Prognostic significance of alterations in IDH enzyme isoforms in patients with AML treated with high-dose cytarabine and idarubicin

Influence of genetic co-mutation on chemotherapeutic outcome in NPM1-mutated and FLT3-ITD wild-type AML patients

BACKGROUND

Nucleophosmin 1 (NPM1) gene-mutated acute myeloid leukemia (NPM1mut AML) is classified as a subtype with a favorable prognosis. However, some patients fail to achieve a complete remission or relapse after intensified chemotherapy. Genetic abnormalities in concomitant mutations contribute to heterogeneous prognosis of NPM1mut AML patients.

METHODS

In this study, 91 NPM1-mutated and FLT3-ITD wild-type (NPM1mut/FLT3-ITDwt) AML patients with intermediate-risk karyotype were enrolled to analyze the impact of common genetic co-mutations on chemotherapeutic outcome.

RESULTS

Our data revealed that TET1/2 (52/91, 57.1%) was the most prevalent co-mutation in NPM1mut AML patients, followed by IDH1/2 (36/91, 39.6%), DNMT3A (35/91, 38.5%), myelodysplastic syndrome related genes (MDS-related genes) (ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1 and ZRSR2 genes) (35/91, 38.5%), FLT3-TKD (27/91, 29.7%) and GATA2 (13/91, 14.3%) mutations. Patients with TET1/2mut exhibited significantly worse relapse-free survival (RFS) (median, 28.7 vs. not reached (NR) months; p = 0.0382) compared to patients with TET1/2wt, while no significant difference was observed in overall survival (OS) (median, NR vs. NR; p = 0.3035). GATA2mut subtype was associated with inferior OS (median, 28 vs. NR months; p < 0.0010) and RFS (median, 24 vs. NR months; p = 0.0224) compared to GATA2wt. By multivariate analysis, GATA2mut and MDS-related genesmut were independently associated with worse survival.

CONCLUSION

Mutations in TET1/2, GATA2 and MDS-related genes were found to significantly influence the chemotherapeutic outcome of patients with NPM1mut AML. The findings of our study have significant clinical implications for identifying patients who have an adverse response to frontline chemotherapy and provide a novel reference for further prognostic stratification of NPM1mut/FLT3-ITDwt AML patients.

IDH2 mutations in acute myeloid leukemia

Advances in the treatment of acute myeloid leukemia (AML) over the last 40 years have been limited. With an improved understanding of the pathophysiology of the disease, the advent of new treatment options has enriched the armamentarium of the physician to combat the disease. Mutations of the isocitrate dehydrogenase (IDHs) genes are common in AML and occur in 20-30% of cases. These mutations lead to DNA hypermethylation, aberrant gene expression, cell proliferation, and abnormal differentiation. Targeting mutant IDH, either as monotherapy or in combination with hypomethylating agents (HMAs) or BCL-2 inhibitors, has opened new avenues of therapy for these patients.This review will outline the function of IDHs and focus on the biological effects of IDH2 mutations in AML, their prognosis and treatment options.

Characteristics and prognostic impact of IDH mutations in AML: a COG, SWOG, and ECOG analysis

Somatic mutations in isocitrate dehydrogenase (IDH) genes occur frequently in adult acute myeloid leukemia (AML) and less commonly in pediatric AML. The objective of this study was to describe the prevalence, mutational profile, and prognostic significance of IDH mutations in AML across age. Our cohort included 3141 patients aged between <1 month and 88 years treated on Children's Cancer Group/Children's Oncology Group (n = 1872), Southwest Oncology Group (n = 359), Eastern Cooperative Oncology Group (n = 397) trials, and in Beat AML (n = 333) and The Cancer Genome Atlas (n = 180) genomic characterization cohorts. We retrospectively analyzed patients in 4 age groups (age range, n): pediatric (0-17, 1744), adolescent/young adult (18-39, 444), intermediate-age (40-59, 640), older (≥60, 309). IDH mutations (IDHmut) were identified in 9.2% of the total cohort (n = 288; IDH1 [n = 123, 42.7%]; IDH2 [n = 165, 57.3%]) and were strongly correlated with increased age: 3.4% pediatric vs 21% older, P < .001. Outcomes were similar in IDHmut and IDH-wildtype (IDHWT) AML (event-free survival [EFS]: 35.6% vs 40.0%, P = .368; overall survival [OS]: 50.3% vs 55.4%, P = .196). IDH mutations frequently occurred with NPM1 (47.2%), DNMT3A (29.3%), and FLT3-internal tandem duplication (ITD) (22.4%) mutations. Patients with IDHmut AML with NPM1 mutation (IDHmut/NPM1mut) had significantly improved survival compared with the poor outcomes experienced by patients without (IDHmut/NPM1WT) (EFS: 55.1% vs 17.0%, P < .001; OS: 66.5% vs 35.2%, P < .001). DNTM3A or FLT3-ITD mutations in otherwise favorable IDHmut/NPM1mut AML led to inferior outcomes. Age group analysis demonstrated that IDH mutations did not abrogate the favorable prognostic impact of NPM1mut in patients aged <60 years; older patients had poor outcomes regardless of NPM1 status. These trials were registered at www.clinicaltrials.gov as #NCT00070174, #NCT00372593, #NCT01371981, #NCT00049517, and #NCT00085709.

Pediatric acute myeloid leukemia: Insight into genetic landscape and novel targeted approaches

Acute myeloid leukemia (AML) is a very heterogeneous hematological malignancy that accounts for approximately 20% of all pediatric leukemia cases. The outcome of pediatric AML has improved over the last decades, with overall survival rates reaching up to 70%. Still, AML is among the leading types of pediatric cancers by its high mortality rate. Modulation of standard therapy, like chemotherapy intensification, hematopoietic stem cell transplantation and optimized supportive care, could only get this far, but for the significant improvement of the outcome in pediatric AML, development of novel targeted therapy approaches is necessary. In recent years the advances in genomic techniques have greatly expanded our knowledge of the AML biology, revealing molecular landscape and complexity of the disease, which in turn have led to the identification of novel therapeutic targets. This review provides a brief overview of the genetic landscape of pediatric AML, and how it's used for precise molecular characterization and risk stratification of the patients, and also for the development of effective targeted therapy. Furthermore, this review presents recent advances in molecular targeted therapy and immunotherapy with an emphasis on the therapeutic approaches with significant clinical benefits for pediatric AML.

