Autologous Bone Marrow Transplantation as an Intensive Consolidation Therapy for Adult Patients in Remission from Acute Myeloid Leukemia.

Introduction: Autologous peripheral blood stem/progenitor cell transplantation (APBSCT) has been investigated as a potential therapeutic option to improve outcome in patients with acute myeloid leukemia. The optimal consolidation therapy for adults in remission without a histo-compatible donor has yet to be clearly established.

Patients and Methods: This was a retrospective analysis of forty patients (23 females and 17 males) diagnosed with de novo acute myeloid leukemia, who were without a histo-compatible donor, that underwent APBSCT between the year 2000 and 2006 at a single institution. The patients’ age ranged from 18 to 73 with a median age of 50. Cytogenetic analysis was available on 37 of the patients. Complete remission (CR) was confirmed by bone marrow morphology and immunophenotype analysis by flow cytometry. Patients in remission were further consolidated with variable cycles of chemotherapy prior to stem cell transplantation. For stem cell mobilization, patients received high-dose cytarabine (2000mg/m2) and etoposide (5mg/kg) for three days followed by G-CSF at 10μg/kg, starting 10 days after the chemotherapy, before the peripheral stem cell collection. The preparative regimen prior to transplantation with unpurged stem/progenitor cells consisted of a combination of intravenous busulfan (0.8 mg/kg for 16 doses) and cyclophosphamide (60 mg/kg for two doses) (37 patients) or busulfan and melphalan (3 patients). Patients were then followed for treatment-related mortality, disease free survival, and overall survival. The analysis was stratified according to age, cytogenetic risk, and remission state.

Results: There was no treatment-related mortality. Nineteen out of forty patients had relapse of their disease. The relapse rate was lowest in the low risk cytogenetic group who were under the age of 60 and highest in the high risk cytogenetic group who were over the age of 60. The overall 5 year survival for all patients was 47%. When stratified for cytogenetic risk and age, the overall survival for low, intermediate, and high cytogenetic risk patients under the age of 60 were 67%, 59%, and 75% respectively. The overall survival for intermediate and high cytogenetic risk patients over the age of 60 were 33% and 0% respectively. The projected rate of disease free survival at 5 years was 40%. When stratified for cytogenetic risk and age, the disease free survival for low, intermediate, and high cytogenetic risk patients under the age of 60 were 33%, 52%, and 50% respectively. Disease free survival for intermediate and high cytogenetic risk patients over the age of 60 were 33% and 0%. Comparing patients in CR1 versus patients in CR2, the overall survival was 47% in CR1 and 50% in CR2. The disease free survival, when grouped as above, were 41% for those in CR1 and 33% for those in CR2.

Conclusion: APBSCT is a reasonable and safe intensive consolidation therapy for those patients without a compatible HLA matched donor in first or second complete remissions, notably for those under the age of 60 regardless of their cytogenetic risk. The number of standard consolidations prior to APBSCT may be an important variable predicting outcome.