Clofarabine with topotecan, vinorelbine, and thiotepa reinduction regimen for children and young adults with relapsed AML

Effective reinduction regimens are needed for children with relapsed and refractory acute myeloid leukemia (AML) as outcomes remain poor. Therapeutic options are limited in this heavily pre-treated patient population, many of whom have reached lifetime recommended doses of anthracycline chemotherapy. The development of effective non-anthracycline based salvage regimens is crucial to these patients who are at significant risk of life-threatening cardiotoxicity. We previously reported results of a phase 2 trial of a clofarabine-based regimen with topotecan, vinorelbine, and thiotepa (TVTC) in patients with relapsed acute leukemias. Here we report on an expanded bicenter cohort of 33 patients, <25 years of age, with relapsed/refractory (R/R) AML treated with up to 2 cycles of the TVTC reinduction regimen from 2007 to 2018. The overall response rate (ORR), defined as complete remission (CR) or CR with partial recovery of platelet count (CRp), was 71.4% (95%CI: 41.9 to 91.6%) for those patients in first relapse (n=14) and 47.4% ( 95%CI: 24.4 to 71.1%) for patients in 2nd or greater relapse or refractory disease. Responses were seen across multiple high risk cytogenetic and molecular subtypes, with 84% of responders successfully bridged to allogeneic stem cell transplantation. The 5-year OS for patients in first relapse was 46.2% (95%CI: 19.1 to 73.3%) and 50.0% (95%CI: 26.9 to 73.1%) for patients who responded to TVTC. For pediatric and young adult patients with R/R AML, TVTC reinduction compares favorably with currently used salvage regimens and warrants further exploration.

Beyond the In-Practice CBC: The Research CBC Parameters-Driven Machine Learning Predictive Modeling for Early Differentiation among Leukemias

A targeted and timely treatment can be a beneficial tool for patients with hematological emergencies (particularly acute leukemias). The key challenges in the early diagnosis of leukemias and related hematological disorders are their symptom-sharing nature and prolonged turnaround time as well as the expertise needed in reporting confirmatory tests. The present study made use of the potential morphological and immature fraction-related parameters (research items or cell population data) generated during complete blood cell count (CBC), through artificial intelligence (AI)/machine learning (ML) predictive modeling for early (at the pre-microscopic level) differentiation of various types of leukemias: acute from chronic as well as myeloid from lymphoid. The routine CBC parameters along with research CBC items from a hematology analyzer in the diagnosis of 1577 study subjects with hematological neoplasms were collected. The statistical and data visualization tools, including heat-map and principal component analysis (PCA,) helped in the evaluation of the predictive capacity of research CBC items. Next, research CBC parameter-driven artificial neural network (ANN) predictive modeling was developed to use the hidden trend (disease’s signature) by increasing the auguring accuracy of these potential morphometric parameters in differentiation of leukemias. The classical statistics for routine and research CBC parameters showed that as a whole, all study items are significantly deviated among various types of leukemias (study groups). The CPD parameter-driven heat-map gave clustering (separation) of myeloid from lymphoid leukemias, followed by the segregation (nodding) of the acute from the chronic class of that particular lineage. Furthermore, acute promyelocytic leukemia (APML) was also well individuated from other types of acute myeloid leukemia (AML). The PCA plot guided by research CBC items at notable variance vindicated the aforementioned findings of the CPD-driven heat-map. Through training of ANN predictive modeling, the CPD parameters successfully differentiate the chronic myeloid leukemia (CML), AML, APML, acute lymphoid leukemia (ALL), chronic lymphoid leukemia (CLL), and other related hematological neoplasms with AUC values of 0.937, 0.905, 0.805, 0.829, 0.870, and 0.789, respectively, at an agreeably significant (10.6%) false prediction rate. Overall practical results of using our ANN model were found quite satisfactory with values of 83.1% and 89.4.7% for training and testing datasets, respectively. We proposed that research CBC parameters could potentially be used for early differentiation of leukemias in the hematology–oncology unit. The CPD-driven ANN modeling is a novel practice that substantially strengthens the predictive potential of CPD items, allowing the clinicians to be confident about the typical trend of the “disease fingerprint” shown by these automated potential morphometric items.

