Some novel features of IDH1-mutated acute myeloid leukemia revealed in Chinese patients

Optimized clinical application of minimal residual disease in acute myeloid leukemia with RUNX1-RUNX1T1

Minimal residual disease (MRD) levels monitored by polymerase chain reaction are associated with outcomes in acute myeloid leukemia with RUNX1-RUNX1T1. The objectives of our study were to quantitatively compare the predictive value of MRD reduction and absolute copies and assess the influence of other prognostic factors on MRD. A total of 224 consecutive patients with RUNX1-RUNX1T1 aged ≤55 years were included in the MRD study. Patients received different induction regimens including conventional- or intermediate-dose cytarabine plus low-dose daunorubicin and omacetaxine mepesuccinate or daunorubicin at 60 mg/m²/day on days 1-3. As continuous variables, both MRD reduction and absolute MRD level were significantly associated with cumulative incidence of relapse (CIR; hazard ratio [HR] = 1.610, 95% confidence interval [CI]: 1.370-1.890, p < 0.001, and HR = 1.170, 95% CI: 1.120-1.230, p < 0.001, respectively). For the CIR, the area under the curves (AUCs) of MRD reduction and absolute MRD level after the first consolidation chemotherapy were 0.629 and 0.629, respectively. Intermediate-dose cytarabine induction (HR = 0.494; p = 0.039 for CIR, HR, 0.451; p = 0.014 for RFS, and HR, 0.262; p = 0.006 for OS) remained significantly associated with outcomes after adjusting for MRD reduction after the first consolidation therapy (HR = 1.456, p < 0.001, for CIR; HR = 1.467, p = 0.001, for relapse-free survival; and HR = 1.468, p = 0.014, for overall survival) in multivariate analyses. In conclusion, the prognostic significance of MRD after the first consolidation therapy was influenced by the induction regimen in acute myeloid leukemia with RUNX1-RUNX1T1.

Chinese and Europeans with acute myeloid leukemia have discordant mutation topographies

Although the topography of mutations in persons of predominately European-descent with acute myeloid leukemia (AML) is well-described this is less so in Asians. We studied AML-related mutations in 289 consecutive Chinese (mostly Han) with newly-diagnosed de novo AML. Full-length coding sequence of NPM1 and CEBPA, IDH1 and IDH2 hotspot mutations and WT1 mutations in exons 7 and 9 were analyzed by PCR as were correlations with clinical and laboratory variables. CEBPA mutations were detected in 20% of subjects (95% confidence interval [CI] 15, 25%), NPM1 mutations in 20% (15, 25%), IDH1 mutations in 4% (1, 6%), IDH2 mutations in 11% (7, 15%) and WT1 mutations in 6% (3, 9%). A comparison of these data with mutation frequencies in persons of predominately European-descent with AML indicates a higher frequency of CEBPA mutations, a similar frequency of IDH2 mutations and lower frequencies of NPM1, IDH1 and WT1 mutations. Our data indicate different topographies of AML-associated mutations in Chinese compared with persons of predominately European descent suggesting genetic background, life-style, environment and perhaps other variables may influence these differences.

Beyond Brooding on Oncometabolic Havoc in IDH-Mutant Gliomas and AML: Current and Future Therapeutic Strategies

Isocitrate dehydrogenases 1 and 2 (IDH1,2), the key Krebs cycle enzymes that generate NADPH reducing equivalents, undergo heterozygous mutations in >70% of low- to mid-grade gliomas and ~20% of acute myeloid leukemias (AMLs) and gain an unusual new activity of reducing the α-ketoglutarate (α-KG) to D-2 hydroxyglutarate (D-2HG) in a NADPH-consuming reaction. The oncometabolite D-2HG, which accumulates >35 mM, is widely accepted to drive a progressive oncogenesis besides exacerbating the already increased oxidative stress in these cancers. More importantly, D-2HG competes with α-KG and inhibits a large number of α-KG-dependent dioxygenases such as TET (Ten-eleven translocation), JmjC domain-containing KDMs (histone lysine demethylases), and the ALKBH DNA repair proteins that ultimately lead to hypermethylation of the CpG islands in the genome. The resulting CpG Island Methylator Phenotype (CIMP) accounts for major gene expression changes including the silencing of the MGMT (O⁶-methylguanine DNA methyltransferase) repair protein in gliomas. Glioma patients with IDH1 mutations also show better therapeutic responses and longer survival, the reasons for which are yet unclear. There has been a great surge in drug discovery for curtailing the mutant IDH activities, and arresting tumor proliferation; however, given the unique and chronic metabolic effects of D-2HG, the promise of these compounds for glioma treatment is uncertain. This comprehensive review discusses the biology, current drug design and opportunities for improved therapies through exploitable synthetic lethality pathways, and an intriguing oncometabolite-inspired strategy for primary glioblastoma.

