Induction Therapy For Acute Myeloid Leukemia Research Articles

Ocular manifestations of acute myeloid leukemia during induction phase of chemotherapy: A case series

The aim of this series is to report diverse ocular features noted in patients during the induction phase in acute myeloid leukemia (AML). Three female patients undergoing induction therapy for AML reporting for various ocular complaints were examined. Detailed history, including the onset of AML and chemotherapy and any past ocular or systemic ailment, was taken. Best-corrected visual acuity, anterior segment, and posterior segment examinations were performed. Intraocular pressure was measured, and color vision was tested. Routine hematological, and biochemical investigations and imaging were done when required. Patients with abnormal parameters were referred to an oncologist for management. A varied spectrum of ocular manifestations was noted in these three female patients, including preseptal cellulitis, orbital cellulitis, and subhyaloid hemorrhages. Immediate treatment was given to patients with vision-threatening conditions in consultation with an oncologist and otorhinolaryngologist, and patients responded well to the treatment. Owing to its cytoreductive action, AML induction therapy exposes the patient to various adverse events, causing significant ocular and systemic morbidity. All the diagnosed patients of AML are recommended to undergo a baseline ocular assessment.

The Occurrence of Infection and TP53 Mutation Are Risk Factors for Cardiovascular Toxicity of Acute Myeloid Leukemia Induction Therapy

Introduction: For almost 50 years,induction therapy (IT) is the standard of care for acute myeloid leukemia (AML) patients. Nevertheless, little is known about cardiovascular (CV) toxicity during IT. We aimed to describe CV events (CVE)occurring during IT and to identify clinical, hematological and molecular risk factors of such events. Methods: Two hundred and twenty-four patients of 18 years or more (median age 61 (51;67) years, 58% males), treated with ITbetween 2014 and 2021 were enrolled in this study. Two hundred and one (90%) received an anthracycline-based IT, the others received gemtuzumab ozogamicin as part of a clinical protocol research. Survival from the time from initiation of IT until death or until the initiation of the second course of therapy (either salvage regimen in case of primary refractory or relapsed AML, or intensive consolidation therapy in case of response) was considered. The primary endpoint was the time to occurrence of the first CVE after IT initiation, with death as a competing event. Multivariate analysis included significant covariate, identified by univariate models among initial characteristics and occurrence of infection (coded as time dependent covariate). Results: Hematological characteristics were as follows: European LeukemiaNet (ELN) 2022 risk of myelodysplastic neoplasm (MDS)/AML was low, intermediate and adverse in 13%, 29% and 58% of patients respectively. Main mutations encounters were: DNMT3A, FLT3, NPM1, TET2, NRAS, RUNX1, ASXL1, IDH2, PTPN11, BCOR, SRSF2, WT1 and TP53. Main CV risk factors were tobacco (36%), arterial hypertension (35%), obesity (24%), hyperlipidemia (22%), diabetes mellitus (11%). Baseline left ventricular ejection fraction (assessed by transthoracic echocardiography) was >45% in all patients, >55% in 95% of patients. Seventy-five patients (33%) presented a CVE during IT. Eighty-six percent of CVE were severe (grade 3 or more). Patients presenting CVE during IT were significantly older (p=0.02) and presented more often a past history of dilated cardiomyopathy (p=0.04), arterial hypertension (p=0.005) or dyslipidemia (p=0.005). At baseline, CVE patients presented a greater left auricle volume (p=0.005), higher tricuspid regurgitation grade (p=0.01), and more often a right ventricular dilatation or a significative valvopathy (respectively p=0.01 and p=0.03). There was no difference in CVE occurrence between patients treated with and without anthracyclin (p=0.2). Competing risk models identified the following adverse characteristic for the risk of first CVE, namely the occurrence of the first infectious event (Hazard ratio [HR]= 2.43, p=0.005), TP53 mutation (HR=1.79, p=0.04). No other clinical characteristics nor mutation (including TET2 and DNMT3A) were identified. Multivariate analyses demonstrated that TP53 mutation (HR=1.78, p=0.04) and occurrence of infection (HR=2.29, p=0.008) retained independent prognostic value, see Table 1. In a response stratified model, only TP53 mutation was a risk factor of first CVE (HR=2.46, p=0.008). Conclusions: CVE occurred in 33% of patients during IT and were severe. The major adverse role of onset of infection for CVE occurrence after IT could overcome the prognostic value of mutations usually associated with CV risk in the healthy population (i.e. TET2, DNMT3A, ASXL1, ...). TP53 mutation was the only molecular abnormality associated with CVE, in agreement with the increased risk of doxorubicin-induced cardiac toxicity in a mouse model of TP53 clonal hematopoiesis developed by Sano et al. These results suggest that TP53 mutated patients could benefit from careful CV monitoring and optimization of primary prevention treatment.

Concurrent Versus Sequential or No Triazole Anti-Fungal Therapy in Patients Undergoing 7+3 Plus Midostaurin Induction for FLT-3 Acute Myelogenous Leukemia

Background Midostaurin is a multikinase inhibitor approved for the treatment of adult patients with newly diagnosed FMS-like tyrosine kinase 3 (FLT3) mutated acute myeloid leukemia (AML) (Stone RM et al. NEJM 2017). Azole antifungal medications are commonly used in AML and are known to interact with anti-cancer drugs such as Midostaurin through the CYP3A pathway. This could result in an increase in midostaurin concentrations and toxicities, and lead to potential dose interruptions or modifications. However, the literature is scarce on outcomes in patients who are receiving an azole antifungal with intensive induction chemotherapy in combination with midostaurin (Sechaud R et al. Cancer Chemother Pharmacol 2022). In addition to the scarcity of literature, there are no midostaurin related dose modifications that are recommended with strong CYP3A inhibitors. The primary objective of this retrospective study was to compare induction efficacy and safety outcomes in patients receiving concurrent azole antifungal to patients receiving sequential or no azole antifungal therapy. Methods: From January 1, 2017, to January 30, 2023, we retrospectively reviewed all adult patients (18 or older) with newly diagnosed AML who received midostaurin in combination with cytarabine and an anthracycline (7+3). Concurrent azole therapy was defined as patients receiving an azole antifungal therapy with midostaurin for more than 70% of the midostaurin doses. Sequential azole therapy was defined as patients receiving azole antifungal therapy with midostaurin for less than 70% of the doses or no azole antifungal therapy with midostaurin therapy. Response outcome CR and CR without hematological recovery (CRi) were defined per standard International Working Group (IWG) AML response criteria. Minimal residual disease (MRD) assessment was done on post-induction bone marrow aspirate using multiparametric flow cytometric assessment. Adverse events were graded using NCI Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. We compared efficacy and safety outcomes in patients who received azole antifungals concurrently to those who did not receive an azole or received it sequentially to midostaurin for treatment of FLT3 AML. Mann-Whitney U test method was used to compare continuous variables between these two groups. Pearson Chi-square test or Fisher Exact test was used to compare categorical variables (count, rate or proportion) between these two groups. The choice of concurrent azole or sequential azole antifungal was determined by physician choice. Results: There were 40 patients treated with 7+3+midostaurin, 18 of whom received concurrent azole therapy, while 22 received sequential or no azole therapy. There were no significant differences in baseline characteristics (Table 1) except for more patients receiving isavuconazole (moderate CYP 3A4 inhibitor) in the concurrent group (50% vs 0%; p<0.01) and more micafungin in the sequential or no azole group (0% vs 72%; p<0.01). Overall CR/CRi rate with concurrent versus sequential or no azole was 72% (13/18) vs 77% (17/22), with no significant difference in median days to ANC recovery (27 vs 29; p=0.98), platelet recovery (28 vs 32 days; p=0.67), and non-hematologic grade 3 toxicities (22% and 45%; p=0.13), respectively. There were higher, but not significant, rates of midostaurin dose reductions (6% vs 0%; p=0.26) and holds (17% vs 14%; p=0.79) in the concurrent azole group. Conclusion: In conclusion, the addition of azole antifungal was found to be equally safe and effective in the treatment of newly diagnosed FTL3 AML. Dose modifications in midostaurin appeared not to be necessary with concurrent azole antifungal therapy. Further analysis based on a larger cohort is needed to confirm the outcomes and safety endpoints reported in the current study. Given the importance of azole anti-fungal therapy in the treatment of AML and specifically in induction therapy for AML (Cornely et al, NEJM 2007), dose modifications for this drug interaction should be studied in the future to help guide clinicians on how to appropriately dose these drugs.

