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Published on: March 26, 2018
Integrative immunophenotypic and genetic characterization of acute myeloid leukemia with CBFB rearrangement
Fnu Sameeta1, Sa A Wang1, Zhenya Tang1
1Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, US.
Insights
This study characterizes acute myeloid leukemia (AML) with CBFB rearrangement, finding myeloblasts positive for CD34, CD117, and myeloperoxidase. The most common genetic alterations include inv(16) and type A fusion transcripts, with NRAS mutations being most frequent.
Area of Science:
- Hematology
- Oncology
- Molecular Biology
Background:
- Acute myeloid leukemia (AML) is a heterogeneous clonal hematopoietic stem cell disorder.
- CBFB rearrangements, particularly inv(16) and t(16;16), are recurrent genetic abnormalities in AML.
- Understanding the immunophenotypic profile and associated molecular alterations in AML with CBFB rearrangement is crucial for diagnosis and prognosis.
Purpose of the Study:
- To characterize the immunophenotype of acute myeloid leukemia (AML) with CBFB rearrangement.
- To correlate immunophenotypic findings with cytogenetic and molecular data.
- To identify common genetic mutations and transcript types in AML with CBFB rearrangement.
Main Methods:
- Flow cytometry immunophenotypic analysis of 61 AML cases with CBFB rearrangement.
- Karyotype analysis to identify cytogenetic abnormalities.
- Molecular analysis including transcript detection (CBFB::MYH11) and mutational analysis (NRAS, FLT3, KIT, NF1, TET2).
Main Results:
- Myeloblasts were consistently positive for CD34, CD117, and myeloperoxidase.
- The most frequent cytogenetic abnormality was inv(16)(p13.1q22) (83%), followed by t(16;16) (10%).
- Type A CBFB::MYH11 transcript was detected in 84% of cases. NRAS (37%), FLT3 (25%), and KIT (24%) mutations were common.
- Specific immunophenotypic differences (e.g., CD64, CD13, CD7, CD56 expression) and genetic alterations (Trisomy 22, KIT, NF1, TET2 mutations) were associated with type A transcripts.
Conclusions:
- AML with CBFB rearrangement typically presents with myeloblasts positive for CD34, CD117, and myeloperoxidase.
- inv(16)(p13.1q22) and type A CBFB::MYH11 fusion transcript are the most common findings.
- NRAS mutation is the most prevalent mutation in this AML subtype.
- Correlations between immunophenotype, transcript type, and genetic mutations provide insights into AML pathogenesis and potential therapeutic targets.
Objectives:
We sought to characterize the immunophenotype of acute myeloid leukemia (AML) with CBFB rearrangement and correlate the results with cytogenetic and molecular data.
Methods:
Sixty-one cases of AML with CBFB rearrangement were evaluated.
Results:
The sample population consisted of 33 men and 28 women, with a median age of 49 years. Flow cytometry immunophenotypic analysis showed that myeloblasts were positive for CD34 and CD117 in all cases, and myeloperoxidase was positive in 52 of 55 (95%) cases. The most common abnormalities included decreased CD38 in 90%, increased CD13 in 85%, increased CD123 in 84%, and decreased HLA-DR in 84% of cases. Monocytes were increased, with a mature immunophenotype, and accounted for 23.7% of total cells. Among 60 cases with available karyotype, inv(16)(p13.1q22) was most common in 50 (83%) cases, followed by t(16;16) (p13.1;q22) in 6 (10%). Type A CBFB::MYH11 transcript was most common, detected in 84% of cases. Mutational analysis showed mutations of NRAS in 37%, FLT3 in 25%, and KIT in 24% of cases. Comparing cases with type A vs non-type A transcripts, blasts in type A cases more frequently exhibited CD64 positivity and increased CD13 levels while showing a lower frequency of CD7 and CD56 expression. Trisomy 22 and mutations in KIT, NF1, and TET2 were identified only in cases with type A transcript.
Conclusions:
Myeloblasts of AML with CBFB rearrangement are positive for CD34, CD117, and myeloperoxidase. These neoplasms most frequently carry inv(16)(p13.1q22) and type A fusion transcript. NRAS mutation was the most common mutation. Some immunophenotypic and genetic correlations occurred with different types of transcripts.
