Comparison of HLA-Identical Sibling Hematopoietic Stem Cell Transplant (HCT) Versus Chemotherapy as Postremission Therapy in t(8;21) Acute Myeloid Leukemia (AML).

The t(8;21) is associated with high complete remission (CR) rates and high survival rates after cytarabine-containing postremission therapy for AML. However, patients with leukocytosis and additional cytogenetic abnormalities, such as loss of sex chromosome (LOS), have worse outcomes. We compared patients ages 16 to 60 years with t(8;21) AML in first CR, comparing 132 patients receiving postremission chemotherapy (chemo) with 118 receiving HLA-identical sibling HCT. The chemo cohort included patients treated with double induction followed by cytarabine-containing regimens in one of eight different German AML Intergroup clinical trials (SHG-Hannover-AML-2/95, SHG-Hannover-AML-1/99, SHG-Dresden-AML-96, AMLHD93, AMLHD98A, AMLCG92, AMLCG99, OSHO-AML-96) between 1993 and 2002. HCT recipients were registered with the CIBMTR from 1990 to 2000. To adjust for potential bias caused by delayed entry in the transplant cohort, left-truncated univariate analysis and Cox multivariate models were used. The median age of patients undergoing chemo and HCT were 42 and 32 years of age, respectively (p<0.001). The table below shows five-year outcomes in months, including relapse rate, treatment related mortality (TRM), adjusted leukemia free survival (LFS) and adjusted overall survival (OS) according to multivariate analysis (Table). WBC > 25.4×10⁹/L was associated with higher relapse risk (RR=2.09, P=0.03), shorter LFS (RR=1.9, P=0.008) and shorter survival (RR=1.91, P=0.012), independent of postremission treatment. Neither year of treatment nor specific chemotherapy protocols were significantly associated with outcomes. HCT and chemotherapy had similar overall survival in patients with LOS and leukocytosis; in those without LOS, survival was significantly higher with chemotherapy. In this cohort of patients with t(8;21) treated in the 1990s, high transplant related mortality offset the antileukemia benefit of HCT, suggesting that HCT be reserved for patients who fail postremission chemotherapy.