IDH1 and IDH2 gene mutations identify novel molecular subsets within de novo cytogenetically normal acute myeloid leukemia: a Cancer and Leukemia Group B study

Isocitrate dehydrogenase inhibitors in acute myeloid leukemia

Isocitrate dehydrogenase (IDH) is a key enzyme involved in the conversion of isocitrate to α-ketoglutarate (α-KG) in the tricarboxylic acid (TCA) cycle. IDH mutation produces a neomorphic enzyme, which can lead to the abnormal accumulation of R-2-HG and promotes leukemogenesis. IDH mutation occurs in 20% of acute myeloid leukemia (AML) patients, mainly including IDH1 R132, IDH2 R140, and IDH2 R172. Different mutant isoforms have different prognostic values. In recent years, IDH inhibitors have shown good clinical response in AML patients. Hence, enasidenib and ivosidenib, the IDH2 and IDH1 inhibitors developed by Agios Pharmaceuticals, have been approved by the Food and Drug Administration on 1 August 2017 and 20 July 2018 for the treatment of adult relapsed or refractory (R/R) AML with IDH2 and IDH1 mutations, respectively. IDH inhibitor monotherapy for R/R AML is efficacious and safe; however, there are problems, such as primary or acquired resistance. Clinical trials of IDH inhibitors combined with hypomethylating agents or standard chemotherapy for the treatment of R/R AML or newly diagnosed AML, as well as in post hematopoietic stem cell transplantation as maintenance therapy, are ongoing. This article summarizes the use of IDH inhibitors in AML with IDH mutations.

Detection Of Mutations In The Isocitrate Dehydrogenase Genes (IDH1/IDH2) Using castPCRTM In Patients With AML And Their Clinical Impact In Mexico City

Objective

Approximately 40–50% of patients with acute myeloid leukaemia (AML) have been reported to present with a normal karyotype and a variable disease-free period, most likely due to the molecular heterogeneity presented by these patients. A variety of mutations have been identified at the molecular level, such as those in the IDH1/2 gene, which causes a gain of function of the isocitrate dehydrogenase enzyme, generating high levels of the (R)-2-hydroxyglutarate oncometabolite, which competitively inhibits dioxygenase enzymes. Therefore, the objective of this study was to evaluate the incidence of IDH1/2 gene mutations in AML patients and their impact on survival.

Materials and methods

A total of 101 patients with a diagnosis of AML were included; mononuclear cells were obtained for DNA extraction and purification. Mutations were detected using TaqMan™ competitive allele-specific probes (castPCR™). Overall survival curves were plotted using IBM SPSS Statistics 23 software.

Results

The frequency of IDH gene mutations was 19.8%. For the IDH1 gene, 13.8% of the mutations identified included R132H, V178I, G105G and R132C. The frequency of mutations of the IDH2 gene was 5.9%; the variants included R172K and R140Q. The mean survival time in patients without IDH1 gene mutations was 173.15 days (120.20–226.10), while the mean survival time for patients with mutations was 54.95 days (9.7–100.18), p = 0.001.

Conclusion

The frequency of IDH1 and IDH2 gene mutations in the sample was similar to that reported in other studies. The analysis of these mutations in AML patients is of great importance as a prognostic factor due to their impact on survival and their use as potential therapeutic targets or as targets of inhibitors of IDH1(Ivosidenib, Tibsovo) and IDH2 (Enasidenib, Idhifa).

Pharmacological characterization of TQ05310, a potent inhibitor of isocitrate dehydrogenase 2 R140Q and R172K mutants

Isocitrate dehydrogenase 2 (IDH2), an important mitochondrial metabolic enzyme involved in the tricarboxylic acid cycle, is mutated in a variety of cancers. AG-221, an inhibitor primarily targeting the IDH2-R140Q mutant, has shown remarkable clinical benefits in the treatment of relapsed or refractory acute myeloid leukemia patients. However, AG-221 has weak inhibitory activity toward IDH2-R172K, a mutant form of IDH2 with more severe clinical manifestations. Herein, we report TQ05310 as the first mutant IDH2 inhibitor that potently targets both IDH2-R140Q and IDH2-R172K mutants. TQ05310 inhibited mutant IDH2 enzymatic activity, suppressed (R)-2-hydroxyglutarate (2-HG) production and induced differentiation in cells expressing IDH2-R140Q and IDH2-R172K, but not in cells expressing wild-type IDH1/2 or mutant IDH1. TQ05310 bound to both IDH2-R140Q and IDH2-R172K, with Q316 being the critical residue mediating the binding of TQ05310 with IDH2-R140Q, but not with IDH2-R172K. TQ05310 also had favorable pharmacokinetic characteristics and profoundly inhibited 2-HG production in a tumor xenografts model. The results of the current study establish a solid foundation for further clinical investigation of TQ05310, and provide new insight into the development of novel mutant IDH2 inhibitors.

Long Non-coding RNAs as Functional and Structural Chromatin Modulators in Acute Myeloid Leukemia

Acute myeloid leukemia is a hematopoietic neoplasm of dismal prognosis that results from the accumulation of immature myeloid blasts in the bone marrow and the peripheral blood. It is strongly dependent on epigenetic regulation for disease onset, maintenance and in response to treatment. Epigenetic regulation refers to the multiple chemical modifications of DNA or DNA-associated proteins that alter chromatin structure and DNA accessibility in a heritable manner, without changing DNA sequence. Unlike sequence-specific transcription factors, epigenetic regulators do not necessarily bind DNA at consensus sequences, but still achieve reproducible target binding in a manner that is cell and maturation-type specific. A growing body of evidence indicates that epigenetic regulators rely, amongst other factors, on their interaction with untranslated RNA molecules for guidance to particular targets on DNA. Non (protein)-coding RNAs are the most abundant transcriptional products of the coding genome, and comprise several different classes of molecules with unique lengths, conformations and targets. Amongst these, long non-coding RNAs (lncRNAs) are species of 200 bp to >100 K bp in length, that recognize, and bind unique and largely uncharacterized DNA conformations. Some have been shown to bind epigenetic regulators, and thus constitute attractive candidates to mediate epigenetic target specificity. Herein, we postulate that lncRNAs are central players in the unique epigenetic programming of AML and review recent evidence in support of this view. We discuss the value of lncRNAs as putative diagnostic, prognostic and therapeutic targets in myeloid leukemias and indicate novel directions in this exciting research field.

A six-gene prognostic model predicts overall survival in bladder cancer patients

Background

The fatality and recurrence rates of bladder cancer (BC) have progressively increased. DNA methylation is an influential regulator associated with gene transcription in the pathogenesis of BC. We describe a comprehensive epigenetic study performed to analyse DNA methylation-driven genes in BC.

