IDH1-mutated Acute Myeloid Leukemia Research Articles

HMA/VEN treatment modifications and associated outcomes in IDH-mutant AML

Hypomethylating agents (HMA) and venetoclax (VEN) are commonly used in patients with IDH-mutated (IDHm) acute myeloid leukemia (AML) ineligible for induction chemotherapy. While prior studies demonstrated high response and survival rates with HMA/VEN in IDHm AML, the impact of treatment modifications in real-world settings is unclear. We retrospectively reviewed 89 IDHm AML patients treated with HMA/VEN from January 2018 to June 2023. CR/CRi rates were 76% in newly diagnosed (ND) and 55% in relapsed/refractory (R/R) patients, and median overall survival was 29.2 months (ND) and 17.1 months (R/R), respectively. Treatment modifications were common. Early VEN reductions were associated with lower response rates but not worse survival. Prolonged cycles were not associated with worse response rates or survival. Significant neutropenia and ED visits or unplanned hospitalizations were considerable before and after CR/CRi, though febrile neutropenia decreased afterward. HMA/VEN is efficacious, with treatment modifications not affecting survival, though long-term toxicities are notable.

RIPK3 deficiency blocks R-2-hydroxyglutarate-induced necroptosis in IDH-mutated AML cells.

Mutant isocitrate dehydrogenases (IDHs) produce R-2-hydroxyglutarate (R-2HG), which inhibits the growth of most acute myeloid leukemia (AML) cells. Here, we showed that necroptosis, a form of programmed cell death, contributed to the antileukemia activity of R-2HG. Mechanistically, R-2HG competitively inhibited the activity of lysine demethylase 2B (KDM2B), an α-ketoglutarate-dependent dioxygenase. KDM2B inhibition increased histone 3 lysine 4 trimethylation levels and promoted the expression of receptor-interacting protein kinase 1 (RIPK1), which consequently caused necroptosis in AML cells. The expression of RIPK3 was silenced because of DNA methylation in IDH-mutant (mIDH) AML cells, resulting in R-2HG resistance. Decitabine up-regulated RIPK3 expression and repaired endogenous R-2HG-induced necroptosis pathway in mIDH AML cells. Together, R-2HG induced RIPK1-dependent necroptosis via KDM2B inhibition in AML cells. The loss of RIPK3 protected mIDH AML cells from necroptosis. Restoring RIPK3 expression to exert R-2HG's intrinsic antileukemia effect will be a potential therapeutic strategy in patients with AML.

Data-driven modeling of core gene regulatory network underlying leukemogenesis in IDH mutant AML

Acute myeloid leukemia (AML) is characterized by uncontrolled proliferation of poorly differentiated myeloid cells, with a heterogenous mutational landscape. Mutations in IDH1 and IDH2 are found in 20% of the AML cases. Although much effort has been made to identify genes associated with leukemogenesis, the regulatory mechanism of AML state transition is still not fully understood. To alleviate this issue, here we develop a new computational approach that integrates genomic data from diverse sources, including gene expression and ATAC-seq datasets, curated gene regulatory interaction databases, and mathematical modeling to establish models of context-specific core gene regulatory networks (GRNs) for a mechanistic understanding of tumorigenesis of AML with IDH mutations. The approach adopts a new optimization procedure to identify the top network according to its accuracy in capturing gene expression states and its flexibility to allow sufficient control of state transitions. From GRN modeling, we identify key regulators associated with the function of IDH mutations, such as DNA methyltransferase DNMT1, and network destabilizers, such as E2F1. The constructed core regulatory network and outcomes of in-silico network perturbations are supported by survival data from AML patients. We expect that the combined bioinformatics and systems-biology modeling approach will be generally applicable to elucidate the gene regulation of disease progression.

Differentiation syndrome associated with treatment with IDH2 inhibitor enasidenib: pooled analysis from clinical trials

AbstractTreatment with enasidenib, a selective mutant isocitrate dehydrogenase isoform 2 (IDH2) inhibitor, has been associated with the development of differentiation syndrome (DS) in patients with acute myeloid leukemia (AML). Studies on the incidence and clinical features of DS are limited in this setting, and diagnosis is challenging because of nonspecific symptoms. This study assessed the incidence, diagnostic criteria, risk factors, and correlation with clinical response of DS based on the pooled analysis of 4 clinical trials in patients with IDH2-mutated AML treated with enasidenib as monotherapy, or in combination with azacitidine or with chemotherapy. Across the total AML population, 67 of 643 (10.4%) had ≥1 any-grade DS event, with highest incidence in patients who received enasidenib plus azacitidine and lowest incidence in patients who received enasidenib plus chemotherapy (13/74 [17.6%] and 2/93 [2.2%]). The most common symptoms of DS were dyspnea/hypoxia (80.6%) and pulmonary infiltrate (73.1%). Median time to onset of first DS event across all studies was 32 days (range, 4-129). Most patients (88.1%) received systemic steroids for treatment of DS. Evaluation of baseline risk factors for DS identified higher levels of bone marrow blasts and lactate dehydrogenase as independent factors associated with increased grade 3 to 5 DS risk. Overall, these results suggest that DS associated with IDH inhibition is manageable, given the benefits of enasidenib treatment in IDH2-mutated AML. We further characterized enasidenib-related DS in these patients and identified risk factors, which could be used for DS management in clinical practice. These trials were registered at www.ClinicalTrials.gov as # NCT01915498, NCT02577406, NCT02677922, and NCT02632708.

Altered Oxidative Phosphorylation Confers Vulnerability on IDH1-Mutant Leukemia Cells: Is This Therapeutically Tractable?

Isocitrate dehydrogenase (IDH)-mutant acute myeloid leukemia (AML) is treatable with inhibitors of mutant IDH and also responds well to combination therapies including venetoclax, but most patients with IDH-mutant AML either never achieve complete remission or relapse because mutant hematopoietic stem cells persist despite treatment. An interesting new study in Blood Cancer Discovery characterizes a specific vulnerability in the mitochondrial oxidative phosphorylation system in preleukemic hematopoietic stem cells from patients with IDH1 mutations that is not present in those with IDH2 mutations; will this susceptibility prove amenable to therapy? See related article by Landberg et al., p. 114 (10).