Novel Gene Mutations Associated with Disease-Free Survival in Elderly Patients with Acute Myeloid Leukemia Receiving First-Line Induction-Consolidation with or without Azacitidine Post-Remission Treatment

Background: The achievement of complete remission (CR) is an important milestone for patients with acute myeloid leukemia (AML) undergoing curative-intent therapy. However, patients who achieve CR with induction therapy for AML will relapse within months. Therefore, research is focused on prolonging leukemia-free survival (DFS). We have recently reported on the randomized phase III study to compare the efficacy and safety of azacitidine (AZA) versus best supportive care (BSC) for treatment of AML in elderly patients who achieved first CR after a homogeneous intensive induction and consolidation phase (QoLESS AZA-AMLE, Oliva et al. Cancers 2023). At 2 and 5 years, DFS was 6.0 (95% CI:0.2-11.7) months in the BSC arm vs. 10.8 (95% CI:1.9-19.6 p=0.23) months in the AZA arm. We report on the ancillary translational study (QOL-ONE Trans-2) to evaluate biological changes in bone marrow samples through Next Generation Sequencing (NGS). Objective: In patients enrolled in the trial who reached CR and were randomized to receive AZA or BSC, the endpoint of the present study was to evaluate the effect modification by gene mutations at AML diagnosis on the relationship between treatment allocation and relapse (disease-free survival, DFS). Methods: The study was performed on available biological samples collected at baseline, randomization, and 6-month post remission. DNA was subjected to high throughput NGS using genes commonly mutated in myeloid malignancies and prepared with a home-set of 350 genes for Illumina (University of Kyoto, Japan) for all subjects with available vials. Only variants with high-quality reads, were considered. A Variant Allele Frequency (VAF) ≥ 4% was considered an appropriate threshold for minimal burden of clonality to be reported. Results: Samples were available for 24 patients, 12 males, of median age 71 (65-74) years, 11 allocated in AZA arm and 13 in BSC arm. At diagnosis, mutations were detected in all patients with a range of 5 to 17 (median 10) simultaneous mutations, the most frequent being DNMT3A (42%), NPM1 (33%) and TET2 (33%). The most frequently mutated genes at diagnosis are represented in the figure. Only FANCA gene, mutated in 4 patients was associated with a hazard risk (HR) 4.96 (95% CI 1.34 - 18.35; p=0.02) of relapse and, interestingly, HLA-A, which was mutated in 7 patients, was associated with a HR 0.277 (95% CI 0.08 - 0.95; p=0.049). Patients with HLA-A mutation had a significantly longer survival (Figure 2). Three HLA-A mutated patients were allocated in 5-Aza arm and 4 in BSC arm. In a multivariate COX model, the effect of baseline HLA-A mutation on DFS is independent of the allocation arm (P=0.041). HLA Class I and Class II alleles were assessed based on the Luminex xMAP technology: for all cases, the HLA-SNPs are located on chromosome 6 in exon 2, 3 and 4 within protein-codifying sequences. Conclusions: HLA gene mutations are not usually investigated for diagnostic or prognostic purposes in AML. The extensive 350-gene panel used in this study included HLA genes and has revealed a possible favorable role of HLA-A polimorphisms for the prognosis of elderly patients with AML undergoing intensive chemotherapy. Further specific HLA NGS analyses are undergoing to determine whether this concerns genuine somatic mutations. The present finding is worthy of further investigation to confirm its value in prognosis and its therapeutic implications.

Centralized MRD Assessment at Early Timepoints in Gimema AML1718 Trial, a Phase 2 Open-Label Study of Venetoclax, Fludarabine, Idarubicin and Cytarabine (V-FLAI) in the Induction Therapy of Non Low-Risk AML

Background: New therapeutic strategies are strongly needed to improve the prognosis of high risk Acute Myeloid Leukemia (AML) patients, such as combination of novel agents and conventional chemotherapy. The Italian GIMEMA AML1718 trial (NCT03455504) investigate the safety and efficacy of the BCL-2 inhibitor venetoclax (VEN) in combination with intensive fludarabine-based induction (FLAI) [fludarabine 30 mg/sqm from day 1 to day 5, cytarabine 2000 mg/sqm from day 1 to day 5, and idarubicin 8 mg/sqm on days 1, 3 and 5] as first-line therapy for newly diagnosed non low-risk ELN AML patients. Results from the Planned Interim Analysis of Safety Run-in and Part 1 (early expansion cohorts) were presented at the last 2022 ASH Meeting. Median overall survival (OS) was not reached; probability of 12-month OS was 76%. Median disease-free survival was not reached. With a median follow-up of 10.5 months, 28 patients (49%) received allogeneic stem cell transplantation (HSCT) in first complete remission (CR). Centralized multicolour flow cytometry minimal residual disease (MFC-MRD) assessment was planned during the phase 2, part 2 of the study (confirmatory cohort) where the lower effective dose of VEN (400 mg/day) was administered in association with FLAI. Here we report results from early time-points (TPs) MRD analysis with the aim of identify the most informative TPs for MRD assessment and prognostic correlations. Methods: Erythrocyte-lysed whole bone marrow (BM) samples obtained at diagnosis from patients enrolled in the confirmatory cohort were centralized and analysed with a broad panel of monoclonal antibodies to identify the leukemia-associated phenotype (LAIP) which was used to track residual leukemic cells during follow-up. Eight color flow cytometry analysis was performed at pre-defined TPs (TP1: post-induction I, TP2: post induction II/consolidation I, following TPs: post consolidation/pre-transplantation) (FACSCantoII; BD Facs Diva Software V6.1.3). A positive flow MRD was defined by the presence of no less than 10 clustered leukemic cells/10^4 total events. Enrollment closed on January 2023. Collection and analysis of later TPs is ongoing. Results: Sixty-seven patients from 11 centers were enrolled in the phase 2, part 2. Risk stratification according to ELN 2017 was intermediate in 46% of patients and high risk in 54%. Fifty-eight/67 patients (87%) obtained CR after induction I. In the centralized MRD analysis, 170 samples has been collected and analysed so far (60 baseline samples, 110 MRD samples). Seven patients lacking baseline sample for LAIP identification were excluded from the analysis. TP1 was available in 57/59 patient achieving CR (97%), and TP2 was available in 29 patients, so far. MFC-MRD negativity was obtained in 31/57 (54%) at TP1 (post V-FLAI, Fig. 1). An increase in MFC-MRD negativity rate was observed at TP2 (post Induction II or consolidation I) with 20 MFC-MRD negative patients/29 available samples (69%, Fig. 1). Thirteen/110 follow up samples (8%), albeit resulting MRD negative, were considered inadequate for the analysis due to haemodilution, 9 from TP1 and 4 from TP2 (Fig. 1). TP1 and TP2 MRD assessment were scheduled at day 28 of Induction I and Induction II/consolidation, respectively. However, in most cases, delayed haematological recovery was observed after V-FLAI, thus resulting in suboptimal samples for MRD evaluation. Conclusions: Preliminary results from centralized MRD analysis confirm that the combination therapy is able to induce high-quality remissions with a very high percentage of MFC-MRD negativity in a difficult cohort of patients, with a higher percentage of MFC-MRD-negative after the completion of the second course of therapy. Delayed haematological recovery may impact on reliability of MRD assessment due to hypocellular and regenerative marrow samples, suggesting that in those cases MRD analysis should be postponed. Correlation with survival will be performed as the data collection will be complete.

