High dose cytarabine, mitoxantrone and l-asparaginase (HAMA) salvage for relapsed or refractory acute myeloid leukemia (AML) in the elderly

Reverse Phase Proteomic Array Profiling of Asparagine Synthetase Expression in Newly Diagnosed Acute Myeloid Leukemia

Asparaginase-based therapy is a cornerstone in acute lymphoblastic leukemia (ALL) treatment, capitalizing on the methylation status of the asparagine synthetase (ASNS) gene, which renders ALL cells reliant on extracellular asparagine. Contrastingly, ASNS expression in acute myeloid leukemia (AML) has not been thoroughly investigated, despite studies suggesting that AML with chromosome 7/7q deletions might have reduced ASNS levels. Here, we leverage reverse phase protein arrays to measure ASNS expression in 810 AML patients and assess its impact on outcomes. We find that AML with inv(16) has the lowest overall ASNS expression. While AML with deletion 7/7q had ASNS levels slightly lower than those of AML without deletion 7/7q, this observation was not significant. Low ASNS expression correlated with improved overall survival (46 versus 54 weeks, respectively, p = 0.011), whereas higher ASNS levels were associated with better response to venetoclax-based therapy. Protein correlation analysis demonstrated association between ASNS and proteins involved in methylation and DNA repair. In conclusion, while ASNS expression was not lower in patients with deletion 7/7q as initially predicted, ASNS levels were highly variable across AML patients. Further studies are needed to assess whether patients with low ASNS expression are susceptible to asparaginase-based therapy due to their inability to augment compensatory ASNS expression upon asparagine depletion.

Impact of pegaspargase dose capping on incidence of pegaspargase-related adverse events in adults

INTRODUCTION

Asparaginase derivatives are essential components of the treatment of acute lymphoblastic leukemia in adolescent and young adult patients. However, their associated toxicities limit wider use in older populations. This study seeks to determine if the practice of capping the pegaspargase dose at 3750 units reduces the risk of related adverse events in adults.

METHODS

Adverse event data were retrospectively collected 28 days following each administration of pegaspargase in a single center. Doses were categorized as either capped (≤3750 units) (n = 57, 47.5%) or non-capped (>3750 units) (n = 63, 52.5%). The primary endpoint of this study was the composite incidence of serious pegaspargase-related adverse events, defined as grade 3 or higher.

RESULTS

Of the 120 doses administered, 47 (39.2%) were administered to patients  > 39 years. For the primary endpoint, 26 doses (45.6%) in the dose capped group versus 22 doses (34.9%) in the non-dose capped group were associated with serious pegaspargase-related adverse events (p = 0.23). Isolated laboratory abnormalities accounted for all hepatotoxicity and pancreatic toxicity events, while venous thromboembolism and bleeding occurred after 8.3% and 13.3% of doses, respectively. Multivariate analysis of the primary outcome to adjust for differences in baseline characteristics found no difference between groups (OR 2.56 (0.84, 7.77, p = 0.098)).

CONCLUSIONS

The incidence of serious clinical toxicities was low in this study, particularly pegaspargase-related venous thromboembolism. This suggests that the practice of capping pegaspargase doses at 3750 units, coupled with vigilant monitoring and prophylaxis for pegaspargase-related adverse events, can allow for the inclusion of this drug in the treatment of older individuals.

Phase II trial of cytarabine and mitoxantrone with devimistat in acute myeloid leukemia

Devimistat is a TCA cycle inhibitor. A previously completed phase I study of devimistat in combination with cytarabine and mitoxantrone in patients with relapsed or refractory AML showed promising response rates. Here we report the results of a single arm phase II study (NCT02484391). The primary outcome of feasibility of maintenance devimistat following induction and consolidation with devimistat in combination with high dose cytarabine and mitoxantrone was not met, as maintenance devimistat was only administered in 2 of 21 responders. The secondary outcomes of response (CR + CRi) and median survival were 44% (21/48) and 5.9 months respectively. There were no unexpected toxicities observed. An unplanned, post-hoc analysis of the phase I and II datasets suggests a trend of a dose response in older but not younger patients. RNA sequencing data from patient samples reveals an age-related decline in mitochondrial gene sets. Devimistat impairs ATP synthesis and we find a correlation between mitochondrial membrane potential and sensitivity to chemotherapy. Devimistat also induces mitochondrial reactive oxygen species and turnover consistent with mitophagy. We find that pharmacological or genetic inhibition of mitochondrial fission or autophagy sensitizes cells to devimistat. These findings suggest that an age related decline in mitochondrial quality and autophagy may be associated with response to devimistat however this needs to be confirmed in larger cohorts with proper trial design.