Methods

Data related to DNA methylation, the gene transcriptome and survival in BC were downloaded from The Cancer Genome Atlas (TCGA). MethylMix was used to detect BC-specific hyper-/hypo-methylated genes. Metascape was used to carry out gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. A least absolute shrinkage and selection operator (LASSO)-penalized Cox regression was conducted to identify the characteristic dimension decrease and distinguish prognosis-related methylation-driven genes. Subsequently, we developed a six-gene risk evaluation model and a novel prognosis-related nomogram to predict overall survival (OS). A survival analysis was carried out to explore the individual prognostic significance of the six genes.

Results

In total, 167 methylation-driven genes were identified. Based on the LASSO Cox regression, six genes, i.e., ARHGDIB, LINC00526, IDH2, ARL14, GSTM2, and LURAP1, were selected for the development of a risk evaluation model. The Kaplan–Meier curve indicated that patients in the low-risk group had considerably better OS (P = 1.679e−05). The area under the curve (AUC) of this model was 0.698 at 3 years of OS. The verification performed in subgroups demonstrated the validity of the model. Then, we designed an OS-associated nomogram that included the risk score and clinical factors. The concordance index of the nomogram was 0.694. The methylation levels of IDH2 and ARL14 were appreciably related to the survival results. In addition, the methylation and gene expression-matched survival analysis revealed that ARHGDIB and ARL14 could be used as independent prognostic indicators. Among the six genes, 6 methylation sites in ARHGDIB, 3 in GSTM2, 1 in ARL14, 2 in LINC00526 and 2 in LURAP1 were meaningfully associated with BC prognosis. In addition, several abnormal methylated sites were identified as linked to gene expression.

Conclusion

We discovered differential methylation in BC patients with better and worse survival and provided a risk evaluation model by merging six gene markers with clinical characteristics.

Enasidenib in acute myeloid leukemia: clinical development and perspectives on treatment

Recently there has been a significant progression in the understanding of molecular mutations driving biochemical and cellular signaling changes leading to survival and proliferation of leukemia cells in patients with acute myeloid leukemia (AML). Preclinical studies have demonstrated a mutated enzyme in the citric acid cycle, isocitrate dehydrogenase (IDH), leads to the production of an oncogenic metabolite R-2-hydroxy-glutarate (R-2-HG). This causes the arrest in the differentiation of hematopoietic stem cells leading to the promotion of leukemia. Inhibitors of the IDH enzyme have been shown in preclinical studies to reduce the production of R-2-HG, resulting in terminal differentiation of leukemia blast cells. In recent phase I and II trials, the IDH2 inhibitor enasidenib has shown clinical activity in patients with relapsed and refractory (R/R) AML. This review will describe the preclinical and clinical developments of enasidenib and its Food and Drug Administration approval in R/R AML, treatment recommendations and management will be outlined.

Targeting Metabolic Reprogramming in Acute Myeloid Leukemia

The cancer metabolic reprogramming allows the maintenance of tumor proliferation, expansion and survival by altering key bioenergetics, biosynthetic and redox functions to meet the higher demands of tumor cells. In addition, several metabolites are also needed to perform signaling functions that further promote tumor growth and progression. These metabolic alterations have been exploited in different cancers, including acute myeloid leukemia, as novel therapeutic strategies both in preclinical models and clinical trials. Here, we review the complexity of acute myeloid leukemia (AML) metabolism and discuss how therapies targeting different aspects of cellular metabolism have demonstrated efficacy and how they provide a therapeutic window that should be explored to target the metabolic requirements of AML cells.

Identification of New Inhibitors of Mutant Isocitrate Dehydrogenase 2 through Molecular Similarity-based Virtual Screening

Background:

Isocitrate dehydrogenase 2 (IDH2) is an enzyme catalyzing the oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG) in the tricarboxylic acid (TCA). Evidences suggest that the specific mutations in IDH2 are critical to the growth and reproduction of severe tumors especially leukemia and glioblastoma. It is found that the inhibitors of mutant IDH2 are promising anti-tumor therapeutics.

Methods:

A virtual screening strategy combining molecular similarity search and molecular docking was performed in the binding site of AGI-6780. YL-16, YL-17 and YL-18 were identified as novel mutant IDH2 inhibitors for the reduction of (D)-2-hydroxyglutarate in cellular evaluation. In addition, all the three compounds showed inhibition against IDH2-R172K mutated HEK-293T cells, while weak inhibition against wide-type IDH2 (WT-IDH2) HEK-293T cells.

Results:

Significantly, YL-17 showed 84.55% inhibitory activity against IDH2-R172K at 1 µM and weak cytotoxicity to wide-type IDH2 at 50 µM.

Conclusion:

YL-17 was highlighted as a new mutant IDH2 inhibitor that could be further developed for therapeutic applications.

Not Only Mutations Matter: Molecular Picture of Acute Myeloid Leukemia Emerging from Transcriptome Studies

The last two decades of genome-scale research revealed a complex molecular picture of acute myeloid leukemia (AML). On the one hand, a number of mutations were discovered and associated with AML diagnosis and prognosis; some of them were introduced into diagnostic tests. On the other hand, transcriptome studies, which preceded AML exome and genome sequencing, remained poorly translated into clinics. Nevertheless, gene expression studies significantly contributed to the elucidation of AML pathogenesis and indicated potential therapeutic directions. The power of transcriptomic approach lies in its comprehensiveness; we can observe how genome manifests its function in a particular type of cells and follow many genes in one test. Moreover, gene expression measurement can be combined with mutation detection, as high-impact mutations are often present in transcripts. This review sums up 20 years of transcriptome research devoted to AML. Gene expression profiling (GEP) revealed signatures distinctive for selected AML subtypes and uncovered the additional within-subtype heterogeneity. The results were particularly valuable in the case of AML with normal karyotype which concerns up to 50% of AML cases. With the use of GEP, new classes of the disease were identified and prognostic predictors were proposed. A plenty of genes were detected as overexpressed in AML when compared to healthy control, including KIT, BAALC, ERG, MN1, CDX2, WT1, PRAME, and HOX genes. High expression of these genes constitutes usually an unfavorable prognostic factor. Upregulation of FLT3 and NPM1 genes, independent on their mutation status, was also reported in AML and correlated with poor outcome. However, transcriptome is not limited to the protein-coding genes; other types of RNA molecules exist in a cell and regulate genome function. It was shown that microRNA (miRNA) profiles differentiated AML groups and predicted outcome not worse than protein-coding gene profiles. For example, upregulation of miR-10a, miR-10b, and miR-196b and downregulation of miR-192 were found as typical of AML with NPM1 mutation whereas overexpression of miR-155 was associated with FLT3-internal tandem duplication (FLT3-ITD). Development of high-throughput technologies and microarray replacement by next generation sequencing (RNA-seq) enabled uncovering a real variety of leukemic cell transcriptomes, reflected by gene fusions, chimeric RNAs, alternatively spliced transcripts, miRNAs, piRNAs, long noncoding RNAs (lncRNAs), and their special type, circular RNAs. Many of them can be considered as AML biomarkers and potential therapeutic targets. The relations between particular RNA puzzles and other components of leukemic cells and their microenvironment, such as exosomes, are now under investigation. Hopefully, the results of this research will shed the light on these aspects of AML pathogenesis which are still not completely understood.