IDH1 and IDH2 Gene Mutations in Omani Patients with Acute Myeloid Leukemia: Prognostic Significance and Clinic-pathologic Features.

We sought to define the prevalence of isocitrate dehydrogenase (IDH) mutations, evaluate the clinicopathologic impact of IDH mutations, assess the effect of IDH mutations on the response to the currently offered treatment for acute myeloid leukemia (AML) cases, and determine the impact of other common concurrent mutations with IDH. A single-center retrospective cohort study was conducted at Sultan Qaboos University Hospital (SQUH) from October 2009 to October 2019. We included all Omani patients (pediatric and adult) treated at SQUH with the standard therapy, for whom DNA extraction was performed at diagnosis. The target mutations in both IDH1 and IDH2 genes were screened using the direct polymerase chain reaction product sequencing method. Statistical analysis was conducted using SPSS software. Survival differences were estimated using the log-rank test. Continuous variables were presented as median (IQRs), while categorical variables were presented as frequency. A total of 61 patients treated, for whom DNA extraction was performed at diagnosis were evaluated. The median age was 40 (range = 25.5-65.5). The prevalence of IDH1 R132, IDH2 R140, and IDH2 R172 mutations among the study group was 6.6%, 3.3%, and 1.6%, respectively. Clinicopathologic characteristics associated with IDH mutations at diagnosis included older age, lower white blood cell count, higher median platelet counts, normal karyotype AML, and cytogenetics intermediate-risk group. The overall survival (OS) in patients harboring IDH mutations was poor, with a median OS of nine months. This analysis confirms that the response rate and OS for both IDH-mutated and IDH wild-type AML patients were comparable. This will provide contemporary data to be used for comparison with the results of novel investigational (e.g., selective IDH inhibitor) strategies. The current study results were consistent with the other international studies of IDH mutations in AML and demonstrate the poor prognosis associated with IDH mutations. Clinicopathologic features associated with IDH mutations included older age, lower white blood cell count, higher median platelet counts, normal karyotype AML, and cytogenetics intermediate-risk group.

D-2-hydroxyglutarate supports a tolerogenic phenotype with lowered major histocompatibility class II expression in non-malignant dendritic cells and acute myeloid leukemia cells.

D-2-hydroxyglutarate (D-2-HG) accumulates in patients with acute myeloid leukemia (AML) with mutated isocitrate dehydrogenase (IDH) and in other malignancies. D-2-HG suppresses antitumor T-cell immunity but little is known about potential effects on non-malignant myeloid cells. Here we show that D-2-HG impairs human but not murine dendritic cell differentiation, resulting in a tolerogenic phenotype with low major histocompatibility class II expression. In line with this, IDH-mutated AML blasts exhibited lower expression of HLA-DP and were less susceptible to lysis by HLA-DP-specific T cells. Interestingly, besides its expected impact on DNA demethylation, D-2-HG reprogrammed metabolism towards increased lactate production in dendritic cells and AML. Vitamin C accelerated DNA demethylation, but only the combination of vitamin C and glycolytic inhibition lowered lactate levels and supported major histocompatibility complex class II expression. Our results indicate an unexpected link between the immunosuppressive metabolites 2-HG and lactic acid and suggest a potentially novel therapeutic strategy with combinations of anti-glycolytic drugs and epigenetic modulators (hypomethylating agents) or other therapeutics for the treatment of AML.

Changes in White Blood Cell Counts Early during Treatment of Acute Leukemia Using Differentiating Chemotherapies

Background: Differentiation syndrome (DS) is a life-threatening complication that can occur with a number of therapies used for the treatment of acute myeloid leukemia (AML). It is best characterized in patients treated with All-trans retinoic acid (ATRA) and Arsenic for acute promyelocytic leukemia (APL), or for patients receiving an IDH inhibitor for IDH1/2 mutant AML, but can also be seen with other therapies such as with FLT3 inhibitors, and in novel therapies under development such as menin inhibitors. It is critical to identify DS early, as corticosteroids can mitigate complications. The diagnosis of DS is made by recognizing a constellation of symptoms, typically including a rising white blood cell count, peripheral edema, rash, shortness of breath, pulmonary edema, and fevers. We evaluated white blood cell (WBC) count changes during treatment according to whether patients DS or not on chemotherapy. Methods: We identified adult patients who received ATRA+Arsenic for newly diagnosed APL, as well as patients with AML harboring a mutation in IDH1 or IDH2 who were treated with monotherapy IDH inhibitors (enasidenib or ivosidenib) at any point during their treatment for active AML and treated at MGH. Patients were treated at MGH between 2015 and 2023. Patients were 18 or older and had a confirmed pathological diagnosis. We interrogated the medical record to identify patients with clinical documentation of DS during treatment, as well as the treatments used for management and clinical complications. Descriptive statistics were used to identify differences in median WBC counts between patients with DS and those without DS, and comparisons were made using Wilcoxon or chi square testing as appropriate. Results: We identified 33 patients with APL who received ATRA+Arsenic, and 35 patients with AML harboring an IDH1/2 mutation treated with monotherapy IDH inhibition. Our analysis revealed that 26% (18/68) of patients had clinical documentation of differentiation syndrome, including 21% (14/33) of patients treated with ATRA+Arsenic and 11% (4/35) of patients on IDH inhibitors. In APL, the median day of a recorded diagnosis of DS was 4 days after treatment start (range 1-14 days). Patients with APL who developed DS had a higher initial WBC at treatment start compared to those who did not develop DS (6.7 vs 1.05 K/uL, p=0.03). There was no difference in hemoglobin, platelets, ANC, and percentage of peripheral blood blasts (Table 1). The WBC in DS patients started rising during the first week of treatment and peaked on Day 15 (Figure 1). Regarding treatment approaches for DS, the majority of patients were treated with steroids, (78%, 11/14) while 43% (6/14) received cytoreduction, most commonly with gemtuzumab. In IDH-mutant AML, the median day of a recorded diagnosis of DS was 35 days after treatment start (range 16-69 days). Patients with IDH-mutated AML on IDH Inhibitor monotherapy who experienced DS had a similar finding of an early temporal rise in WBC to those with APL on ATRA+Arsenic, although this rise started on day 12 and peaked on day 16 of monotherapy. Of note, these peaks occurred prior to the documentation of a clinical DS diagnosis. In contrast to APL, patients with IDH-mutant AML who developed DS had a lower baseline ANC (p=0.03) and higher percentage of peripheral blasts circulating than those without DS (p=0.03). All patients with IDH inhibitor associated DS received dexamethasone. Discussion: Patients with DS during treatment for APL on ATRA+Arsenic, as well as patients with DS with IDHmut AML on IDH inhibitors, had similar early peaks in the WBC count, occurring around 2 weeks from the start of treatment. In this small group, the IDHmut AML showed a rise in WBC that preceded the actual DS diagnosis. Understanding the timing of and risk factors for DS may help to identify at risk patients early for mitigation strategies.