Effective and Safe Molecular-Pharmacodynamic Once Weekly Dosing of Decitabine and Venetoclax Is a Highly Effective and Well-Tolerated Induction Therapy for AML: Interim Results of a Phase 2 Trial

Background: Hypomethylating agents (HMAs) (5-azacytidine or decitabine) combined with venetoclax (Ven) have become the new standard of care for patients with acute myeloid leukemia (AML) who are unfit for intensive chemotherapy. However, myelosuppression and infectious complications are common adverse events of currently approved HMA/Ven regimens, requiring dose interruptions/delays that often undermine treatment goals. Previous studies have identified the minimum dose of decitabine needed to deplete DNA methyltransferase-1 (DNMT1) without causing cytotoxicity. Administration of a single venetoclax dose synergizes with low dose weekly decitabine by inhibiting de-novo pyrimidine synthesis - a major mechanism of resistance to HMAs. A recently reported retrospective experience has shown proof of concept for a regimen of once weekly low dose decitabine combined with a single weekly dose of venetoclax in MDS and AML. Here, we report the feasibility portion of an ongoing Phase II clinical trial evaluating tolerability and efficacy of a metronomic dosing of decitabine and venetoclax for treatment of older patients with AML. Aims: The primary endpoint of this study is percentage of patients who are able to continue on treatment during the 12-week induction period without dose interruptions or delays. The key secondary endpoints include best overall response, rate of Grade >3 adverse events, infections, and hospitalizations. Correlative studies evaluate DNMT1 depletion in bone marrow at the time of diagnosis and at week 12. Methods: This is a single arm open-label Phase II clinical trial (NCT05184842). Patients >18 years old with a diagnosis of AML, MDS, CMML, MDS/MPN, and MDS/AML not fit for intensive chemotherapy are eligible. Subcutaneous decitabine and oral venetoclax are administered on the same day, once a week at 0.2mg/kg and 400mg, respectively. A bone marrow exam and measurable residual disease (MRD) assessment by multiparametric flow cytometry (MFC) are performed following 12-week induction period. Results: Between June 2022 and April 2023, twenty patients on this study have completed the 12-week induction period, these included AML (n=14), MDS (n=2), MF (n=1), MDS/MPN (n=1), CMML (n=2). Median age was 75 and 50% of patients were minorities (Table 1). Seventeen patients (85%) were able to complete all 12 weeks of induction treatment without dosing interruptions or delays and only one patient (5%) had a dose interruption post-induction. There were no Grade > 3 non-heme therapy-related adverse events. Eight patients (40%) required hospitalization during the induction period and no patient required hospitalization post-induction. Of the 14 AML patients who have completed the 12-week induction period, the median age was 75 years old (63-87). At the end of induction, the ORR was 71% with 8 patients (57%) achieving a CR, 1 CRI and 1 PR; 5/8 CRs were MRD negative by MFC. At a median followup of 10.9 months, 7/14 (50%) responses are ongoing and 11/14 patients (79%) remain alive. Of the six patients with TP53 mutations, four achieved MRD-negative CR with transfusion independence and two with no response (one post-MPN AML and other with erythroid leukemia). During the induction period, four patients (29%) had progression of disease (POD). The primary refractory cases included one patient with post-MPN AML, one patient with FLT3-ITD and two patients with monocytic-M5 AML with RAS mutations. One of two patients with MDS, had an MRD negative CR and achieved transfusion independence while the other transformed to erythroid leukemia. Of the two patients with CMML, one had a CR with transfusion independence, and one with stable disease. The 30 and 60-day mortality was zero. Studies evaluating DNMT1 staining on bone marrow samples from patients treated on this study are ongoing. Summary/Conclusion: In this preliminary analysis we demonstrate safety and efficacy of weekly, low-dose, metronomic dosing of decitabine and venetoclax, by allowing frequent sustained drug exposure often not possible with standard HMA/Ven regimens. The minimal cytotoxic nature of this regimen allowed for blood count recovery without drug interruptions with a high rate of clinical responses. (Figure 1). Additional cohorts are being enrolled in an expansion phase of the study in order to more fully assess the efficacy of this regimen in subsets of AML and MDS patients, including patients with p53 mutations.

A Prospective Study to Evaluate the Effect of Therapeutic Drug Monitoring-Based Posaconazole Prophylaxis on Invasive Fungal Infection Rate During Acute Myeloid Leukemia Induction Therapy.

The online version contains supplementary material available at 10.1007/s12288-023-01709-3.

Incidence of breakthrough fungal infections on isavuconazole prophylaxis compared to posaconazole and voriconazole.

Invasive fungal infections (IFIs) are a common infectious complication during the treatment of acute myeloid leukemia (AML), high-risk myelodysplastic syndrome (MDS) or post hematopoietic cell transplantation (HCT). For these patients, the National Comprehensive Cancer Network recommends posaconazole or voriconazole for IFI prophylaxis. In clinical practice, however, there has been increased use of isavuconazole due to favorable pharmacokinetic and pharmacodynamic parameters despite limited data for this indication. The comparative prophylactic efficacy of antifungals in this patient population has not been reported, and an analysis is warranted. This retrospective, matched cohort, single-center study, included AML, MDS, or HCT patients who began treatment or underwent transplant between January 1, 2015 and July 31, 2021. Isavuconazole patients were matched 1:2 with patients receiving posaconazole or voriconazole prophylaxis. A total of 126 patients were included, 42 received isavuconazole, 81 received posaconazole, and three received voriconazole. The majority of patients were male receiving secondary IFI prophylaxis while receiving steroids for treatment of GVHD. The incidence of possible, probable or proven IFI was 16.7% in the isavuconazole group compared to 10.7% in the posaconazole and voriconazole group (OR 1.28, 95% CI -0.9-1.4; p = .67). Hepatotoxicity occurred in 16 total patients, 14 receiving posaconazole and two receiving isavuconazole. Patients who received isavuconazole prophylaxis during AML induction therapy or post-HCT experienced a similar incidence of breakthrough fungal infections compared to those who received posaconazole or voriconazole. These results suggest no difference in antifungal prophylactic efficacy; however larger prospective comparative studies are needed.