Molecularly Targeted Therapy in Acute Myeloid Leukemia: Current Treatment Landscape and Mechanisms of Response and Resistance

Treatment for acute myeloid leukemia (AML) has evolved rapidly over the last decade as improved understanding of cytogenetic and molecular drivers of leukemogenesis refined survival prognostication and enabled development of targeted therapeutics. Molecularly targeted therapies are now approved for the treatment of FLT3 and IDH1/2-mutated AML and additional molecularly and cellularly targeted therapeutics are in development for defined patient subgroups. Alongside these welcome therapeutic advancements, increased understanding of leukemic biology and treatment resistance has resulted in clinical trials investigating combinations of cytotoxic, cellular, and molecularly targeted therapeutics resulting in improved response and survival outcomes in patients with AML. Herein, we comprehensively review the current landscape of IDH and FLT3 inhibitors in clinical practice for the treatment of AML, highlight known resistance mechanisms, and discuss new cellular or molecularly targeted therapies currently under investigation in ongoing early phase clinical trials.

Impact of mutations in epigenetic modifiers in acute myeloid leukemia: A systematic review and meta-analysis

This is a systematic review and meta-analysis evaluating the prognostic significance of epigenetic mutations on the overall survival (OS) in Acute Myeloid Leukemia (AML). We searched for studies evaluating epigenetic mutations in AML (up to November 2018) in PubMed, Trip database and Cochrane library. Hazard ratio (HR) of outcomes were extracted, and random-effects model was used to pool the results. A total of 10,002 citations were retrieved from the search strategy; 42 articles were identified for the meta-analysis (ASXL1 = 7, TET2 = 8, DNMT3A = 12, IDH =15), with fair to good-quality studies. The pooled HR was 1.88 (95% CI: 1.49-2.36) for ASXL1 mutation, 1.39 (95% CI: 1.18-1.63) for TET2 mutation, 1.35 (95% CI 1.16-1.56) for DNMT3a and 1.54 (95% CI: 1.15-2.06) for IDH mutation. However, there was a substantial heterogeneity in the DNMT3a and IDH studies. In conclusion epigenetic mutations in ASXL1, TET2, DNMT3a and IDH adversely impact OS in patients with AML albeit with considerable heterogeneity and possibly publication bias. Further studies are required to address these limitations.

Contemporary outcomes in IDH-mutated acute myeloid leukemia: The impact of co-occurring NPM1 mutations and venetoclax-based treatment

Isocitrate dehydrogenase 1 or 2 (IDH1 or IDH2) mutations occur frequently in newly diagnosed (ND) acute myeloid leukemia (AML) often with co-occurring NPM1 mutations, which may influence treatment outcomes. Detailed analysis of IDH-mutated AML treated with venetoclax and influence of co-occurring NPM1 mutations remains unclear. This retrospective single-center cohort study evaluated clinical and molecular demographics,response and survival, and impact of co-occurring NPM1 mutations in patients with IDH1 or IDH2-mutated AML. 556 patients with IDH1, IDH2, and/or NPM1 mutated AML were included. Patients with IDH1^mut AML (N = 119) were more likely to have older age, sAML, ELN-adverse risk disease, and adverse-risk cytogenetics compared to those with IDH2^mut (N = 229) or IDH^wt /NPM1^mut AML (N = 208). In multivariate analysis, patients with IDH2^mut (HR 0.61 [95%CI: 0.43-0.88], p value: .007) or IDH^wt /NPM1^mut (HR 0.65 [95% CI: 0.45-0.94], p value: .024) AML had a decreased risk of death versus IDH1^mut AML. Venetoclax-based lower-intensity regimens partially abrogated the detrimental effect of IDH1^mut with similar OS observed between IDH1^mut /NPM1^wt , IDH2^mut /NPM1^wt , and IDH^wt /NPM1^mut AML. With regards to the influence of IDH^mut /NPM1^mut cases, IC improved survival in IDH2^mut /NPM1^mut versus IDH2^mut /NPM1^wt AML (HR: 0.54 [95% CI: 0.2644-1.082], p value: .077), while venetoclax-based therapy improved survival in IDH1^mut /NPM1^mut versus IDH1^mut /NPM1^wt AML (HR: 0.094 [95% CI: 0.01-0.74], p value: .0056). Differing outcomes were observed in IDH1^mut versus IDH2^mut or NPM1^mut AML which were influenced by co-occurring NPM1 mutations and partially abrogated with venetoclax-based therapy. Given the differing biology and survival in IDH1^mut AML, investigations incorporating molecularly targeted therapies such as IDH inhibitors remain warranted in this subgroup.

Impact of IDH1 and IDH2 mutation detection at diagnosis and in remission in patients with AML receiving allogeneic transplantation

Somatic mutations in the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) are common in acute myeloid leukemia (AML). The prognostic impact of the presence of IDH mutations may be influenced by the comutational status, the specific location of the mutation (ie, IDH1 R132, IDH2 R140, and IDH2 R172) at diagnosis, and the dynamics of the mutation burden during disease course. Even though many patients with IDH-mutated AML are consolidated by hematopoietic stem cell transplantation (HSCT), the underlying biology and prognostic consequences remain largely unknown. Here, we present a large analysis of 292 patients with AML who received HSCT in complete remission (CR) or CR with incomplete peripheral recovery (CRi), in which we assessed the IDH mutation status at diagnosis and HSCT as a potential marker for measurable residual disease (MRD). About a quarter of all patients were IDH-mutated at diagnosis. The diagnostic presence of IDH mutations in AML did not have a significant prognostic impact when consolidated with HSCT. However, IDH1 R132 and IDH2 R172 MRD positivity in remission at HSCT associated with an increased risk of relapse, while IDH2 R140 mutations did not. The IDH2 R140 variant allele frequency (VAF) at diagnosis was higher, clustering around 50%, and the mutation clearance at HSCT in morphologic remission was much lower compared with IDH1 R132 and IDH2 R172. In our cohort, IDH2 R140 mutations behaved more like a clonal hematopoiesis-related aberration, while IDH1 R132 and IDH2 R172 harbored AML disease-specific features.