Prevalence and Prognostic Value of IDH1 R132 Mutation in Newly Diagnosed AML Egyptian Patients with Normal Karyotype

Mutation in IDH1 gene was suggested to be associated with bad prognosis in cytogenetically normal AML (CN-AML). However, there are conflicting data about its prognostic impact. Besides, its prevalence and prognostic significance in Egyptian patients still not fully stated. We aimed to assess the prevalence of IDH1^R132 mutation in Egyptian CN-AML patients, its correlation with FAB subtypes, and clinical outcome of those patients. Sequencing of amplified IDH1 gene exon four from 50 patients was performed to detect codon R132 point mutation. High prevalence of IDH1 mutation was detected in our patients (9/50, 18 %). Mutated IDH1^R132 was associated with older age and higher platelets count (p = 0.04 and 0.01 respectively). The most common FAB subtype associated with mutated IDH1^R132 was AML-M2 followed by M4. In multivariate analysis, IDH1^R132 mutation was found as independent prognostic variable. It was significantly associated with lower CR and shorter OS (p = 0.06 and 0.009 respectively).

Mutation Analysis of IDH1/2 Genes in Unselected De novo Acute Myeloid Leukaemia Patients in India - Identification of A Novel IDH2 Mutation

IDH1/2 mutations which result in alternation in DNA methylation pattern are one of the most common methylation associated mutations in Acute myeloid leukaemia. IDH1/2 mutations frequently associated with higher platelet level, normal cytogentics and NPM1 mutations. Here we analyzed IDH1/2 mutations in 200 newly diagnosed unselected Indian adult AML patients and investigated their correlation with clinical, cytogenetic parameters along with cooperating NPM1 mutation. We detected 5.5% and 4% mutations in IDH1/2 genes, respectively. Except IDH2 c.515_516GG>AA mutation, all the other identified mutations were reported mutations. Similar to reported c.515G>A mutation, the novel c.515_516GG>AA mutation replaces 172nd arginine to lysine in the active site of the enzyme. Even though there was a preponderance of IDH1/2 mutations in NK-AML, cytogenetically abnormal patients also harboured IDH1/2 mutations. IDH1 mutations showed significant higher platelet count and NPM1 mutations. IDH2 mutated patients displayed infrequent NPM1 mutations and lower WBC count. All the NPM1 mutations in the IDH1/2 mutated cases showed type A mutation. The present data suggest that IDH1/2 mutations are associated with normal cytogenetics and type A NPM1 mutations in adult Indian AML patients.

IDH1/IDH2 but not TP53 mutations predict prognosis in Bulgarian glioblastoma patients

Mutations in genes encoding isocitrate dehydrogenase isoforms 1 (IDH1) and 2 (IDH2) have been associated with good prognosis for patients with brain neoplasias and have been commonly found together with mutated TP53 gene. To determine the prevalence of IDH1, IDH2, and TP53 mutations and their impact on overall survival 106 glioblastoma patients were analysed. IDH1 mutations were detected in 13 and IDH2 mutation in one patient. Two homozygous samples with R132H mutation in IDH1 gene and a novel aberration K129R in IDH2 gene were found. Sixty-four percent of IDH1/IDH2 mutated tumours harboured also a mutation in TP53 gene. Genetic aberrations in TP53 were present in 37 patients. Statistical analysis of the impact of the studied factors on the overall survival showed that the mutations in IDH1/IDH2, but not the ones in TP53, were associated with longer survival. Also, the impact of age on prognosis was confirmed. This is the first comprehensive study on glioblastomas in Bulgaria. Our results suggest that IDH1/IDH2 but not TP53 mutations together with other prognostic factors such as age might be applied in clinical practice for prediction of outcome in patients with glioblastomas.

The Frequency and clinical significance of IDH1 mutations in Chinese acute myeloid leukemia patients

Objective

Mutations in the gene encoding isocitrate dehydrogenease 1 (IDH1) occur in various hematopoietic tumors including acute myeloid leukemia (AML), myeloproliferative neoplasms and myelodysplastic syndromes. IDH1 mutations are significant in both diagnosis and prognosis of these conditions. In the present study we determined the prevalence and clinical significance of IDH1 mutations in 349 samples from newly diagnosed AML patients.