Impact of rhG-CSF on Clinical Efficacy and Immune Cell Subsets after Initial Induction Chemotherapy in AML.

The impact of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in acute myeloid leukemia (AML) is still controversial. The purpose of this study is to explore the impact of rhG-CSF administration on clinical efficacy and immune cell subsets after initial induction chemotherapy in AML. The clinical efficacy and immune cell subsets were compared in the newly diagnosed patients with AML according to whether rhG-CSF was used after initial induction chemotherapy. Next, rhG-CSF stimulation experi-ments on leukemia cell lines and primary leukemia blasts were performed in vitro. There was no statistical difference between control group and rhG-CSF therapy group in complete remission rate and relapse free survival. The duration of agranulocytosis was significantly shortened in rhG-CSF therapy group compared with control group. The percentage of circulating monocytic myeloid-derived suppressor cells (M-MDSCs) and regulatory T cells (Tregs) were significantly increased after the administration of rhG-CSF. Furthermore, it was found that rhG-CSF did not promote the proliferation of leukemia cell lines and primary leukemia blasts, but increased the proportion of M-MDSCs and Tregs in vitro. Administration of rhG-CSF after initial induction therapy of AML does not affect the clinical remission and relapse rate, but reduces the duration of agranulocytosis and increases the proportion of M-MDSCs and Tregs.

Inhibition of Stearoyl-CoA Desaturase Has Anti-Leukemic Properties in Acute Myeloid Leukemia

Metabolic rewiring, a hallmark of acute myeloid leukemia (AML), contributes to the development of resistance to intensive chemotherapy and has been shown to play an essential role in leukemic cell maintenance. Several metabolic alterations have been described in AML, such as dependence on amino acids to fuel oxidative phosphorylation or ability of leukemic cells to switch energy dependence to fatty acid oxidation in response to treatment. However, little is known about the functional significance of the fatty acid synthesis (FAS) pathway in AML. Here we have identified stearoyl-CoA desaturase (SCD), a key enzyme responsible for the conversion of saturated fatty acids (SFA) into monounsaturated fatty acids (MUFA), as a novel therapeutic target in AML. High SCD expression predicts worse survival across several patient datasets, even after correction for gender, age and AML European LeukemiaNet risk category. Moreover, genetic and chemical inhibition of SCD reduces growth and induces cell death in AML cells. Since targeting SCD with currently available inhibitors has been challenging because of their toxicity profile in vivo, we have accessed a novel pharmacological SCD inhibitor with a more favorable toxicity profile, SSI-4 (Modulation Therapeutics Inc., Morgantown, USA). SSI-4 reduces viability in several human and mouse AML models in vitro and in about half of the 36 primary AML samples tested ex vivo. Moreover, SSI-4 displays anti-leukemic effects in AML murine models and patient-derived xenografts (PDX). Since we could not correlate susceptibility to SCD inhibition with any genetic characteristic of AML cells, we aimed to determine the molecular basis of cell sensitivity using phosphoproteomic, proteomic and transcriptomic approaches coupled with metabolic analyses of sensitive and resistant cell lines and primary AML cells. Sensitivity to SCD inhibition directly correlates with rate of de novo FAS, as measured by fatty acid labeling with 13C-glucose. Moreover, modulation of FAS by the AMPK signaling activity dictates sensitivity to SCD inhibition and AMPK activation rescues the anti-leukemic effects of SSI-4. The anti-leukemic effects of SCD inhibition are secondary to the induction of SFA mediated lipotoxicity, as demonstrated by the increased sensitivity of previously resistant cells to SSI-4, when grown in the presence of the SFA palmitate. Conversely, growing cells in the presence of the MUFA oleate, as well as inhibition of FAS by targeting enzymes upstream of SCD, results in resistance to SSI-4, thus confirming that the increased SFA/MUFA ratio drives leukemic cell death. SFA mediated lipotoxicity leads to both increased lipid peroxidation and activation of the unfolded protein response (UPR), namely its PERK branch, which in turn leads to apoptotic cell death. Indeed, inhibition of PERK, but not of other branches of UPR, rescues SCD-mediated cytotoxicity. Despite causing disease debulking in vivo, SSI-4 does not prolong survival in murine AML models as a single agent and the toxic effects of SSI-4 are decreased when AML cells are grown in co-culture with stroma, suggesting a protective role of tumor microenvironment. However, we consistently detect increased lipid peroxidation and DNA damage both in vitro and in vivo following SCD inhibition. We therefore combined SSI-4 with doxorubicin, a known inducer of lipid peroxidation and DNA damage, which is routinely used in AML induction therapy. Indeed, both genetic depletion and pharmacological inhibition of SCD renders AML cells more sensitive to doxorubicin, and addition of SSI-4 to a standard AML chemotherapy protocol consisting of doxorubicin and cytarabine significantly extends survival in AML mouse models. In summary, we identify and validate SCD as a therapeutic target in AML. The novel SCD inhibitor SSI-4 displays anti-leukemic properties both in vitro and in vivo across different AML models and particularly when combined with standard chemotherapy while showing minimal toxicity in vivo. We show that sensitivity to SCD inhibition is driven by metabolic rather than genetic AML features, thus making this therapeutic approach potentially applicable across several AML subtypes, including high risk ones. Finally, the mechanism of toxicity following SCD inhibition suggests that this can be further enhanced by modulating the levels of SFA/MUFA through dietary interventions or by combining it with DNA damaging agents. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Personalization of Induction Therapy for Pediatric AML to Ara-C+Dauno+ Etoposide (ADE) or Clofarabine+Ara-C According to a Polygenic Ara-C SNP Score- ACS10

