Differential impact of IDH1/2 mutational subclasses on outcome in adult AML: Results from a large multicenter study

Somatic gene mutation patterns and burden influence outcomes with enasidenib in relapsed/refractory IDH2-mutated AML

Limited treatment options are available for patients with relapsed/refractory acute myeloid leukemia (R/R AML). We recently reported results from the phase 3 IDHENTIFY trial (NCT02577406) showing improved response rates and event-free survival with enasidenib monotherapy compared with conventional care regimens (CCR) in heavily pretreated, older patients with late-stage R/R AML bearing IDH2 mutations. Here we investigated the prognostic impact of mutational burden and different co-mutation patterns at study entry within the predominant IDH2 variant subclasses, IDH2-R140 and IDH2-R172. The prognostic relevance of these variants is well documented in newly diagnosed AML, but data are lacking in R/R AML. In this large R/R AML patient cohort, targeted next-generation sequencing at baseline (screening) revealed distinct co-mutation patterns and mutational burden between subgroups bearing different IDH2 variants: variant IDH2-R140 was associated with greater mutational burden and was enriched predominantly with poor-risk mutations, including FLT3, RUNX1, and NRAS, while variant IDH2-R172 was associated with lower mutational burden and was preferentially co-mutated with DNMT3A. In multivariable analyses, RAS and RTK pathway mutations were significantly associated with decreased overall survival, after adjusting for treatment arm, IDH2 variant, and mutational burden. Importantly, enasidenib-mediated survival benefit was more pronounced in patients with IDH2-R172 variants.

Single-center, observational study of AML/MDS-EB with IDH1/2 mutations: genetic profile, immunophenotypes, mutational kinetics and outcomes

OBJECTIVE

IDH1/2 mutations, intervening in epigenetic procedures, are frequently encountered in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Knowledge of the genetics, immunophenotypes, and mutational kinetics of IDH1/2-mutated AML can contribute to the understanding of AML clonal architecture and inform therapeutics and monitoring.

METHODS

We retrospectively analyzed 50 IDH1/2-mutated AML/MDS-EB cases of our institution, to identify recurrent co-mutations, immunophenotypes, patterns of co-variance of IDH1/2 allele burdens with those of recurrent co-mutations, frequency of persistent IDH1/2 mutation as clonal hematopoiesis of indeterminate potential (CHIP) in remission and response to hypomethylating agents.

RESULTS

Most frequently co-mutated genes were DNMT3A, SRSF2 and NPM1. Most cases with co-existent IDH1/2 and NPM1 mutations (11/13) showed an 'APL-like' immunophenotype (CD34-HLADR-). Allele burdens of mutated IDH1/2 were identical to mutated SRSF2 allele burdens at diagnosis and remission, but not always to mutated NPM1 allele burden in remission. We show persistence of significant mutIDH1/2 allele burden in approximately one-fourth of patients with deep remissions. IDH1/2 mutations were significantly more frequent among responders to first-line HMA-based regimens than among non-responders, in patients treated for myeloid neoplasms with excess blasts.

CONCLUSIONS

IDH1/2 mutations are most frequently accompanied by DNMT3A, SRSF2 and NPM1 mutations. NPM1-IDH1/2 mutated AML has a mature phenotype possibly amenable to differentiation therapies. IDH1/2 and SRSF2 mutations probably arise at the same developmental stage of the disease, as their allele burdens covariate. IDH1/2 mutation represents CHIP in a substantial proportion of cases and is therefore no reliable residual disease marker. The preferential presence of IDH1/2 mutations among HMA-responders could inform therapeutic decisions if confirmed in larger series.

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.

