Significance of WT1 and multiparameter flow cytometry assessment in patients with chronic myelomonocytic leukemia receiving allogeneic hematopoietic stem cell transplantation.

INTRODUCTION: The objective of this study was to investigate the clinical significance of minimal residual disease (MRD) monitoring through Wilms tumor 1 (WT1) gene expression and multicolor flow cytometry (FCM) in patients with chronic myelomonocytic leukemia (CMML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: For this purpose, WT1 gene expression and the CMML-related abnormal immunophenotype were examined using real-time quantitative polymerase chain reaction and FCM, respectively. RESULTS: In total, 59 patients with CMML who underwent allo-HSCT were enrolled in this study. Thirteen cases (22.0%) developed hematological relapse, and 15 patients (25.4%) expired during the follow-up period. Thirty-four patients (37.6%) were positive for WT1 (WT1+), and 44 patients (74.6%) were positive for FCM prior to allo-HSCT. After allo-HSCT, there were 21 WT1+ patients (35.6%) and 10 patients (16.9%) who were positive in FCM (FCM+). Post-transplant WT1+ (post-WT1 0.6+; 50.7% vs. 7.6%, p < .001) and post-transplant FCM+ (post-FCM+; 90.0% vs. 8.8%, p < .001) indicated a higher 3-year cumulative incidence of relapse (CIR) compared with the WT1- or FCM-patients. Multivariate analysis of event-free survival (EFS), overall survival (OS), and CIR showed that the FCM status after transplantation was an independent prognostic factor for relapse (p < .05). CONCLUSION: Both FCM and WT1 after HSCT were identified as important predictors of recurrence of CMML following transplantation and may be useful in guiding interventions against disease relapse.

Pre-transplant minimal residual disease assessment and transplant-related factors predict the outcome of acute myeloid leukemia patients undergoing allogeneic stem cell transplantation.

We studied pretransplant minimal residual disease (MRD) in 224 patients (median age 44 years; range 17-65) with acute myeloid leukemia (AML) undergoing allogeneic stem cell transplant (HSCT) in complete remission. MRD was evaluated on marrow samples using multicolor flow cytometry and assessment of WT1 gene expression. Both methods showed a strong prognostic value and their combination allowed the identification of three groups of patients with different risk of relapse. In multivariate analysis, combined MRD was the only predictor of cumulative incidence of relapse, regardless of donor type, conditioning regimen, first or second CR at HSCT, HSCT year, and ELN risk group. Multivariate regression model showed that only negative combined MRD status (P < .001) and myeloablative conditioning (P = .004) were independently associated with better OS. Among MRD-positive patients, a reduced incidence of relapse was observed in patients receiving haplo transplant (P < .05) and in patients who showed grade II-IV aGVHD (P < .03). In patients with negative combined MRD, the intensity of conditioning regimen did not affect the overall favorable outcome. We suggest that pretransplant MRD evaluation combined with transplant-related factors can identify AML patients at higher risk for relapse and might help in defining the overall transplant strategy.

Laboratory quality assessment of candidate gene panel testing for acute myeloid leukaemia: a joint ALLG / RCPAQAP initiative.

Accurate classification of acute myeloid leukaemia (AML) has become increasingly reliant on molecular characterisation of this blood cancer. Throughout Australia and New Zealand massively parallel sequencing (MPS) is being adopted by diagnostic laboratories for the routine evaluation of patients with AML. This technology enables the surveying of many genes simultaneously, with many technical advantages over single gene testing approaches. However, there are many variations in wet and dry lab MPS procedures, which raises the prospect of discordant results between laboratories. This study compared the results obtained from MPS testing of ten diagnostic AML bone marrow aspirate samples sent to eight participating laboratories across Australasia. A reassuringly high concordance of 94% was observed with regard to variant detection and characterisation of pathogenicity. The level of discordance observed, although low, demonstrates the need for ongoing assessment of concordance between diagnostic testing laboratories through quality assurance programs.

Levofloxacin prophylaxis in hospitalized children with leukemia: A cost-utility analysis.