Acute myeloid leukemia (AML) is a heterogenous disease with overall suboptimal outcome. Although chemotherapy regimens that include cytarabine (ara-C) induce remission in a majority of pediatric AML patients, approximately 30% relapse and subsequently have very dismal outcome. Ara-C is a prodrug requiring activation to ara-CTP which induces leukemic cell death. Thus, inter-patient variation in each patient's ability to activate ara-C is a significant contributor to clinical outcomes. We recently performed a comprehensive pharmacogenomics evaluation of SNPs in ara-C metabolism pathway genes and developed a polygenic ara-C 10-SNP genotype (ACS10) score based on association with leukemic intracellular ara-CTP levels and clinical outcome (Elsayed et al, 2022, JCO1). Our results demonstrated that patients with low ACS10 score had poor outcomes when given standard induction including low-dose ara-C, daunorubicin and etoposide (ADE); however their outcomes were much better by augmenting therapy with either an increased dose of ara-C or the addition of gemtuzumab ozogamicin1. Conversely, patients with a high ACS10 score fared worse when given high-dose ara-C than low ara-C dose-based ADE induction (LDAC). These results suggest that pediatric AML patients may benefit from pharmacogenetic personalization of ADE therapy according to their ACS10 scores. Additionally, these results motivate research regarding the utility of ACS10 for pharmacogenetic personalization of other therapies for pediatric AML. Clofarabine is another nucleoside analog that inhibits both DNA polymerase as well as ribonucleotide reductase, thus enhancing the activity of ara-C. Recent data from the AML08 clinical trial [NCT00703820] has shown promising results with use of clofarabine with cytarabine during remission induction in pediatric AML patients.2 Therefore, we evaluated the association of ACS10 score with outcomes among 91 patients randomly assigned standard ADE induction on the AML02 clinical trial (LDAC arm) [NCT00136084] and 117 patients randomly assigned an induction of clofarabine and ara-C (Clo+Ara-C arm) on the AML08 trial [NCT00703820] (Figure 1A shows the study design). 5-year event-free survival (EFS) and overall survival (OS) of patients treated with ADE improved with increasing ACS10 score; however, for patients treated with Clo+Ara-C, improvement with increasing ACS10 score was not observed (OS shown in Figure 1A). This differential outcome association pattern suggests that thresholding the ACS10 score at 0 could be used to classify patients into low (<=0) and high (>0) ACS10 groups. Patients within low ACS10 score group had a better outcome with Clo+AraC whereas the high ACS10 score patient group fared better with ADE. In particular, there is significant improvement in EFS and OS within the low-ACS10 score patients when treated with Clo+Ara-C as compared to ADE (Clo+AraC vs. ADE; EFS HR=0.45, 95% CI: 0.23-0.82; p=0.01; OS HR=0.45, 95% CI: 0.19-0.93, p=0.028; Figure 1B). In contrast, patients with a high ACS10 score had worse EFS and OS with Clo+AraC induction than with ADE induction (EFS HR= 1.84, 95% CI: 0.99-3.41, p=0.05; OS HR= 2.40, 95%CI: 1.13-5.13; p=0.02, Figure 1B). These results are unlikely to suffer from a strong historical comparison bias because there are not statistically significant differences in the outcomes of the randomly assigned therapies of the AML02 and AML08 trials as well as outcome by the clinical trial (EFS/OS of each arm of the two trials as well as between AML02 and AML08 trials; p=0.8, data not shown). In summary, consistent with our recent report, these results show that for patients with Low-ACS10 genetic score prognosis is poor with standard ADE induction. However, therapy augmentation options such as Clo+AraC, ADE with high-dose Ara-C, and ADE+gemtuzumab may improve the prognosis. This calls for an action on using preemptive genotyping for selection of the most effective induction 1 chemotherapy regimen to achieve maximum clinical benefit. References. 1. Elsayed AH, et al: Polygenic Ara-C Response Score Identifies Pediatric Patients With Acute Myeloid Leukemia in Need of Chemotherapy Augmentation. JCO 2022, PMID:34990262 2. Rubnitz JE, et al: Clofarabine Can Replace Anthracyclines and Etoposide in Remission Induction Therapy for Childhood Acute Myeloid Leukemia: The AML08 Multicenter, Randomized Phase III Trial. JCO 2019, PMID:3124652 Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Effect of cumulative daunorubicin dose on cardiotoxicity after allogeneic stem cell transplantation

Cardiotoxicity after allogeneic stem cell transplantation (SCT) is associated with a high rate of mortality and worsening quality of life. The relation between daunorubicin dose and post- allogeneic stem cell transplantation (SCT) cardiotoxicity remains unclear. We retrospectively evaluated 171 patients with acute myeloid leukemia (AML) who underwent their first allogeneic SCT at our institution between 2005 and 2021. High-dose daunorubicin (50 mg/m2/day for 5 days) and cytarabine were usually used as induction therapy for AML. The median cumulative daunorubicin dose was 310 mg/m2 (range, 0–950 mg/m2), and 43 patients received two courses of induction therapy with high-dose daunorubicin (daunorubicin doses of ≥500 mg/m2). Cardiotoxicity developed in 12 patients, and the cumulative incidence at 2 years after SCT was 7.1%. Univariable analysis revealed that female sex, left ventricular ejection fraction (LVEF) of < 60% before SCT, and daunorubicin doses of ≥ 500 mg/m2 were associated with cardiotoxicity. Multivariable analysis showed that a daunorubicin dose of ≥ 500 mg/m2 was an independent risk factor for cardiotoxicity. LVEF decline during the study was observed with an increase in the daunorubicin dose, and only a daunorubicin dose of ≥ 500 mg/m2 was associated with a pre-SCT decreased LVEF. Second induction therapy with high-dose daunorubicin is a risk factor for cardiotoxicity after SCT. This should be taken into consideration when determining reinduction therapies for SCT-eligible patients with relapsed or refractory AML.

PB1850: A DOSE FINDING AND EXPANSION OPEN LABEL, MULTICENTER STUDY OF IADADEMSTAT AND GILTERITINIB IN PATIENTS WITH RELAPSE/REFRACTORY ACUTE MYELOID LEUKEMIA WITH MUTATED FLT3: THE FRIDA STUDY

Background: Despite improvements in therapy for acute myeloid leukemia (AML), relapses remain a common challenge, contributing to the death of more than 50% of AML patients (pts). Approximately a third of pts with newly diagnosed AML harbor mutations in the fms-like tyrosine kinase 3 (FLT3) gene. Current guidelines recommend molecular testing for FLT3-mut at diagnosis and at relapse, for earlier incorporation of targeted agents FLT3 inhibitors (FLT3i). The approval of the FLT3i midostaurin with induction therapy in FLT3mut AML, and of a more specific potent FLT3i, gilteritinib, as monotherapy for relapsed/refractory (R/R) pts have resulted in improved outcomes. Nevertheless, the duration of remission achieved with single-agent gilteritinib in R/R disease is transient and often brief. Iadademstat (iada) is a highly selective and potent covalent inhibitor of LSD1/KDM1A (lysine demethylase 1) that induces differentiation of AML cells in vitro and decreases leukemic stem cell survival in preclinical models. More than 100 subjects have been treated with iada, including R/R AML pts with monotherapy and naïve AML pts in combination with azacitidine, revealing a manageable safety profile and encouraging response rates. The purpose of the FRIDA clinical trial is to evaluate the safety and effect of iada in combination with the standard-of-care gilteritinib for the treatment of R/R FLT3-mut AML pts. The preclinical rationale supporting the combination is based on: 1) a potent synergistic activity in FLT3-AML in several preclinical models, and 2) the anti-leukemic activity of iada, mediated by preventing the interaction between LSD1 and the GFI1 transcription factor and modifying the epigenetic marks of genes resulting on macrophage/monocytic differentiation. These data, together with iada’s favorable ADME and low DDI risk, warrants further exploration of this combination with the aim of improving outcomes for FLT3-mut R/R AML pts. Aims: The FRIDA study will establish the safety, tolerability and determine the recommended phase 2 dose (RP2D), and preliminary activity for the combination of iada and gilteritinib in pts with FLT3mut R/R AML. Methods: Adult pts with a body weight >50Kg and ECOG 0-2, with relapsed or refractory disease, after 1 or 2 prior lines of therapy, and with FLT3-mutations will be enrolled. In a 3 + 3 escalation phase, up to 18 pts would receive iada at doses of 75 to 150 ug, orally, on 5 days ON -2 days OFF schedule, with continuous gilteritinib PO, at 120 mg/day. In the expansion phase, up to 14 pts at the selected safe and pharmacologically active dose/s will be enrolled. Primary endpoints of the study are safety and RP2D determination (based on PK, PD, safety, tolerability, and preliminary activity). Bayesian efficacy monitoring will be performed with cumulating enrollment to ensure futility boundaries are not crossed and to evaluate the activity of the combination. Secondary endpoints include Overall Survival, Event-Free-Survival, Overall Response Rate, Time to Response, Duration of Response and Transfusion rate. Exploratory endpoints include measurable residual disease and gene mutational analysis. Results: This is a clinical trial in progress. No results available. Summary/Conclusion: Study recruiting in Q2 2022 in US.