First-Line Venetoclax and a Hypomethylating Agent or Conventional Chemotherapy in Older Adults with IDH-Mutated AML

Introduction The treatment of older adults with acute myeloid leukemia (AML) remains challenging. Although next-generation sequencing has allowed for the molecular characterization of AML at an increasing rate, relatively little is known about the outcomes of molecularly selected cohorts of older adults with AML. Up to 20% of patients with AML harbor IDH mutations, which confer BCL2 dependence and sensitivity to venetoclax. Therefore, we sought to compare the outcomes of intensive chemotherapy (IC) to venetoclax and a hypomethylating agent in older adults with IDHmutAML. Methods From the Project ERIS database, we analyzed 50 patients aged 60 years or older with AML and an IDH1 or IDH2 mutation identified on next-generation sequencing at diagnosis from January 1, 2013 to April 18, 2023 at VCU Massey Comprehensive Cancer Center. We recorded baseline patient-related and disease characteristics, including age, ECOG, Charlson comorbidity index (CCI) scores, molecular profiling and ELN 2022 cytogenetic risk, dates of regimen initiation, and survival. We separated patients by receipt of therapy type: IC with conventional 7+3 or CPX-351, venetoclax with a hypomethylating agent (decitabine or azacitidine; VEN+HMA), and HMA monotherapy as a comparison arm. We used the D'Agostino & Pearson method for normality testing and the t-test, Mann-Whitney, or ANOVA (as applicable) tests for between-group comparisons. Categorical comparisons used Fischer's exact test. We applied the Bonferroni correction if multiple comparisons were made. We analyzed survival by the Kaplan-Meier method with significance determined by the log-rank test. The event for calculating the overall survival (OS) was the date of death. Patients were otherwise censored at the date of last contact. Results Among 50 older patients with IDHmut AML, 24 (48.0%) received IC, 18 (36.0%) received VEN+HMA, and eight (16.0%) were treated with HMA monotherapy (Table A). In the overall cohort, the median IDH1 variant allele frequency (VAF) was 41.2% (range: 8.3-48.2), and the median IDH2 VAF was 43.8% (range: 6.8-51.0). The most common mutations in IDH1 and IDH2 were Arg132Cys (52.9%) and Arg140Gln (83.3%), respectively. Patients treated with IC were significantly younger compared with the VEN+HMA cohort (64 vs 74 y., p < 0.0001). The IC cohort also had significantly better ECOG scores compared with the VEN+HMA cohort (1 vs 2, p = 0.0023), but no difference in CCI scores (5 vs 6, p = 0.163). Consequently, significantly more patients in the IC cohort proceeded to an allogeneic stem cell transplant (alloSCT) compared with VEN+HMA (29.2% vs 0%, p = 0.014). Strikingly, there was no significant difference in the median overall survival between the IC and VEN+HMA cohorts (14.1 m. vs 12.2 m., p = 0.485). Next, we analyzed the addition of the HMA monotherapy cohort - which had no significant difference in any baseline characteristic compared with the VEN+HMA cohort. Both IC and VEN+HMA significantly prolonged overall survival compared with HMA monotherapy in IDHmut AML (p = 0.043, Figure B). Discussion Despite significantly older age, worse ECOG PS, and fewer patients proceeding to alloSCT in the VEN+HMA cohort compared with IC, there was no significant difference in overall survival between the two treatment modalities. These findings provide evidence suggestive of the comparable efficacy of VEN+HMA and IC in older adults with IDHmut AML. Both treatment strategies appear to offer significantly prolonged survival relative to HMA monotherapy. Prospective trial designs in molecularly selected cohorts are needed to confirm these findings.

Comparison of Response and Survival with Chemotherapy and Targeted Therapies between IDH mut Isoforms in Acute Myeloid Leukemia

1. Introduction Isocitrate dehydrogenase (IDH) mutations are among the most frequent genetic alterations in acute myeloid leukemia (AML) - they are detected in approximately 20% of patients. While ivosidenib and enasidenib have been approved as targeted therapy for IDH1 and IDH2-mutated AML, respectively, relative outcomes between the IDHmut isoforms remain unclear across various therapeutic options. The aim of this study was to compare response and survival between IDH-mutated cohorts of AML when treated with intensive chemotherapy, venetoclax-based strategies, or targeted therapies. 2. Methods We analyzed 93 patients with newly diagnosed or relapsed or refractory IDHmut AML from January 1, 2013 to April 18, 2023 at VCU Massey Comprehensive Cancer Center. We recorded baseline patient-related and disease characteristics, including dates of regimen initiation and survival. Categorical comparisons used Fischer's exact test. We excluded those with cooperating IDH1 and IDH2 mutations. We analyzed survival by the Kaplan-Meier method with significance determined by the log-rank test. The event for calculating the overall survival (OS) was the date of death. Patients were otherwise censored at the date of last contact. 3. Results We analyzed 43 patients with IDH1mut or IDH2mut AML treated with first-line intensive chemotherapy with conventional 7+3, CPX-351, or FLAG-IDA with or without venetoclax; we divided the patients into two cohorts: IDH1 and IDH2. We noted no significant differences in the presence of cooperating NPM1 mutations (25.0% vs 37.0%, p = 0.529) or in the proportion of ELN 2022 adverse-risk disease (45.0% vs 40.7%, p > 0.999). The composite complete remission (CRc; CR + CRi + CRh) rate for IDH1mut AML was 66.7% (95% CI, 43.7-83.7) compared to 60.0% (95% CI, 40.7-76.6, p = 0.755) for IDH2mut. The rate of MRD negativity was 50.0% (95% CI, 18.8-81.2) for IDH1mut and 30.0% for IDH2mut (95% CI, 10.8-60.3, p = 0.607). Strikingly, the median overall survival significantly favored the IDH2mut cohort at 25.5 months vs 11.3 months for IDH1mut (p = 0.047, Figure A). Next, we analyzed the outcomes of 19 patients with IDHmut AML treated with first-line venetoclax and a hypomethylating agent (VEN+HMA). We noted a lower proportion of cooperating NPM1 mutations in the IDH2mut cohort compared with the IDH1mut cohort (36.4% vs 75.0%, p = 0.170). Despite this, the CRc rate favored the IDH2mut cohort compared with the IDH1mut cohort (62.5%; 95% CI, 40.7-76.6, vs 20.0%; 95% CI, 30.6-86.3, p = 0.266). We noted no significant difference in overall survival between the IDH1mut or IDH2mut cohorts treated with HMA+VEN (12.2 months vs 14.8 months, p = 0.834). In the relapsed or refractory setting, we analyzed 17 patients that received either ivosidenib or enasidenib with or without azacitidine. The CRc for the ivosidenib cohort was 33.3% (95% CI, 5.9-70.0), compared with 28.6% (95% CI, 5.1-64.1, p > 0.999) for the enasidenib cohort. The median overall survival favored the ivosidenib cohort at 18.8 months compared to 2.7 months for the enasidenib cohort, which approached statistical significance (p = 0.069). 4. Discussion The median overall survival of IDH1mut AML is significantly worse compared to IDH2mut AML when treated with intensive chemotherapy. The significance of the survival disparity disappears with patients treated with HMA+VEN, suggesting both isoforms of IDHmut AML benefit from venetoclax. Investigators should be cautious when combining IDHmut AML cohorts while reporting the results of clinical trials in molecularly selected patients.