Exploiting metabolic vulnerabilities for personalized therapy in acute myeloid leukemia

Changes in cell metabolism and metabolic adaptation are hallmark features of many cancers, including leukemia, that support biological processes involved into tumor initiation, growth, and response to therapeutics. The discovery of mutations in key metabolic enzymes has highlighted the importance of metabolism in cancer biology and how these changes might constitute an Achilles heel for cancer treatment. In this Review, we discuss the role of metabolic and mitochondrial pathways dysregulated in acute myeloid leukemia, and the potential of therapeutic intervention targeting these metabolic dependencies on the proliferation, differentiation, stem cell function and cell survival to improve patient stratification and outcomes.

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.

The Role of Forkhead Box Proteins in Acute Myeloid Leukemia

Forkhead box (FOX) proteins are a group of transcriptional factors implicated in different cellular functions such as differentiation, proliferation and senescence. A growing number of studies have focused on the relationship between FOX proteins and cancers, particularly hematological neoplasms such as acute myeloid leukemia (AML). FOX proteins are widely involved in AML biology, including leukemogenesis, relapse and drug sensitivity. Here we explore the role of FOX transcription factors in the major AML entities, according to "The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia", and in the context of the most recurrent gene mutations identified in this heterogeneous disease. Moreover, we report the new evidences about the role of FOX proteins in drug sensitivity, mechanisms of chemoresistance, and possible targeting for personalized therapies.

Prognostic and Biologic Relevance of Clinically Applicable Long Noncoding RNA Profiling in Older Patients with Cytogenetically Normal Acute Myeloid Leukemia

We have previously shown that expression levels of 48 long noncoding RNAs (lncRNA) can generate a prognostic lncRNA score that independently associates with outcome of older patients with cytogenetically normal acute myeloid leukemia (CN-AML). However, the techniques used to identify and measure prognostic lncRNAs (i.e., RNA sequencing and microarrays) are not tailored for clinical testing. Herein, we report on an assay (based on the nCounter platform) that is designed to produce targeted measurements of prognostic lncRNAs in a clinically applicable manner. We analyzed a new cohort of 76 older patients with CN-AML and found that the nCounter assay yielded reproducible measurements and that the lncRNA score retained its prognostic value; patients with high lncRNA scores had lower complete remission (CR) rates (P = 0.009; 58% vs. 87%), shorter disease-free (P = 0.05; 3-year rates: 0% vs. 21%), overall (OS; P = 0.02, 3-year rates: 10% vs. 29%), and event-free survival (EFS; P = 0.002, 3-year rates: 0% vs. 18%) than patients with low lncRNA scores. In multivariable analyses, the lncRNA score independently associated with CR rates (P = 0.02), OS (P = 0.02), and EFS (P = 0.02). To gain biological insights, we examined our initial cohort of 71 older patients with CN-AML, previously analyzed with RNA sequencing. Genes involved in immune response and B-cell receptor signaling were enriched in patients with high lncRNA scores. We conclude that clinically applicable lncRNA profiling is feasible and potentially useful for risk stratification of older patients with CN-AML. Furthermore, we identify potentially targetable molecular pathways that are active in the high-risk patients with high lncRNA scores.

Mutant Isocitrate Dehydrogenase Inhibitors as Targeted Cancer Therapeutics

The identification of heterozygous neomorphic isocitrate dehydrogenase (IDH) mutations across multiple cancer types including both solid and hematologic malignancies has revolutionized our understanding of oncogenesis in these malignancies and the potential for targeted therapeutics using small molecule inhibitors. The neomorphic mutation in IDH generates an oncometabolite product, 2-hydroxyglutarate (2HG), which has been linked to the disruption of metabolic and epigenetic mechanisms responsible for cellular differentiation and is likely an early and critical contributor to oncogenesis. In the past 2 years, two mutant IDH (mutIDH) inhibitors, Enasidenib (AG-221), and Ivosidenib (AG-120), have been FDA-approved for IDH-mutant relapsed or refractory acute myeloid leukemia (AML) based on phase 1 safety and efficacy data and continue to be studied in trials in hematologic malignancies, as well as in glioma, cholangiocarcinoma, and chondrosarcoma. In this review, we will summarize the molecular pathways and oncogenic consequences associated with mutIDH with a particular emphasis on glioma and AML, and systematically review the development and preclinical testing of mutIDH inhibitors. Existing clinical data in both hematologic and solid tumors will likewise be reviewed followed by a discussion on the potential limitations of mutIDH inhibitor monotherapy and potential routes for treatment optimization using combination therapy.

Salvage Therapy after Allogeneic Hematopoietic Cell Transplantation: Targeted and Low-Intensity Treatment Options in Myelodysplastic Syndrome and Acute Myeloid Leukemia

Patients with high-risk myeloid neoplasms, including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), are offered allogeneic hematopoietic cell transplantation (alloHCT) to improve the likelihood of long-term disease control. More than 50% of patients with high-risk disease will relapse after HCT and face a poor prognosis with shortened survival. The recent development of targeted therapies and effective, low-intensity treatment strategies will likely improve the outcomes of these patients. In MDS, hypomethylating agents (HMAs) are the mainstay of salvage therapy but new treatments with APR-246 and luspatercept demonstrate excellent results in phase 1 and phase 3 clinical studies, respectively. In AML, new directed agents in the relapsed/refractory setting include gilteritinib (FLT3-ITD/-TKD), ivosidenib (IDH1), and enasidenib (IDH2). In patients without targetable mutations, HMAs may be used, and early data with venetoclax-based regimens are encouraging.

Functional analysis and clinical significance of the isocitrate dehydrogenase 2 gene in papillary thyroid carcinoma

Objective: Mitochondrial NADP+-dependent isocitrate dehydrogenase 2 (IDH2) is a major producer of mitochondrial NADPH. IDH2-related research has focused on its mutation mechanism and its clinical significance, but the role of wild-type IDH2 in carcinoma remains controversial. Altered IDH2 levels have been identified in several types of carcinomas. However, the significance and expression of IDH2 in thyroid cancer remains unknown.

Methods: We examined the expression of IDH2 in thyroid cancer and adjacent normal tissues using quantitative real-time PCR (qRT-PCR), immunohistochemical (IHC) staining analyses, and western blot analysis with frozen tissues. The relationship between IDH2 and the clinicopathological features of thyroid cancer was analyzed by IHC. Subsequently, we investigated the function of wild-type IDH2 in thyroid cancer cells in vitro.