SOHO State of the Art Updates and Next Questions: IDH Inhibition

There has been extraordinary progress in the field of targeted therapy for myeloid malignancies in the last few years, especially due to the approval of various agents that can be used as monotherapy or in combination as first-line treatment or when facing a refractory or relapsed disease. Many successful trials have been conducted recently, and a consistent body of work about the efficacy of novel molecules is now available. In this review, we sought to explain how enasidenib and ivosidenib have changed the face of myeloid neoplasm treatment through isocitrate dehydrogenase inhibition and to summarize the trials results that have led to the current commercial indications for the two molecules.

Adverse Impact of DNA Methylation Regulatory Gene Mutations on the Prognosis of AML Patients in the 2017 ELN Favorable Risk Group, Particularly Those Defined by NPM1 Mutation

The 2017 ELN risk stratification has been widely adopted, but some studies have suggested the outcomes are heterogenous within the ELN risk groups and may be affected by other co-existing genetic mutations. This study evaluated the impact of DNA methylation regulatory gene (TET2, IDH1/2, DNMT3A, SETBP1) mutations (DMRGM) evaluated by NGS in the outcome of AML patients in each ELN risk group. A total of 114 patients were analyzed with a median follow-up of 12 months. Overall, 30.7% (35/114) of patients had DMRGM. DMRGM status had no impact on CR rate in each ELN risk group. The OS, however, was significantly shorter in patients with DMRGM compared to those without DMRGM (median OS: 12 vs. 33 months, p = 0.0053). Multivariate analysis showed DMRGM status was an independent unfavorable factor for OS (HR: 2.704, 95% CI: 1.451–5.041, p = 0.0017). The adverse OS impact of DMRGM was only observed in the ELN favorable group (7 months vs. not reached, p = 0.0001), but not in the intermediate or adverse group. Among the favorable group with DMRGM (n = 16), DMRGM occurred predominantly in cases with mutated NPM1 (15/16, or 93.8%). Our results suggest that DMRGM adversely impact the outcomes of ELN favorable group patients, particularly those with mutated NPM1. Further studies are warranted to confirm our observations.

IDH2 mutations in patients with normal karyotype AML predict favorable responses to daunorubicin, cytarabine and cladribine regimen

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) genes occur in about 20% patients with acute myeloid leukemia (AML), leading to DNA hypermethylation and epigenetic deregulation. We assessed the prognostic significance of IDH1/2 mutations (IDH1/2⁺) in 398 AML patients with normal karyotype (NK-AML), treated with daunorubicine + cytarabine (DA), DA + cladribine (DAC), or DA + fludarabine. IDH2 mutation was an independent favorable prognostic factor for 4-year overall survival (OS) in total NK-AML population (p = 0.03, censoring at allotransplant). We next evaluated the effect of addition of cladribine to induction regimen on the patients’ outcome according to IDH1/2 mutation status. In DAC group, 4-year OS was increased in IDH2⁺ patients, compared to IDH-wild type group (54% vs 33%; p = 0.0087, censoring at allotransplant), while no difference was observed for DA-treated subjects. In multivariate analysis, DAC independently improved the survival of IDH2⁺ patients (HR = 0.6 [0.37–0.93]; p = 0.024; censored at transplant), indicating that this group specifically benefits from cladribine-containing therapy. In AML cells with R140Q or R172K IDH2 mutations, cladribine restrained mutations-related DNA hypermethylation. Altogether, DAC regimen produces better outcomes in IDH2⁺ NK-AML patients than DA, and this likely results from the hypomethylating activity of cladribine. Our observations warrant further investigations of induction protocols combining cladribine with IDH1/2 inhibitors in IDH2-mutant.

IDH1/2 mutations in acute myeloid leukemia patients and risk of coronary artery disease and cardiac dysfunction-a retrospective propensity score analysis

Clonal hematopoiesis of indeterminate potential (CHIP) is linked to leukemia gene mutations and associates with an increased risk for coronary artery disease and poor prognosis in ischemic cardiomyopathy. Two recurrently mutated genes in CHIP and adult acute myeloid leukemia (AML) encode for isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2). Global expression of mutant IDH2 in transgenic mice-induced dilated cardiomyopathy and muscular dystrophy. In this retrospective observational study, we investigated whether mutant IDH1/2 predisposes to cardiovascular disease in AML patients. Among 363 AML patients, IDH1 and IDH2 mutations were detected in 26 (7.2%) and 39 patients (10.7%), respectively. Mutant IDH1 patients exhibited a significantly higher prevalence of coronary artery disease (26.1% vs. 6.4%, p = 0.002). Applying inverse probability-weighting analysis, patients with IDH1/2 mutations had a higher risk for a declining cardiac function during AML treatment compared to IDH1/2 wild type patients [left ventricular ejection fraction pretreatment compared to 10 months after diagnosis: 59.2% to 41.9% (p < 0.001) vs 58.5% to 55.4% (p = 0.27), respectively]. Mechanistically, RNA sequencing and immunostaining in hiPS-derived cardiomyocytes indicated that the oncometabolite R-2HG exacerbated doxorubicin mediated cardiotoxicity. Evaluation of IDH1/2 mutation status may therefore help identifying AML patients at risk for cardiovascular complications during cytotoxic treatment.

A novel Cas9-targeted long-read assay for simultaneous detection of IDH1/2 mutations and clinically relevant MGMT methylation in fresh biopsies of diffuse glioma

Molecular biomarkers provide both diagnostic and prognostic results for patients with diffuse glioma, the most common primary brain tumor in adults. Here, we used a long-read nanopore-based sequencing technique to simultaneously assess IDH mutation status and MGMT methylation level in 4 human cell lines and 8 fresh human brain tumor biopsies. Currently, these biomarkers are assayed separately, and results can take days to weeks. We demonstrated the use of nanopore Cas9-targeted sequencing (nCATS) to identify IDH1 and IDH2 mutations within 36 h and compared this approach against currently used clinical methods. nCATS was also able to simultaneously provide high-resolution evaluation of MGMT methylation levels not only at the promoter region, as with currently used methods, but also at CpGs across the proximal promoter region, the entirety of exon 1, and a portion of intron 1. We compared the methylation levels of all CpGs to MGMT expression in all cell lines and tumors and observed a positive correlation between intron 1 methylation and MGMT expression. Finally, we identified single nucleotide variants in 3 target loci. This pilot study demonstrates the feasibility of using nCATS as a clinical tool for cancer precision medicine.