Results

Of the 349 AML patient specimens analyzed, 35 (10.03%) were found to have IDH1 mutations including 4 IDH1 R132 mutations and 31 non-R132 mutations. IDH1 non-R132 mutations were largely concentrated within AML-M₁ (35.72%, p<0.01). We identified five IDH1 mutations that were novel to AML: (1) c.299 G>A, p.R100Q; (2) c.311G>T, p.G104V; (3) c.322T>C, p.F108L; (4) c.356G>A, p.R119Q; and (5) c.388A>G, p.I130V. In addition, we identified three IDH1 mutations that were previously described in AML. The frequency of IDH1 mutations in AML patients with normal karyotype was 9.9%. IDH1 non-R132 mutations were concurrent with mutations in FLT3-ITD (p<0.01), CEBPA (p<0.01), and NRAS (p<0.01), as well as the overexpression of MN1 (p<0.01) and WT1(p<0.01). The overall survival (OS) in the patients with IDH1 non-R132 mutations compared to patients without IDH1 mutations don't reach statistically significance (median 521 days vs median: not reached; n.s.).

Conclusion

IDH1 non-R132 mutations occurred frequently in newly diagnosed adult Chinese AML patients, and these mutations were associated with genetic alterations. The OS was not influenced by IDH1 non-R132 mutations in the present study.

Molecular evaluation of DNMT3A and IDH1/2 gene mutation: frequency, distribution pattern and associations with additional molecular markers in normal karyotype Indian acute myeloid leukemia patients

Mutations in the DNMT3A and IDH genes represent the most common genetic alteration after FLT3/NPM1 in acute myeloid leukemia (AML). We here analyzed the frequency and distribution pattern of DNMT3A and IDH mutations and their associations with other molecular markers in normal karyotype AML patients. Forty- five patients were screened for mutations in DNMT3A (R882), IDH1 (R132) and IDH2 (R140 and R172) genes by direct sequencing. Of the 45 patients screened, DNMT3A and IDH mutations were observed in 6 (13.3%) and 7 (15.4%), respectively. Patients with isolated DNMT3A mutations were seen in 4 cases (9%), isolated IDH mutations in 5 (11.1%), while interestingly, two cases showed both DNMT3A and IDH mutations (4.3%). Nucleotide sequencing of DNMT3A revealed missense mutations (R882H and R882C), while that of IDH revealed R172K, R140Q, R132H and R132S. Both DNMT3A and IDH mutations were observed only in adults, with a higher frequency in males. DNMT3A and IDH mutations were significantly associated with NPM1, while trends towards higher coexistence with FLT3 mutations were observed. This is the first study to evaluate DNMT3A/ IDH mutations in Indian patients. Significant associations among the various molecular markers was observed, that highlights cooperation between them and possible roles in improved risk stratification.

Prognostic value of IDH1 mutations identified with PCR-RFLP assay in acute myeloid leukemia patients

BACKGROUND

Somatic mutations in isocitrate dehydrogenase 1 (IDH1) gene occur frequently in primary brain tumors. Recently theses mutations were demonstrated in acute myeloid leukemia (AML). So far, assessment of these mutations relied on the DNA sequencing technique.

AIM OF THE WORK

The aim of this study was to detect somatic mutations in IDH1 gene using mismatched primers suitable for endonuclease based detection, without the need for DNA sequencing, and to estimate its prognostic value, on patients with de novo AML.

METHODS

Residual DNA extracted from pretreatment bone marrow (BM) samples of 100 patients with de novo AML was used. The polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) was adapted to IDH1gene, codon 132 mutations screening.

RESULTS

The frequency of IDH1 mutations was 13%. In the non-acute promyelocytic leukemia group (non-APL), IDH1 mutations were significantly associated with FLT3-ITD negative patients (p=0.03). Patients with IDH1 mutations did not achieve complete remission (CR). There was a trend for shorter overall survival (OS) in patients with IDH1 mutation compared to those with wild type (p=0.08).

CONCLUSION

IDH1 mutations are recurring genetic alterations in AML and they may have unfavorable impact on clinical outcome in adult AML. The PCR-RFLP method allows for a fast, inexpensive, and sensitive method for the detection of IDH1 mutations in AML.

Expanding the spectrum of IDH1 mutations in gliomas

Mutations in isocitrate dehydrogenase -1 or -2 (IDH1 or IDH2) are found in the majority of WHO grade II and III diffuse gliomas and secondary glioblastomas. IDH mutation screening is rapidly becoming part of the routine pathological work up of human brain tumors, providing both diagnostic and prognostic information. Here, we characterize four rare and novel IDH1 mutations identified in surgical human glioma samples: two instances of an IDH1 p.R132S mutation caused by a previously undescribed dinucleotide deletion/insertion mutation, a novel homozygous somatic IDH1 p.R132L mutation, and an IDH1 p.R100Q mutation. Characterization of novel and rare IDH mutations may provide additional insight into the mechanisms of mutant IDH in neoplasia. Furthermore, given the clinical import of IDH status, these results highlight the need for comprehensive mutation screening, beyond the targeted identification of common pathogenic variants.

