Identical Outcome Following Autologous or Allogeneic Genoidentical Hematopoietic Stem Cell Transplantation in First Complete Remission for Good Risk Acute Myelocytic Leukemia Carrying INV 16 or t(8;21): A Retrospective Comparison from the Acute Leukemia Working Party (ALWP) of the European Cooperative Group for Blood and Marrow Transplantation (EBMT).

Patients with acute myelocytic leukaemia (AML) with core binding factor mutations (CBF), bearing abnormalities of chromosome 16 or t(8;21) are classified as good risk with chemotherapy regimens including high dose cytosine arabinoside and are not subjected to hemopoietic stem cell transplantation (HSC) front line. However there are limited data from old studies indicating good outcome following HSC, autografting in particular, and there has been recently some concern about higher than expected relapse incidence following conventional chemotherapy in this patient population. From January 1990 to December 2004, a total of 325 adult patients were reported to the EBMT Acute Leukemia registry as receiving a transplant in first remission (CR1). Of these, 159 had an inversion 16, including 124 with no additional chromosome abnormality and 35 with other abnormalities. 166 had a t(8;21) translocation, as the only chromosome abnormality in 106 and associated to other abnormalities in 60. 64 patients with inv 16 and 81 patients with t(8;21) received a geno-identical allograft. 95 patients with inv 16 and 85 patients with t(8;21) translocation received an autograft. In patients with inv 16, following allogeneic and autologous transplantation respectively, the LFS were 59 ± 7% and 66 ± 5% (p=0.5), the RI 27 ± 6% and 32 ± 4% (p=0.45) and the TRM 14 ± 4% and 2 ± 2% (p=0.003). The LFS was significantly higher after January 2001. Female patients had a significantly lower incidence of relapse and a higher LFS. The existence of additional chromosome abnormalities not only did not worsen the prognosis but was associated with less relapses (12±5% vs 34 ± 4%, p= 0.01), and a better LFS (78 ± 7% vs 59 ± 5%, p=0.04). In patients with t(8;21), following allogeneic and autologous transplantation respectively, the LFS were 60 ± 5% and 66 ± 5% (p=0.69), the RI 15 ± 2% and 28 ± 3% (p=0.03) and the TRM 24 ± 3% and 6 ± 1% (p=0.003). Younger age and a lower white cell count at diagnosis were associated with a lower TRM and a better LFS.There was no difference in outcome between female and male patients. Following autologous transplantation as compared to allogeneic, the TRM was significantly lower and the relapse incidence significantly higher. For all adult CBF AML, the LFS did not differ between autologous and allogeneic transplants. Although the reasons why these patients were transplanted are unclear, considering the low TRM of autologous stem cell transplantation and the possibility to monitor in vivo purging by molecular biology, the data support the inclusion of ASCT in the front line treatment of CBF AML and suggest that a randomized prospective trial comparing high dose ARA-C and ASCT would be of interest.