Presence but not number of secondary type mutations influences outcome in de novo AML without MDS‐associated or recurring cytogenetic abnormalities

Abstract A group of gene mutations has been identified to be strongly associated with secondary acute myeloid leukemias (AML) arising from prior myeloid neoplasms. The International Consensus Classification (ICC) and proposed 5th edition of the World Health Organization (WHO) classification differ by inclusion of RUNX1. A recent study suggested that having two or more secondary mutations is associated with a particularly poor prognosis. In a study of 294 de novo AML patients, we found that patients with at least one ICC‐defined secondary mutation had shorter survival when compared to those without secondary mutations, and ICC/WHO groups of two or more mutations did not predict for worse outcomes.

. In both the WHO5 and ICC, the finding of morphologic dysplasia in AML is no longer used to distinguish de novo and secondary AML. A group of gene mutations has been identified to This  with lower blast counts and higher incidence of antecedent hematologic disease, but significant association with adverse outcomes was limited to patients with two or more mutations [7].
The majority of AML cases present de novo, without any known history of an antecedent myeloid neoplasm or exposure to cytotoxic therapy and are associated with heterogenous clinical outcomes, necessitating risk stratification at the time of diagnosis by clinicopathologic and genetic criteria [8]. We sought to determine the significance of 1 versus ≥2 secondary-type mutations in a series of de novo AML cases lacking specific recurrent cytogenetic abnormalities in order to evaluate the impact of ICC and WHO-defined secondary mutations on patient outcomes.

METHODS
We retrospectively identified de novo AML cases lacking cytogenetic features of AML with recurrent genetic abnormalities (AML-RGA) or AML with myelodysplasia-related changes (AML-MRC) per revised 4th edition WHO classification; cases with history of cytotoxic therapy or any prior myeloid neoplasm were excluded [9]. Patient and clinical characteristics, including treatments administered, patient follow-up, and outcome measures, were collected using the electronic health record. This study was approved by the institutional review boards of all participating institutions.
Next-generation sequencing (NGS) was performed on specimens taken either at the time of initial diagnosis or after the initial diagnosis in patients who had not been treated by any disease-modifying ther- Overall survival (OS) and event-free survival (EFS) were assessed using Kaplan-Meier method and groups were compared using log rank test.

RESULTS
A total of 294 patients of de novo AML were included in the study, with a median age of 65 years (range 18-100 In patients treated with induction or hypomethylating agents In multivariable analysis (Table S1), presence of ICC-SM1 (p = 0.038) and Tazi-SM2 (p = 0.004) predicted for shorter OS, while WHO-SM1 was not significant. Similar findings were also seen in multivariable analysis for EFS (Table S2).

DISCUSSION
The AML has historically been associated with resistance to conventional cytotoxic chemotherapy and with significantly lower complete remission rates and inferior OS [10,11]. Other studies have suggested that the prognosis of mutated RUNX1 AML is context dependent, with worse outcomes observed mainly in patients with ASXL1, SRSF2, and/or PHF6 co-mutations [12]. We found that ICC-SM1 group was associated with shorter OS and EFS regardless of therapy when compared with ICC-SM0, unlike WHO-SM1 group, which was only associated with worse OS.
Tazi et al. found that two or more secondary mutations are associated with a particularly poor prognosis versus the requirement of only a single mutation for MDS-related AML and included additional mutations in RUNX1, as well as NF1, CUX1, PHF6, SETBP1, and KMT2A PTD in defining secondary mutations [7]. PHF6 and NF1 mutations have been reported to be associated with worse prognosis in AML, including intermediate-risk subtype [13,14], while CUX1 mutations have been reported to be more common in secondary AML [15]. We confirm that Tazi