BACKGROUND: Infections are common and are a major cause of morbidity and mortality during treatment of childhood leukemia. We evaluated the cost effectiveness of levofloxacin antibiotic prophylaxis, compared to no prophylaxis, in children receiving chemotherapy for acute myeloid leukemia (AML) or relapsed acute lymphoblastic leukemia (ALL). PROCEDURES: A cost-utility analysis was conducted from the perspective of the single-payer health care system using a lifetime horizon. A comprehensive literature review identified available evidence for effectiveness, safety, costs of antibiotic prophylaxis in children with leukemia, and health utilities associated with the relevant health states. The effects of levofloxacin prophylaxis on health outcomes, quality-adjusted life-years (QALY), and direct health costs were derived from a combined decision tree and state-transition model. One-way deterministic and probabilistic sensitivity analyses were performed to test the sensitivity of results to parameter uncertainty. RESULTS: The literature review revealed one randomized controlled trial on levofloxacin prophylaxis in childhood AML and relapsed ALL, by Alexander et al, that showed a significant reduction in rates of fever and neutropenia (71.2% vs 82.1%) and bacteremia (21.9% vs 43.4%) with levofloxacin compared to no prophylaxis. In our cost-utility analysis, levofloxacin prophylaxis was dominant over no prophylaxis, resulting in cost savings of $542.44 and increased survival of 0.13 QALY. In probabilistic sensitivity analysis, levofloxacin prophylaxis was dominant in 98.8% of iterations. CONCLUSIONS: The present analysis suggests that levofloxacin prophylaxis, compared to no prophylaxis, is cost saving in children receiving intensive chemotherapy for AML or relapsed ALL.

Cost-effectiveness of levofloxacin prophylaxis against bacterial infection in pediatric patients with acute myeloid leukemia.

BACKGROUND: Infections are the leading cause of therapy-related mortality in pediatric patients with acute myeloid leukemia (AML). Although effectiveness of levofloxacin antibacterial prophylaxis in oncology patients is recognized, its cost-effectiveness is unknown. This study evaluated epidemiologic data regarding levofloxacin use and the cost-effectiveness of this strategy as the cost per bacteremia episode, intensive care unit (ICU) admission, and death avoided in children with AML. PROCEDURE: A retrospective cohort study using the Pediatric Health Information System (PHIS) database compared demographic and clinical characteristics and receipt of levofloxacin prophylaxis in children with AML admitted for chemotherapy from January 1, 2014, through December 31, 2018. We then developed a decision analysis model in this population that compared costs associated with bacteremia, ICU admission, or death secondary to bacteremia to levofloxacin prophylaxis cost from a healthcare perspective. Time horizon is one chemotherapy cycle. Probabilistic and one-way sensitivity analyses evaluated model uncertainty. RESULTS: Prophylaxis cost $8491 per bacteremia episode prevented compared with an average added hospital cost of $119 478. Prophylaxis cost $81 609 per ICU admission avoided, compared with an average added hospital cost of $94 181. Prophylaxis cost $220 457 per death avoided. In sensitivity analysis, at a willingness-to-pay threshold of $100 000 per bacteremia episode avoided, prophylaxis remained cost-effective in 94.6% of simulations. Prophylaxis use was more common in recent years in patients with relapsed disease and with chemotherapy regimens considered more intensive. CONCLUSION: Prophylaxis is cost-effective in preventing bacterial infections in patients with AML. Findings support increased use in patients considered at high risk of bacterial infection secondary to myelosuppression.

Acute Myeloid Leukemia iPSCs Reveal a Role for RUNX1 in the Maintenance of Human Leukemia Stem Cells.

Leukemia stem cells (LSCs) are believed to have more distinct vulnerabilities than the bulk acute myeloid leukemia (AML) cells, but their rarity and the lack of universal markers for their prospective isolation hamper their study. We report that genetically clonal induced pluripotent stem cells (iPSCs) derived from an AML patient and characterized by exceptionally high engraftment potential give rise, upon hematopoietic differentiation, to a phenotypic hierarchy. Through fate-tracking experiments, xenotransplantation, and single-cell transcriptomics, we identify a cell fraction (iLSC) that can be isolated prospectively by means of adherent in vitro growth that resides on the apex of this hierarchy and fulfills the hallmark features of LSCs. Through integrative genomic studies of the iLSC transcriptome and chromatin landscape, we derive an LSC gene signature that predicts patient survival and uncovers a dependency of LSCs, across AML genotypes, on the RUNX1 transcription factor. These findings can empower efforts to therapeutically target AML LSCs.

