Molecular Malfeasance Mediating Myeloid Malignancies: The Genetics of Acute Myeloid Leukemia

Assessing acquired resistance to IDH1 inhibitor therapy by full-exon IDH1 sequencing and structural modeling

Somatic mutations in hotspot regions of the cytosolic or mitochondrial isoforms of the isocitrate dehydrogenase gene (IDH1 and IDH2, respectively) contribute to the pathogenesis of acute myeloid leukemia (AML) by producing the oncometabolite 2-hydroxyglutarate (2-HG). The allosteric IDH1 inhibitor, ivosidenib, suppresses 2-HG production and induces clinical responses in relapsed/refractory IDH1-mutant AML. Herein, we describe a clinical case of AML in which we detected the neomorphic IDH1 p.R132C mutation in consecutive patient samples with a mutational hotspot targeted next-generation sequencing (NGS) assay. The patient had a clinical response to ivosidenib, followed by relapse and disease progression. Subsequent sequencing of the relapsed sample using a newly developed all-exon, hybrid-capture-based NGS panel identified an additional IDH1 p.S280F mutation known to cause renewed 2-HG production and drug resistance. Structural modeling confirmed that serine-to-phenylalanine substitution at this codon sterically hinders ivosidenib from binding to the mutant IDH1 dimer interface and predicted a similar effect on the pan-IDH inhibitor AG-881. Joint full-exon NGS and structural modeling enables monitoring IDH1 inhibitor-treated AML patients for acquired drug resistance and choosing follow-up therapy.

Gene mutation patterns of Chinese acute myeloid leukemia patients by targeted next-generation sequencing and bioinformatic analysis

PURPOSES

The conventional risk stratification of acute myeloid leukemia (AML), based on cytogenetics, cannot meet the demand for accurate prognostic evaluations. In recent years, gene mutations are found to be potential markers for more accurate risk stratification, but reports on mutation screening of Chinese AML are limited. We aim to display the mutation patterns of Chinese AML patients, reveal the genotype-phenotype correlations and make a comparison with Caucasians patients.

METHODS

Genome DNA from 78 patients' bone marrow were extracted for targeted gene mutation panel by next-generation sequencing (NGS) technology. Statistics and bioinformatics were used to analyze the correlations between gene mutations and clinical features, as well as the comparison of our results with the Cancer Genome Atlas Research Network (TCGA) public AML dataset.

RESULTS

We found patients with mutations of FLT3 and TET2 had higher bone marrow blasts, peripheral blasts and white blood cell (WBC) count, mutations of SRSF2 were related with age, and mutations of FLT3-ITD, DNMT3A, IDH1, TET2 and SRSF2 were risk factors for overall survival. What's more, we discovered 15 novel mutations and difference of mutational incidence in 6 genes between Chinese and Caucasians AML. Bioinformatic analysis revealed some relationship between gene mutations and expressions as well as drug sensitivities.

CONCLUSIONS

We made an investigation on the mutation patterns of Chinese AML patients by NGS technique and revealed correlations between gene mutations and clinical features. Thus we recommend routine testing of suspected genes for better prognostic prediction and individualized treatment.