Intensive Induction Chemotherapy (IC) Vs Hypomethylating Agents + Venetoclax (HMA/VEN) in IDH1- or IDH2-Mutant Newly Diagnosed Acute Myeloid Leukemia (AML) - a Multicenter Cohort Study

Introduction: Intensive induction chemotherapy (IC) remains the standard of care for younger and fit patients (pts) with acute myeloid leukemia (AML). Post-hoc analyses from clinical trials have associated IDH1 and IDH2 mutations with high rates of durable responses to venetoclax (VEN)-based therapies. However, these trials were conducted in pts ≥75 years of age or unfit for IC. As there are currently no trials comparing hypomethylating agents (HMA)+VEN and IC directly in IDH-mutant AML, we conducted a large multicenter retrospective cohort study of pts with newly diagnosed AML with IDH1 and IDH2 mutations to assess the impact of clinical and molecular characteristics on response and survival to IC versus HMA+VEN. Methods: We included pts with newly diagnosed IDH1- and IDH2-mutant AML who were treated at 4 large academic centers with IC (conventional 7+3 or liposomal cytarabine/daunorubicin) or HMA/VEN. Detection of IDH1 and IDH2 mutations was performed by next-generation sequencing per local standards at the participating sites. Responses were recorded according to European LeukemiaNet 2017 criteria. Composite complete response (cCR) was defined as complete response (CR) + CRi (CR with incomplete count recovery). Overall survival (OS) was compared between groups by log-rank test. Cox regression for OS was fitted to evaluate the effect of treatment, allogeneic stem cell transplantation (allo-SCT) as a time-varying covariate and additional covariates. All variables with p<0.1 in the univariate model were included in the multivariable stepwise backward selection model. Results: We reviewed 1132 pts with AML and included 98 and 131 pts with IDH1/2-mutant AML, respectively (9 pts had IDH1 and IDH2 co-mutations). As pts with IDH1-and IDH2-mutant AML had similar baseline demographic and disease characteristics, we combined both groups for further analyses. Of the 220 ptswith IDH1/2-mutant AML, 150 and 70 received IC and HMA+VEN, respectively ( Table 1). Twenty pts in the IC group received concurrent treatment with the IDH1 inhibitor ivosidenib. Compared to pts treated with IC, pts who received HMA+VEN were older (median age 75 years with HMA+Ven [Range: 60 - 88 years] vs 63 years [R: 24 -76] with IC; p<0.001) and had higher rates of molecular defined secondary AML (57% vs 41%; p<0.001), CEBPA mutations (10.0% vs 2.7%; p=0.040), and TP53 mutations (13% vs 2.7%; p=0.005) Despite these differences in baseline characteristics, rates of cCR were similar for IC and HMA+VEN-treated pts (68% vs 67%; p=0.90) with higher rates of CR seen with IC (64% vs 46%; p=0.010). The rate of allo-SCT was higher in pts treated with IC than with HMA+VEN (63% vs 23%; p<0.001). The median OS for the entire cohort was 32 months (95% CI: 24 months [mo] - not reached [NR]) with a significant difference in OS by treatment type favoring IC over HMA+VEN (52 mo [95% CI: 30 mo - NR] vs 14 mo [95% CI: 11 - 39 mo]; p=0.002). However, in pts > 60 years (n=168 pts), median OS was 21 mo (95% CI: 16 - 32 mo) and not statistically significant ( p=0.11) between IC (27 mo [95% CI: 20-57 mo]) and HMA+VEN (15 mo [95% CI: 11 mo - NR]). Comparable OS was seen among pts undergoing allo-SCT (n=111 pts; 24-mo OS 75% [95% CI: 66 - 84%] with IC vs 24-mo OS 79% [95% CI: 61 - 100% with HMA+VEN, p=0.71), as well as when censored at allo-SCT (IC 12 mo [95% CI: 7.7 - 25 mo]; HMA+VEN 12 mo [95% CI: 8.2 - 18 mo], p=0.58) Although treatment with HMA+VEN vs IC was found to be associated with worse OS in univariable analysis ( Table 2) it did not retain its prognostic value in the multivariable analysis (HR: 1.28; 95% CI: 0.74 - 2.19; p=0.37). Conversely, prior HMA, monosomal karyotype, JAK2 and FLT3-ITD mutations were associated with worse survival suggesting that these factors are more relevant for OS than the type of treatment. Conclusion: In pts with newly diagnosed IDH1/2-mutant AML, cCR rates were similar for pts treated with IC and HMA+VEN. While there was a difference in OS favoring treatment with IC over HMA+VEN in the unselected patient cohort, this difference was no longer present in subgroup analyses based on age >60 years and in pts who received an allo-SCT. Furthermore, treatment type did not impact OS in multivariable regression models suggesting that differences in OS between treatment groups are more likely to be explained by differences in patient and disease characteristics rather than treatment type. Due to the limitations of retrospective, real-world studies, a randomized clinical trial is needed.