Validation of the Functional Assessment of Cancer Therapy-Leukemia instrument in patients with acute myeloid leukemia who are not candidates for intensive therapy.

BACKGROUND: The objective of this study was to validate the Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu) in patients with acute myeloid leukemia (AML) who are not candidates for intensive therapy. METHODS: A sample of 317 patients with AML who were not eligible for intensive chemotherapy completed the FACT-Leu and EuroQol 5-Dimension (EQ-5D) measures (Utility Index and Visual Analogue Scale) every 28 days until the end of treatment. Internal consistency reliability was estimated with Cronbach's α. Concurrent validity was examined with correlations between FACT-Leu and EQ-5D scales, and known-groups validity was examined by determining whether FACT-Leu scales distinguished between Eastern Cooperative Oncology Group (ECOG) performance status ratings (PSRs) and between maximum adverse event toxicities at the baseline. This study examined responsiveness to change by anchoring change in the FACT-Leu scales to a 0.10 change in the EQ-5D Health Utility Index. RESULTS: Cronbach's α usually exceeded the threshold for good (≥0.80) or excellent reliability (≥0.90). Correlations between FACT-Leu and EQ-5D scales were moderate (r > 0.50) or high (r > 0.70). FACT-Leu scales distinguished between ECOG PSR groups with large effect sizes for an ECOG PSR of 0 versus an ECOG PSR of 2 (0.50 ≤ d < 0.80). In addition, Functional Assessment of Cancer Therapy-General, Additional Concerns, FACT-Leu Total, and Trial Outcomes Index scales distinguished between patients with grade 3 or lower maximum adverse event toxicities and those with maximum adverse event toxicities higher than grade 3, but effect sizes were small (d < 0.50). Finally, FACT-Leu scale coefficients for a 0.10 change in the 5-level version of the EQ-5D HUI ranged between -0.01 and 4.30. CONCLUSIONS: The FACT-Leu is a suitable outcome measure for AML clinical trials among patients not eligible for intensive therapy, and it may have value for clinical monitoring.

Clonal hematopoiesis and measurable residual disease assessment in acute myeloid leukemia.

Current objectives regarding treatment of acute myeloid leukemia (AML) include achieving complete remission (CR) by clinicopathological criteria followed by interrogation for the presence of minimal/measurable residual disease (MRD) by molecular genetic and/or flow cytometric techniques. Although advances in molecular genetic technologies have enabled highly sensitive detection of AML-associated mutations and translocations, determination of MRD is complicated by the fact that many treated patients have persistent clonal hematopoiesis (CH) that may not reflect residual AML. CH detected in AML patients in CR includes true residual or early recurrent AML, myelodysplastic syndrome or CH that is ancestral to the AML, and independent or newly emerging clones of uncertain leukemogenic potential. Although the presence of AML-related mutations has been shown to be a harbinger of relapse in multiple studies, the significance of other types of CH is less well understood. In patients who undergo allogeneic hematopoietic cell transplantation (HCT), post-HCT clones can be donor-derived and in some cases engender a new myeloid neoplasm that is clonally unrelated to the recipient's original AML. In this article, we discuss the spectrum of CH that can be detected in treated AML patients, propose terminology to standardize nomenclature in this setting, and review clinical data and areas of uncertainty among the various types of posttreatment hematopoietic clones.

Applicability and reproducibility of acute myeloid leukaemia stem cell assessment in a multi-centre setting.

