Use of Measurable Residual Disease to Evolve Transplant Policy in Acute Myeloid Leukemia: A 20-Year Monocentric Observation

SIMPLE SUMMARY: Upfront genetics/cytogenetics and minimal measurable disease (MRD) are becoming relevant biomarkers in the process of post-remission transplant allocation in AML. However, until recently the transplantation choice relied on the availability of a fully matched familiar donor, whereas individual patient- and disease-related characteristics played a secondary role in transplant allocation. In this paper we analyzed the evolution of the transplantation policy at our center in a 20-year time interval. At the beginning of our observation patients were submitted to allogeneic transplant, per protocol, mostly if a fully matched family donor was available or to autologous transplant if no fully matched family donor was identified (“donor vs. no donor” strategy) regardless of upfront genetics/cytogenetics or MRD status. Thereafter, persistence of MRD after consolidation cycle was included in the decision-making process for transplant selection. Patients with favorable and intermediate-risk cytogenetic risk were to receive allogeneic or autologous stem cell transplantation if MRD positive or negative, respectively, (“transplant vs. no transplant” strategy). In this cohort, patients with FLT3-ITD or adverse risk karyotype were submitted to allogeneic transplant as well. ABSTRACT: Measurable residual disease (MRD) is increasingly employed as a biomarker of quality of complete remission (CR) in intensively treated acute myeloid leukemia (AML) patients. We evaluated if a MRD-driven transplant policy improved outcome as compared to a policy solely relying on a familiar donor availability. High-risk patients (adverse karyotype, FLT3-ITD) received allogeneic hematopoietic cell transplant (alloHCT) whereas for intermediate and low risk ones (CBF-AML and NPM1-mutated), alloHCT or autologous SCT was delivered depending on the post-consolidation measurable residual disease (MRD) status, as assessed by flow cytometry. For comparison, we analyzed a matched historical cohort of patients in whom alloHCT was delivered based on the sole availability of a matched sibling donor. Ten-years overall and disease-free survival were longer in the MRD-driven cohort as compared to the historical cohort (47.7% vs. 28.7%, p = 0.012 and 42.0% vs. 19.5%, p = 0.0003). The favorable impact of this MRD-driven strategy was evident for the intermediate-risk category, particularly for MRD positive patients. In the low-risk category, the significantly lower CIR of the MRD-driven cohort did not translate into a survival advantage. In conclusion, a MRD-driven transplant allocation may play a better role than the one based on the simple donor availability. This approach determines a superior outcome of intermediate-risk patients whereat in low-risk ones a careful evaluation is needed for transplant allocation.