Results: We found that the mRNA expression and protein levels of IDH2 were higher in tumor than in adjacent tissues, when evaluated by qRT-PCR, western blot, and IHC analyses. Tumor size, T stage, lymph node metastasis, and TNM stage showed significant differences between the IDH2 high expression and low expression groups. Multiple logistic regression analyses indicated that tumor size and IDH2 expression were significantly correlated with the occurrence of neck LNM. Furthermore, CCK8 levels, colony formation, and invasive cell number were decreased in the sh-IDH2 groups. The upregulation of IDH2 in thyroid cancer cells showed opposite effects.

Conclusion: Our results indicated that IDH2 may play an important role in the development of thyroid cancer. IDH2 can be used as a potential biomarker for diagnosis and prognosis and may be a potential therapeutic target for thyroid cancer.

Outcome of AML patients with IDH2 mutations in real world before the era of IDH2 inhibitors

Describing the prognosis of sub-groups of acute myeloid leukemia (AML) patients treated in real world with current therapies is becoming increasingly relevant to estimate the benefit that new targeted drugs will bring in the field. This is particularly the case when novel drugs are registered on the basis of non-randomized studies. IDH2 inhibitors have recently emerged as promising drugs in patients with IDH2^R140 or IDH2^R172 mutations. Enasidenib, a first-in-class IDH2 inhibitor, has been approved following promising results of a phase 1-2 clinical trial in relapsed or refractory AML patients with IDH2 mutations. In this study, we described the characteristics, treatments and outcome of 75 IDH2 mutated patients both at diagnosis and relapse or refractory disease. Among the 33 relapsed/refractory AML patients with either IDH2^R140 or IDH2^R172, 28 (84.8%) patients received salvage therapy and 14 achieved a complete response (50%). Median duration of response was 15.2 months. Median, 1-y, 3-y and 5-y OS were 15.1 months (IQR, 4.6-37.7), 53.1% (95% CI, 33.2-69.5), 29.2% (95% CI, 12.6-48.1) and 24.4% (95% CI, 9.3-43.1), respectively. In responding patients, median OS was 37.7 months and 1-y, 3-y and 5-y OS was 85.7%, 57.1% and 47.6%, respectively. In non-responding patients, median OS was 5.0 months (IQR, 4.5-8.6) and 1-y and 3-y OS was 17.9% and 0%, respectively. Thus, a substantial number of R/R AML patients with IDH2 mutations can be salvaged by current treatments and benefit from prolonged survival. It is expected that novel targeted agents such as enasidenib will further improve efficacy and safety in the next future.

Enasidenib in the treatment of relapsed/refractory acute myeloid leukemia: an evidence-based review of its place in therapy

Introduction: Acute myeloid leukemia (AML) remains a disease with high mortality, especially for older patients and those with relapsed/refractory (R/R) disease. With recent advances in molecular testing, targeting particular leukemogenic mutations such as those occurring in isocitrate dehydrogenase (IDH) became possible. Enasidenib is a new small-molecule inhibitor of mutant isocitrate dehydrogenase-2 (IDH2). Aim: The objective of this article is to review the evidence for the use of enasidenib in R/R AML, as well as to outline future directions of enasidenib therapy. Evidence Review: Enasidenib was approved in August 2017, after a successful Phase I/II trial showing an overall response rate (ORR) of 40.3% in R/R disease, with 19.3% of patients achieving complete remission (CR). Enrollees in the trial were mostly older adults. The most prominent toxicities were hyperbilirubinemia and IDH-differentiation syndrome (IDH-DS), though the drug was generally well tolerated and the maximum tolerated dose was not reached. A Phase III trial is currently ongoing. Conclusion: Enasidenib provides a new therapeutic option for patients with R/R AML. Further studies are ongoing to ascertain its role in combination with other agents and newly diagnosed disease.

Real-World Impact of Physician and Patient Discordance on Health-Related Quality of Life in US Patients with Acute Myeloid Leukemia

Introduction

There is limited understanding concerning the health-related quality of life (HRQoL) in acute myeloid leukemia (AML) patients. Due to an overlap of symptoms, it can be difficult to separate disease versus treatment-related effects. Study objectives were to understand the impact of factors that might influence patients’ HRQoL, assess the degree of concordance in symptom reporting by patients and physicians, and assess the impact of any discordance on HRQoL in AML patients.

Methods

Physicians in the USA captured demographics, current AML treatment and symptoms for 82 AML patients who completed the Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu), 5-Dimension EuroQol Questionnaire (EQ-5D-3L) and Cancer Treatment Satisfaction Questionnaire (CTSQ). Effect size (ES) and clinically meaningful differences between AML subgroups were assessed, as was the impact of disagreement between patients and physicians regarding symptom recognition.

Results

Clinically meaningful lower overall FACT-Leu scores were observed for: relapsed/refractory versus non-relapsed/refractory AML patients (92.5 vs. 103.7; P = 0.09; ES = 0.439), hypomethylating agent (HMA) monotherapy versus other therapies in patients with low treatment intensity (89.9 vs. 112.9; P = 0.0021; ES = 0.971) and presence/absence of FLT3-ITD mutation (85.5 vs. 100; P = 0.148; ES = 0.816). Differences in health state were also clinically meaningful between patients with/without FLT3-ITD; EQ-5D-Visual Analog Scale (VAS) (47.6 vs. 63.7; P = 0.0428; ES = 0.816). Patients were more likely than physicians to report bruising (κ = 0.1292), fatigue (κ = 0.0836), bleeding (κ = 0.0177), weight loss (κ = 0.0821) and appetite loss (κ = − 0.0246). FACT-Leu was associated with patient-physician discordance on bleeding (difference − 14.12; P = 0.046), weight loss (− 21.22; P = 0.001) and appetite loss (− 12.58; P = 0.027).

Conclusions

HRQoL is generally low for AML patients, especially for particular subgroups. Discordance in symptom reporting between patients and physicians was common and associated with further negative impacts on HRQoL. There may be many reasons for this but better communication between physicians and patients may lead to shared objectives and improvement in patients’ HRQoL.

Funding

Astellas Pharma, Inc.

Electronic supplementary material

The online version of this article (10.1007/s40487-019-0094-x) contains supplementary material, which is available to authorized users.

Protein interaction disruption in cancer

Background

Most methods that integrate network and mutation data to study cancer focus on the effects of genes/proteins, quantifying the effect of mutations or differential expression of a gene and its neighbors, or identifying groups of genes that are significantly up- or down-regulated. However, several mutations are known to disrupt specific protein-protein interactions, and network dynamics are often ignored by such methods. Here we introduce a method that allows for predicting the disruption of specific interactions in cancer patients using somatic mutation data and protein interaction networks.

Methods

We extend standard network smoothing techniques to assign scores to the edges in a protein interaction network in addition to nodes. We use somatic mutations as input to our modified network smoothing method, producing scores that quantify the proximity of each edge to somatic mutations in individual samples.