Leukotrienes promote stem cell self-renewal and chemoresistance in acute myeloid leukemia.

Acute myeloid leukemia (AML) is characterized by poor clinical outcomes due to high rates of relapse following standard-of-care induction chemotherapy. While many pathogenic drivers have been described in AML, our understanding of the molecular mechanisms mediating chemotherapy resistance remains poor. Therefore, we sought to identify resistance genes to induction therapy in AML and elucidated ALOX5 as a novel mediator of resistance to anthracycline-based therapy. ALOX5 is transcriptionally upregulated in AML patient blasts in comparison to normal hematopoietic stem/progenitor cells (HSPCs) and ALOX5 mRNA, and protein expression is increased in response to induction therapy. In vitro, and in vivo genetic, and pharmacologic perturbation studies confirm that ALOX5 positively regulates the leukemogenic potential of AML LSCs, and its loss does not significantly affect the function of normal HSPCs. ALOX5 mediates resistance to daunorubicin (DNR) and promotes AML cell survival and maintenance through its leukotriene (LT) synthetic capacity, specifically via modulating the synthesis of LTB4 and its binding to LTB receptor (BLTR). Our study reveals a previously unrecognized role of LTs in AML pathogenesis and chemoresistance, whereby inhibition of ALOX5 mediated LTB4 synthesis and function could be combined with standard chemotherapy, to enhance the overall therapeutic efficacy in AML.

Outcomes of TP53‐mutated AML with evolving frontline therapies: Impact of allogeneic stem cell transplantation on survival

Outcomes of <scp><i>TP53</i></scp>‐mutated <scp>AML</scp> with evolving frontline therapies: Impact of allogeneic stem cell transplantation on survival

Standard-Intensity Induction and Intermediate/High-Dose Cytarabine Consolidation Can Improve Survival for Elderly Patients with Newly Diagnosed Acute Myeloid Leukemia: A Retrospective Cohort Study.

BackgroundThere is great uncertainty in the treatment of elderly patients with acute myeloid leukemia (AML), which leads to great challenges in treatment decision. The aim of this study is to find more suitable induction therapy and consolidation therapy for elderly AML patients.MethodsA total of 149 consecutive newly diagnosed elderly AML patients (aged ≥60 years) who received induction chemotherapy in our medical center from January 2015 to December 2019 were retrospectively analyzed.ResultsAfter the first induction treatment, the complete remission/or complete remission with incomplete hematologic recovery (CR/CRi) rates in the standard-intensity chemotherapy group was significantly higher than that in the low-intensity chemotherapy group (58.2% vs 32.9%, p = 0.003). Compared with the low-intensity chemotherapy, the incidence of severe infection in the standard-intensity chemotherapy was significantly increased (p < 0.001), but the early mortality was comparable. One hundred and seven patients received minimal residual disease (MRD) examination after the first induction treatment; and MRD was negative accounting for 51.9% in the standard-intensity chemotherapy group, while only 32.7% in the low-intensity group (p = 0.05). The 2-year-overall survival (OS) of patients in standard-intensity induction chemotherapy group (37.2%) was slightly higher than that in low-intensity induction chemotherapy group (23.4%) (p = 0.075). Eighty-one CR/CRi patients received intermediate or high dose cytarabine (n = 35) or sequential chemotherapy regimens (n = 46) as consolidation treatment. The 2-year OS and event-free survival (EFS) of patients in the intermediate or high-dose cytarabine group were significantly higher than those in the sequential chemotherapy regimens group (73.0% vs 38.5%, p = 0.002; 54.8% vs 35.0%, p = 0.035).ConclusionOur results showed that standard-intensity induction chemotherapy can significantly improve the CR rate for elderly AML patients, and does not increase the early mortality; consolidation therapy with intermediate or high-dose cytarabine can significantly improve EFS and OS for elderly AML patients achieved CR.

Low Exposure Extended Dosing Mimicking Clinical Exposures of the Oral Formulation of Azacitidine Results in a Sustained Hypomethylation and Targets Leukemic Stem Cells