Measurable Residual IDH1 before Allogeneic Transplant for Acute Myeloid Leukemia

Measurable residual disease (MRD) in adults with acute myeloid leukemia (AML) in complete remission is an important prognostic marker, but detection methodology requires optimization. The persistence of mutated NPM1 or FLT3-ITD in the blood of adult patients with AML in first complete remission (CR1) prior to allogeneic hematopoetic cell transplant (alloHCT) has been established as associated with increased relapse and death after transplant. The prognostic implications of persistence of other common AML-associated mutations, such as IDH1, at this treatment landmark however remains incompletely defined. We performed testing for residual IDH1 variants (IDH1m) in pre-transplant CR1 blood of 148 adult patients undergoing alloHCT for IDH1-mutated AML at a CIBMTR site between 2013-2019. No post-transplant differences were observed between those testing IDH1m positive (n=53, 36%) and negative pre-transplant (overall survival: p = 0.4; relapse: p = 0.5). For patients with IDH1 mutated AML co-mutated with NPM1 and/or FLT3-ITD, only detection of persistent mutated NPM1 and/or FLT3-ITD was associated with significantly higher rates of relapse (p = 0.01). These data, from the largest study to date, do not support the detection of IDH1 mutation in CR1 blood prior to alloHCT as evidence of AML MRD or increased post-transplant relapse risk.

IDH Mutations in Chondrosarcoma: Case Closed or Not?

Chondrosarcomas are malignant cartilage-producing tumours that frequently harbour isocitrate dehydrogenase 1 and -2 (IDH) gene mutations. Several studies have confirmed that these mutations are key players in the early stages of cartilage tumour development, but their role in later stages remains ambiguous. The prognostic value of IDH mutations remains unclear and preclinical studies have not identified effective treatment modalities (in)directly targeting these mutations. In contrast, the IDH mutation status is a prognostic factor in other cancers, and IDH mutant inhibitors as well as therapeutic strategies targeting the underlying vulnerabilities induced by IDH mutations seem effective in these tumour types. This discrepancy in findings might be ascribed to a difference in tumour type, elevated D-2-hydroxyglutarate levels, and the type of in vitro model (endogenous vs. genetically modified) used in preclinical studies. Moreover, recent studies suggest that the (epi)genetic landscape in which the IDH mutation functions is an important factor to consider when investigating potential therapeutic strategies or patient outcomes. These findings imply that the dichotomy between IDH wildtype and mutant is too simplistic and additional subgroups indeed exist within chondrosarcoma. Future studies should focus on the identification, characterisation, and tailoring of treatments towards these biological subgroups within IDH wildtype and mutant chondrosarcoma.

Genetic, Phenotypic, and Clinical Heterogeneity of NPM1-Mutant Acute Myeloid Leukemias

The current classification of acute myeloid leukemia (AML) relies largely on genomic alterations. AML with mutated nucleophosmin 1 (NPM1-mut) is the largest of the genetically defined groups, involving about 30% of adult AMLs and is currently recognized as a distinct entity in the actual AML classifications. NPM1-mut AML usually occurs in de novo AML and is associated predominantly with a normal karyotype and relatively favorable prognosis. However, NPM1-mut AMLs are genetically, transcriptionally, and phenotypically heterogeneous. Furthermore, NPM1-mut is a clinically heterogenous group. Recent studies have in part clarified the consistent heterogeneities of these AMLs and have strongly supported the need for an additional stratification aiming to improve the therapeutic response of the different subgroups of NPM1-mut AML patients.

Prognostic value of IDH2R140 and IDH2R172 mutations in patients with acute myeloid leukemia: a systematic review and meta-analysis

BACKGROUND

Whether isocitrate dehydrogenase 2 (IDH2) R140 and R172 gene mutations affect the prognosis of patients with acute myeloid leukemia (AML) is controversial. Here, we performed a meta-analysis to assess their prognostic value.

METHODS

Eligible studies were systematically searched from PubMed, Embase, the Cochrane Library and Chinese databases up to June 1, 2022. We extracted the hazard ratios (HRs) and their 95% confidence intervals (CIs) of overall survival (OS) and progression-free survival (PFS) to carry out a meta-analysis by a fixed effect model or random effect model according to the heterogeneity between studies.