Insights into Modern Therapeutic Approaches in Pediatric Acute Leukemias

Pediatric cancers predominantly constitute lymphomas and leukemias. Recently, our knowledge and awareness about genetic diversities, and their consequences in these diseases, have greatly expanded. Modern solutions are focused on mobilizing and impacting a patient’s immune system. Strategies to stimulate the immune system, to prime an antitumor response, are of intense interest. Amid those types of therapies are chimeric antigen receptor T (CAR-T) cells, bispecific antibodies, and antibody–drug conjugates (ADC), which have already been approved in the treatment of acute lymphoblastic leukemia (ALL)/acute myeloid leukemia (AML). In addition, immune checkpoint inhibitors (ICIs), the pattern recognition receptors (PRRs), i.e., NOD-like receptors (NLRs), Toll-like receptors (TLRs), and several kinds of therapy antibodies are well on their way to showing significant benefits for patients with these diseases. This review summarizes the current knowledge of modern methods used in selected pediatric malignancies and presents therapies that may hold promise for the future.

Whole genome and transcriptome analysis of genetic determinants associated with cyclophosphamide in vitro in pediatric acute leukemias

Introduction: The main objective was to implement the determinations of the ex vivo resistance to cyclophosphamide and to identify the genetic profile for pediatric patients with acute leukemias. Methods: In order to determine the ex vivo drug resistance profile, MTT cytotoxicity assay was performed on mononuclear cells. Gene expression profiles were prepared on the basis of cRNA hybridization to oligonucleotide arrays of the human genome (Affymetrix). We performed also array-based comparative genomic hybridization using a SurePrint G3 Human CGH Microarray. Data was analyzed by bioinformatics tools. Verification of the relative expression level of 20 genes was carried out by qRT- PCR. Results: We observed a multitude of differentially expressed genes, e.g. ANXA1 (FC=3,04), BCL2A1 (FC=2,69), SERPINA1 (FC=2,12), DHRS7 (FC=2,13), PCDH9 (FC=- 4,58), TTC28 (FC=-2,25) and DUSP1 (FC=-2,91). The expression of genes that code for inflammation mediated by chemokine and cytokine signaling, Wnt, angiogenesis and integrin signaling and T cell activation pathways genes affect the sensitivity of leukemic blasts to cyclophosphamide. Transcriptome level changes are associated with chromosomal aberrations, especially located on chromosomes 8, 10, 14, 15, 16 and 22. Conclusion: Our work delineated genes with differentiated expression and recurrent copy number changes, and revealed novel amplified loci and frequent deletions in resistant to cyclophosphamide cells, which may guide future work aimed at identifying the relevant target genes. In particular, deletion seems to be a frequent mechanism of IFIT3 gene inactivation. ANXA1, SERPINA1, TCF7 and BCL2A1 may also be included among the candidate genes of resistance (Ontological analysis).

Application of the International Society on Thrombosis and Haemostasis Scoring System in Evaluation of Disseminated Intravascular Coagulation in Patients with Acute Leukemias

Background Coagulation abnormalities are common in acute leukemia (AL) and disseminated intravascular coagulation (DIC) frequently complicates the onset of AL. Aim To determine the prevalence of overt DIC in AL using the International Society on Thrombosis and Haemostasis (ISTH) scoring system. Materials and Methods This prospective observational study was performed on 57 newly diagnosed or relapsed cases of AL. Detailed clinical history and coagulation profile of the patients were evaluated. Diagnosis of overt and nonovert DIC was established using the ISTH scoring system and results tabulated. Observations A total of 57 patients with AL participated in the study, including 31 (54.39%) patients with acute lymphoblastic leukemia (ALL) and 26 (45.61%) with acute myeloid leukemia (AML). In total, 18 of 57 patients (31.58%) with AL fulfilled the criteria of overt DIC according to the ISTH scoring system, including 10 (32.25%) patients with ALL and 8 (30.76%) patients with AML. The highest prevalence of DIC was seen in the M3 subtype among AML and the L1 subtype among ALL, respectively. The mean ISTH score in patients of overt DIC in ALL and AML patients was 5.1 and 5, respectively. Abnormalities in platelet count and D-dimer levels were the most useful parameters in diagnosing overt DIC and the difference between overt DIC and nonovert DIC groups was highly significant. Conclusions Overt DIC was observed in approximately one-third of patients with AL. Prevalence of overt DIC was found to be comparable in patients with ALL and AML. Mean platelet count and D-dimer levels were the most useful parameters in detecting overt DIC.