Results

Using breast cancer mutation data, we show that predicted edges are significantly associated with patient survival and known ligand binding site mutations. In-silico analysis of protein binding further supports the ability of the method to infer novel disrupted interactions and provides a mechanistic explanation for the impact of mutations on key pathways.

Conclusions

Our results show the utility of our method both in identifying disruptions of protein interactions from known ligand binding site mutations, and in selecting novel clinically significant interactions.Supporting website with software and data: https://www.cs.cmu.edu/~mruffalo/mut-edge-disrupt/.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5532-5) contains supplementary material, which is available to authorized users.

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.

Emerging drug profile: Krebs cycle and cancer: IDH mutations and therapeutic implications

Mutations in IDH1 and IDH2 genes occur frequently in myeloid malignancies and certain solid tumors. IDH1 and IDH2 are enzymes that are involved in the tricarboxylic acid (TCA) cycle. Activating mutations in IDH1 and IDH2 leads to increased production of 2-hydroxygluterate and epigenetic modification, affecting cell differentiation. Small molecule inhibitors of mutated IDH1 and IDH2 have shown promising anti-cancer activity in both preclinical models and early clinical trials. Recently, enasidenib and ivosidenib, oral inhibitors of mutated IDH2 and IDH1 genes, respectively, were approved for use in relapsed or refractory acute myeloid leukemia. This review will focus on the underlying biological mechanism and clinical relevance of IDH mutations in cancer.

Mutant and Wild-Type Isocitrate Dehydrogenase 1 Share Enhancing Mechanisms Involving Distinct Tyrosine Kinase Cascades in Cancer

Isocitrate dehydrogenase 1 (IDH1) is important for reductive carboxylation in cancer cells, and the IDH1 R132H mutation plays a pathogenic role in cancers including acute myeloid leukemia (AML). However, the regulatory mechanisms modulating mutant and/or wild-type (WT) IDH1 function remain unknown. Here, we show that two groups of tyrosine kinases (TK) enhance the activation of mutant and WT IDH1 through preferential Y42 or Y391 phosphorylation. Mechanistically, Y42 phosphorylation occurs in IDH1 monomers, which promotes dimer formation with enhanced substrate (isocitrate or α-ketoglutarate) binding, whereas Y42-phosphorylated dimers show attenuated disruption to monomers. Y391 phosphorylation occurs in both monomeric and dimeric IDH1, which enhances cofactor (NADP⁺ or NADPH) binding. Diverse oncogenic TKs phosphorylate IDH1 WT at Y42 and activate Src to phosphorylate IDH1 at Y391, which contributes to reductive carboxylation and tumor growth, whereas FLT3 or the FLT3-ITD mutation activates JAK2 to enhance mutant IDH1 activity through phosphorylation of Y391 and Y42, respectively, in AML cells. SIGNIFICANCE: We demonstrated an intrinsic connection between oncogenic TKs and activation of WT and mutant IDH1, which involves distinct TK cascades in related cancers. In particular, these results provide an additional rationale supporting the combination of FLT3 and mutant IDH1 inhibitors as a promising clinical treatment of mutant IDH1-positive AML.See related commentary by Horton and Huntly, p. 699.This article is highlighted in the In This Issue feature, p. 681.

A Noninvasive Comparison Study between Human Gliomas with IDH1 and IDH2 Mutations by MR Spectroscopy

The oncogenes that are expressed in gliomas reprogram particular pathways of glucose, amino acids, and fatty acid metabolism. Mutations in isocitrate dehydrogenase genes (IDH1/2) in diffuse gliomas are associated with abnormally high levels of 2-hydroxyglutarate (2-HG) levels. The aim of this study was to determine whether metabolic reprogramming associated with IDH mutant gliomas leads to additional ¹H MRS-detectable differences between IDH1 and IDH2 mutations, and to identify metabolites correlated with 2-HG. A total of 21 glioma patients (age= 37 ± 11, 13 males) were recruited for magnetic resonance spectroscopy (MRS) using semi-localization by adiabatic selective refocusing pulse sequence at an ultra-high-field (7T). For 20 patients, the tumor mutation subtype was confirmed by immunohistochemistry and DNA sequencing. LCModel analysis was applied for metabolite quantification. A two-sample t-test was used for metabolite comparisons between IDH1 (n = 15) and IDH2 (n = 5) mutant gliomas. The Pearson correlation coefficients between 2-HG and associated metabolites were calculated. A Bonferroni correction was applied for multiple comparison. IDH2 mutant gliomas have a higher level of 2-HG/tCho (total choline=phosphocholine+glycerylphosphorylcholine) (2.48 ± 1.01vs.0.72 ± 0.38, Pc < 0.001) and myo-Inositol/tCho (2.70 ± 0.90 vs. 1.46 ± 0.51, Pc = 0.011) compared to IDH1 mutation gliomas. Associated metabolites, myo-Inositol and glucose+taurine were correlated with 2-HG levels. These results show the improved characterization of the metabolic pathways in IDH1 and IDH2 gliomas for precision medicine.

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.

The role of a monoclonal antibody 11C8B1 as a diagnostic marker of IDH2-mutated sinonasal undifferentiated carcinoma

IDH2 R172 mutations occur in >80% sinonasal undifferentiated carcinomas ("SNUC") and ~80% of these are R172S and R172T variants. We examined the utility of the monoclonal antibody 11C8B1 to IDH2 R172S in IDH2 R172-mutated tumors to establish an immunohistochemistry protocol as a surrogate method for IDH2 R172S mutation detection. Eighty-eight formalin-fixed paraffin-embedded tumors including 42 sinonasal tumors and a variety of IDH1/2-mutated malignancies were tested by immunohistochemistry. The IDH1/2 mutation status was determined in 86 cases by a targeted massively parallel sequencing MSK-IMPACT^TM assay. Interestingly, monoclonal antibody 11C8B1 was reactive with all IDH2 R172S (N = 15) mutated tumors including 12 sinonasal carcinomas, 2 high-grade sarcomas and one intrahepatic cholangiocarcinoma, and with all R172T (N = 3) mutated sinonasal carcinomas displaying a distinct granular cytoplasmic labeling in all R172S/T mutated malignancies. 11C8B1 immunohistochemistry was also positive in 2 of 6 IDH1 R132S-mutated tumors, including one intrahepatic cholangiocarcinoma and one chondrosarcoma showing a smooth homogeneous cytoplasmic staining pattern. All IDH2 R172G/K/M/W (N = 22) and IDH1 132H/C/G/L (N = 15) mutated tumors, and all IDH1/2-wild-type tumors (N = 25), including a histologic variety of 23 sinonasal tumors, were immunonegative. Importantly, 11 sinonasal undifferentiated carcinomas (N = 14, 79%) and 3 (100%) high-grade neuroendocrine carcinomas, large cell type were 11C8B1 immunopositive. Literature search revealed a virtual absence of IDH2 R172 and IDH1 R132S mutations in >1000 cases of 8 different malignancies included in the differential diagnosis of sinonasal undifferentiated carcinoma. Our study suggests that positive IDH2 11C8B1 immunohistochemistry in sinonasal carcinomas would be highly predictive of the presence of IDH2 R172S/T mutations and could serve as a reliable adjunct diagnostic marker of sinonasal undifferentiated carcinomas in >70% cases.

