Contributions
Abstract: PB1616
Type: Publication Only
Session title: Myelodysplastic syndromes - Biology & Translational Research
Background
Chronic Myelomonocytic Leukemia (CMML) is a heterogeneous disease, with overlapping features of myelodysplastic and myeloproliferative syndromes. Both immunophenotypic alterations and recurrent somatic mutations are found in CMML patients and can provide useful information on diagnosis and prognosis.
Aims
Immunophenotypic characterization of bone marrow compartments and its correlation with genetic alterations in a group of CMML patients (WHO2016).
Methods
Retrospective immunophenotypic analysis was performed according to EuroFlow panels and the Mean Fluorescence Intensity (MFI) from bone marrow (BM) granulocyte, monocyte and erythroid compartments of CMML patients (n=47) and from a normal BM (healthy group HG, n=16) was recorded. In 33 patients, targeted gene sequencing of 45 genes recurrently mutated in myeloid malignancies was performed on an Ion S5 (Thermo Fisher). Statistical analysis was done using SPSSv26.
Results
CMML patients were 70% male, median age 72y. WHO Classification: 42% CMML-0; 42% CMML-1; 16% CMML-2. FAB-Classification: 40% proliferative, 60% dysplastic. AML progression occurred in 13%, with a median time of 15 months. Mutations were identified in 97% of patients, with a median of 3 (0-7). ASXL1 (55%), TET2 (52%) and RAS pathway (22%) were the most frequently mutated genes. CPSS-Mol risk score was: 14% low; 20% int-1; 33% int-2; 33% high. Mutations in epigenetic modifiers genes alone (group A) were found in 21% and simultaneously with signal transduction genes (group B) in 36% of patients. Patients with mutated epigenetic modifiers had lower hemoglobin levels (p<0.05). We found an association between ASXL1 mutations and increased leukocyte count and between ASXL1 and RAS mutations with proliferative-CMML (p<0.05). Flow cytometry analysis of CMML BM revealed statistically significant differences in MFI in granulocyte (CD10, CD13, CD45), monocyte (CD11b, CD36, CD45, HLA-DR) and erythroid (CD45, CD105, CD117) maturation, compared with HG. Both genetic groups A and B showed an increased MFI in CD45 in granulocyte and CD36, CD45, HLA-DR in monocyte maturation when compared to HG and increased CD11b MFI in monocyte maturation on group B. Decreased MFI in CD10, CD13 in granulocyte and CD45, CD105, CD117 in erythroid maturation also occurred in both groups. The more pronounced changes found in erythroid maturation in group A patients could be related to their lower hemoglobin levels, but further studies are required. We observed no differences in MFI in the analysed markers among WHO classification or CPSS-Mol Score groups, but progression to AML was associated with increased MFI in CD45, CD11b, CD13 in granulocyte and CD45, HLA-DR in monocyte maturation (p<0.05).
Conclusion
In CMML, there seems to be a specific immunophenotypic expression pattern in granulocyte, monocyte and erythroid maturation. Contrary to the remaining CMML BM, patients with mutations in epigenetic modifiers genes alone did not show a significant increase in CD11b expression in monocyte maturation. In our cohort, progression to AML was associated with specific immunophenotypic changes. Detailed immunophenotyping of different BM maturation compartments can further improve our understanding of CMML and help to better refine risk and prognosis classification of such heterogeneous disease.
Keyword(s): Chronic myelomonocytic leukemia, Flow cytometry, Mutation status
Abstract: PB1616
Type: Publication Only
Session title: Myelodysplastic syndromes - Biology & Translational Research
Background
Chronic Myelomonocytic Leukemia (CMML) is a heterogeneous disease, with overlapping features of myelodysplastic and myeloproliferative syndromes. Both immunophenotypic alterations and recurrent somatic mutations are found in CMML patients and can provide useful information on diagnosis and prognosis.
Aims
Immunophenotypic characterization of bone marrow compartments and its correlation with genetic alterations in a group of CMML patients (WHO2016).
Methods
Retrospective immunophenotypic analysis was performed according to EuroFlow panels and the Mean Fluorescence Intensity (MFI) from bone marrow (BM) granulocyte, monocyte and erythroid compartments of CMML patients (n=47) and from a normal BM (healthy group HG, n=16) was recorded. In 33 patients, targeted gene sequencing of 45 genes recurrently mutated in myeloid malignancies was performed on an Ion S5 (Thermo Fisher). Statistical analysis was done using SPSSv26.
Results
CMML patients were 70% male, median age 72y. WHO Classification: 42% CMML-0; 42% CMML-1; 16% CMML-2. FAB-Classification: 40% proliferative, 60% dysplastic. AML progression occurred in 13%, with a median time of 15 months. Mutations were identified in 97% of patients, with a median of 3 (0-7). ASXL1 (55%), TET2 (52%) and RAS pathway (22%) were the most frequently mutated genes. CPSS-Mol risk score was: 14% low; 20% int-1; 33% int-2; 33% high. Mutations in epigenetic modifiers genes alone (group A) were found in 21% and simultaneously with signal transduction genes (group B) in 36% of patients. Patients with mutated epigenetic modifiers had lower hemoglobin levels (p<0.05). We found an association between ASXL1 mutations and increased leukocyte count and between ASXL1 and RAS mutations with proliferative-CMML (p<0.05). Flow cytometry analysis of CMML BM revealed statistically significant differences in MFI in granulocyte (CD10, CD13, CD45), monocyte (CD11b, CD36, CD45, HLA-DR) and erythroid (CD45, CD105, CD117) maturation, compared with HG. Both genetic groups A and B showed an increased MFI in CD45 in granulocyte and CD36, CD45, HLA-DR in monocyte maturation when compared to HG and increased CD11b MFI in monocyte maturation on group B. Decreased MFI in CD10, CD13 in granulocyte and CD45, CD105, CD117 in erythroid maturation also occurred in both groups. The more pronounced changes found in erythroid maturation in group A patients could be related to their lower hemoglobin levels, but further studies are required. We observed no differences in MFI in the analysed markers among WHO classification or CPSS-Mol Score groups, but progression to AML was associated with increased MFI in CD45, CD11b, CD13 in granulocyte and CD45, HLA-DR in monocyte maturation (p<0.05).
Conclusion
In CMML, there seems to be a specific immunophenotypic expression pattern in granulocyte, monocyte and erythroid maturation. Contrary to the remaining CMML BM, patients with mutations in epigenetic modifiers genes alone did not show a significant increase in CD11b expression in monocyte maturation. In our cohort, progression to AML was associated with specific immunophenotypic changes. Detailed immunophenotyping of different BM maturation compartments can further improve our understanding of CMML and help to better refine risk and prognosis classification of such heterogeneous disease.
Keyword(s): Chronic myelomonocytic leukemia, Flow cytometry, Mutation status