RESULTS

A total of 12725 AML patients from 11 studies were included in this meta-analysis, of which 1111 (8.7%) and 305 (2.4%) had IDH2R140 and IDH2R172 mutations, respectively. The results revealed that both IDH2R140 and IDH2R172 mutations had no significant effect on OS (IDH2R140: HR = 0.92, 95% CI: 0.77-1.10, P = 0.365; IDH2R172: HR = 0.91, 95% CI: 0.65-1.28, P = 0.590) or PFS (IDH2R140: HR = 1.02, 95% CI: 0.75-1.40, P = 0.881; IDH2R172: HR = 1.31, 95% CI: 0.78-2.22, P = 0.306) in AML patients. Subgroup analysis of AML patients with IDH2R140 mutation revealed that studies from the USA (HR = 0.60, 95% CI: 0.41-0.89, P = 0.010) and ≤ 50 years old (HR = 0.63, 95% CI: 0.50-0.80, P = 0.000) had longer OS. However, studies from Sweden (HR = 1.94, 95% CI: 1.07-3.53, P = 0.030) had shorter OS. Meanwhile, subgroup analysis of AML patients with IDH2R172 mutation showed that studies from Germany/Austria (HR = 0.76, 95% CI: 0.61-0.94, P = 0.012) and from Sweden (HR = 0.22, 95% CI: 0.07-0.74, P = 0.014) had longer OS, whereas studies from the UK (HR = 1.49, 95% CI: 1.13-1.96, P = 0.005) and studies with nonmultivariate analysis of data type (HR = 1.35, 95% CI: 1.06-1.73, P = 0.014) had shorter OS. In addition, our study also found that patients with IDH2R140 mutation had significantly longer OS (HR = 0.61, 95% CI: 0.39-0.96, P = 0.032) and PFS (HR = 0.31, 95% CI: 0.18-0.52, P = 0.021) than patients with IDH2R172 mutation, despite some degree of heterogeneity.

CONCLUSIONS

This meta-analysis demonstrates that IDH2R140 mutation improves OS in younger AML patients and that the prognostic value of IDH2R172 mutation is significantly heterogeneous. Differences in region and data type have a significant impact on the prognosis of AML patients with IDH2R140 and/or IDH2R172 mutations. Additionally, AML patients with IDH2R140 mutation have a better prognosis than those with IDH2R172 mutations, albeit with some degree of heterogeneity.

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.

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 mutational subgroups in AML patients after allogeneic stem cell transplantation

Background

The role of allogeneic hematopoietic cell transplantation (alloHCT) in acute myeloid leukemia (AML) with mutated IDH1/2 has not been defined. Therefore, we analyzed a large cohort of 3234 AML patients in first complete remission (CR1) undergoing alloHCT or conventional chemo-consolidation and investigated outcome in respect to IDH1/2 mutational subgroups (IDH1 R132C, R132H and IDH2 R140Q, R172K).

Methods

Genomic DNA was extracted from bone marrow or peripheral blood samples at diagnosis and analyzed for IDH mutations with denaturing high-performance liquid chromatography, Sanger sequencing and targeted myeloid panel next-generation sequencing, respectively. Statistical as-treated analyses were performed using R and standard statistical methods (Kruskal–Wallis test for continuous variables, Chi-square test for categorical variables, Cox regression for univariate and multivariable models), incorporating alloHCT as a time-dependent covariate.

Results

Among 3234 patients achieving CR1, 7.8% harbored IDH1 mutations (36% R132C and 47% R132H) and 10.9% carried IDH2 mutations (77% R140Q and 19% R172K). 852 patients underwent alloHCT in CR1. Within the alloHCT group, 6.2% had an IDH1 mutation (43.4% R132C and 41.4% R132H) and 10% were characterized by an IDH2 mutation (71.8% R140Q and 24.7% R172K). Variants IDH1 R132C and IDH2 R172K showed a significant benefit from alloHCT for OS (p = .017 and p = .049) and RFS (HR = 0.42, p = .048 and p = .009) compared with chemotherapy only. AlloHCT in IDH2 R140Q mutated AML resulted in longer RFS (HR = 0.4, p = .002).

