Cytogenetic Profiles of 472 Indian Children with Acute Myeloid Leukemia

Molecular evaluation of gene mutation profiles and copy number variations in pediatric acute myeloid leukemia

BACKGROUND

The objectives of this study were to investigate the mutation profiles of targeted genes and copy number variations (CNVs) in normal cytogenetics (CN) pediatric acute myeloid leukemia (AML).

METHODS

This prospective study was conducted from October 2018 to December 2020. The next-generation sequencing (NGS) and chromosomal microarray analyses (CMA) were performed in pediatric CN-AML patients.

RESULTS

Out of 94 children (aged ≤18 years), 70 patients with AML (24 excluded) underwent conventional karyotyping/cytogenetic analyses. Forty-five (64.3%) of patients had abnormal/ recurrent cytogenetic abnormalities and 25 (35.7%) had normal cytogenetics. Twenty-three out of 25 CN-AML were further processed for gene mutation profile and CNVs using NGS and CMA, respectively. Twenty-two out of 23 (95.7%) patients were detected to have mutations in various genes. The common mutations were: NRAS, NPM1, CEBPA, KRAS, KIT, RUNX1, NOTCH1, WT1, GATA1, GATA2, FLT3, KMT2D, FLT3-TKD, and PHF6. Copy number variations (CNVs) were detected in nine patients (39%), and eight (34.8%) had a long contiguous stretch of homozygosity (LCSH) /loss of heterozygosity (LOH). An LCSH was detected on chromosomes 5, 7, 11, and 19. The gains were more common than losses (8 vs 2). The gains were observed on chromosomes 8, 9, 14, 19, 21, and 22, and the losses were detected on chromosomes 7 and 10. Monosomy was observed in three patients. Three patients (monosomy7, n = 2, and FLT-ITD, n = 1) were reclassified into the high-risk category. Post-induction, complete remission was achieved in all evaluable patients.

CONCLUSION

CN-AML patients have genetic abnormalities that can be detected by more advanced techniques like NGS and CMA. These genetic abnormalities play a role in risk stratification that may remain hidden in otherwise CN-AML.

Molecular genetic characterization of acute myeloid leukemia with isolated trisomy of chromosomes 4, 11, and 21

BACKGROUND

Autosomal trisomy is a relatively rare abnormality observed in AML, occurring singly or as a secondary event in association with other karyotypic changes, and associated with prognosis. The molecular genetic and clinical characterizations of acute myeloid leukemia (AML) with isolated trisomy 4, 11, or 21 have been poorly investigated.

MATERIALS AND METHODS

Interphase fluorescence in situ hybridization, reverse transcriptase-quantitative polymerase chain reaction for 41 chromosomal gene translocations/fusion genes, and next-generation sequencing (NGS) were performed on 29 AML patients with trisomy 4, 11, or 21 as the sole chromosomal anomaly.

RESULTS

Of the 29 patients, one or more mutations were detected in 93.1% of patients. CEBPA had the highest mutation frequency, followed by TET2, NPM1, DNMT3A, and FLT3-ITD. The sole +11 AML patients exhibited more mutations in FLT3-ITD (P = .031) than the sole +21 AML patients, while CEBPA mutation was more frequently found in the sole +21 AML patients than that in the sole +11 AML patients(P = .07). The median overall survival (OS) and disease-free survival (DFS) for patients with +11 were shorter than those with +4(P = .015, 0.046) or +21 (0.057, 0.064), but no difference was found between +4 patients and +21 patients. In the whole cohort, only the FLT3-ITD mutation was significantly associated with inferior OS (18 vs. 35 months, P = .023) and DFS (12 months vs. NR, P = .046). There were no significant differences in OS and DFS according to the gene mutation status of CEBPA, TET2, NPM1, DNMT3A, and IDH1/2.

CONCLUSION

There was a significantly different mutation profile among the sole +4, +11, +21 AML patients. Our research provided new insight into the molecular characteristics of AML with isolated trisomy.

Allogeneic hematopoietic stem cell transplant in pediatric acute myeloid leukemia: Lessons learnt from a tertiary care center in India

There is paucity of data on outcomes of MSD-HSCT in children with relapsed or high-risk AML from developing countries, which have unique challenges including adverse host factors and resource constraints. We retrospectively reviewed records of children (age ≤ 18 years) who underwent MSD-HSCT for AML at our center from 2009 to 2019 to evaluate clinical outcome and its predictors using Cox proportional hazards model. There were 46 children (36 boys and 10 girls) with mean age 10.7 ± 4.8 years. Indication for HSCT was relapsed AML in CR2 (n = 37), primary refractory (n = 3), or relapsed refractory disease (n = 3); high-risk (n = 1) or secondary (n = 2) AML in CR1. Five-year EFS and OS were 33.3 ± 7.2% and 36.3 ± 7.6%, respectively. On multivariate analysis, CR1 duration less than 12 months, presence of active disease at transplant, and use of bone marrow stem cell graft were associated with poorer EFS and OS. There was one (2.2%) TRM, while disease relapse occurred in 20/40 patients who underwent HSCT in remission. Though the 5-year EFS and OS were inferior to results reported from high-income countries, relapse (and not TRM) was the major cause of treatment failure. A well-sustained CR1, achievement of disease remission, and use of peripheral blood allograft seem imperative to a successful transplant. Targeted therapy along with HSCT may be the option for those with early relapse.