IDH1-mutated relapsed or refractory AML: current challenges and future prospects

The prognosis of patients with relapsed or refractory acute myeloid leukemia (R/R AML) is discouraging with salvage standard approaches. Mutations of isocitrate dehydrogenase 1 (IDH1^mut), present in 7–14% of AML patients, have been discovered recently, opening the door to targeted agents aiming to improve the outcomes in this setting. Several oral selective IDH1^mut inhibitors are under investigation, ivosidenib being the first approved for R/R AML. We performed a systematic review to analyze the clinical outcomes and safety reported with IDH1^mut inhibitors and other agents in adult patients with IDH1^mut R/R AML. Ivosidenib in monotherapy achieved complete remission (CR) of 24%, overall response of 42%, and median overall survival of 9 months in R/R AML, and promising outcomes were reported with IDH305 and FT-2102. IDH1^mut inhibitors were generally well tolerated, but some therapy-related toxicities should be monitored, including IDH-differentiation syndrome, prolongation of the QT interval, and leukocytosis, all manageable and reversible. Also, venetoclax, CB-839, PARP inhibitors, and IDH1 peptide vaccine are being studied in IDH1^mut AML. The results of the ongoing and upcoming clinical trials will bring new evidence to establish the role of IDH1^mut inhibitors in therapeutic strategies of AML.

Characterization of cancer-associated IDH2 mutations that differ in tumorigenicity, chemosensitivity and 2-hydroxyglutarate production

The family of isocitrate dehydrogenase (IDH) enzymes is vital for cellular metabolism, as IDH1 and IDH2 are required for the decarboxylation of isocitrate to α-ketoglutarate. Heterozygous somatic mutations in IDH1 or IDH2 genes have been detected in many cancers. They share the neomorphic production of the oncometabolite (R)-2-hydroxyglutarate [(R)-2-HG]. With respect to IDH2, it is unclear whether all IDH2 mutations display the same or differ in tumorigenic properties and degrees of chemosensitivity. Here, we evaluated the three most frequent IDH2 mutations occurring in cancer. The predicted changes to the enzyme structure introduced by these individual mutations are supported by the observed production of (R)-2-HG. However, their tumorigenic properties, response to chemotherapeutic agents, and baseline activation of STAT3 differed. Paradoxically, the varying levels of endogenous (R)-2-HG produced by each IDH2 mutant inversely correlated with their respective growth rates. Interestingly, while we found that (R)-2-HG stimulated the growth of non-transformed cells, (R)-2-HG also displayed antitumor activity by suppressing the growth of tumors harboring wild type IDH2. The mitogenic effect of (R)-2-HG in immortalized cells could be switched to antiproliferative by transformation with oncogenic RAS. Thus, our findings show that despite their shared (R)-2-HG production, IDH2 mutations are not alike and differ in shaping tumor cell behavior and response to chemotherapeutic agents. Our study also reveals that under certain conditions, (R)-2-HG has antitumor properties.

Isocitrate dehydrogenase 1 and 2 mutations, 2-hydroxyglutarate levels, and response to standard chemotherapy for patients with newly diagnosed acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) cells harboring mutations in isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2) produce the oncometabolite 2-hydroxyglutarate (2HG). This study prospectively evaluated the 2HG levels, IDH1/2 mutational status, and outcomes of patients receiving standard chemotherapy for newly diagnosed AML.

METHODS

Serial samples of serum, urine, and bone marrow aspirates were collected from patients newly diagnosed with AML, and 2HG levels were measured with mass spectrometry. Patients with baseline serum 2HG levels greater than 1000 ng/mL or marrow pellet 2HG levels greater than 1000 ng/2 × 10⁶ cells, which suggested the presence of an IDH1/2 mutation, underwent serial testing. IDH1/2 mutations and estimated variant allele frequencies were identified. AML characteristics were compared with the Wilcoxon test and Fisher's exact test. Disease-free survival and overall survival (OS) were evaluated with log-rank tests and Cox regression.

RESULTS

Two hundred and two patients were treated for AML; 51 harbored IDH1/2 mutations. IDH1/2-mutated patients had significantly higher 2HG levels in serum, urine, bone marrow aspirates, and aspirate cell pellets than wild-type patients. A serum 2HG level greater than 534.5 ng/mL was 98.8% specific for the presence of an IDH1/2 mutation. Patients with IDH1/2-mutated AML treated with 7+3-based induction had a 2-year event-free survival (EFS) rate of 44% and a 2-year OS rate of 57%. There was no difference in complete remission rates, EFS, or OS between IDH1/2-mutated and wild-type patients. Decreased serum 2HG levels on day 14 as a proportion of the baseline were significantly associated with improvements in EFS (P = .047) and OS (P = .019) in a multivariate analysis.

CONCLUSIONS

Among patients with IDH1/2-mutated AML, 2HG levels are highly specific for the mutational status at diagnosis, and they have prognostic relevance in patients receiving standard chemotherapy.

