The dynamics of RUNX1-RUNX1T1 transcript levels after allogeneic hematopoietic stem cell transplantation predict relapse in patients with t(8;21) acute myeloid leukemia

Background: The optimal monitoring schedules and cutoff minimal residual disease (MRD) levels for the accurate prediction of relapse at all time points after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remain unclear in patients with t(8;21) acute myeloid leukemia (AML). Methods: RUNX1-RUNX1T1 transcript levels were measured in bone marrow samples collected from 208 patients at scheduled time points after transplantation (1530 samples in total). Results: A total of 92.3% of the requested samples were collected, and 74.0% of patients had complete sample collection. The 1-, 3-, and 6-month RUNX1-RUNX1T1 transcript levels could significantly discriminate between continuous complete remission and a hematologic relapse at 1.5-3, 4-6, and 7-12 months but not at >3, >6, and >12 months, respectively. Over 90% of the 175 patients who were in continuous complete remission had a >= 3-log reduction in RUNX1-RUNX1T1 transcript levels from the time of diagnosis at each time point after transplantation and a >= 4-log reduction at >= 12 months. A <3-log reduction within 12 months and/or a <4-log reduction at >= 12 months was significantly related to a higher 3-year cumulative incidence of relapse (CIR) rate in both the entire cohort and the patients with no intervention after HSCT (58.4 vs. 2.2%, 76.5 vs. 2.0%; all P < 0.0001). Patients who had received a preemptive donor lymphocyte infusion when the increase in RUNX1-RUNX1T1 transcripts was <= 1-log according to the above dual cutoff values had significantly lower 1-year CIR rate after intervention than the patients who had received an infusion when the increase was >1-log (0 vs. 55.0%, P = 0.015). Conclusions: RUNX1-RUNX1T1 transcripts with a <3-log reduction from diagnosis within 12 months and/or a <4-log reduction at = 12 months after allo-HSCT could accurately predict relapse and may prompt a timely intervention in patients with t(8;21) AML.