Combining cytarabine and mitoxantrone with the tricarboxylic acid cycle inhibitor devimistat has been reported in a phase I clinical trial with relapsed or refractory acute myeloid leukaemia (AML). Here, the authors report the outcomes of a phase II study, analyse samples from both phases and perform preclinical analyses that show mitochondrial fission or autophagy inhibition sensitizes AML cells to devimistat.

Exploring the Metabolic Landscape of AML: From Haematopoietic Stem Cells to Myeloblasts and Leukaemic Stem Cells

Despite intensive chemotherapy regimens, up to 60% of adults with acute myeloid leukaemia (AML) will relapse and eventually succumb to their disease. Recent studies suggest that leukaemic stem cells (LSCs) drive AML relapse by residing in the bone marrow niche and adapting their metabolic profile. Metabolic adaptation and LSC plasticity are novel hallmarks of leukemogenesis that provide important biological processes required for tumour initiation, progression and therapeutic responses. These findings highlight the importance of targeting metabolic pathways in leukaemia biology which might serve as the Achilles' heel for the treatment of AML relapse. In this review, we highlight the metabolic differences between normal haematopoietic cells, bulk AML cells and LSCs. Specifically, we focus on four major metabolic pathways dysregulated in AML; (i) glycolysis; (ii) mitochondrial metabolism; (iii) amino acid metabolism; and (iv) lipid metabolism. We then outline established and emerging drug interventions that exploit metabolic dependencies of leukaemic cells in the treatment of AML. The metabolic signature of AML cells alters during different biological conditions such as chemotherapy and quiescence. Therefore, targeting the metabolic vulnerabilities of these cells might selectively eradicate them and improve the overall survival of patients with AML.

Clinical progress and advanced research of red blood cells based drug delivery system

Red blood cells (RBCs) are biocompatible carriers that can be employed to deliver different bioactive substances. In the past few decades, many strategies have been developed to encapsulate or attach drugs to RBCs. Osmotic-based encapsulation methods have been industrialized recently, and some encapsulated RBC formulations have reached the clinical stage for treating tumors and neurological diseases. Inspired by the intrinsic properties of intact RBCs, some advanced delivery strategies have also been proposed. These delivery systems combine RBCs with other novel systems to further exploit and expand the application of RBCs. This review summarizes the clinical progress of drugs encapsulated into intact RBCs, focusing on the loading and clinical trials. It also introduces the latest advanced research based on developing prospects and limitations of intact RBCs drug delivery system (DDS), hoping to provide a reference for related research fields and further application potential of intact RBCs based drug delivery system.

Amino Acid Metabolic Vulnerabilities in Acute and Chronic Myeloid Leukemias

Amino acid (AA) metabolism plays an important role in many cellular processes including energy production, immune function, and purine and pyrimidine synthesis. Cancer cells therefore require increased AA uptake and undergo metabolic reprogramming to satisfy the energy demand associated with their rapid proliferation. Like many other cancers, myeloid leukemias are vulnerable to specific therapeutic strategies targeting metabolic dependencies. Herein, our review provides a comprehensive overview and TCGA data analysis of biosynthetic enzymes required for non-essential AA synthesis and their dysregulation in myeloid leukemias. Furthermore, we discuss the role of the general control nonderepressible 2 (GCN2) and-mammalian target of rapamycin (mTOR) pathways of AA sensing on metabolic vulnerability and drug resistance.

Mitochondrial metabolism as a target for acute myeloid leukemia treatment

Acute myeloid leukemias (AML) are a group of aggressive hematologic malignancies resulting from acquired genetic mutations in hematopoietic stem cells that affect patients of all ages. Despite decades of research, standard chemotherapy still remains ineffective for some AML subtypes and is often inappropriate for older patients or those with comorbidities. Recently, a number of studies have identified unique mitochondrial alterations that lead to metabolic vulnerabilities in AML cells that may present viable treatment targets. These include mtDNA, dependency on oxidative phosphorylation, mitochondrial metabolism, and pro-survival signaling, as well as reactive oxygen species generation and mitochondrial dynamics. Moreover, some mitochondria-targeting chemotherapeutics and their combinations with other compounds have been FDA-approved for AML treatment. Here, we review recent studies that illuminate the effects of drugs and synergistic drug combinations that target diverse biomolecules and metabolic pathways related to mitochondria and their promise in experimental studies, clinical trials, and existing chemotherapeutic regimens.