Acute Myeloid Leukemia (AML) is characterized by uncontrolled proliferation of incompletely differentiated myeloid stem/ progenitor cells. Despite recent advances in therapy, high rates of clinical relapse, even in patients who achieve complete remission, remains a critically unmet need. One of the strategies to prolong remission post-induction in AML is to employ effective maintenance therapies. Oral Azacitidine (Oral-AZA; CC-486) is the first and only currently approved maintenance therapy in AML. However, the mechanism of action of Oral-AZA and whether it is differentiated from the Injectable-AZA used in AML induction therapy, remains unclear.In this work, we explore the mechanism of Oral-AZA by in vitro modelling of the relative clinical exposures of Oral-AZA vs Injectable-AZA in AML cell line models. Following Vu et al (Nat. Commun. 2020), we used the Injectable-AZA concentration (1 μM aZA) as a single dose (HELD - High Exposure Limited Duration). A fractionated dose of 0.2 μM each day over 5 days (LEED - Low Exposure Extended Duration) was used to model Oral-AZA.Azacitidine incorporates into RNA and DNA of AML cells leading to hypomethylation driven gene expression changes. We found that HELD but not LEED dosing produced an acute anti-proliferative effect in sensitive AML cell lines suggesting potential for a non-hypomethylation mediated/integrated stress response (ISR) driven mechanism. This ISR effect was rescued by co-treatment with ISRIB, an ISR inhibitor. With HELD, we observed robust ATF4 activation as early as 6 hours that was sustained up to 24 hours. In contrast, LEED induced modest and transient ATF4 activation. Thus, an Injectable-AZA-like regimen activated the ISR pathway more robustly than an Oral-AZA-like regimen. Interestingly, decitabine, a DNA-only incorporating cytidine analog did not activate ISR.In AML cell lines, the target of Azacitidine, DNMT1 was depleted (about 90% compared to control) within 24 hours in both HELD and LEED regimens. However, LEED produced a more sustained DNMT1 loss, up to 7 days whereas in HELD, DNMT1 protein levels recovered 96 hours post-dosing. Given the relative level and duration of DNMT1 loss, we hypothesized that LEED would lead to a more durable hypomethylation. We performed whole genome bisulfite sequencing (WGBS) in 3 AML cell lines (OCI-AML2, MV-4-11 and SKM1) at 48- and 96-hours post-initiation of HELD and LEED dosing. Consistent with the DNMT1 depletion kinetics, at 48 hours we observed almost 75% global DNA hypomethylation with both HELD and LEED treatments. At 96 hours, HELD demonstrated a recovery effect and reverted to 50% hypomethylation. In contrast, LEED showed up to 85% hypomethylated sites, demonstrating the durability of the hypomethylation mediated by an Oral-AZA-like (LEED) regimen.Next, we explored the effect of Oral-AZA-like dosing in the differentiation of leukemic stem cells (LSCs) towards a more mature phenotype. In an in vitro LSC model (OCI-AML-20) with flow cytometry analysis, LEED dosing resulted in a greater depletion (2-fold more) of LSCs (CD34+/38- or 38 low) and concomitant enrichment of cells with more differentiated phenotype (CD34+/38+) compared to HELD dosing. To further validate these observations at the transcriptomic level, we performed single cell RNAseq in OCI-AML-20 cells at different timepoints (3, 5 and 7 days). Data were analyzed using a classifier to identify leukemic myeloid cell lineages (Van Galen et al., Cell 2019). Compared to untreated cells, at day 7, both LEED and HELD dosing resulted in an increase of GMP and promonocytes and those differences were more pronounced with Oral-AZA-like (50% GMP and 20% promonocytic) than the Injectable-AZA-like regimen (28% GMP and 12.5% promonocytic).Taken together, our in vitro modeling of the clinically relevant exposures of Oral-AZA vs Injectable-AZA by using HELD and LEED dosing strategies show a shift of the molecular mechanism between the clinical entities. Our work demonstrates that an Injectable-AZA-like regimen mediates cytotoxicity through an early ISR driven effect. Oral-AZA mechanism leads to a more sustained pharmacodynamic DNA hypomethylation effect that in turn could be linked to a differentiation inducing effect on the LSC population. DisclosuresJeyaraju: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Alapa: Bristol Myers Squibb: Current Employment. Polonskaia: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Risueño: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Ahsan: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Wang: Bristol Myers Squibb: Current Employment. Subramanyam: Bristol Myers Squibb: Current Employment. Sriganesh: Bristol Myers Squibb: Current Employment. Anand: Bristol Myers Squibb: Current Employment. Jain: Bristol Myers Squibb: Current Employment. Reddy: Bristol Myers Squibb: Current Employment. Ghosh: Bristol Myers Squibb: Current Employment. Kyriakopoulos: Bristol Myers Squibb: Current Employment. Lailler: Rancho Biosciences: Current Employment. Hartl: Rancho Biosciences: Current Employment. Lopes de Menezes: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Hagner: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Thakurta: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties.

DNMT3A Mutations Should be Considered in the Risk Stratification for Pediatric and Adolescent and Young Adult Patients with Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) is rare but accounts for 20% of leukemia in the pediatric, adolescent and young adult (AYA) population. Five-year survival ranges widely from 22-90% based on subtype and cytogenetic abnormalities. The risk stratification of AML continues to evolve with increased recognition of inferior prognostic factors in the adult population; however, there has been a lack of similar progress in pediatrics. The DNA methyltransferase 3A (DNMT3A) mutation, most frequently at arginine 882 (DNMT3A mut) is observed in 14-34% of adult AML patients and is associated with inferior outcomes. This mutation shows evidence of anthracycline resistance, which may contribute to its poor prognosis as standard induction therapy for AML consists of a backbone of anthracyclines and purine analogs. Overall survival (OS) and disease-free survival (DFS) are improved in adult patients with DNMT3A mutation who receive consolidative allogeneic hematopoietic stem cell transplant (allo-HSCT). DNMT3A mutation has also been reported in the pediatric and AYA AML in 0-1.5% of cases with unclear prognostic implications. In case its presence in this patient population confers inferior outcomes similar to those seen in adults, these patients may also benefit from allo-HSCTObjective: Describe the outcome of pediatric and AYA AML patients with DNMT3A mutationsMethods: This study was approved by the institutional review board at the University of Texas at MD Anderson Cancer Center. All patients aged ≤25 years, diagnosed with AML who underwent treatment at our institution between May 1st, 2014 and November 30 th 2020 were screened. Patients who did not undergo testing for DNMT3A mutation were excluded. Outcomes for patients with and without the DNMT3A mutation who underwent allo-HSCT were compared.Results: One hundred and five patients were diagnosed with AML during the study period. Forty-five patients were not tested for the DNMT3A mutation and were excluded. Sixty patients were tested for the DNMT3A mutation and were included in the analysis. Seven patients (11.7%) (4 males, 3 females) were found to be DNMT3A mutation positive (+ve). Four of them had the R882 missense mutation. Thirty-three patients (33/60; 55%) (16 males, 17 females) underwent allo-HSCT, with 6 of those being DNMT3A+ve. The median age of DNMT3A+ve and DNMT3A negative(-ve) patients undergoing allo-HSCT was 18.5 years (12.6-22.7) and 20 years (11.1-24) respectively (Figure1). Five patients who were DNMT3A+ve underwent allo-HSCT due to disease relapse and 1 patient due to associated FLT3 mutation. Median overall survival was similar in patients with and without DNMT3A mutations who received allo-HSCT at 744 (515-2473) days and 729(48-2492) days respectively (p value =0.77) (Figure 1). Median OS was significantly lower in the one DNMT3A +ve patient who did not undergo allo-HSCT at 430 days compared to those who underwent allo-HSCT (p value=0.01). Two of the six (33.3%) DNMT3A +ve patients who underwent allo HSCT died due to disease relapse (DR). The one DNMT3A patient who did not undergo allo HSCT died due to refractory disease. In the 27 patients who were DNMT3A -ve and received allo-HSCT, 13 died (13/27;48.1%), 6 from disease relapse (6/27; 22.2%), 2 due to multiorgan failure (2/27; 7.4%) and 5 unknown (5/27;18.5%). Relapse-free survival (RFS) was not significantly different between DNMT3A+ve and DNMT3A -ve patients who underwent allo-HSCT at 422 (31-1948) days and 271 (65-2048) days respectively (p value = 0.7).Of the four patients with the R882 missense mutation, 2 died due to DR (one patient at 192 days post allo-HSCT, one patient who did not undergo allo-HSCT at 352 days after achieving clinical remission one(CR1). Of the 3 patients with non R882 mutations, one died due to DR at 98 days post allo-HSCT.Conclusion: DNMT3A mutations, although rare in AML, may be associated with poor prognosis and impact risk stratification. This study suggest that consolidative allogeneic HSCT is a reasonable management consideration for this subgroup of patients. DNMT3A is not included in the current AML risk stratification of pediatric and young adult patients and further research is needed to determine the clinical significance of DNMT3A mutations in pediatric and AYA patients with AML and the impact of upfront allo-HSCT. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Blast cells surviving acute myeloid leukemia induction therapy are in cycle with a signature of FOXM1 activity