Characterization of IDH1 p.R132H Mutant Clones Using Mutation-specific Antibody in Myeloid Neoplasms

Isocitrate dehydrogenase 1 (IDH1) and IDH2 mutations occur in a variety of myeloid neoplasms. Immunohistochemistry (IHC)-based direct visualization of mutant clones of hematopoietic cells can be useful for rapid diagnostic screening and for monitoring treatment response. In this study, we first evaluated the sensitivity and specificity of the IDH1 p.R132H mutation-specific antibody by IHC. All IDH1 wild type cases (n=11) and IDH1 mutant cases with a non-p.R132H mutation (n=30) were negative by IHC, demonstrating 100% antibody specificity. All the initial diagnostic specimens with IDH1 p.R132H mutation including acute myeloid leukemia (n=30), myelodysplastic syndromes (MDS) (n=10), MDS/myeloproliferative neoplasms (MPN) (n=4), and MPN (n=5) were positive by IHC, demonstrating 100% antibody sensitivity. Both immature and mature myeloid cells showed immunoreactivity. Erythroid precursors, lymphoid cells, endothelial cells, and osteoblasts were consistently negative by IHC. We then evaluated the follow-up specimens with a known IDH1 mutation status including acute myeloid leukemia (n=23), MDS (n=2), MDS/MPN (n=2), and MPN (n=2). Thirty-three IDH1 p.R132H mutant cases were positive by IHC and 12 IDH1 mutation negative cases were negative by IHC. However, IHC reactivity in up to 25% of bone marrow cells was noted in 8 of 20 polymerase chain reaction-negative cases, all from patients with a known history of IDH1 p.R132H mutation indicating sampling error or a sensitivity issue with molecular tests. These data indicate that IHC is a highly specific and sensitive tool to detect IDH1 p.R132H mutation in bone marrow involved by myeloid neoplasms. In addition, IDH1 p.R132H IHC also allows localization and assessment of the maturation stage of the clones carrying the mutation.

The role of IDH mutations in acute myeloid leukemia

Isocitrate dehydrogenases (IDHs) are enzymes involved in multiple metabolic and epigenetic cellular processes. Mutations in IDH1 or IDH2 are detected in approximately 20% of patients with acute myeloid leukemia (AML) and induce amino acid changes in conserved residues resulting in neomorphic enzymatic function and production of an oncometabolite, 2-hydroxyglutarate (R-2-HG). This leads to DNA hypermethylation, aberrant gene expression, cell proliferation and abnormal differentiation. IDH mutations diversely affect prognosis of patients with AML based on the location of the mutation and other co-occurring genomic abnormalities. Recently, novel therapies specifically targeting mutant IDH have opened new avenues of therapy for these patients. In the present review, we will provide an overview of the biological, clinical and therapeutic implications of IDH mutations in AML.

Correlation Between Isocitrate Dehydrogenase Gene Aberrations and Prognosis of Patients with Acute Myeloid Leukemia: A Systematic Review and Meta-Analysis

Purpose: Whether isocitrate dehydrogenase (IDH) gene aberrations affected prognosis of patients with acute myeloid leukemia (AML) was controversial. Here, we conducted a meta-analysis to evaluate their prognostic value.Experimental Design: PubMed, Embase, Cochrane, and Chinese databases were searched to identify studies exploring how IDH gene aberrations affected AML outcome. Pooled HRs and relative risks (RR) were calculated, along with 95% confidence intervals (CI).Results: Thirty-three reports were included. IDH mutations seemed not to affect overall survival (OS: HR, 1.05; 95% CI, 0.89-1.23) and event-free survival (EFS: HR, 0.97; 95% CI, 0.80-1.18) when considered as a single factor, but improved accumulative incidence of relapse (CIR: HR, 1.44; 95% CI, 1.18-1.76) in patients with intermediate-risk karyotypes (IR-AML). However, IDH1 mutation conferred worse OS (HR, 1.17; 95% CI, 1.05-1.31) and EFS (HR, 1.29; 95% CI, 1.07-1.56), especially in patients with normal cytogenetics (OS: HR, 1.21; 95% CI, 1.01-1.46; EFS: HR, 1.56; 95% CI, 1.23-1.98). Prognosis of the IDH1 single-nucleotide polymorphism rs11554137 was also poor (OS: HR, 1.34; 95% CI, 1.03-1.75). IDH2 mutation improved OS (HR, 0.78; 95% CI, 0.66-0.93), particularly in IR-AML patients (OS: HR, 0.65; 95% CI, 0.49-0.86). The IDH2 (R140) mutation was associated with better OS among younger cases (HR, 0.64; 95% CI, 0.49-0.82). Treatment outcome was poor [RR for complete remission rates in IDH1 mutation: 1.21; 95% CI, 1.02-1.44; IDH2 (R172) mutation: 2.14; 95% CI, 1.61-2.85].Conclusions: Various subtypes of IDH mutations might contribute to different prognosis and be allowed to stratify IR-AML further. Clin Cancer Res; 23(15); 4511-22. ©2017 AACR.

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).

Mutational analysis of disease relapse in patients allografted for acute myeloid leukemia

Disease relapse is the major cause of treatment failure after allogeneic stem cell transplantation (allo-SCT) in acute myeloid leukemia (AML). To identify AML-associated genes prognostic of AML relapse post-allo-SCT, we resequenced 35 genes in 113 adults at diagnosis, 49 of whom relapsed. Two hundred sixty-two mutations were detected in 102/113 (90%) patients. An increased risk of relapse was observed in patients with mutations in WT1 (P = .018), DNMT3A (P = .045), FLT3 ITD (P = .071), and TP53 (P = .06), whereas mutations in IDH1 were associated with a reduced risk of disease relapse (P = .018). In 29 patients, we additionally compared mutational profiles in bone marrow at diagnosis and relapse to study changes in clonal structure at relapse. In 13/29 patients, mutational profiles altered at relapse. In 9 patients, mutations present at relapse were not detected at diagnosis. In 15 patients, additional available pre-allo-SCT samples demonstrated that mutations identified posttransplant but not at diagnosis were detectable immediately prior to transplant in 2 of 15 patients. Taken together, these observations, if confirmed in larger studies, have the potential to inform the design of novel strategies to reduce posttransplant relapse highlighting the potential importance of post-allo-SCT interventions with a broad antitumor specificity in contrast to targeted therapies based on mutational profile at diagnosis.

