A Retrospective Study Evaluating the Efficacy of Fludarabine, Cytarabine, and Granulocyte Colony Stimulating Factor with/without Idarubicin Followed by Second Allogeneic Stem Cell Transplant in the Treatment of Relapsed/Refractory Acute Myeloid Leukemia/Myelodysplastic Syndrome Following First Allogeneic Stem Cell Transplant.

Allogeneic stem cell transplantation (allo-SCT) remains the only curative treatment for most patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Unfortunately, a significant number of patients with AML/MDS will remain refractory to or subsequently relapse following allo-SCT. There is no consensus currently regarding the standard of care for relapsed AML/MDS after allo-SCT. Thirty-two patients with relapsed AML/MDS following first allo-SCT were treated with fludarabine, cytosine arabinoside, and granulocyte colony-stimulating factor, with or without idarubicin (FLAG ± Ida), followed by a second-allo-SCT from the initial donor. Patients were assessed for treatment response, acute graft-versus-host disease (aGVHD), and chronic GVHD (cGVHD). Non-relapse mortality (NRM) rates were calculated at 100 d and 1 yr. Kaplan-Meier curves were used to estimate 2- and 5-yr rates of progression-free survival and overall survival (OS). Overall, 84% of patients were able to achieve complete response after receiving FLAG ± Ida followed by second allo-SCT. Two- and five-year OS were 32% and 17%, respectively, and 2- and 5-yr disease-free survival were 20% and 6%, respectively. Overall, 85% of patients experienced GVHD. Overall, 48% of patients with aGVHD had grade 3 or higher disease; 29% of patients with cGVHD had severe disease. NRM was 19% and 31% at 100 d and 1 yr, respectively. FLAG ± Ida followed by allo-SCT appears to be a promising salvage strategy for patients with relapsed AML/MDS after allo-SCT. However, more research is needed to identify the circumstances for which this treatment option should be selected. Additionally, given the high rate of GVHD, additional research is needed to determine how to maximize the graft versus leukemia effect while minimizing the development of GVHD.