Leukaemic stem cells (LSC) have been experimentally defined as the leukaemia-propagating population and are thought to be the cellular reservoir of relapse in acute myeloid leukaemia (AML). Therefore, LSC measurements are warranted to facilitate accurate risk stratification. Previously, we published the composition of a one-tube flow cytometric assay, characterised by the presence of 13 important membrane markers for LSC detection. Here we present the validation experiments of the assay in several large AML research centres, both in Europe and the United States. Variability within instruments and sample processing showed high correlations between different instruments (Rpearson  > 0·91, P < 0·001). Multi-centre testing introduced variation in reported LSC percentages but was found to be below the clinical relevant threshold. Clear gating protocols resulted in all laboratories being able to perform LSC assessment of the validation set. Participating centres were nearly unanimously able to distinguish LSChigh (>0·03% LSC) from LSClow (<0·03% LSC) despite inter-laboratory variation in reported LSC percentages. This study proves that the LSC assay is highly reproducible. These results together with the high prognostic impact of LSC load at diagnosis in AML patients render the one-tube LSC assessment a good marker for future risk classification.

Highly multiplexed proteomic assessment of human bone marrow in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a genetically heterogeneous disease that is characterized by abnormal clonal proliferation of myeloid progenitor cells found predominantly within the bone marrow (BM) and blood. Recent studies suggest that genetic and phenotypic alterations in the BM microenvironment support leukemogenesis and allow leukemic cells to survive and evade chemotherapy-induced death. However, despite substantial evidence indicating the role of tumor-host interactions in AML pathogenesis, little is known about the complex microenvironment of the BM. To address this, we performed novel proteomic profiling of the noncellular compartment of the BM microenvironment in patients with AML (n = 10) and age- and sex-matched healthy control subjects (n = 10) using an aptamer-based, highly multiplexed, affinity proteomics platform (SOMAscan). We show that proteomic assessment of blood or RNA-sequencing of BM are suboptimal alternate screening strategies to determine the true proteomic composition of the extracellular soluble compartment of AML patient BM. Proteomic analysis revealed that 168 proteins significantly differed in abundance, with 91 upregulated and 77 downregulated in leukemic BM. A highly connected signaling network of cytokines and chemokines, including IL-8, was found to be the most prominent proteomic signature associated with AML in the BM microenvironment. We report the first description of significantly elevated levels of the myelosuppressive chemokine CCL23 (myeloid progenitor inhibitory factor-1) in both AML and myelodysplastic syndrome patients and perform functional experiments supportive of a role in the suppression of normal hematopoiesis. This unique paired RNA-sequencing and proteomics data set provides innovative mechanistic insights into AML and healthy aging and should serve as a useful public resource.

Identification of leukemia stem cell expression signatures through Monte Carlo feature selection strategy and support vector machine.

Acute myeloid leukemia (AML) is a type of blood cancer characterized by the rapid growth of immature white blood cells from the bone marrow. Therapy resistance resulting from the persistence of leukemia stem cells (LSCs) are found in numerous patients. Comparative transcriptome studies have been previously conducted to analyze differentially expressed genes between LSC+ and LSC- cells. However, these studies mainly focused on a limited number of genes with the most obvious expression differences between the two cell types. We developed a computational approach incorporating several machine learning algorithms, including Monte Carlo feature selection (MCFS), incremental feature selection (IFS), support vector machine (SVM), Repeated Incremental Pruning to Produce Error Reduction (RIPPER), to identify gene expression features specific to LSCs. One thousand 0ne hudred fifty-nine features (genes) were first identified, which can be used to build the optimal SVM classifier for distinguishing LSC+ and LSC- cells. Among these 1159 genes, the top 17 genes were identified as LSC-specific biomarkers. In addition, six classification rules were produced by RIPPER algorithm. The subsequent literature review on these features/genes and the classification rules and functional enrichment analyses of the 1159 features/genes confirmed the relevance of extracted genes and rules to the characteristics of LSCs.

SERS assessment of the cancer-specific methylation pattern of genomic DNA: towards the detection of acute myeloid leukemia in patients undergoing hematopoietic stem cell transplantation.

