VALIDATION OF THE REVISED 2022 EUROPEAN LEUKEMIANET RISK STRATIFICATION IN ADULT PATIENTS WITH ACUTE MYELOID LEUKEMIA

Abstract

In 2022, the European LeukemiaNet (ELN) risk stratification for patients with AML has been updated. We aimed to validate the prognostic value of the 2022 ELN classification (ELN22) evaluating 1,570 newly diagnosed AML patients (median age, 56 years) treated with cytarabine-based intensive chemotherapy regimens. As compared to the 2017 ELN classification (ELN17), allocating 595 (38%), 413 (26%) and 562 (36%) patients to the favorable, intermediate and adverse risk category, ELN22 risk was favorable, intermediate, and adverse in 575 (37%), 410 (26%), and 585 (37%) patients, respectively. Risk group allocation was revised in 340 patients (22%). Most patients were re-classified into 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 (RFS), and overall survival (OS). As compared to ELN17, reallocation according to the ELN22 recommendations resulted in a significantly improved prognostic discrimination for OS (3-year area under the curve (AUC) 0.71 vs. 0.67). In patients with ELN22 favorable risk AML, co-occurring MR gene mutations did not significantly impact outcome. 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 myelodysplasia-related (MR) gene mutations and TP53-mutated patients, 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 HCT, EFS and OS significantly differed between ELN22 risk groups, while prognostic abilities of ELN17 and ELN22 classifications were similar. In conclusion, the ELN22 risk stratification improves prognostic discrimination in a large cohort of intensively treated AML patients. Given the heterogeneous outcome in patients with MR gene alterations, ranging between those of intermediate and adverse risk patients, we suggest reevaluation of risk allocation in these patients.