Cytogenetics and FLT3-ITD mutation predict clinical outcomes in non transplant patients with acute myeloid leukemia

Background

Cytogenetic abnormalities and mutated genes indicate the role of consolidation therapy with hematopoietic stem cell transplantation (HSCT) or chemotherapy in acute myeloid leukemia (AML). In this study, we conducted a retrospective study in adult AML patients with newly diagnosed with de novo AML who did not undergo HSCT, to study long term relapse free survival (RFS) and overall survival (OS) after consolidation chemotherapy.

Methods

We recruited 141 consecutive AML patients during January 2010–June 2017, the patients received induction chemotherapy with standard dose Ara-C and Idarubicin (7 + 3 or 5 + 2 regimen) followed by intermediate (IDAC) or high dose Ara-c (HiDAC) consolidation therapy.

Results

Normal karyotype, complex, favorable, intermediate and adverse chromosomal aberrations were found in 59%, 16%, 5%, 14% and 6%, respectively. Mutated NPM1, FLT3-ITD and CEBPA genes in CN-AML were seen in 33%, 18% and 19%, respectively. A 5 year follow up, 5y-RFS was 16% and 5y-OS was 14% in the whole study population. 5y-RFS and 5y-OS in patients completed 4 cycles of consolidation therapy were 25% and 40%, respectively. Adverse cytogenetic risk and mutated FLT3-ITD were significantly associated with poor RFS (9 and 15 months, respectively) and OS (14 and 16 months, respectively), whereas patients with mutant NPM1 had favorable outcomes (RFS/OS = 51/63 months). Patients receiving 4 cycles of consolidation therapy had significantly impacts on median RFS and OS compared with those treated with 1 or 2 cycles; 15 versus 11 months (p = 0.006) and 31 versus 15 months (p < 0.001), respectively.

Conclusions

Cytogenetic and mutation tests for FLT3-ITD, NPM1 and CEBPA genes were meaningful for predicting outcomes in adult AML patients. Adverse cytogenetic abnormalities and FLT3-ITD mutation showed dismal RFS and OS.

Initial Diagnostic Work-Up of Acute Leukemia: ASCO Clinical Practice Guideline Endorsement of the College of American Pathologists and American Society of Hematology Guideline

PURPOSE

The College of American Pathologists (CAP) and the American Society of Hematology (ASH) developed an evidence-based guideline on the initial diagnostic work-up of acute leukemia (AL). Because of the relevance of this topic to the ASCO membership, ASCO reviewed the guideline and applied a set of procedures and policies for endorsing clinical practice guidelines that have been developed by other professional organizations.

METHODS

The CAP-ASH guideline on initial diagnostic work-up of AL was reviewed for developmental rigor by methodologists. Then, an ASCO Endorsement Expert Panel updated the literature search and reviewed the content and recommendations.

RESULTS

The ASCO Expert Panel determined that the recommendations from the guideline, published in 2016, are clear, thorough, and based on the most relevant scientific evidence. ASCO fully endorsed the CAP-ASH guideline on initial diagnostic work-up of AL and included some discussion points according to clinical practice and updated literature.

CONCLUSION

Twenty-seven guideline statements were reviewed. Some discussion points were included to better assess CNS involvement in leukemia and to provide novel insights into molecular diagnosis and potential markers for risk stratification and target therapy. These discussions are categorized into four sections: (1) initial diagnosis focusing on basic diagnostics and determination of risk parameters, (2) molecular markers and minimal residual disease detection, (3) context of referral to another institution with expertise in the management of AL, and (4) reporting and record keeping for better outlining and follow-up discussion. Additional information is available at: www.asco.org/hematologic-malignancies-guidelines .

Isocitrate dehydrogenase gene mutations and 2-hydroxyglutarate accumulation in esophageal squamous cell carcinoma

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are key metabolic enzymes that convert isocitrate to α-ketoglutarate. Somatic point mutations in IDH1/2 confer a gain-of-function in cancer cells, resulting in overproduction of an oncometabolite, 2-hydroxyglutarate (2HG). 2HG interferes with cellular metabolism and epigenetic regulation, contributing to oncogenesis. Given that IDH1 and IDH2 are attracting attention as promising therapeutic targets, better evaluation of the incidence of IDH1 and IDH2 mutations and 2HG level in human cancers is clinically important. This is the first study to assess their incidence in esophageal squamous cell carcinomas (ESCCs). First, we established pyrosequencing assays for IDH1 and IDH2 mutations and revealed that these mutations were absent in 10 ESCC cell lines and 96 ESCC tissues. Second, utilizing IDH1 and IDH2 overexpression vectors, we demonstrated that LC-MS/MS assays can accurately evaluate 2HG level and found that some ESCC cases presented a high level of 2HG. In conclusion, IDH1 or IDH2 mutations play a limited role in the development of ESCC. 2HG is potentially synthesized to high levels in the absence of IDH1 and IDH2 mutations, and this may correlate with progression of ESCCs.

Molecular landscape and targeted therapy of acute myeloid leukemia

For decades, genetic aberrations including chromosome and molecular abnormalities are important diagnostic and prognostic factors in acute myeloid leukemia (AML). ATRA and imatinib have been successfully used in AML and chronic myelogenous leukemia, which proved that targeted therapy by identifying molecular lesions could improve leukemia outcomes. Recent advances in next generation sequencing have revealed molecular landscape of AML, presenting us with many molecular abnormalities. The individual prognostic information derived from a specific mutation could be modified by other molecular lesions. Therefore, the genomic complexity in AML poses a huge challenge to successful translation into more accurate risk stratification and targeted therapy. Herein, a summary of these mutations and targeted therapies are described. We focus on the prognostic information of recent identified molecular lesions and emerging targeted therapy.