In this label-free surface-enhanced Raman scattering (SERS) study of genomic DNA, we demonstrate that the cancer-specific DNA methylation pattern translates into specific spectral differences. Thus, DNA extracted from an acute myeloid leukemia (AML) cell line presented a decreased intensity of the 1005 cm-1 band of 5-methylcytosine compared to normal DNA, in line with the well-described hypomethylation of cancer DNA. The unique methylation pattern of cancer DNA also influences the DNA adsorption geometry, resulting in higher adenine SERS intensities for cancer DNA. The possibility of detecting cancer DNA based on its SERS spectrum was validated on peripheral blood genomic DNA samples from n = 17 AML patients and n = 17 control samples, yielding an overall classification of 82% based on the 1005 cm-1 band of 5-methylcytosine. By demonstrating the potential of SERS in assessing the methylation status in the case of real-life DNA samples, the study paves the way for novel methods of diagnosing cancer. Graphical abstract.

Can we incorporate MRD assessment into clinical practice in AML?

Measurable residual disease (MRD) can be assessed either by flow cytometry or molecular techniques. It has been proven to be highly prognostic in quite a number of prospective clinical studies. The recently published ELN MRD recommendations aim harmonize the approaches to MRD assessment in order to improve its overall quality. The predictive value leading to the usage as a surrogate endpoint for survival which would be instrumental for faster drug approvals has still to be proven. Nevertheless, many AML centers use MRD status to inform treatment.

Preclinical Assessment of Suitable Natural Killer Cell Sources for Chimeric Antigen Receptor Natural Killer-Based "Off-the-Shelf" Acute Myeloid Leukemia Immunotherapies.

The introduction of chimeric antigen receptors (CARs) to augment the anticancer activity of immune cells represents one of the major clinical advances in recent years. This work demonstrates that sorted CAR natural killer (NK) cells have improved antileukemia activity compared to control NK cells that lack a functional CAR. However, in terms of viability, effectiveness, risk of side effects, and clinical practicality and applicability, an important question is whether gene-modified NK cell lines represent better CAR effector cells than primary human donor CAR-NK (CAR-dNK) cells. Comparison of the functional activities of sorted CAR-NK cells generated using the NK-92 cell line with those generated from primary human dNK cells demonstrated that CAR-NK-92 cells had stronger cytotoxic activity against leukemia cells compared to CAR-dNK cells. CAR-NK-92 and CAR-dNK cells had similar CD107a surface expression upon co-incubation with leukemia cells. However, CAR-NK-92 cells secreted higher granzyme A and interleukin-17A levels, while CAR-dNK cells secreted more tumor necrosis factor alpha, interferon gamma, and granulysin. In addition, CAR-NK-92 cells revealed a significantly higher potential for adverse side effects against nonmalignant cells. In short, this work shows the feasibility for further development of CAR-NK strategies to treat leukemia.

Quantitative profiling of CD13 on single acute myeloid leukemia cells by super-resolution imaging and its implication in targeted drug susceptibility assessment.

Quantitative profiling of membrane proteins on the cell surface is of great interest in tumor targeted therapy and single cell biology. However, the existing technologies are either of insufficient resolution, or unable to provide precise information on the localization of individual proteins. Here, we report a new method that combines the use of quantum dot labeling, super-resolution microscopy (structured illumination microscopy, SIM) and software modeling. In this proof-of-principle study, we assessed the biological effects of Bestatin on individual cells from different AML cell lines expressing CD13 proteins, a potential target for tumor targeted therapy. Using the proposed method, we found that the different AML cell lines exhibit different CD13 expression densities, ranging from 0.1 to 1.3 molecules per µm2 cell surface, respectively. Importantly, Bestatin treatment assays shows that its effects on cell growth inhibition, apoptosis and cell cycle change are directly proportional to the density of CD13 on the cell surface of these cell lines. The results suggest that the proposed method advances the quantitative analysis of single cell surface proteins, and that the quantitative profiling information of the target protein on single cells has potential value in targeted drug susceptibility assessment.

Population pharmacokinetics and exposure-response assessment of veliparib co-administered with temozolomide in patients with myeloid leukemias.