Frontline treatment of acute myeloid leukemia in adults

Recent years have highlighted significant progress in understanding the underlying genetic and epigenetic signatures of acute myeloid leukemia(AML). Most importantly, novel chemotherapy and targeted strategies have led to improved outcomes in selected genetic subsets. AML is a remarkably heterogeneous disease, and individualized therapies for disease-specific characteristics (considering patients' age, cytogenetics, and mutations) could yield better outcomes. Compared with the historical 5-to 10-year survival rate of 10%, the survival of patients who undergo modern treatment approaches reaches up to 40-50%, and for specific subsets, the improvements are even more dramatic; for example, in acute promyelocytic leukemia, the use of all-trans retinoic acid and arsenic trioxide improved survival from 30 to 40% up to 80 to 90%. Similar progress has been documented in core-binding-factor-AML, with an increase in survival from 30% to 80% upon the use of high-dose cytarabine/fludarabine/granulocyte colony-stimulating factor combination regimens. AML treatment was also recently influenced by the discovery of the superiority of regimens with higher dose Ara-C and nucleoside analogues compared with the "7+3"regimen, with about a 20% improvement in overall survival. Despite these significant differences, most centers continue to use the "7+3" regimen, and greater awareness will improve the outcome. The discovery of targetable molecular abnormalities and recent studies of targeted therapies (gemtuzumab ozagomycin, FLT3 inhibitors, isocitrate dehydrogenase inhibitors, and epigenetic therapies), future use of checkpoint inhibitors and other immune therapies such as chimeric antigen receptor T-cells, and maintenance strategies based on the minimal residual disease evaluation represent novel, exciting clinical leads aimed to improve AML outcomes in the near future.

Isocitrate dehydrogenase mutations in myeloid malignancies

Alterations to genes involved in cellular metabolism and epigenetic regulation are implicated in the pathogenesis of myeloid malignancies. Recurring mutations in isocitrate dehydrogenase (IDH) genes are detected in approximately 20% of adult patients with acute myeloid leukemia (AML) and 5% of adults with myelodysplastic syndromes (MDS). IDH proteins are homodimeric enzymes involved in diverse cellular processes, including adaptation to hypoxia, histone demethylation and DNA modification. The IDH2 protein is localized in the mitochondria and is a critical component of the tricarboxylic acid (also called the ‘citric acid' or Krebs) cycle. Both IDH2 and IDH1 (localized in the cytoplasm) proteins catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG). Mutant IDH enzymes have neomorphic activity and catalyze reduction of α-KG to the (R) enantiomer of 2-hydroxyglutarate, which is associated with DNA and histone hypermethylation, altered gene expression and blocked differentiation of hematopoietic progenitor cells. The prognostic significance of mutant IDH (mIDH) is controversial but appears to be influenced by co-mutational status and the specific location of the mutation (IDH1-R132, IDH2-R140, IDH2-R172). Treatments specifically or indirectly targeted to mIDH are currently under clinical investigation; these therapies have been generally well tolerated and, when used as single agents, have shown promise for inducing responses in some mIDH patients when used as first-line treatment or in relapsed or refractory AML or MDS. Use of mIDH inhibitors in combination with drugs with non-overlapping mechanisms of action is especially promising, as such regimens may address the clonal heterogeneity and the multifactorial pathogenic processes involved in mIDH myeloid malignancies. Advances in mutational analysis have made testing more rapid and convenient, and less expensive; such testing should become part of routine diagnostic workup and repeated at relapse to identify patients who may benefit from treatments that target mIDH.

Somatic mutations of isocitrate dehydrogenases 1 and 2 are prognostic and follow-up markers in patients with acute myeloid leukaemia with normal karyotype

Background

Mutations in the isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) genes are frequent molecular lesions in acute myeloid leukaemia with normal karyotype (AML-NK). The effects of IDH mutations on clinical features and treatment outcome in AML-NK have been widely investigated, but only a few studies monitored these mutations during follow-up.

Patients and methods

In our study samples from 110 adult de novo AML-NK were studied for the presence of IDH1 and IDH2 mutations, their associations with other prognostic markers and disease outcome. We also analyzed the stability of these mutations during the course of the disease in complete remission (CR) and relapse.

Results

IDH mutations were found in 25 (23%) patients. IDH+ patients tend to have lower CR rate compared to IDH-patients (44% vs 62.2%, p = 0.152), and had slightly lower disease free survival (12 months vs 17 months; p = 0.091). On the other hand, the presence of IDH mutations had significant impact on overall survival (2 vs 7 months; p = 0.039). The stability of IDH mutations were studied sequentially in 19 IDH+ patients. All of them lost the mutation in CR, and the same IDH mutations were detected in relapsed samples.

Conclusions

Our study shows that the presence of IDH mutations confer an adverse effect in AML-NK patients, which in combination with other molecular markers can lead to an improved risk stratification and better treatment. Also, IDH mutations are very stable during the course of the disease and can be potentially used as markers for minimal residual disease detection.

Evaluation of IDH1G105 polymorphism as prognostic marker in intermediate-risk AML

Germline polymorphisms in genes mutated in acute myeloid leukemia (AML) may have prognostic impact. Therefore, the relevance of the polymorphism IDH1G105 (IDH1105(GGT) minor allele) was evaluated in the context of concomitant molecular mutations in a cohort of 507 AML cases with intermediate-risk cytogenetics. In addition, a cohort of 475 healthy controls was analyzed for this polymorphism. IDH1105(GGT) minor allele was found in 10 % of AML patients and 9 % of healthy controls. While no differences were seen with regard to cytomorphology or cytogenetics, immunophenotyping revealed significantly reduced expression of the progenitor marker CD34 in AML cases harboring IDH1105(GGT) minor allele. Cases with IDH1105(GGT) minor allele as compared to those with the IDH1105(GGC) major allele had significantly longer event-free survival (EFS) (median 16 vs 11 months, p = 0.013) which was most pronounced in the age group >60 years (median 14 vs 9 months, p = 0.007) and in the NPM1 mutated/FLT3-ITD/FLT3wt ratio <0.5 group (median 61 vs 13 months, p = 0.012). However, this association is not independent of other prognostic parameters, and we conclude that IDH1105(GGT) minor allele has to be considered in the context of the genetic background of the individual AML analyzed.

