Upfront Allogeneic Blood Stem Cell Transplantation for Patients with High-Risk Myelodysplastic Syndrome or Secondary Acute Myeloid Leukemia Using a FLAMSA-Based High-Dose Sequential Conditioning Regimen

Patients suffering from high-risk myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML) secondary to MDS (sAML) are characterized by poor response to conventional cytotoxic chemotherapy. The purpose of our prospective single-center study was to examine the safety and efficacy of an allogeneic hematopoietic stem cell transplantation (HSCT) following a sequential conditioning regimen as first-line therapy for previously untreated patients with high-risk MDS or sAML. Between November 2003 and June 2010, 30 patients (20 high-risk MDS, 10 sAML) received fludarabine (4 × 30 mg/m2), amsacrine (4 × 100 mg/m2), and Ara-C (4 × 2 g/m2, FLAMSA). After 2 to 3 days of rest, patients received high-dose melphalan alone (200 mg/m2 for patients with an age <50 years, 150 mg/m2 for patients with an age between 50 and 60 years, and 100 mg/m2 for patients with an age >60 years; n = 24) or melphalan and thiotepa (10 mg/kg, Mel/Thio, n = 6). Following these high-dose conditioning regimens, a median number of 7.7 × 106 CD34+ cells/kg body weight (range: 2.9 × 106-17.2 × 106) were transplanted from 13 related or 17 unrelated donors. Antithymocyte globulin (Fresenius 30-60 mg/kg) as well as tacrolimus and mycophenolate mofetil were used for graft-versus-host disease (GVHD) prophylaxis. All patients except 1 with primary graft failure achieved complete remission after HSCT. After a median follow-up time of 28 months (range: 7-81), 21 patients (70%) were alive and free of disease. Overall, 4 patients relapsed. At 2 years, overall survival, event-free survival, and treatment-related mortality were 70%, 63%, and 30%, respectively. Because of undue toxicity, thiotepa is no longer part of the conditioning regimen. Our results add to the body of evidence that a FLAMSA-based sequential conditioning therapy is effective for previously untreated patients with high-risk MDS or sAML.