Molecular disease eradication is a prerequisite for long-term remission in patients with t(8;21) positive acute myeloid leukemia:: a single center study

Association of long-term clinical remission and molecular disease-eradication is well established in acute myeloid leukemia (AML) patients with t(15; 17) and inv(16). In patients with t( 8; 21) positive AML no consensus exists over the disappearance of the AML1/ETO fusion transcript during the course of disease and most studies reported reverse transcriptase polymerase chain reaction (RT-PCR) positivity as a common finding after consolidation chemotherapy, autologous and allogeneic stem cell transplantation (alloSCT). In our single center study, we performed RT-PCR monitoring in 14 patients with t(8; 21) in CR1 (n = 13) and/or CR2 (n = 4). The median number of bone marrow ( BM) and/or peripheral blood (PB) samples per patient was 18 ( range, 2 - 43). In 5 out of 6 cases relapse occurred after persistence of minimal residual disease (MRD) in CR for 4 - 14 months. The sixth patient relapsed despite molecular remission (MR) in BM and PB for 3 months, molecular relapse preceded hematological relapse for 7 months. Eleven patients with a median follow-up of 7.8 ( range, 1.5 - 15.4) years are in persistent CR and MR after consolidation chemotherapy (n = 7), mainly with repetitive cycles of high-dose Ara-C, autologous (n = 1) or myeloablative allogeneic (n = 3) stem cell transplantation. Molecular remission was attained immediately after alloSCT, but after 6 - 26 months in CR in patients with consolidation chemotherapy. In 7 patients, MRD was only studied in long-term remission. In conclusion, long-term CR was associated with persistent molecular disease-eradication. In our patients, molecular remission was a prerequisite but not a guarantee for long-term disease-free survival. Hematological relapse never occurred without prior molecular relapse. Due to the slow kinetics of AML1/ETO after consolidation chemotherapy the value of qualitative RT-PCR to predict early relapse is limited. In this situation quantitative RT-PCR might help to de. ne individual relapse risk and to improve as well as facilitate clinical decision-making.