Deconvoluting Clonal and Cellular Architecture in IDH-Mutant Acute Myeloid Leukemia

Introduction Mutations in Isocitrate dehydrogenase 1/2 ( IDH) occur in 20% of acute myeloid leukemias (AML) and frequently co-occur with DNMT3A, NPM1, SRSF2, and NRAS. In clonal hematopoiesis (CH), IDH mutations confer high risk of AML transformation. Recently developed methods linking single cell genotype to single cell transcriptomic profiles and cell lineage offer the opportunity to define the transcriptomic consequences of each mutation across leukemic cell lineages and clonal phylogenies. Here, we develop an integrative single cell laboratory and analytical framework to study the genetic, clonal and cellular heterogeneity of IDH mutated CH and AML, across disease stages (diagnosis and relapse) and deliver a high-resolution map of IDH-mutant AML. Methods Bone marrow or peripheral blood mononuclear samples from 15 AML patients, 2 CH individuals, and 12 unaffected age-matched donors were profiled by single cell RNA-sequencing. For the AML cases, a median of 3 samples per patient were profiled under treatment with IDH inhibitor (IDHi) monotherapy (n=5 patients), IDHi in combination with intensive chemotherapy (NCT02632708, n=6) or in combination with hypomethylating agent (n=2). This dataset comprised 259,610 cells across AML (n=190,133), CH (n=16,705) and normal controls (n=52,772). Genotyping of Transcriptomes (Nam et al., 2019) (for IDH1/2, NPM1, SRSF2, and NRAS mutations) across 6 AML patients enabled genotyping 23% of cells at diagnosis for at least one clone-defining mutation. Results Through meta-analysis of 3,653 diagnostic AML samples profiled by a targeted DNA panel (Papaemmanuil et al., 2016; Tazi et al., 2022), we identified DNMT3A, SRSF2 and NPM1 as critical co-operative mutations in IDH-mutant AML. Amongst the 15 AML patients, 6 had IDH1 mutation, 8 had IDH2 mutations, and 1 had both IDH1 and IDH2. The co-occurring mutations in DNMT3A (n=11 patients), NPM1 (n=5), SRSF2 (n=5) reflected the genomic landscape of IDH-mutant AML. At diagnosis, IDH-mutant AML was enriched in immature hematopoietic stem and progenitor-like blasts. Compared to normal hematopoiesis, IDH-mutant AML blasts upregulated inflammatory response markers including TNFɑ/NFκB-signaling and downregulated proliferation-associated pathways including G2M Checkpoint, and MYC and E2F Targets, and DNA damage response. To investigate how co-mutations modify the IDH-mutant phenotype, we established an integrative single-cell profiling approach to assign single cells to distinct phylogenetic subclones and extract clone-specific transcriptional programs. SRSF2 and NPM1 co-mutations modulated the AML blast phenotype, towards erythroid ( SRSF2) or granulomonocytic lineage ( NPM1). NRAS- or SRSF2-mutant subclones defined distinct gene expression-derived clusters and upregulated proliferation and metabolic pathways. Furthermore, NPM1 co-mutated blasts upregulated KMT2A-target genes. Next, we tracked clonal responses to combination IDHi and chemotherapy using GoT and targeted DNA sequencing. In 4 cases, the ancestral clone, defined by IDH and DNMT3A mutations, retained clonal dominance in both mature and immature myeloid compartments at complete response (median 4 weeks). Conversely, subclones defined by mutations in NPM1, NRAS, or SRSF2, were either reduced or not detectable (limit of detection 2%). In two cases, mutations were not detected after therapy. In patients who relapsed after IDHi monotherapy treatment, blasts upregulated stemness, fatty acid metabolism, OxPHOS, and inflammation at relapse compared to diagnosis. Furthermore, MHC Class II was downregulated at relapse, pointing to immune evasion of AML as a potential relapse mechanism. Finally, we investigated the role of IDH2 mutations at CH. IDH-mutant CH-derived monocytes upregulated inflammation-associated pathways, mirroring the phenotypes observed in IDH-mutant AML at diagnosis. Conclusion We defined how IDH mutations and their frequent co-mutations dysregulated hematopoiesis. We leveraged state-of-the-art single cell techniques to assign leukemic cells to phylogenetic subclones and delineated the role of serially acquired co-mutations in shaping lineage bias and transcriptional programs. Furthermore, we defined genetic, clonal and transcriptional changes at three stages of the AML disease process: diagnosis, remission, and relapse under IDH inhibitor therapy.

INNV-07. ADJUVANT POST-SURGERY TREATMENT OF RECURRENT IDH2 MUTANT ANAPLASTIC OLIGODENTROGLIOMA (AO) WITH IDH2 INHIBITOR, ENASIDENIB: A CASE REPORT

Abstract INTRODUCTION Recent phase III trial presented by Mellinghoff at 2023 ASCO demonstrated successful treatment of Isocitrate dehydrogenase (IDH)–mutant grade 2 gliomas with Vorasidenib, an oral brain-penetrant inhibitor of mutant IDH1 and IDH2 enzymes. Ivosidenib and enasidenib are separate inhibitors of mutant IDH1 and IDH2, which have shown single-agent activity for the treatment of IDH1- or IDH2-mutant acute myeloid leukemia but the effect in the treatment of glioma is uncertain. Here we report a case of IDH2 mutant AO, who was treated with enasidenib for about two years with fair tolerance and was postponed the next intervention. CASE REPORT A 36 yo female was diagnosed anaplastic ogligodentroglioma in 2006, 17 yrs ago. The patient underwent surgery resection, radiation and Temozolomide (TMZ), and 4 cycles of adjuvant TMZ. In 2021, fifteen years later, she was found tumor recurrence. She had a second surgery with near gross total resection. Pathology confirmed anaplastic oligodentraglioma with negative IDH1 mutation but positive IDH2 R172K mutation. To avoid re-radiation nor re-challenge with TMZ, the patient opted IDH2 inhibitor therapy after surgery. The patient tolerated the treatment, and her brain MRI demonstrated no tumor recurrence until one year later when her brain MRI showed vague sub-centimeter nodular non-enhancing lesion at surgical area. Enasidenib was continued for additional 6 months until recent MRI showed small and slow growth. Total therapy is 20 months. Clinically, the patient has no symptoms from tumor. DISCUSSION Our case review found post-surgery therapy with IDH2 inhibitor Enasidenib for IDH2 mutant recurrent AO is tolerated and could postpone next intervention such as re-radiation or re-challenge with TMZ.