Impact of Perioperative Absolute Neutrophil Count on Central Line-Associated Bloodstream Infection in Children With Acute Lymphoblastic and Myeloid Leukemia

BackgroundThere is lack of evidence concerning safety of placement of tunneled central venous catheters (TCVCs) in neutropenic children with acute leukemias. Here, we evaluate the impact of absolute neutrophil count (ANC) at the time of TCVC placement on development of central line-associated bloodstream infections (CLABSI) in children with lymphoblastic (ALL) or myeloid leukemia (AML).Materials and MethodsA retrospective observational study of children undergoing TCVC placement at a tertiary referral hospital between January 2000 and December 2019 was performed. Traditional and competing-risks regression models were used to estimate the effect of perioperative ANC on development of CLABSI.ResultsA total of 350 children (median age 6.4 [IQR: 3.1–10.9] years) underwent 498 consecutive TCVC implantations in neutropenic (n = 172, 34.5%) and non-neutropenic conditions (n = 326, 65.5%). The median length of observation per TCVC was 217.1 (IQR: 116.1–260.5) days with a total of 99,681 catheter days (CD). There were no differences in early (within first 30 days after TCVC placement) and overall CLABSI rates between neutropenic and non-neutropenic patients (HR 1.250, p = 0.502; HR 1.633, p = 0.143). We identified female sex (HR 2.640, p = 0.006) and the use of TCVC for treatment of relapsed leukemia (HR 4.347, p < 0.0001) as risk factors for early CLABSI and the use of double-lumen catheters (HR 2.607, p = 0.003) and use of TCVCs during leukemia relapse (HR 2.004, p = 0.005) for overall study period.ConclusionThe placement of TCVC in children with neutropenia undergoing anticancer therapy for acute leukemia is safe and not associated with an elevated rate of CLABSI.

Targeted Next Generation Sequencing Reveals a Third Breakpoint Cluster Region and New Partner Genes in the KMT2A Recombinome

Chromosomal rearrangements of the KMT2A gene are associated with acute leukemias and myelodysplastic syndromes. The large number of known KMT2A fusions (>100) renders a precise diagnosis a demanding task. More than 50% of all KMT2A partner genes have been analyzed at the DCAL, including the novel partner genes BCAS4, FAM13A, RANBP3, and STK4. Even though all KMT2A rearrangements are associated with high-risk acute leukemia, the outcome (poor or very poor) is influenced by the partner gene. So far, we have analyzed more than 3,200 patients positive for a KMT2A rearrangement. The breakpoints of these cases are located mainly in the major breakpoint cluster region (bcr1) and to a small extent in the recently described minor bcr (bcr2). A small number of breakpoints were also found outside of these two bcrs. Most of these patients were analyzed by long distance inverse (LDI)- or multiplex-PCR which only cover bcr1. More recently, we used targeted KMT2A-NGS with whole gene coverage in over 450 patients, which was initially applied selectively in patients negative by LDI- and multiplex-PCR and then used more widely. Within the KMT2A-NGS group, 410 patients had bcr1 breakpoints mainly between the KMT2A exons 7 and 13, while 46 patients bcr2 breakpoints mainly between exons 20 and 24. Of note, five patients had their breakpoint outside of these two bcrs: three of them within intron 2 and no functional KMT2A rearrangement; the other two within intron 35 and intron 36, fusing almost the whole KMT2A gene in frame to the respective partner genes ARHGEF12 and MLLT4. These two breakpoints may define a third and rare bcr (bcr3), although further cases are needed to support this hypothesis. Interestingly, 70 patients displayed a 3'-KMT2A deletion, indicating that the number of terminal deletions is higher than described previously. Two patients had a 5'-KMT2A deletion. All deletions started or ended in bcr1 and bcr2. We also observed a striking difference in the distribution of partner genes between bcr1 and bcr2. The most frequent translocation partners fused to bcr1 sites are transcription factors, while the partner genes linked to bcr2 sites generally code for cytosolic proteins. In bcr1, the 4 most frequent partner genes AFF1, MLLT3, MLLT1, and MLLT10, found in 80% of cases, all code for transcription factors that are part of the super elongation complex (SEC). These fusions therefore all lead to disruption of the hematopoietic lineage commitment. In contrast in bcr2, 3 partner genes USP2, MLLT4, and USP8 account for 85% of the cases. USP2 and USP8 are ubiquitin specific peptidases involved in cell signaling and exclusively fused to bcr2 in KMT2A. While MLLT4 is found as a partner in bcr1, bcr2 and bcr3 fusions; unlike other recurrent KMT2A partners linked to bcr1, it is not a transcription factor and it exerts oncogenic potential via dimerization like other cytosolic partners. We hypothesize that the oncogenic properties of USP2 and USP8 are dependent on dimerization like MLLT4 and that the most frequent fusions involving at different bcrs favor different oncogenic mechanisms: bcr1 transactivation and bcr2 dimerization. Further studies are needed to explain why USP2 and USP8 are exclusively associated with bcr2, and why the most frequent partner genes AFF1 and MLLT3 of the bcr1 are less frequent in bcr2. In conclusion, targeted NGS combined with bioinformatic analysis has expanded our knowledge of the KMT2A recombinome to include more fusion partners and has generated new hypotheses for future research on oncogenic mechanisms. Disclosures No relevant conflicts of interest to declare.