PURPOSE: Veliparib is an oral inhibitor of poly(ADP-ribose) polymerase enzyme. Combination of veliparib and temozolomide was well-tolerated and demonstrated clinical activity in older patients with relapsed or refractory acute myeloid leukemia (AML) or AML arising from pre-existing myeloid malignancies. We aimed to perform quantitative assessments of pharmacokinetics, efficacy, and safety of veliparib in this patient population to inform future trial design. METHODS: Population pharmacokinetic analysis was performed using Phoenix® NLME with pharmacokinetic data obtained from 37 subjects after oral administration of veliparib in a Phase I study with and without temozolomide. Effect of covariates (age, sex, BMI, creatinine clearance (CLCR), and co-administration of temozolomide) on the pharmacokinetics of veliparib were evaluated, as well as impact of veliparib exposure on mucositis (dose-limiting toxicity), objective response rate (ORR), and overall survival. RESULTS: A two-compartment model with first-order elimination and a first-order absorption with lag-time adequately described veliparib pharmacokinetics. CLCR and body weight were clinically significant covariates for veliparib disposition. The proportion of subjects with all grade mucositis increased with veliparib exposure (AUC). However, no trend in ORR and overall survival was observed with increasing exposure. CONCLUSIONS: Veliparib with temozolomide presents a promising combination for older patients with myeloid leukemias. An exposure-safety relationship was established for this combination. Further clinical investigations aimed at elucidating the veliparib exposure-efficacy/safety relationship and optimizing dosing recommendations for maximizing benefit-risk in patients with advanced myeloid malignancies should study veliparib doses ranging up to 120 mg in combination with temozolomide.

The Assessment of Left Ventricle Function and Subclinical Atherosclerosis in Patients with Acute Myeloid Leukemia.

Aim To assess the onset of early left ventricular (LV) systolic and diastolic function impairment and the subclinical atherosclerosis following chemotherapy in patients diagnosed with acute myeloid leukemia (AML). MATERIALS AND METHODS: Thirty patients diagnosed with AML with no cardiac history, having LV ejection fraction (LVEF) >50%, were evaluated at baseline and 6 months after starting four cycles of chemotherapy. We measured LV function, global longitudinal strain and subclinical atherosclerosis markers: intima-media thickness (IMT), arterial stiffness aortic pulse wave velocity (PWVAo) and ankle-brachial index (ABI). RESULTS: LVEF had decreased at 6 months after treatment initialization (p<0.001), the same changes being observed for LV fraction shortening (p<0.001), mitral annular plane systolic excursion and S' wave (p<0.001 and p<0.05). Bilateral IMT and PWVAo significantly increased, 12 out of 30 patients (40%) had LVEF ≤50% after 6 months of chemotherapy, five of them receiving daunorubicin at more than 500 mg/m2/injection. CONCLUSION: LV function is impaired after 6 months of chemotherapy, with early changes of subclinical atherosclerosis becoming evident.

Marrow Hypocellularity, But Not Residual Blast Count or Receipt of Reinduction Chemotherapy, Is Prognostic on Day-14 Assessment in Acute Myeloid Leukemia Patients With Morphologic Residual Disease.

BACKGROUND: Induction chemotherapy for acute myeloid leukemia (AML) is based on the "7+3" cytarabine/anthracycline regimen. A nonhypocellular day 14 (D14) bone marrow sample with a blast count > 5% to 10% is suggestive of residual leukemia, for which a second course of induction chemotherapy has been recommended. Although the prognostic value of D14 bone marrow findings has been established, its use as a decision point is controversial because the benefit of repeat induction has been questioned. PATIENTS AND METHODS: In the present single-center retrospective study of 113 patients with newly diagnosed AML, we evaluated the role of cellularity on the clinical outcomes of patients with residual morphologic leukemia (blasts ≥ 5%). Among 64 patients with D14 bone marrow samples, 31 had residual morphologic leukemia. RESULTS: The complete remission (CR) rates were greater for the hypocellular (11 of 16) than for the nonhypocellular (4 of 15) patients (P = .03). The median overall survival (OS) for the hypocellular D14 patients was longer than that for the nonhypocellular patients (17 vs. 8 months; P = .02). No significant difference between the receipt of reinduction therapy and CR or OS was found on logistic or survival model analysis. The specificity for residual leukemia on D14 bone marrow samples was better for cellularity ≥ 20% and blasts ≥ 20% than for blasts ≥ 5%. CONCLUSION: The results of our study have shown that patients with < 20% cellularity and < 20% blasts on the D14 bone marrow assessment should continue observation until recovery rather than receive additional immediate therapy.