Characteristics, clinical outcome, and prognostic significance of IDH mutations in AML

The pathophysiology of IDH mutations in tumorigenesis is increasingly described, yet the prognostic significance of IDH1 and IDH2 mutations in AML remains controversial. The primary objective of this study was to define the natural history and prognosis of patients with AML and IDH1 or IDH2 mutations and provide historical survival expectations. A total of 826 patients treated from 2010 to 2014 at a single institution were evaluated, including 167 patients (20%) with AML and IDH1 or IDH2 mutations. Median age was 62 years (range 18-92). There were 59 IDH1-R132, 83 IDH2-R140, and 23 IDH2-R172 mutations. Clinicopathologic characteristics associated with IDH-mutations included older age, less frequent therapy-related status, and increased incidence of intermediate-risk cytogenetics, FLT3-ITD mutations, and NPM1 mutations. Remission rates (CR/CRi) by AML treatment status were: induction, 68%; Salvage-1 (S1), 42%; and Salvage-2 and beyond (S2+), 27%. No difference in response was identified by IDH mutation status. Similarly, overall survival (OS) was not dependent on IDH status within any cohort. The median OS was 15.4 months in induction, 8.7 months in S1, and 4.8 months in S2+. This analysis defines the clinical outcome associated with IDH-mutations in both the front-line and salvage AML treatment settings, and confirms that response rate and OS for both IDH-mutated and IDH wild-type AML patients is comparable. This provides contemporary data to be used for comparison with results of novel investigational (e.g., selective IDH inhibitor) strategies.

Incidence and prognostic impact of DNMT3A mutations in Korean normal karyotype acute myeloid leukemia patients

Background. DNA methyltransferase 3A (DNMT3A) mutation was recently introduced as a prognostic indicator in normal karyotype (NK) AML and we evaluated the incidence and prognostic impact of DNMT3A mutations in Korean NK AML patients. Methods. Total 67 NK AML patients diagnosed during the recent 10 years were enrolled. DNMT3A mutations were analyzed by direct sequencing and categorized into nonsynonymous variations (NSV), deleterious mutations (DM), and R882 mutation based on in silico analysis results. Clinical features and prognosis were compared with respect to DNMT3A mutation status. Results. Three novel (I158M, K219V, and E177V) and two known (R736H and R882H) NSVs were identified and the latter three were predicted as DMs. DNMT3A NSVs, DMs, and R882 mutation were identified in 14.9%–17.9%, 10.3%–10.4%, and 7.5% of patients, respectively. DNMT3A mutations were frequently detected in FLT3 ITD mutated patients (P = 0.054, 0.071, and 0.071 in NSV, DMs, and R882 mutation, resp.) but did not affect clinical features and prognosis significantly. Conclusions. Incidences of DNMT3A NSVs, DMs, and R882 mutation are 14.9%–17.9%, 10.3%–10.4%, and 7.5%, respectively, in Korean NK AML patients. DNMT3A mutations are associated with FLT3 ITD mutations but do not affect clinical outcome significantly in Korean NK AML patients.

Progress in acute myeloid leukemia

Significant progress has been made in the treatment of acute myeloid leukemia (AML). Steady gains in clinical research and a renaissance of genomics in leukemia have led to improved outcomes. The recognition of tremendous heterogeneity in AML has allowed individualized treatments of specific disease entities within the context of patient age, cytogenetics, and mutational analysis. The following is a comprehensive review of the current state of AML therapy and a roadmap of our approach to these distinct disease entities.

Small molecule inhibitors in acute myeloid leukemia: from the bench to the clinic

Many patients with acute myeloid leukemia will eventually develop refractory or relapsed disease. In the absence of standard therapy for this population, there is currently an urgent unmet need for novel therapeutic agents. Targeted therapy with small molecule inhibitors represents a new therapeutic intervention that has been successful for the treatment of multiple tumors (e.g., gastrointestinal stromal tumors, chronic myelogenous leukemia). Hence, there has been great interest in generating selective small molecule inhibitors targeting critical pathways of proliferation and survival in acute myeloid leukemia. This review highlights a selective group of intriguing therapeutic agents and their presumed targets in both preclinical models and in early human clinical trials.

DNMT3A and IDH mutations in acute myeloid leukemia and other myeloid malignancies: associations with prognosis and potential treatment strategies

The development of effective treatment strategies for most forms of acute myeloid leukemia (AML) has languished for the past several decades. There are a number of reasons for this, but key among them is the considerable heterogeneity of this disease and the paucity of molecular markers that can be used to predict clinical outcomes and responsiveness to different therapies. The recent large-scale sequencing of AML genomes is now providing opportunities for patient stratification and personalized approaches to treatment that are based on individual mutational profiles. It is particularly notable that studies by The Cancer Genome Atlas and others have determined that 44% of patients with AML exhibit mutations in genes that regulate methylation of genomic DNA. In particular, frequent mutation has been observed in the genes encoding DNA methyltransferase 3A (DNMT3A), isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2), as well as Tet oncogene family member 2. This review will summarize the incidence of these mutations, their impact on biochemical functions including epigenetic modification of genomic DNA and their potential usefulness as prognostic indicators. Importantly, the presence of DNMT3A, IDH1 or IDH2 mutations may confer sensitivity to novel therapeutic approaches, including the use of demethylating agents. Therefore, the clinical experience with decitabine and azacitidine in the treatment of patients harboring these mutations will be reviewed. Overall, we propose that understanding the role of these mutations in AML biology will lead to more rational therapeutic approaches targeting molecularly defined subtypes of the disease.

Prognostic significance of 2-hydroxyglutarate levels in acute myeloid leukemia in China

The 2-hydroxyglutarate (2-HG) has been reported to result from mutations of isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) genes and to function as an "oncometabolite." To evaluate the clinical significance of serum 2-HG levels in hematologic malignancies, acute myeloid leukemia (AML) in particular, we analyzed this metabolite in distinct types of human leukemia and lymphoma and established the range of serum 2-HG in appropriate normal control individuals by using gas chromatograph-time-of-flight mass spectrometry. Aberrant serum 2-HG pattern was detected in the multicenter group of AML, with 62 of 367 (17%) patients having 2-HG levels above the cutoff value (2.01, log2-transformed from 4.03 μg/mL). IDH1/2 mutations occurred in 27 of 31 (87%) AML cases with very high 2-HG, but were observed only in 9 of 31 (29%) patients with moderately high 2-HG, suggesting other genetic or biochemical events may exist in causing 2-HG elevation. Indeed, glutamine-related metabolites exhibited a pattern in favor of 2-HG synthesis in the high 2-HG group. In AML patients with cytogenetically normal AML (n = 234), high 2-HG represented a negative prognostic factor in both overall survival and event-free survival. Univariate and multivariate analyses confirmed high serum 2-HG as a strong prognostic predictor independent of other clinical and molecular features. We also demonstrated distinct gene-expression/DNA methylation profiles in AML blasts with high 2-HG compared with those with normal ones, supporting a role that 2-HG plays in leukemogenesis.