Stable Isotope Labeling Highlights Enhanced Fatty Acid and Lipid Metabolism in Human Acute Myeloid Leukemia

Background: In Acute Myeloid Leukemia (AML), a complete response to chemotherapy is usually obtained after conventional chemotherapy but overall patient survival is poor due to highly frequent relapses. As opposed to chronic myeloid leukemia, B lymphoma or multiple myeloma, AML is one of the rare malignant hemopathies the therapy of which has not significantly improved during the past 30 years despite intense research efforts. One promising approach is to determine metabolic dependencies in AML cells. Moreover, two key metabolic enzymes, isocitrate dehydrogenases (IDH1/2), are mutated in more than 15% of AML patient, reinforcing the interest in studying metabolic reprogramming, in particular in this subgroup of patients. Methods: Using a multi-omics approach combining proteomics, lipidomics, and isotopic profiling of [U-¹³C] glucose and [U-¹³C] glutamine cultures with more classical biochemical analyses, we studied the impact of the IDH1 R132H mutation in AML cells on lipid biosynthesis. Results: Global proteomic and lipidomic approaches showed a dysregulation of lipid metabolism, especially an increase of phosphatidylinositol, sphingolipids (especially few species of ceramide, sphingosine, and sphinganine), free cholesterol and monounsaturated fatty acids in IDH1 mutant cells. Isotopic profiling of fatty acids revealed that higher lipid anabolism in IDH1 mutant cells corroborated with an increase in lipogenesis fluxes. Conclusions: This integrative approach was efficient to gain insight into metabolism and dynamics of lipid species in leukemic cells. Therefore, we have determined that lipid anabolism is strongly reprogrammed in IDH1 mutant AML cells with a crucial dysregulation of fatty acid metabolism and fluxes, both being mediated by 2-HG (2-Hydroxyglutarate) production.

Clinical implications of molecular markers in acute myeloid leukemia

The recently updated World Health Organization (WHO) Classification of myeloid neoplasms and leukemia reflects the fact that research in the underlying pathogenic mechanisms of acute myeloid leukemia (AML) has led to remarkable advances in our understanding of the disease. Gene mutations now allow us to explore the enormous diversity among cytogenetically defined subsets of AML, particularly the large subset of cytogenetically normal AML. Despite the progress in unraveling the tumor genome, only a small number of recurrent mutations have been incorporated into risk-stratification schemes and have been proven to be clinically relevant, targetable lesions. We here discuss the utility of molecular markers in AML in prognostication and treatment decision making, specifically highlighting the aberrations included in the current WHO classification.

Persistent IDH1/2 mutations in remission can predict relapse in patients with acute myeloid leukemia

Persistence of IDH1 or IDH2 mutations in remission bone marrow specimens of patients with acute myeloid leukemia has been observed, but the clinical impact of these mutations is not well known. In this study, we evaluated 80 acute myeloid leukemia patients with known IDH1 R132 or IDH2 R140/R172 mutations and assessed their bone marrow at the time of remission to determine the potential impact of persistent IDH1/2 mutations. Approximately 40% of acute myeloid leukemia patients given standard treatment in this cohort had persistent mutations in IDH1/2 Patients with an IDH1/2 mutation had an increased risk of relapse after 1 year of follow-up compared to patients without a detectable IDH1/2 mutation (59% versus 24%; P<0.01). However, a persistent mutation was not associated with a shorter time to relapse. High IDH1/2 mutation burden (mutant allelic frequency ≥10%) did not correlate with relapse rate (77% versus 86% for patients with a low burden, i.e., mutant allelic frequency <10%; P=0.66). Persistent mutations were also observed in NPM1, DNMT3A and FLT3 during remission, but IDH1/2 mutations remained significant in predicting relapse by multivariate analysis. Flow cytometry was comparable and complementary to next-generation sequencing-based assay for predicting relapse. Monitoring for persistent IDH1/2 mutations in patients with acute myeloid leukemia in remission can provide information that could be used to justify early interventions, with the hope of facilitating longer remissions and better outcomes in these patients.

NPM1 alternative transcripts are upregulated in acute myeloid and lymphoblastic leukemia and their expression level affects patient outcome

Background

Expression of the NPM1 gene, encoding nucleophosmin, is upregulated in cancers. Although more than ten NPM1 transcripts are known, the reports were usually limited to one predominant transcript. In leukemia, the NPM1 expression has not been widely studied so far. In acute myeloid leukemia (AML), the mutational status of the gene seems to play a pivotal role in carcinogenesis. Therefore, the aim of the study was to quantify alternative NPM1 transcripts in two types of acute leukemia, AML and ALL (acute lymphoblastic leukemia).

Methods

Using droplet digital PCR, we analyzed the levels of three protein-coding NPM1 transcripts in 66 samples collected from AML and ALL patients and 16 control samples. Using RNA-seq, we detected 8 additional NPM1 transcripts, including non-coding splice variants with retained introns. For data analysis, Welch two sample t-test, Pearson’s correlation and Kaplan–Meier analysis were applied.

Results

The levels of the particular NPM1 transcripts were significantly different but highly correlated with each other in both leukemia and control samples. Transcript NPM1.1, encoding the longest protein (294 aa), had the highest level of accumulation and was one of the most abundant transcripts in the cell. Comparing to NPM1.1, the levels of the NPM1.2 and NPM1.3 transcripts, encoding a 265-aa and 259-aa proteins, were 30 and 3 times lower, respectively. All three NPM1 transcripts were proportionally upregulated in both types of leukemia compared to control samples. In AML, the levels of NPM1 transcripts decreased in complete remission and increased again with relapse of the disease. Low levels of NPM1.1 and NPM1.3 were associated with better prognosis. The contribution of non-coding transcripts to the total level of NPM1 gene seemed to be marginal, except for one short 5-end transcript accumulated at high levels in AML and control cells. Aberrant proportions of particular NPM1 splice variants could be linked to abnormal expression of genes encoding alternative splicing factors.

Conclusions

The levels of the studied NPM1 transcripts were different but highly correlated with each other. Their upregulation in AML and ALL, decrease after therapy and association with patient outcome suggests the involvement of elevated NPM1 expression in the acute leukemia pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1608-2) contains supplementary material, which is available to authorized users.

New and emerging therapies for acute myeloid leukaemia

The treatment of acute myeloid leukemia (AML) has remained relatively unchanged for the past 3-4 decades with generally poor outcomes, especially in elderly populations unfit for intensive therapy. Recent advancements, however, have identified several cytogenetic and molecular markers that have not only improved prognostication but have also led to the development of several new targeted therapies for specific subpopulations. In 2017, the US Food and Drug Administration approved four new treatments with indications for fms like tyrosine kinase 3 (FLT3)-mutated AML (midostaurin), newly diagnosed or relapsed/refractory CD33+AML (gemtuzumab ozogamicin), newly diagnosed therapy-related AML or AML with myelodysplasia-related changes (CPX-351) and relapsed/refractory AML with an isocitrate dehydrogenase (IDH)2 mutation (enasidenib). These newly approved therapies have demonstrated improved response in their target populations in several pivotal clinical trials with some also demonstrating improved overall survival. Additional novel therapies in development for AML include agents that target B cell lymphoma 2, FLT3, IDH1, the ubiquitination pathway, as well as cell therapy using engineered T cells with chimeric antigen receptors. This review provides a summary of the four newly approved therapies for AML, as well as several promising therapies currently in development.

