Measurable residual disease (MRD) before or after allogeneic hematopoietic cell transplantation (HCT) was an established independent predictor of poor prognosis in acute myeloid leukemia (AML). For a study, researchers sought to investigate how peri-HCT MRD dynamics could refine risk assessment across different conditioning intensities, they examined 810 adults in first or second remission after myeloablative conditioning (MAC; n=515) or non-MAC (n=295) who underwent multiparameter flow cytometry-based MRD testing before and 20 to 40 days after allografting. Patients who did not have MRD before and after HCT (MRDneg/MRDneg) had the lowest risk of recurrence and the best relapse-free survival (RFS) and overall survival (OS). In comparison to those patients, MRDpos/MRDpos and MRDneg/MRDpos patients had poor results regardless of conditioning intensity. MRDpos/MRDneg patients had intermediate outcomes. 

MRD was resolved more often with a MAC regimen (85 of 104; 81.7%) than with a non-MAC regimen (33 of 57; 57.9%) in 161 patients with MRD prior to HCT (P=.002). Although non-MAC regimens were less likely to eradicate MRD, the impact on outcome was larger if they did. Thus, for relapse (P=.020), RFS (P=.002), and OS (P=.001), there was a significant interaction between conditioning intensity and “MRD conversion.” Identical results were achieved in a sample of 590 patients who received HLA-matched allografts. C-statistic values for peri-HCT MRD dynamics were greater (meaning higher predictive accuracy) as compared to the solitary use of pre-HCT MRD status or post-HCT MRD status for prediction of relapse, RFS, and OS. In individuals with AML, peri-HCT MRD dynamics outperform solitary pre-or- post-HCT MRD measurements across conditioning intensities.