Standardization in the Diagnosis of Mixed Phenotype Acute Leukemia (MPAL): Semiquantitative, Universally Applicable Flow Cytometric Criteria for Immunophenotypic Lineage Assignment and Isolated MPO

Mixed phenotype acute leukemia (MPAL) is a rare group of acute leukemias defined by immunophenotypic expression of more than one hematopoietic cell lineage. The World Health Organization (WHO) diagnostic immunophenotypic criteria for MPAL rely on the intensity of lineage-defining antigen expression, predominantly a qualitative assessment, and are often difficult to apply to a phenotypically heterogeneous leukemia. Cases of MPAL defined by isolated myeloperoxidase (isoMPO) expression on otherwise typical acute lymphoblastic leukemia (ALL) are variably diagnosed as MPAL or ALL based on the incompletely defined criteria for assigning MPO expression. We hypothesized that quantitative criteria for antigen intensity could be developed and applied in a uniform manner across flow cytometry instruments, reagents, and analysis software to enable a consistent approach to diagnosing MPAL and better defining isoMPO. We previously reported on a multicenter cohort identified by respective institutions as MPAL with subsequent central review according to 2008 WHO criteria (Oberley et al 2020). Of these, 100 had suitable dot plots for reevaluation (89: B/Myeloid, 10: T/Myeloid, 1: B/T). Antigen expression was concurrently reviewed by two hematopathologists to reach consensus (BLW, AEK). The cohort was divided a priori into randomly selected training and testing cases (n=30/n=70). Classification criteria were generated in the training cohort for WHO lineage-defining antigen expression (myeloid: cMPO, CD64, CD14; B: CD19, T: cCD3) from 10 cases and then refined through review of an additional 20 cases. Positive antigen expression was classified as maximal intensity approaching that of the mature normal counterpart population (NCP) (cMPO: neutrophils; CD64, CD14 and CD11c: monocytes; CD19: B cells; cCD3: T cells) either by 1) range of expression recapitulating maturation of the NCP, irrespective of the percentage on the leukemic population (Figure 1A); or 2) uniform expression above background on a discrete (sub)population (Figure 1B). To account for technical variation within and among laboratories, maximal antigen intensity on the leukemic population was measured in 0.5 log increments and normalized to the maximal intensity of the NCP. An intensity of ≥50% of the NCP above background was defined as sufficient for MPAL lineage assignment and <50% consistent with isoMPO. This approach was then used to classify the remaining 70 cases. Using this approach, 41/98 (42%) cases previously classified as MPAL remained classified as MPAL: 31 as B/Myeloid (25 by maturational MPO expression, 6 by maturational CD64 and/or CD14 expression); 9 as T/Myeloid (8 by maturational MPO expression, 1 with maturational CD64, CD14 and CD11c expression); and 1 as B/T. No cases in the cohort showed uniform expression ≥50% of the NCP. The remaining 57 showed isolated low-level MPO expression (maximal intensity <50% of the NPC) on a uniform leukemic population or on a dichotomous subpopulation (isoMPO), 56 B/Myeloid and 1 T/Myeloid. Two cases of otherwise typical B-ALL without myeloid or monocytic antigen expression were reclassified as B-ALL, one of which showed low variable CD10 suggestive of DUX4-rearranged B-ALL. In comparison to our previously reported study of 2008 WHO-defined MPAL, 53/89 (60%) centrally-confirmed cases would be classified here as isoMPO. Conversely, five cases excluded under 2008 WHO central review would be reclassified as having sufficient antigen expression to qualify as MPAL (2 B/Myeloid, 3 T/Myeloid). Novel semiquantitative immunophenotypic criteria applied to a large cohort of acute leukemias originally diagnosed as MPAL was able to objectively identify a large subset as having dim, uniform MPO expression (isoMPO). Our approach emphasizes antigen expression recapitulating maturational expression similar to their non-leukemic cellular counterparts, normalizes absolute intensities to internal positive and negative control populations to minimize technical variability between observers and assays, and as per the 2017 WHO, does not require a specific percent threshold of positivity. While requiring validation, this is a critical first step toward establishing a reproducible delineation of these complex cases to practically implement the WHO classification to support treatment decisions and ongoing investigation into MPAL genomics and outcomes (available for this cohort by ASH). Figure 1 Figure 1. Disclosures Oberley: Caris LIfe Science: Current Employment. Orgel: Jazz Pharmaceuticals: Consultancy.