Characterization of Cases with the Rare Cytogenetic Abnormality I(7)(p10) Reveals an Association with IDH2 Mutated Acute Myeloid Leukemia

Background: The chromosomal alteration i(7)(p10) is a rare abnormality in hematological malignancies. It leads to a loss of the long arm (7q) and duplication of the short arm (7p) of chromosome 7. However, the presence, frequency and clinical implications of i(7)(p10) in hematological neoplasms has not been analyzed systematically to date. Aim: (1) Analysis of the frequencyand occurrence of i(7)(p10) in hematological malignancies. (2) Characterization of additional cytogenetic alterations and co-occurring mutations. (3) Analysis of potential clinical implications. Patients and methods: All samples sent for diagnosis of suspected hematologic neoplasms between 08/2005 - 05/2023 were used for detection of i(7)(p10). Presence of i(7)(p10) was analyzed using chromosome banding analysis (CBA). In cases with available molecular genetic analyses the following genes were analyzed: ASXL1, BCOR, CEBPA, DNMT3A, EZH2, FLT3-ITD, IDH1, IDH2, KRAS, NPM1, NRAS, RUNX1, SF3B1, SRSF2, STAG2, TET2, TP53, U2AF1 and ZRSR2. Variants of unknown significance were excluded from statistical analysis. All reported p-values are two-sided and were considered significant at p<0.05. Results: In 34 cases an i(7)(p10) was detected. Regarding specific entities, i(7)(p10) was mainly found in AML (23/34, 68%) and rarely in other entities (mature B-cell neoplasms (B-NHL): 6/34, 18%; MDS: 4/34, 12%; ALL: 1/34, 3%). In 20/34 cases, i(7)(p10) comprised the sole cytogenetic abnormality, including 19 AML cases and 1 MDS case. In 10/34 cases, additional chromosomal alterations were detected, leading to a complex karyotype in 5 of these cases. Of note, all cases with a complex karyotype were B-NHL. Additionally, in 4 cases i(7)(p10) was present only in a subclone (1 AML, 1 B-NHL, 2 MDS cases) (Figure A). In 18/34 cases, molecular genetic data was available, revealing DNMT3A (15/18), IDH2 (14/18) and BCOR (7/18) as most frequently mutated genes. As these 18 cases comprised n=15 cases diagnosed as AML, further analysis focused on these patients only. 14/15 cases harbored a mutation in IDH2, the remaining case showed an IDH1 mutation. Further, in 14/15, 7/15 and 4/15 cases, mutations in DNMT3A, BCOR and EZH2 were detected, respectively. By contrast, mutations that are known to frequently co-occur with IDH2 mutations in AML ( SRSF2, ASXL1, NPM1, STAG2, RUNX1, NRAS) were absent or only very rarely detected (Figure B). 12/14 cases with IDH2 mutations showed the mutation site p.Arg172Lys, 2/14 cases p.Arg140Leu, which is known to be the most frequent IDH2 mutation site. This is corroborated by analysis of a control cohort of n=60 IDH2 mutated AML cases without i(7)(p10), in which only 8/60 cases with p.Arg172Lys were detected (86% vs. 13%, p<0.001). Further, comparison of variant allele frequency (VAF) of IDH2 with the VAF of co-mutations suggested the presence of IDH2 in the main clone of all cases, although IDH2 VAF of cases with i(7)(p10) was slightly but not significantly lower than the IDH2 VAF of AML cases without i(7)(p10) (38.3 vs. 45.9). Moreover, comparison of IDH2 mutated AML with and without i(7)(p10) revealed a predominance of females (13/14, 93% vs. 29/60, 48%, p<0.001) and of younger age (63 vs. 72 years, p=0.015) in cases with i(7)(p10). Analysis of overall survival (OS) did not reveal a significant difference between IDH2 mutated AML cases with and without i(7)(p10), although cases with i(7)(p10) showed a trend towards a better outcome (37 vs. 14 months). Conclusions: (1) The rare but recurrent cytogenetic aberration i(7)(p10) is mainly found in AML, where associations with mutations in IDH2, DNMT3A and BCOR were observed. By contrast, other AML-defining mutations ( NPM1, FLT3-ITD, CEPBA) were largely absent, further no defining fusions/rearrangements or a complex karyotype were detected. (2) The vast majority of patients were female and younger than patients with IDH2 mutation without i(7)(p10). (3) Almost all cases showed the rare hotspot p.Arg172Lys and i(7)(p10) as sole aberration, thus it can be speculated that these cases define a distinct subgroup. (4) OS seems to be slightly better than in IDH2 mutated AML without i(7)(p10), although this difference was not statistically significant. (5) Taking into account that the IDH2 mutation was always detected in the main clone and that no other targetable genes/aberrations were observed, these patients are potentially suitable for targeted therapy with IDH inhibitors.

Emerging Trends in Frontline Treatment for Acute Myeloid Leukemia (AML): A Survey of NCI-Designated Cancer Centers