Novel epigenetic therapies in hematological malignancies: Current status and beyond

Over the last decade transcriptional dysregulation and altered epigenetic programs have emerged as a hallmark in the majority of hematological cancers. Several epigenetic regulators are recurrently mutated in many hematological malignancies. In addition, in those cases that lack epigenetic mutations, altered function of epigenetic regulators has been shown to play a central role in the pathobiology of many hematological neoplasms, through mechanisms that are becoming increasingly understood. This, in turn, has led to the development of small molecule inhibitors of dysregulated epigenetic pathways as novel targeted therapies for hematological malignancies. In this review, we will present the most recent advances in our understanding of the role played by dysregulated epigenetic programs in the development and maintenance of hematological neoplasms. We will describe novel therapeutics targeting altered epigenetic programs and outline their mode of action. We will then discuss their use in specific conditions, identify potential limitations and putative toxicities while also providing an update on their current clinical development. Finally, we will highlight the opportunities presented by epigenetically targeted therapies in hematological malignancies and introduce the challenges that need to be tackled by both the research and clinical communities to best translate these novel therapies into clinical practice and to improve patient outcomes.

A distinct immunophenotype identifies a subset of NPM1-mutated AML with TET2 or IDH1/2 mutations and improved outcome

Recent work has identified distinct molecular subgroups of acute myeloid leukemia (AML) with implications for disease classification and prognosis. NPM1 is one of the most common recurrently mutated genes in AML. NPM1 mutations often co-occur with FLT3-ITDs and mutations in genes regulating DNA methylation, such as DNMT3A, TET2, and IDH1/2. It remains unclear whether these genetic alterations are associated with distinct immunophenotypic findings or affect prognosis. We identified 133 cases of NPM1-mutated AML and correlated sequencing data with immunophenotypic and clinical findings. Of 84 cases (63%) that lacked monocytic differentiation ("myeloid AML"), 40 (48%) demonstrated an acute promyelocytic leukemia-like (APL-like) immunophenotype by flow cytometry, with absence of CD34 and HLA-DR and strong myeloperoxidase expression, in the absence of a PML-RARA translocation. Pathologic variants in TET2, IDH1, or IDH2 were identified in 39/40 APL-like cases. This subset of NPM1-mutated AML was associated with longer relapse-free and overall survival, when compared with cases that were positive for CD34 and/or HLA-DR. The combination of NPM1 and TET2 or IDH1/2 mutations along with an APL-like immunophenotype identifies a distinct subtype of AML. Further studies addressing its biology and clinical significance may be especially relevant in the era of IDH inhibitors and recent work showing efficacy of ATRA therapy in NPM1 and IDH1-mutated AML.

Targeting IDH1 and IDH2 Mutations in Acute Myeloid Leukemia

PURPOSE OF REVIEW

Over the past decade, the pathogenic role of mutations in isocitrate dehydrogenases (IDH) 1 and 2, affecting approximately 20% of patients with AML, has been defined, allowing for the development of specific therapeutic strategies for IDH-mutant AML. In this review, the landscape and progress of targeted therapeutics aimed at IDH mutations in AML and related myeloid malignancies will be described.

RECENT FINDINGS

Since 2013, several mutant IDH-targeted inhibitors have been developed, and nearly a dozen clinical trials have opened specifically for IDH-mutant hematologic malignancies. Preliminary results for several of these investigations have shown evidence of safety, tolerability, and encouraging evidence of efficacy. Targeting IDH mutations in AML is a biologically informed and rational strategy to promote clinical responses, primarily through differentiation and maturation of the malignant clone. The use of IDH targeted therapy is expected to soon become part of a genomically defined and individualized AML treatment strategy.

Evolving Treatment Strategies for Elderly Leukemia Patients with IDH Mutations

Acute myeloid leukemia (AML) is a debilitating and life-threatening condition, especially for elderly patients who account for over 50% of diagnoses. For over four decades, standard induction therapy with intensive cytotoxic chemotherapy for AML had remained unchanged. However, for most patients, standard therapy continues to have its shortcomings, especially for elderly patients who may not be able to tolerate the complications from intensive cytotoxic chemotherapy. New research into the development of targeted and alternative therapies has led to a new era in AML therapy. For the nearly 20% of diagnoses harboring a mutation in isocitrate dehydrogenase 1 or 2 (IDH1/2), potential treatment options have undergone a paradigm shift away from intensive cytotoxic chemotherapy and towards targeted therapy alone or in combination with lower intensity chemotherapy. The first FDA approved IDH2 inhibitor was enasidenib in 2017. In addition, IDH1 inhibitors are in ongoing clinical studies, and the oral BCL-2 inhibitor venetoclax shows preliminary efficacy in this subset of patients. These new tools aim to improve outcomes and change the treatment paradigm for elderly patients with IDH mutant AML. However, the challenge of how to best incorporate these agents into standard practice remains.

The role of enasidenib in the treatment of mutant IDH2 acute myeloid leukemia

Recurrent mutations affecting cellular metabolism and epigenetic regulation are implicated in the pathogenesis of acute myeloid leukemia (AML). Isocitrate dehydrogenase 2 (IDH2) gene mutations are described in 12% of patients with AML and 5% of patients with myelodysplastic syndromes. IDH2 enzyme is involved in the Krebs cycle, catalyzing α-ketoglutarate from isocitrate. Mutant IDH2 enzymes acquire a neomorphic enzymatic activity with the ability to produce 2-hydroxyglutarate from α-ketoglutarate, inhibiting multiple α-ketoglutarate-dependent dioxygenase reactions; leading to aberrant DNA hypermethylation and differentiation block in myeloid precursors and ultimately promoting leukemogenesis. Enasidenib (formerly AG-221) is an oral small molecule selective targeted inhibitor of the mutant IDH2 enzyme, approved in August 2017 by the United States Food and Drug Administration for the treatment of patients with relapsed or refractory (R/R) IDH2-mutated AML. Preclinical studies showed the effectiveness of enasidenib in inhibiting the production of 2-hydroxyglutarate with high potency, and alleviating the mutant IDH2-induced differentiation block. In the original AG221-001 phase I/II trial, patients with R/R AML were treated with enasidenib single agent therapy at escalating doses up to 650 mg daily, with the 100 mg dose level identified to be safe and effective for further evaluation. Overall, 113 patients were treated in the dose-escalation and 126 in the dose-expansion cohorts. The overall response rate for R/R patients was 40%, including a complete remission of 19%. At a median follow up of 7.7 months, the median overall survival was 9.3 months, and reached 19.7 months in responders. Enasidenib was well tolerated, although adverse events of clinical interest include indirect hyperbilirubinemia and IDH-inhibitor-induced differentiation syndrome, which can be life threatening if not identified and treated promptly. Ongoing clinical trials evaluating enasidenib in combination with intensive chemotherapy and hypomethylating agents in newly diagnosed AML, and in rational combinations for R/R AML patients are underway.

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.

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.