CEBPA single mutation can be a possible favorable prognostic indicator in NPM1 and FLT3-ITD wild-type acute myeloid leukemia patients with intermediate cytogenetic risk

The aim of this study was to evaluate the prognostic impact of CEBPA single mutation in acute myeloid leukemia (AML) patients with intermediate cytogenetic risk. CEBPA single and double mutations were detected in 11 (9.7%) and 17 (15.1%) of 113 NPM1 wild-type patients, but no CEBPA mutations were detected in a group of 44 NPM1 mutated patients. Among patients with NPM1/FLT3-ITD wild-type, those with CEBPA double mutations (P=0.013 and 0.007 for overall survival and relapse-free survival, respectively) or a single mutation (P=0.039 and 0.020 for overall survival and relapse-free survival, respectively) demonstrated a favorable prognosis compared with CEBPA wild-type patients. Subsequent multivariate analysis confirmed the favorable prognostic impact of CEBPA single and double mutations. Despite the low statistical power of this study due to the small number of patients, our preliminary data suggest that CEBPA single mutation may be associated with favorable clinical outcomes in NPM1/FLT3-ITD wild-type AML patients with intermediate cytogenetic risk.

Serum 2-hydroxyglutarate levels predict isocitrate dehydrogenase mutations and clinical outcome in acute myeloid leukemia

Cancer-associated isocitrate dehydrogenase (IDH) mutations produce the metabolite 2-hydroxyglutarate (2HG), but the clinical utility of 2HG has not been established. We studied whether 2HG measurements in acute myeloid leukemia (AML) patients correlate with IDH mutations, and whether diagnostic or remission 2HG measurements predict survival. Sera from 223 de novo AML patients were analyzed for 2HG concentration by reverse-phase liquid chromatography-mass spectrometry. Pretreatment 2HG levels ranged from 10 to 30 000 ng/mL and were elevated in IDH-mutants (median, 3004 ng/mL), compared to wild-type IDH (median, 61 ng/mL) (P < .0005). 2HG levels did not differ among IDH1 or IDH2 allelic variants. In receiver operating characteristic analysis, a discriminatory level of 700 ng/mL optimally segregated patients with and without IDH mutations, and on subsequent mutational analysis of the 13 IDH wild-type samples with 2HG levels >700 ng/mL, 9 were identified to have IDH mutations. IDH-mutant patients with 2HG levels >200 at complete remission had shorter overall survival compared to 2HG ≤200 ng/mL (hazard ratio, 3.9; P = .02). We establish a firm association between IDH mutations and serum 2HG concentration in AML, and confirm that serum oncometabolite measurements provide useful diagnostic and prognostic information that can improve patient selection for IDH-targeted therapies.

High-risk acute myelogenous leukemia: treatment today ... and tomorrow

High-risk acute myelogenous leukemia (AML) constitutes a distinct subset of disease based on clinical and biological characteristics and comprises a significant percentage of all cases of adult AML. Biologic features such as distinct clonal cytogenetic and molecular abnormalities identify a subgroup of AML patients characterized by poor response to induction chemotherapy and poor long-term survival after treatment with consolidation chemotherapy. Clinical variables that predict for poor response include AML relapsed after less than 1 year of remission and AML characterized by resistance to conventional agents. We review here our understanding of the defining biologic subtypes of AML and discuss how adequate initial evaluation can be used to inform the choice of treatment. By defining high-risk biologic and clinical variables, a strong case can be made for treating patients with investigational agents, with treatment directed at distinct cytogenetic or molecular abnormalities. Allogeneic transplantation is the only form of therapy available outside of the setting of a clinical trial that may offer a chance for long-term survival for patients with high-risk AML.

Prognostic significance of IDH1 mutations in acute myeloid leukemia: a meta-analysis

Isocitrate dehydrogenase 1 (IDH1) gene aberrations have recently been reported in acute myeloid leukemia (AML). To evaluate the prognostic significance of IDH1 mutations in AML, we performed a meta-analysis. Fifteen studies covering a total of 8121 subjects were included in this analysis. The frequency of IDH1 R132 mutations were 4.4-9.3% for AML patients and 10.9-16.0% for cytogenetically normal (CN)-AML patients. The IDH1 mutations were associated with NPM1 mutations in 6 studies and normal cytogenetics in 5 studies. AML patients with IDH1 mutations had inferior overall survival compared to patients without the mutations (hazard ratio 1.17, 95% CI: 1.02-1.36). Additionally, in CN-AML patients, IDH1 mutations were associated with a lower complete remission rate (risk ratio 1.30, 95% CI: 1.04-1.63). Although the available literature is limited to observational studies, these results may justify the risk-adapted therapeutic strategies for AML according to the IDH1 status.

Molecular markers in acute myeloid leukaemia

An increasing number of cytogenetic and molecular genetic aberrations have been identified in acute myeloid leukaemia (AML), highlighting the biological heterogeneity of the disease. Moreover, the characterisation of specific molecular abnormalities provides the basis for targeted therapies, such as all trans retinoic acid (ATRA) and arsenic trioxide treatment in acute promyelocytic leukaemia or tyrosine kinase inhibitors in AML with FLT3 mutations. Several cytogenetic and molecular genetic changes have been shown to be prognostically relevant and have been acknowledged in the latest WHO classification of AML as separate entities. A detailed marker assessment at diagnosis is crucial for risk-stratification of AML patients, allowing the identification of those at high risk of relapse, who may benefit from early allogeneic stem cell transplantation. Finally, molecular markers are important for the detection of minimal residual disease after initial therapy and during long-term follow-up, which enables a more tailored treatment approach for individual AML patients.