Introduction: For the past several decades the standard of care treatment for frontline therapy for acute myeloid leukemia (AML) in individuals that are eligible for intensive induction therapy has been 7 + 3 (7 days of cytarabine (Ara-C) + 3 days of danuorubicin). Older individuals with AML and those that are ineligible for intensive induction tend to be a more difficult population to treat. Since 2018, venetoclax + hypomethylating agents (HMA) (azacitidine or decitabine) has been considered the standard of care frontline treatment for AML in those who are induction ineligible. Over the past decade there have been significant improvements in genetic and molecular testing that have greatly impacted the development of new frontline treatment therapies for individuals with acute myeloid leukemia (AML) with promising treatment outcomes. Methods: In an effort to quantify the impact that these evolving therapies have had on influencing leukemia treatment practices, a questionnaire was sent to every director/chair of Leukemia at each National Cancer Institute (NCI) designated center. Our two-question questionnaire centered around determining the preferred AML treatment for both patients who are not on clinical trials that are eligible and those that are ineligible for intensive induction therapy. Questions were created based on the 2019 NCCN clinical practice guidelines for AML. The survey was limited to 2 questions so as to elicit higher response rate to the questionnaire. Question #1: What is the preferred induction regimen backbone used at your center - In patients eligible for intense chemo, off-study? 7+3FLAG-IDACLAG-IDAVenetoclax w/ 5-azacytidine or decitabineOther Question #2: What is the preferred induction regimen backbone at your center - In patients who are ineligible for intensive chemo, off-study, and having actionable mutations (IDH or FLT3)? Venetoclax + Hypomethylating agentTargeted agent against IDH or FLT3 withoutvenetoclax +/- hypomethylating agentTargeted agent against IDH or FLT3 withvenetoclax +/- hypomethylating agentOther Results: From our study, we received 31/63 (49.2%) responses and saw that for the intensive induction 90.3% (28/31) respondents selected 7 +3 as the preferred treatment with 3.2% (1/31) choosing FLAG-IDA, with the remaining 6.5% (2/31) choosing “other” ((7 +3) w/ FLT3 inhibitor). Comparatively, for the intensive induction ineligible treatment, 61.3% (19/31) respondents preferred venetoclax + HMAs with 38.7% (12/31) preferring targeted agent w/ venetoclax +/- HMA. Of note, four respondents selected venetoclax + HMA as the preferred treatment, but also preferred aza-ivosidenib for IDH1 mutant AML. Conclusion: Preliminary findings from our survey suggest that results from genetic molecular testing may have a greater influence on the evolution in treatment for the intensive induction ineligible population. As more data comes out regarding combining targeted therapy with more broad-based treatments, clarity will emerge on the most appropriate standard-of-care approach. Additionally, improved turnaround time of testing methodology will likely modify treatment approaches. Our next steps include repeat outreach to obtain 100% response rate and sending a follow-up questionnaire to understand the rational for each specific treatment choice.

Metformin-Induced Ferroptosis Is a Therapeutic Vulnerability in IDH2-Mutant AML Linked to Metabolic Rewiring Towards Fatty Acid Oxidation

Metabolic rewiring is an essential feature of leukemic cells to sustain tumorigenesis and is largely influenced by mutational status. We previously demonstrated this phenomenon in FLT3-ITD acute myeloid leukemia (AML) upon combined inhibition of complex II activity and lactate import (Erdem et al., 2022). Mutations in isocitrate dehydrogenase ( IDH1/2mut) occur in about 20% of AML cases, and despite the emergence of targeted therapies, patients often relapse. The molecular and epigenetic outcomes of 2-R-hydroxyglutarate accumulation and competitive inhibition of histone demethylases have been extensively studied in IDH1/2mut AMLs, but the metabolic consequences are still largely unexplored. Here, we applied multi-omics studies on cell line models and primary AML samples combined with functional studies to unravel the metabolic rewiring of IDH1/2mut AMLs. Transcriptional characterization of isogenic TF1 wt and IDH2R140Q cell lines (10978 genes) revealed increased expression of CD36, a major fatty acid (FA) transporter, and gene set enrichment analysis (GSEA) associated IDH2R140Q cells with terms related to FA processes and activity of mitochondrial complex I. Quantitative metabolome analysis of TF1 wt and IDH2R140Q (180 metabolites) revealed lower levels of acylcarnitines of variable carbon lengths, suggesting increased FA oxidation, and upregulation of glycerophospholipid and glycerolipid metabolism in IDH2R140Q cells. Next, we validated our findings by performing a metabolomic profiling (172 metabolites) on primary AML samples (n=26, including 4 IDH1mut and 2 IDH2mut), for which label-free quantitative proteome data (11272 proteins) was also generated. Proteome analysis confirmed increased CD36 expression and enrichment for FA and mitochondrial processes in IDH1/2mut patients. In line, metabolome data also revealed increased oxidation of branched-chain FAs in this sample group. Altogether, these findings suggested a profound disturbance in lipid metabolism and supported the notion that IDH1/2 mutant cells rely on mitochondrial respiration, whereby FAs seem to be the preferred carbon source. Next, we performed an in vitro drug screen targeting the main metabolic pathways, which revealed increased sensitivity of IDH2R140Q cells to the FDA-approved complex I inhibitor metformin. Extracellular flux analysis indicated no significant difference in the oxygen consumption rate (OCR) between TF1 wt and IDH2R140Q upon metformin treatment, while the viability of mutant cells was significantly diminished. Contrarily, the basal extracellular acidification rate (ECAR) was increased in TF1 wt cells upon complex I inhibition, suggesting that these cells rewire their metabolism towards glycolysis more efficiently than mutant cells. Furthermore, we knocked down CD36 expression to investigate whether disrupting lipid metabolism in IDH2R140Q cells would constitute a metabolic vulnerability. Notably, CD36 knockdown resulted in increased resistance to metformin in IDH2R140Q cells. These data suggested that enhanced lipid uptake mediated by CD36 in IDH2R140Q cells not only boosts OCR but may also disrupt lipid homeostasis, causing cells to become more susceptible to lipid peroxidation. Since the role of metformin-induced ferroptosis in AML is still unclear, we performed an RNA-seq analysis on TF1 wt and IDH2R140Q cells treated with metformin (5 mM) for 72 hours (10326 genes). Single-sample GSEA associated the transcriptome of metformin-treated cells with ferroptosis signatures in both cell lines but to a significantly higher extent in IDH2R140Q. We functionally validated this finding by using the BODIPY C11 probe, a lipid peroxidation sensor. After 24h of metformin treatment, both TF1 wt and IDH2R140Q displayed increased lipid ROS. Lipid peroxidation levels were further enhanced by combining metformin with palmitate, a saturated FA, supporting the notion that elevated lipid availability and uptake may increase cell death via ferroptosis. Altogether, we identified a new metabolic vulnerability in IDH1/2mut AMLs associated with a profound disturbance in lipid metabolism. Moreover, we show that treatment with metformin not only inhibits complex I but also induces cell death via ferroptosis in IDH2mut cells providing an alternative treatment option in combination with available IDH2mut targeted therapies for this subgroup of patients.

