Prognostic impact of t(9;11) and del(7q) as intermediate-risk abnormalities in acute myeloid leukemia following allo-transplant: an Acute Leukemia Working Party study from the European Society for Blood and Marrow Transplantation

The European LeukemiaNet (ELN) 2022 classification categorized both t(9;11)(p21.3;q23.3) and isolated del(7q) in acute myeloid leukemia (AML) as intermediate-risk when treated with intensive chemotherapy. However, their prognostic relevance in the context of allogeneic hematopoietic cell transplantation (allo-HCT) needs further validation. This retrospective, registry-based analysis from the EBMT assessed outcomes in adults with AML who underwent allo-HCT in first complete remission between 2010 and 2022. In the first cohort, data from 141 patients with t(9;11) were analyzed, of whom 23% had additional adverse cytogenetic abnormalities (ACA), primarily complex karyotype. Most had de novo AML (72%), had received myeloablative conditioning (57%), and peripheral blood stem cells (88%). After a median follow-up of 3 years, there were no significant differences in 2-year relapse incidence (22% vs. 18.2%, p=0.85), leukemia-free survival (66% vs. 76%, p=0.42), or overall survival (72% vs. 75%, p=0.68) between patients with non-adverse t(9;11) and those with additional ACA. The second cohort included 250 patients: 84 with del(7q), 95 with monosomy 7, and 71 with del(5q), and all without additional ACA. Most had de novo AML (59%) and had received reduced-intensity conditioning (65%). After similar follow-up, survival outcomes did not differ significantly across the groups (2-year leukemia-free survival: 61% vs. 59% vs. 52% for del(7q), monosomy 7 and del(5q), respectively). In conclusion, these findings suggest that the prognostic value of t(9;11) as intermediate-risk remains consistent in the setting of allo-HCT regardless of additional ACA, whereas del(7q), even without additional ACA, confers a risk comparable to monosomy 7 and del(5q).