Antiproliferative effects of L-asparaginase in acute myeloid leukemia

The antitumor enzyme L-asparaginase (L-Asp) has commonly been used for the treatment of acute lymphoblastic leukemia. However, the effects of L-Asp on acute myeloid leukemia (AML) and their underlying mechanisms have not been fully elucidated. In the present study, the effects of L-Asp on cell proliferation and apoptosis were investigated using the AML cell lines U937, HL-60 and KG-1a. The effects of combining L-Asp with mitoxantrone (MIT) and cytarabine (Ara-c) were also analyzed. The combination of MIT and Ara-C is known as MA therapy, and is a widely used therapeutic regimen for the treatment of elderly patients with refractory AML. When applied alone, L-Asp inhibited cell proliferation and induced apoptosis in each of the cell lines tested. Furthermore, the combined use of L-Asp with MA therapy further potentiated the inhibition of cell proliferation while increasing the induction of apoptosis. These findings provide evidence for the potential antitumor effect of L-Asp in AML, and indicate that improved efficacy maybe achieved by combining L-Asp with MIT and Ara-c. This combination may provide a promising new therapeutic strategy for the treatment of AML.

Comparison of High-Dose Cytarabine, Mitoxantrone, and Pegaspargase (HAM-pegA) to High-Dose Cytarabine, Mitoxantrone, Cladribine, and Filgrastim (CLAG-M) as First-Line Salvage Cytotoxic Chemotherapy for Relapsed/Refractory Acute Myeloid Leukemia

Currently, no standard of care exists for the treatment of relapsed or refractory acute myeloid leukemia (AML). We present our institutional experience with using either CLAG-M or HAM-pegA, a novel regimen that includes pegaspargase. This is a retrospective comparison of 34 patients receiving CLAG-M and 10 receiving HAM-pegA as first salvage cytotoxic chemotherapy in the relapsed or refractory setting. Composite complete response rates were 47.1% for CLAG-M and 90% for HAM-pegA (p = 0.027). Event-free survival was significantly different in favor of HAM-pegA (p = 0.045), though overall survival was similar between groups. There were no significant differences in toxicities experienced by patients treated with the two regimens, including adverse events of special interest related to pegaspargase (venous thromboembolism, hemorrhage, hepatotoxicity, pancreatitis, and hypersensitivity reactions). HAM-pegA is a novel regimen for relapsed or refractory AML that resulted in improved response rates and similar toxicities compared to CLAG-M.

Real-Time NMR Spectroscopy for Studying Metabolism

Current metabolomics approaches utilize cellular metabolite extracts, are destructive, and require high cell numbers. We introduce here an approach that enables the monitoring of cellular metabolism at lower cell numbers by observing the consumption/production of different metabolites over several kinetic data points of up to 48 hours. Our approach does not influence cellular viability, as we optimized the cellular matrix in comparison to other materials used in a variety of in-cell NMR spectroscopy experiments. We are able to monitor real-time metabolism of primary patient cells, which are extremely sensitive to external stress. Measurements are set up in an interleaved manner with short acquisition times (approximately 7 minutes per sample), which allows the monitoring of up to 15 patient samples simultaneously. Further, we implemented our approach for performing tracer-based assays. Our approach will be important not only in the metabolomics fields, but also in individualized diagnostics.

Devimistat in combination with high dose cytarabine and mitoxantrone compared with high dose cytarabine and mitoxantrone in older patients with relapsed/refractory acute myeloid leukemia: ARMADA 2000 Phase III study

Devimistat (CPI-613®) is an intravenously administered, novel lipoate analog that inhibits two key tricarboxcylic acid (TCA) cycle enzymes, pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase complexes (KGDH). These complexes control TCA cycle entry of glucose and glutamine-derived carbons, respectively. Acute myeloid leukemia (AML) cells upregulate the TCA cycle in response to DNA damaging agents and treatment with devimistat increases sensitivity to them. A Phase I study of devimistat in combination with cytarabine and mitoxantrone produced a complete remission rate of 50% in patients with relapsed or refractory AML. In the combined Phase I/II experience, older patients with R/R AML treated with 2000 mg/m2 of devimistat had a 52% complete remission/complete remission with incomplete hematologic recovery rate and a median survival of 12.4 months. This report outlines the rationale and design of the ARMADA 2000 study, a Phase III clinical trial of devimistat in combination with high dose cytarabine and mitoxantrone compared with high dose cytarabine and mitoxantrone alone for older patients (≥60 years of age) with relapsed or refractory AML. Clinical trial registration: NCT#03504410.