A study to assess the efficacy of enasidenib and risk-adapted addition of azacitidine in newly diagnosed IDH2-mutant AML

AbstractEnasidenib (ENA) is an inhibitor of isocitrate dehydrogenase 2 (IDH2) approved for the treatment of patients with IDH2-mutant relapsed/refractory acute myeloid leukemia (AML). In this phase 2/1b Beat AML substudy, we applied a risk-adapted approach to assess the efficacy of ENA monotherapy for patients aged ≥60 years with newly diagnosed IDH2-mutant AML in whom genomic profiling demonstrated that mutant IDH2 was in the dominant leukemic clone. Patients for whom ENA monotherapy did not induce a complete remission (CR) or CR with incomplete blood count recovery (CRi) enrolled in a phase 1b cohort with the addition of azacitidine. The phase 2 portion assessing the overall response to ENA alone demonstrated efficacy, with a composite complete response (cCR) rate (CR/CRi) of 46% in 60 evaluable patients. Seventeen patients subsequently transitioned to phase 1b combination therapy, with a cCR rate of 41% and 1 dose-limiting toxicity. Correlative studies highlight mechanisms of clonal elimination with differentiation therapy as well as therapeutic resistance. This study demonstrates both efficacy of ENA monotherapy in the upfront setting and feasibility and applicability of a risk-adapted approach to the upfront treatment of IDH2-mutant AML. This trial is registered at www.clinicaltrials.gov as #NCT03013998.

Phospholipid metabolic adaptation promotes survival of IDH2 mutant acute myeloid leukemia cells.

Genetic mutations in the isocitrate dehydrogenase (IDH) gene that result in a pathological enzymatic activity to produce oncometabolite have been detected in acute myeloid leukemia (AML) patients. While specific inhibitors that target mutant IDH enzymes and normalize intracellular oncometabolite level have been developed, refractoriness and resistance has been reported. Since acquisition of pathological enzymatic activity is accompanied by the abrogation of the crucial WT IDH enzymatic activity in IDH mutant cells, aberrant metabolism in IDH mutant cells can potentially persist even after the normalization of intracellular oncometabolite level. Comparisons of isogenic AML cell lines with and without IDH2 gene mutations revealed two mutually exclusive signalings for growth advantage of IDH2 mutant cells, STAT phosphorylation associated with intracellular oncometabolite level and phospholipid metabolic adaptation. The latter came to light after the oncometabolite normalization and increased the resistance of IDH2 mutant cells to arachidonic acid-mediated apoptosis. The release of this metabolic adaptation by FDA-approved anti-inflammatory drugs targeting the metabolism of arachidonic acid could sensitize IDH2 mutant cells to apoptosis, resulting in their eradication invitro and invivo. Our findings will contribute to the development of alternative therapeutic options for IDH2 mutant AML patients who do not tolerate currently available therapies.

Molecular Features Associated with Response to Enasidenib Plus Azacitidine in Newly Diagnosed IDH2-Mutated Acute Myeloid Leukemia

IDH2 gene mutations, typically at residues R140 and R172, occur in 8–19% of patients with acute myeloid leukemia (AML). These mutations induce production of 2-hydroxyglutarate (2-HG), an oncometabolite that causes DNA and histone hypermethylation, and subsequent blockade of hematopoietic cell differentiation. In a phase 1b/2 trial (NCT02677922), combination therapy with azacitidine + enasidenib significantly improved overall response rate compared with azacitidine only therapy (74% vs 36%; P<0.001) in patients with newly diagnosed IDH2-mutated AML not eligible for intensive chemotherapy. We investigated the association between molecular features and clinical outcomes from that trial. In all, 101 patients were randomized to enasidenib + azacitidine (n=68) or azacitidine only (n=33); 74% of patients had IDH2-R140. Baseline 2-HG levels and IDH2 variant allele frequency (VAF) were similar between treatment arms and IDH2 variants and were not significantly different between clinical response categories. Significant 2-HG and IDH2 VAF reductions from baseline were observed with combination therapy compared with azacitidine only. Molecular profiling revealed SRSF2 preferentially co-mutated with IDH2-R140, and DNMT3A co-mutated with IDH2-R172. IDH2 VAF was reduced to <1% in 50% of patients who achieved CR with combination therapy (18/36) and azacitidine only (2/4). VAFs of genes in the DNA methylation, receptor-tyrosine-kinase, and RAS canonical pathways were reduced in patients achieving CR. Of note, combination therapy improved event-free survival in patients with RAS-pathway mutations, which have been associated with resistance to enasidenib monotherapy.

Olutasidenib (FT-2102) induces durable complete remissions in patients with relapsed or refractory IDH1-mutated AML.

Olutasidenib (FT-2102) is a potent, selective, oral, small-molecule inhibitor of mutant isocitrate dehydrogenase 1 (mIDH1). Overall, 153 IDH1 inhibitor-naive patients with mIDH1R132 relapsed/refractory (R/R) acute myeloid leukemia (AML) received olutasidenib monotherapy 150mg twice daily in the pivotal cohort of this study. The median age of participants was 71 years (range, 32-87 years) and the median number of prior regimens received by patients was 2 (1-7). The rate of complete remission (CR) plus CR with partial hematologic recovery (CRh) was 35%, and the overall response rate was 48%. Response rates were similar in patients who had, and who had not, received prior venetoclax. With 55% of patients censored at the time of data cut-off, the median duration of CR/CRh was 25.9months. The median duration of overall response was 11.7months, and the median overall survival was 11.6months. Of 86 patients who were transfusion dependent at baseline, a 56-day transfusion independence was achieved in 29 (34%), which included patients in all response groups. Grade 3 or 4 treatment-emergent adverse events (≥10%) were febrile neutropenia and anemia (n= 31; 20% each), thrombocytopenia (n= 25; 16%), and neutropenia (n= 20; 13%). Differentiation syndrome adverse events of special interest occurred in 22 (14%) patients, with 14 (9%) grade ≥3 and 1 fatal case reported. Overall, olutasidenib induced durable remissions and transfusion independence with a well-characterized and manageable side effect profile. The observed efficacy represents a therapeutic advance in this molecularly defined, poor-prognostic population of patients with mIDH1 R/R AML. This trial was registered at www.clinicaltrials.gov as #NCT02719574.