Conclusion

In this large as-treated analysis, we showed that alloHCT is able to overcome the negative prognostic impact of certain IDH mutational subclasses in first-line consolidation treatment and could pending prognostic validation, provide prognostic value for AML risk stratification and therapeutic decision making.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01339-8.

IDH2: A novel biomarker for environmental exposure in blood circulatory system disorders (Review)

As the risk of harmful environmental exposure is increasing, it is important to find suitable targets for the diagnosis and treatment of the diseases caused. Isocitrate dehydrogenase 2 (IDH2) is an enzyme located in the mitochondria; it plays an important role in numerous cell processes, including maintaining redox homeostasis, participating in the tricarboxylic acid cycle and indirectly taking part in the transmission of the oxidative respiratory chain. IDH2 mutations promote progression in acute myeloid leukemia, glioma and other diseases. The present review mainly summarizes the role and mechanism of IDH2 with regard to the biological effects, such as the mitophagy and apoptosis of animal or human cells, caused by environmental pollution such as radiation, heavy metals and other environmental exposure factors. The possible mechanisms of these biological effects are described in terms of IDH2 expression, reduced nicotine adenine dinucleotide phosphate content and reactive oxygen species level, among other variables. The impact of environmental pollution on human health is increasingly attracting attention. IDH2 may therefore become useful as a potential diagnostic and therapeutic target for environmental exposure-induced diseases.

The Molecular Mechanisms of Resistance to IDH Inhibitors in Acute Myeloid Leukemia

Gain-of-function mutations of isocitrate dehydrogenases 1/2 (IDH1/2) play crucial roles in the development and progression of acute myeloid leukemia (AML), which provide promising therapeutic targets. Two small molecular inhibitors, ivosidenib and enasidenib have been approved for the treatment of IDH1- and IDH2-mutant AML, respectively. Although these inhibitors benefit patients with AML clinically, drug resistance still occurs and have become a major problem for targeted therapies of IDH-mutant AML. A number of up-to-date studies have demonstrated molecular mechanisms of resistance, providing rationales of novel therapeutic strategies targeting mutant IDH1/2. In this review, we discuss mechanisms of resistance to ivosidenib and enasidenib in patients with AML.

Prevalence and Prognostic Role of IDH Mutations in Acute Myeloid Leukemia: Results of the GIMEMA AML1516 Protocol

IDH1/2 mutations are common in acute myeloid leukemia (AML) and represent a therapeutic target. The GIMEMA AML1516 observational protocol was designed to study the prevalence of IDH1/2 mutations and associations with clinico-biological parameters in a cohort of Italian AML patients. We analyzed a cohort of 284 AML consecutive patients at diagnosis, 139 females and 145 males, of a median age of 65 years (range: 19−86). Of these, 38 (14%) harbored IDH1 and 51 (18%) IDH2 mutations. IDH1/2 mutations were significantly associated with WHO PS >2 (p < 0.001) and non-complex karyotype (p = 0.021) when compared to IDH1/2-WT. Furthermore, patients with IDH1 mutations were more frequently NPM1-mutated (p = 0.007) and had a higher platelet count (p = 0.036). At relapse, IDH1/2 mutations were detected in 6 (25%) patients. As per the outcome, 60.5% of IDH1/2-mutated patients achieved complete remission; overall survival and event-free survival at 2 years were 44.5% and 36.1%, respectively: these rates were similar to IDH1/2-WT. In IDH1/2-mutated patients, high WBC proved to be an independent prognostic factor for survival. In conclusion, the GIMEMA AML1516 confirms that IDH1/2 mutations are frequently detected at diagnosis and underlines the importance of recognizing IDH1/2-mutated cases up-front to offer the most appropriate therapeutic strategy, given the availability of IDH1/2 inhibitors.

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.