Validation of the revised 2022 European LeukemiaNet risk stratification in adult patients with acute myeloid leukemia

In 2022, the European LeukemiaNet (ELN) risk stratification for patients with acute myeloid leukemia (AML) has been updated. We aimed to validate the prognostic value of the 2022 ELN classification (ELN22) by evaluating 1570 patients with newly diagnosed AML (median age, 56 years) treated with cytarabine-based intensive chemotherapy regimens. Compared with 2017 ELN classification (ELN17), which allocated 595 (38%), 413 (26%), and 562 patients (36%) to the favorable-, intermediate-, and adverse-risk categories, ELN22 classified 575 (37%), 410 (26%), and 585 patients (37%) as favorable, intermediate, and adverse risk, respectively. Risk group allocation was revised in 340 patients (22%). Most patients were reclassified into the ELN22 intermediate- or ELN22 adverse-risk group. The allocation of patients according to the ELN22 risk categories resulted in a significantly distinct event-free survival (EFS), relapse-free survival, and overall survival (OS). Compared with ELN17, reallocation according to the ELN22 recommendations resulted in a significantly improved prognostic discrimination for OS (3-year area under the curve, 0.71 vs 0.67). In patients with ELN22 favorable-risk AML, co-occurring myelodysplasia-related (MR) gene mutations did not significantly affect outcomes. Within the ELN22 adverse-risk group, we observed marked survival differences across mutational groups (5-year OS rate of 21% and 3% in patients with MR gene mutations and TP53 mutations, respectively). In patients harboring MR gene mutations, EZH2-, STAG2-, and ZRSR2-mutated patients showed an intermediate-like OS. In patients with secondary AML and those who underwent allogeneic hematopoietic cell transplantation, EFS and OS significantly differed between ELN22 risk groups, whereas the prognostic abilities of ELN17 and ELN22 classifications were similar. In conclusion, ELN22 improves prognostic discrimination in a large cohort of intensively treated patients with AML. Given the heterogeneous outcome in patients with MR gene alterations, ranging between those of intermediate and adverse risk patients, we suggest re-evaluation of risk allocation in these patients.