatment of such patients has been established. Although there is no available clinical data as references in performing the third allogeneic HSCT currently, this has been performed sporadically at experienced transplant centers as one of options for treatment of patients with multiple relapsed AML, because the HSCT is regarded as the best way to achieve potential cure for refractory or relapsed AML. Here, we report a case who received the third allogeneic HSCT successfully without life-threatening complications and maintaining complete remission (CR) for 8 months. 2. Case Report A female patient had been diagnosed with myelodysplastic syndrome, refractory anemia with excess blasts-2 (MDS, RAEB-2), at the age of 49. The disease progressed to AML showing nearly 50% blasts in bone marrow (BM), when she received bone marrow transplantation (BMT) from an HLA-matched unrelated donor. Her conditioning regimen comprised 120？mg/kg cyclophosphamide and 12？Gy that was administered as six doses of fractionated total body irradiation. Tacrolimus and short-term methotrexate were used for graft-versus-host disease (GVHD) prophylaxis. Engraftment was achieved on posttransplant day 15, and a BM examination on day 27 showed >99% donor chimerism. The patient developed grade I acute GVHD (skin, stage 1). Relapse of AML was diagnosed 14 months after the transplantation. A combination chemotherapy comprising idarubicin and