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Secondary or therapy-related acute myeloid leukemia (s/tAML) differs biologically from de novo disease. In general s/tAML patients have inferior outcomes after chemotherapy, compared to de novo cases and often receive allogeneic stem cell transplantation (HSCT) for consolidation. The European LeukemiaNet (ELN) risk stratification system is commonly applied in AML but the clinical significance is unknown in s/tAML. We analyzed 644 s/tAML or de novo AML patients receiving HSCT. s/tAML associated with older age and adverse risk, including higher ELN risk. Overall, s/tAML patients had similar cumulative incidence of relapse (CIR), but higher non-relapse mortality (NRM) and shorter overall survival (OS). In multivariate analyses, after adjustment for ELN risk and pre-HSCT measurable residual disease status, disease origin did not impact outcomes. Within the ELN favorable risk group, CIR was higher in s/tAML compared to de novo AML patients likely due to a different distribution of genetic aberrations, which did not translate into shorter OS. Within the ELN intermediate and adverse group outcomes were similar in de novo and s/tAML patients. Thus, not all s/tAML have a dismal prognosis and outcomes of s/tAML after allogeneic HSCT in remission are comparable to de novo patients when considering ELN risk.

In 2017, an updated European LeukemiaNet (ELN) risk classification was published allocating patients with acute myeloid leukemia (AML) to 3 risk groups on the basis of certain cytogenetic and molecular aberrations. To date, studies of the prognostic significance of the ELN2017 risk classification in the context of an allogeneic hematopoietic stem cell transplantation (HSCT) are lacking. We performed risk stratification according to the ELN2017 classification in 234 patients with AML who underwent allogeneic HSCT as a consolidation therapy. In our cohort, the risk of 39.7% of the patients was classified as favorable, that of 12.8% as intermediate, and that of 47.4% as adverse. In the context of allogeneic HSCT, the assignment to the 3 ELN2017 risk groups retained its prognostic significance, with patients with favorable risk having the best prognosis and those with adverse risk having the worst one. Subgroup analyses showed that patients with a monosomal karyotype or TP53 mutation had considerably increased relapse rates, even in the adverse-risk group. When we analyzed the impact of digital droplet PCR-based measurable residual disease (MRD) before allogeneic HSCT, MRD+ patients had impaired prognoses, with cumulative incidence of relapse and overall survival comparable to those of patients classified as having an ELN2017 adverse genetic risk. This study is the first to demonstrate that the ELN2017 classification distinguishes the 3 risk groups with significantly distinct prognoses, even after allogeneic HSCT, and emphasizes the dismal prognosis of patients with AML with TP53 mutations, monosomal karyotype, or MRD positivity after allogeneic HSCT., (© 2020 by The American Society of Hematology.)

Age-related somatic mutations linked to clonal hematopoiesis have been found in apparently healthy individuals and increase the risk of developing hematologic malignancies. In acute myeloid leukemia (AML) the clinical relevance of clonal hematopoiesis remains controversial and data on patients with detectable clonal hematopoiesis, consolidated with hematopoietic stem cell transplantation are limited. We analyzed samples from 113 AML patients in complete remission prior to hematopoietic stem cell transplantation for the presence of clonal hematopoiesis-associated mutations. The results were correlated with clinical and biological data. In complete remission we found 75 mutations previously linked to clonal hematopoiesis in 47 patients (41.6%). Twenty patients had ≥2 mutations linked to clonal hematopoiesis. DNMT3A, TET2, and ASXL1 were most frequently mutated. When compared to pre-treatment samples we found variable patterns of mutation persistence depending on the gene mutated. In AML patients after allogeneic hematopoietic stem cell transplantation the presence of clonal hematopoiesis-associated mutations in complete remission did not associate with inferior clinical outcome. This study demonstrates that clonal hematopoiesis is a frequent phenomenon in AML patients. Presence of clonal hematopoiesis has no negative prognostic impact in the context of an allogeneic hematopoietic stem cell transplantation and might be beneficial if certain genes are affected.