Previously, we observed that transcription factor RUNX1 mutations (RUNX1-MT) coexisted with ASXL1-MT in CMML and at myeloid blast phase of chronic myeloid leukemia.
In addition, the adverse prognostic impact of ASXL1<sup>MT</sup> was partially mitigated by concurrent TET2<sup>MT</sup>, with the ASXL1<sup>WT</sup>/TET2<sup>MT</sup> genotype having better outcomes and resulting in further risk stratification of ASXL1 inclusive CMML prognostic models, in comparison to ASXL1<sup>MT</sup> alone.
During the median follow-up of 14 months (range, 0-111 months), the overall survival (OS) of ASXL1⁺ CMML patients was significantly inferior to that of ASXL1⁻ CMML patients with a median survival of 11 months and 19 months, respectively (log-rank P=0.049).
This has resulted in the development of contemporary, molecularly integrated (inclusive of ASXL1 mutations) CMML prognostic models, including Molecular Mayo Model and the Groupe Français des Myélodysplasies model.
Exome sequencing studies in chronic myelomonocytic leukemia (CMML) illustrate a mutational landscape characterized by few somatic mutations involving a subset of recurrent gene mutations in ASXL1, SRSF2, and TET2, each approaching 40% in incidence.
Contemporary molecularly integrated CMML-specific prognostic models include the Groupe Francais des Myelodysplasies (GFM) model and the Molecular Mayo Model, both incorporating ASXL1 mutational status.
Here, we review recent biologic observations that support the current CMML WHO classification, such as the high frequency of SRSF2 and ASXL1 mutations compared with MDS and critical dependence of CMML cells on granulocyte-macrophage colony-stimulating factor signaling.
The current study confirms the independent prognostic value of nonsense/frameshift ASXL1 mutations in CMML and signifies its added value to the Mayo prognostic model, as had been shown previously in the French consortium model.
Somatic, heterozygous ASXL1 mutations were identified in 14/48 (29%) of patients with GATA2 deficiency, including four out of five patients who developed a proliferative chronic myelomonocytic leukemia.
We screened 45 patients with chronic myelomonocytic leukemia (n = 39 patients, including seven with transformed-acute myeloid leukemia), MDS/MPN unclassifiable (n = 5), and atypical BCR-ABL1-negative CML (n = 1) for mutations in ASXL1, CBL, NRAS, and TET2 genes by molecular genetics including a sensitive next-generation sequencing (NGS) technique.
In particular, ASXL1 mutations are common in patients with hematologic malignancies associated with myelodysplasia, including myelodysplastic syndromes (MDSs), and chronic myelomonocytic leukemia.
SRSF2 and U2AF1 along with TET2 (48%) and ASXL1 (38%) are frequently affected by somatic mutations in chronic myelomonocytic leukemia, quite distinctly from the profile seen in juvenile myelomonocytic leukemia.
We genotyped ASXL1 and up to 18 other genes including epigenetic (TET2, EZH2, IDH1, IDH2, DNMT3A), splicing (SF3B1, SRSF2, ZRSF2, U2AF1), transcription (RUNX1, NPM1, TP53), and signaling (NRAS, KRAS, CBL, JAK2, FLT3) regulators in 312 patients with CMML.
ASXL1 mutations are found in myeloproliferative neoplasms (MPN), myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia (AML).
Mutations of ASXL1 correlated with an evolution toward an acutely transformed state: all CMMLs that progressed to acute phase were mutated and none of the unmutated patients had evolved to acute leukaemia.