Metabolic Plasticity of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is one of the most common and life-threatening leukemias. A highly diverse and flexible metabolism contributes to the aggressiveness of the disease that is still difficult to treat. By using different sources of nutrients for energy and biomass supply, AML cells gain metabolic plasticity and rapidly outcompete normal hematopoietic cells. This review aims to decipher the diverse metabolic strategies and the underlying oncogenic and environmental changes that sustain continuous growth, mediate redox homeostasis and induce drug resistance in AML. We revisit Warburg's hypothesis and illustrate the role of glucose as a provider of cellular building blocks rather than as a supplier of the tricarboxylic acid (TCA) cycle for energy production. We discuss how the diversity of fuels for the TCA cycle, including glutamine and fatty acids, contributes to the metabolic plasticity of the disease and highlight the roles of amino acids and lipids in AML metabolism. Furthermore, we point out the potential of the different metabolic effectors to be used as novel therapeutic targets.

Acute myeloid leukaemia niche regulates response to L-asparaginase

Eradicating the malignant stem cell is the ultimate challenge in the treatment of leukaemia. Leukaemic stem cells (LSC) hijack the normal haemopoietic niche, where they are mainly protected from cytotoxic drugs. The anti-leukaemic effect of L-asparaginase (ASNase) has been extensively investigated in acute lymphoblastic leukaemia, but only partially in acute myeloid leukaemia (AML). We explored the susceptibility of AML-LSC to ASNase as well as the role of the two major cell types that constitute the bone marrow (BM) microenvironment, i.e., mesenchymal stromal cells (MSC) and monocytes/macrophages. Whilst ASNase was effective on both CD34⁺ CD38⁺ and CD34⁺ CD38^- LSC fractions, MSC and monocytes/macrophages partially counteracted the effect of the drug. Indeed, the production of cathepsin B, a lysosomal cysteine protease, by BM monocytic cells and by AML cells classified as French-American-British M5 is related to the inactivation of ASNase. Our work demonstrates that, while MSC and monocytes/macrophages may provide a protective niche for AML cells, ASNase has a cytotoxic effect on AML blasts and, importantly, LSC subpopulations. Thus, these features should be considered in the design of future clinical studies aimed at testing ASNase efficacy in AML patients.

Optimizing pegylated asparaginase use: An institutional guideline for dosing, monitoring, and management

The incorporation of L-asparaginase and pegylated asparaginase into pediatric-inspired regimens has conferred a survival advantage in treatment of adults with acute lymphoblastic leukemia. Use of asparaginase products requires careful prevention, monitoring, and management of adverse effects including hypersensitivity, hepatotoxicity, pancreatitis, coagulopathy, and thrombosis. Currently, there is limited published literature to offer guidance on management of these toxicities. At the University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center, a standard of practice guideline was created to prevent and manage asparaginase-related adverse events. By sharing our long-term experience with asparaginase products and clinical management of asparaginase-induced toxicities, this article aims to improve patient safety and optimize treatment outcomes.

A Phase I Study of CPI-613 in Combination with High-Dose Cytarabine and Mitoxantrone for Relapsed or Refractory Acute Myeloid Leukemia

Purpose: CPI-613, a lipoate analogue that inhibits pyruvate dehydrogenase (PDH) and α-ketogluterate dehydrogenase (KGDH), has activity in patients with myeloid malignancies. This study explored the role of mitochondrial metabolism in chemotherapy response and determined the MTD, efficacy, and safety of CPI-613 combined with high-dose cytarabine and mitoxantrone in patients with relapsed or refractory acute myeloid leukemia.Experimental Design: The role of mitochondrial response to chemotherapy was assessed in cell lines and animal models. A phase I study of CPI-613 plus cytarabine and mitoxantrone was conducted in patients with relapsed or refractory AML.Results: Exposure to chemotherapy induced mitochondrial oxygen consumption that depended on PDH. CPI-613 sensitized AML cells to chemotherapy indicating that mitochondrial metabolism is a source of resistance. Loss of p53 did not alter response to CPI-613. The phase I study enrolled 67 patients and 62 were evaluable for response. The overall response rate was 50% (26CR+5CRi/62). Median survival was 6.7 months. In patients over 60 years old, the CR/CRi rate was 47% (15/32) with a median survival of 6.9 months. The response rate for patients with poor-risk cytogenetics also was encouraging with 46% (11/24 patients) achieving a CR or CRi. RNA sequencing analysis of a subset of baseline bone marrow samples revealed a gene expression signature consistent with the presence of B cells in the pretreatment marrow of responders.Conclusions: The addition of CPI-613 to chemotherapy is a promising approach in older patients and those with poor-risk cytogenetics. Clin Cancer Res; 24(9); 2060-73. ©2018 AACR.