Clinical Significance of Mitochondrial DNA Content in Acute Promyelocytic Leukemia

Used in the clinical practice for more than three decades, the all-trans retinoic acid (ATRA) rendered acute promyelocytic leukemia (APL) the most curable subtype of acute myeloid leukemia, and currently, its combination with arsenic trioxide (ATO) exceeded all expectations for a chemotherapy-free protocol. In terms of metabolic importance, ATRA can also modulate the mitochondria-mediated cellular metabolism and promote a shift from a glycolytic-driven metabolism to an oxidative phosphorylation profile, although this effect has never been demonstrated in APL. As part of the cellular metabolic machinery, mitochondrial DNA (mtDNA) content has been reported to be altered in different types of solid tumors with clinical implication on patient treatment outcomes, although its clinical significance in acute leukemias has not been investigated to the same extent. Particularly in acute promyelocytic leukemia (APL), the role of mtDNA content on prognostication is completely unknown. Considering that mostly APL samples display a glycolytic-driven metabolism, it is conceivable that APL patients harboring high mtDNA content may present a better response to ATRA-based therapies. To test this hypothesis, we determined the mtDNA content in samples from patients with APL enrolled in the International Consortium on Acute Promyelocytic Leukemia study (Rego et al. Blood. 2013 Mar 14;121(11):1935-43) and analyzed its relationship to treatment outcomes. Diagnostic bone marrow (BM) mononuclear cells from 156 consecutive patients with APL (median age: 35 years, range: 18-82 years; 45% male) were obtained at diagnosis. For comparison purposes, we also included peripheral blood (PB) from 293 age- and sex-adjusted healthy volunteers. First, we determined whether mtDNA content could be compared between PB mononuclear cells and BM. To do so, we measured the mtDNA content of 22 APL patients, for whom paired samples were available at the time of diagnosis and detected a strong correlation between PB and BM samples (Pearson correlation coefficient, r=0.78, 95% confidence interval, CI: 0.54 to 0.9). Next, we used the values of mtDNA higher than the 95 th percentile of healthy subjects (≥1.63. Note: this value represents a fold change relative to healthy control) to define APL patients with high mtDNA content. Patients that presented values within the range of normal control samples (<1.63) were classified as normal mtDNA content. The median follow-up among survivals was 40 months (95%CI: 34-47 months). Of the 131/156 patients who achieved complete remission, 18 patients (14%) relapsed. mtDNA content had no impact on complete remission achievement (84% for normal mtDNA versus 83% for high mtDNA; P=0.924) or overall survival (78% for normal mtDNA versus 80% for high mtDNA; P=0.69). In contrast, patients with high mtDNA content had a significantly high 5-year disease-free survival rate (86%, 95%CI: 78-95%) than patients with normal mtDNA content (61%, 95%CI: 46-82%). Considering non-relapse death as a competing cause of failure, the 5-year cumulative incidence of relapse (CIR) for patients with high and normal mtDNA content were 35% (95%CI: 16-49%) and 10% (95%CI: 2-17%), respectively. The multivariate Cox proportional hazards model showed that mtDNA content was independently associated with CIR (hazard ratio, HR: 0.31, 95%CI: 0.12-0.8) considering PETHEMA/GIMEMA risk of relapse subgroups and age as confounders. To functionally evaluate the metabolic alterations in APL cells upon ATRA treatment, NB4 cell line was treated with ATRA (1 µM) for 48 and 72 hours. In vitro analyses demonstrated (as expected) that the treatment with resulted in increased levels of myeloid maturation markers (CD11b/CD11c/CD15), with morphological changes being only observed at 72 hours. Metabolically, we observed an increase in mitochondrial mass and potential upon ATRA-treatment after 48 hours, which was also reflected by increase in the mtDNA content (2-fold increase in comparison with the vehicle). Together, these findings demonstrate an important, but not completely understood role for mtDNA content in APL. Disclosures Silveira: BMS/Celgene: Research Funding; Servier/Agios: Research Funding; Abbvie: Speakers Bureau; Astellas: Speakers Bureau. Pagnano: EMS: Other: Lecture; Jansenn: Other: Lecture; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pintpharma: Other: Lecture.