Promoter Methylation Analysis of IDH Genes in Human Gliomas

Mutations in isocitrate dehydrogenase (IDH)-1 or -2 are found in the majority of WHO grade II and III astrocytomas and oligodendrogliomas, and secondary glioblastomas. Almost all described mutations are heterozygous missense mutations affecting a conserved arginine residue in the substrate binding site of IDH1 (R132) or IDH2 (R172). But the exact mechanism of IDH mutations in neoplasia is not understood. It has been proposed that IDH mutations impart a “toxic gain-of-function” to the mutant protein, however a dominant-negative effect of mutant IDH has also been described, implying that IDH may function as a tumor suppressor gene. As most, if not all, tumor suppressor genes are inactivated by epigenetic silencing, in a wide variety of tumors, we asked if IDH1 or IDH2 carry the epigenetic signature of a tumor suppressor by assessing cytosine methylation at their promoters. Methylation was quantified in 68 human brain tumors, including both IDH-mutant and IDH wildtype, by bisulfite pyrosequencing. In all tumors examined, CpG methylation levels were less than 8%. Our data demonstrate that inactivation of IDH function through promoter hypermethylation is not common in human gliomas and other brain tumors. These findings do not support a tumor suppressor role for IDH genes in human gliomas.

Mutation analysis of isocitrate dehydrogenase in acute lymphoblastic leukemia

BACKGROUND

Mutations at arginine 132 of isocitrate dehydrogenase 1/2 (IDH1/2) have recently been demonstrated to be recurrent gene alterations in acute myeloid leukemia (AML). Subsequently, this mutation was also found in a variety of other hematologic malignancies, including myelodysplastic syndromes, myeloproliferative diseases, and non-Hodgkin lymphoma. Only a few cases were so far identified in acute lymphoblastic leukemia (ALL). To study the IDH status in ALL patients, we analyzed 54 adult and 34 pediatric ALL samples' IDH1/2 gene.

RESULTS

Three adult cases and no pediatric case with an isocitrate dehydrogenase 1 (IDH1) mutation were identified. No isocitrate dehydrogenase 2 (IDH2) mutation was identified in the total of 88 samples. The frequency of the IDH1 mutation in adult ALL was 5.5%. Among the three IDH1-mutated patients, two had normal karyotype and expressed the myeloid lineage markers. All three patients with an IDH1 mutation relapsed or died within 6 months.

CONCLUSIONS

The results suggested that the IDH1 R132 mutation might be a recurrent gene alteration in ALL; patients carrying the mutation have a trend to aberrantly express myeloid antigen and the mutation may imply a dismal outcome.

Molecular alterations of isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) metabolic genes and additional genetic mutations in newly diagnosed acute myeloid leukemia patients

BACKGROUND

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) metabolic genes encode cytosolic and mitochondrial enzymes that catalyze the conversion of isocitrate to α-ketoglutarate. Acquired somatic mutations of IDH1 and IDH2 have recently been reported in some types of brain tumors and a small proportion of acute myeloid leukemia (AML) cases.

METHODS

Two-hundred and thirty newly diagnosed AML patients were analyzed for the presence of IDH1 and IDH2 heterozygous mutations by polymerase chain reaction-denaturing high performance liquid chromatography (PCR-DHPLC) followed by direct sequencing. Clinical and biological characteristics were analyzed and correlated to the IDH mutational status. Coexisting mutations such as FLT3, PML-RARA, RAS, AML1, and NPM1 mutations were additionally explored.

RESULTS

The prevalence of IDH1 and IDH2 mutations was 8.7% (20/230) and 10.4% (24/230), respectively. Six missense mutations were identified among IDH1-mutated cases; p.R132H (n = 8), p.R132C (n = 6), p.R132S (n = 2), p.R132G (n = 2), p.R132L (n = 1), and p.I99M (n = 1). Two missense mutations were found in IDH2-mutated cases; p.R140Q (n = 20) and p.R172K (n = 4). No patients had dual IDH1 and IDH2 mutations. About 18% of AML with normal cytogenetics and 31% of acute promyelocytic leukemia had IDH mutations. Half of the IDH-mutated cohort had normal karyotype and the major FAB subtype was AML-M2. Interestingly, IDH1- and IDH2-mutated cases predominantly had NPM1 mutations (60-74%) as compared to the wild type (P < 0.001). Very few IDH-mutated cases had FLT3 and/or RAS abnormalities and none of them had AML1 mutations. Older age and higher median platelet counts were significantly associated with IDH2 mutations although the clinical impact of either IDH1 or IDH2 mutations on patients' overall survival could not be observed.

CONCLUSION

Overall, 19% of newly diagnosed AML patients had alterations of IDH genes. No patients concurrently carried both IDH1 and IDH2 mutations suggesting that these mutations were mutually exclusive. NPM1 mutation appears as a major coexisting genetic mutation in IDH-mutated patients. Our present data failed to support the prognostic relevance of IDH mutations although alterations of these metabolic genes potentially have an important role in leukemia development.