Asparaginase Erwinia chrysanthemi effectively depletes plasma glutamine in adult patients with relapsed/refractory acute myeloid leukemia

Depletion of glutamine (Gln) has emerged as a potential therapeutic approach in the treatment of acute myeloid leukemia (AML), as neoplastic cells require Gln for synthesis of cellular components essential for survival. Asparaginases deplete Gln, and asparaginase derived from Erwinia chrysanthemi (Erwinaze) appears to have the greatest glutaminase activity of the available asparaginases. In this Phase I study, we sought to determine the dose of Erwinaze that safely and effectively depletes plasma Gln levels to ≤ 120 μmol/L in patients with relapsed or refractory (R/R) AML. Five patients were enrolled before the study was halted due to issues with Erwinaze manufacturing supply. All patients received Erwinaze at a dose of 25,000 IU/m² intravenously three times weekly for 2 weeks. Median trough plasma Gln level at 48 h after initial Erwinaze administration was 27.6 μmol/L, and 80% (lower limit of 1-sided 95% CI 34%) of patients achieved at least one undetectable plasma Gln value (< 12.5 μmol/L), with the fold reduction (FR) in Gln level at 3 days, relative to baseline, being 0.16 (p < 0.001 for rejecting FR = 1). No dose-limiting toxicities were identified. Two patients responded, one achieved partial remission and one achieved hematologic improvement after six doses of Erwinaze monotherapy. These data suggest asparaginase-induced Gln depletion may have an important role in the management of patients with AML, and support more pharmacologic and clinical studies on the mechanistically designed asparaginase combinations in AML.

Long-Term Follow-Up and Impact of Comorbidity before Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Relapsed or Refractory Acute Myeloid Leukemia-Lessons Learned from the Prospective BRIDGE Trial

In patients with relapsed or refractory (r/r) acute myeloid leukemia (AML), allogeneic hematopoietic stem cell transplantation (HSCT) is considered to be the only treatment providing long-term disease control. The BRIDGE trial studied the safety and efficacy of a clofarabine-based salvage therapy before HSCT in patients with r/r AML. Here, we report the long-term follow-up of this phase II multicenter trial and exploratory analyses on the impact of comorbidity on outcome. Eighty-four patients with a median age of 61 years (range, 40 to 75) were enrolled. Patients were scheduled for at least 1 cycle of salvage therapy with CLARA (clofarabine 30 mg/m²; cytarabine 1 g/m², days 1 to 5). Chemo-responsive patients with a donor received HSCT after first CLARA. The conditioning regimen consisted of clofarabine 30 mg/m², day -6 to -3, and melphalan 140 mg/m² day -2. The Eastern Cooperative Oncology Group (ECOG) score, the hematopoietic cell transplantation-specific comorbidity index (HCT-CI), and the Cumulative Illness Rating Scale were obtained at study enrollment as well as before HSCT. Sixty-seven percent of the patients received HSCT within the trial. After a median follow up of 40 months, the estimated 3-year overall survival (OS) for all enrolled patients and those with HSCT within the trial was 40% and 55%, respectively. Relapse-free survival for patients who underwent transplantation with a complete remission afterwards (n = 50) was 48%, calculated from the day of transplantation. In multivariate analysis, both the HCT-CI and ECOG score had a statistically significant impact on OS with a hazard ratio of 1.22 (P = .025)and 1.72 (P = .001), respectively. Using a clofarabine-based salvage therapy combined with early allogeneic HSCT, we were able to achieve good long-term results for patients with r/r AML. In this cohort, both the HCT-CI and the ECOG scores gave prognostic information on OS, showing the feasibility and clinical relevance of comorbidity evaluation at the time of diagnosis of r/r AML patients.

Erythrocyte encapsulated l-asparaginase (GRASPA) in acute leukemia

l-asparaginase, an enzyme originally derived from Escherichia coli, represents a major drug in the treatment of acute lymphoblastic leukemia. However, the occurrence of major adverse effects often leads to early withdrawal of the enzyme. Main side effects include immune-allergic reactions, coagulopathy, pancreatitis and hepatic disorders. Novel asparaginase formulations and alternative sources have been developed to address this issue, but the results were not totally satisfactory. l-asparaginase loaded red blood cells (RBCs; GRASPA) represent a new asparaginase presentation with reduced immunological adverse reactions. RBCs protect l-asparaginase, enhance its half-life and reduce the occurrence of adverse events. We reviewed the history, biology and clinical experiences with l-asparaginase, and the characteristics and first clinical experiences with GRASPA in the treatment of acute leukemia.