BackgroundDisease relapse remains common following treatment of acute myeloid leukemia (AML) and is due to chemoresistance of leukemia cells with disease repopulating potential. To date, attempts to define the characteristics of in vivo resistant blasts have focused on comparisons between leukemic cells at presentation and relapse. However, further treatment responses are often seen following relapse, suggesting that most blasts remain chemosensitive. We sought to characterise in vivo chemoresistant blasts by studying the transcriptional and genetic features of blasts from before and shortly after induction chemotherapy using paired samples from six patients with primary refractory AML.MethodsLeukemic blasts were isolated by fluorescence-activated cell sorting. Fluorescence in situ hybridization (FISH), targeted genetic sequencing and detailed immunophenotypic analysis were used to confirm that sorted cells were leukemic. Sorted blasts were subjected to RNA sequencing. Lentiviral vectors expressing short hairpin RNAs were used to assess the effect of FOXM1 knockdown on colony forming capacity, proliferative capacity and apoptosis in cell lines, primary AML cells and CD34+ cells from healthy donors.ResultsMolecular genetic analysis revealed early clonal selection occurring after induction chemotherapy. Immunophenotypic characterisation found leukemia-associated immunophenotypes in all cases that persisted following treatment. Despite the genetic heterogeneity of the leukemias studied, transcriptional analysis found concerted changes in gene expression in resistant blasts. Remarkably, the gene expression signature suggested that post-chemotherapy blasts were more proliferative than those at presentation. Resistant blasts also appeared less differentiated and expressed leukemia stem cell (LSC) maintenance genes. However, the proportion of immunophenotypically defined LSCs appeared to decrease following treatment, with implications for the targeting of these cells on the basis of cell surface antigen expression. The refractory gene signature was highly enriched with targets of the transcription factor FOXM1. shRNA knockdown experiments demonstrated that the viability of primary AML cells, but not normal CD34+ cells, depended on FOXM1 expression.ConclusionsWe found that chemorefractory blasts from leukemias with varied genetic backgrounds expressed a common transcriptional program. In contrast to the notion that LSC quiescence confers resistance to chemotherapy we find that refractory blasts are both actively proliferating and enriched with LSC maintenance genes. Using primary patient material from a relevant clinical context we also provide further support for the role of FOXM1 in chemotherapy resistance, proliferation and stem cell function in AML.

Prognosis and Application of Day 14 Bone Marrow Results in Acute Myeloid Leukemia Induction

▪Introduction:The 2017 National Comprehensive Cancer Network (NCCN) guidelines for Acute Myeloid Leukemia (AML) recommend performing a bone marrow aspirate (BMA) and trephine biopsy (BMTB) 14-21 days after starting induction therapy (commonly referred to as a “Day 14 [D14] marrow”). Those who do not achieve a hypoplastic marrow, with cellularity <10-20% and blasts <5-10%, are recommended to undergo a second induction cycle (IC). We performed a retrospective analysis to determine the impact of day 14 bone marrow (D14 BM) characteristics in predicting remission, association with overall survival (OS) and the impact of a second IC based on D14 BM results.Methods:Patients with AML aged 18-70 years undergoing induction therapy with standard “7+3” regimens at Vancouver General Hospital or University of Alberta Hospital from 2007-2015 and 2005-2015 respectively were included. D14 cellularity was determined on BMTB and blast percentage (blast %) was assessed by morphology on BMA and BMTB. We examined outcomes by three D14 risk categories: 1. blast % (<5/≥5%), 2. cellularity (<20%/≥20%) or 3. blast % and cellularity (< 5% blasts or <20% cellularity/ ≥5% blasts and ≥20% cellularity). Overall response rate was determined at peripheral count recovery and defined as complete remission (CR) or CR with incomplete count recovery (CRi), (Cheson B J Clin Onc 2003; 21(24):4642-9). Differences in categorical variables were determined using Mantel-Haenszel tests. Binary logistic regression was used to determine association between D14 BM and other covariates on CR/CRi rate. Cox regression was used to determine association between covariates with OS.Results:546 patients were identified with 486 (89.0%) undergoing a D14 BM (Table 1). On the D14 BM, 190 patients had blasts ≥5%, 96 had cellularity ≥20% (with 12 patients also having blasts <5%) and 84 had both blasts ≥5% and cellularity ≥20%. The CR/CRi rate stratified by D14 categories was: 87% vs. 56%, p<0.001 (< 5% vs. ≥ 5% blasts), 79% vs. 57%, p<0.001 (< 20% vs. ≥20% cellularity) and 79% vs. 54%, p<0.001 (<5% blasts or <20% cellularity vs. ≥5% blasts and ≥20% cellularity).In univariate analysis, D14 low-risk categories were associated with higher CR/CRi rates (D14 blasts <5%, OR 5.4, 95% CI 3.5-8.4, p<0.001, D14 cellularity <20%, OR 2.9, 95% CI 1.8-4.6, p<0.001 and D14 blasts <5% or cellularity <20%, OR 3.4, 95% CI 2.1-5.5, p<0.001) and improved OS (D14 blasts <5%, HR 0.66, 95% CI 0.51-0.84, p<0.001, D14 cellularity <20% ,HR 0.55, 95% CI 0.42-0.73, p<0.001 and D14 blasts <5% or D14 cellularity<20% ,HR 0.52, 95% CI 0.39-0.70, p<0.001). In multivariate analysis, the diagnostic cytogenetics and D14 blasts <5% predicted CR/CRi at count recovery whereas age, cytogenetics and D14 blasts <5% were significantly associated with improved OS (Table 2). The risk category using both blast % and cellularity was not included in the multivariate model due to multicollinearity with D14 blast % and cellularity.131 patients (27%) underwent a second IC, most commonly with etoposide/cyclophosphamide (n=48) or mitoxantrone/etoposide (n=48) regimens based upon the results of the D14 BM. CR/CRi rates for patients receiving 1 vs. 2 ICs in high risk D14 groups were: 43% vs. 62%, p=0.01 (D14 blasts ≥ 5%), 67% vs. 55%, p=0.33 (D14 cellularity >20%) and 38% vs. 55%, p=0.35 (D14 blasts ≥5% and cellularity ≥20%). In patients with ≥5% residual blasts on D14 marrow but <20% cellularity there was significant variation in use of D14 BM results with only 49/106 (46.2%) patients undergoing a second IC. In this group, a second IC improved CR/CRi (43.9% vs. 72.0%, P=0.004) but there was no difference in OS (HR 1.08, 95% CI 0.63-1.86, p=0.77). Furthermore, in this group leukemia free survival following CR/CRi was worse in patients that received a second IC (HR 2.24, 95% CI 1.00-4.98, p=0.05).Conclusion:D14 BM results are prognostic for achievement of CR/CRi following induction therapy for AML. D14 blasts <5% predicted CR/CRi in multivariate analysis, despite possible confounding of this analysis by the use of second IC based on D14 BM results. In addition, D14 blasts <5% are prognostic for OS in multivariate analysis including other recognized prognostic factors. For patients with residual blasts but hypocellular marrow on D14 BM, second IC was associated with greater CR/CRi rates but no difference in OS. This finding suggests that for this subset of patients, treatment decisions based on D14 BM may not significantly improve OS. [Display omitted] DisclosuresHogge:Novartis, Roche, and Sanofi: Consultancy.