Primary Acute Lymphoblastic Leukemia Research Articles

Evaluation of lipopolymer as therapeutic siRNA delivery agents in non-malignant and malignant primary cells.

e15189 Background: Targeting leukemia-driving oncogenes via short interfering RNA (siRNA) offers an alternative approach to leukemia treatment that can overcome the limitations of current therapies. Low molecular weight polyethyleneimine grafted with lipids (lipopolymers) have emerged as promising carriers for siRNA delivery to leukemia cells. Lipopolymers harboring select lipids were recently shown to downregulate target oncogene leading to significant anti-leukemic activity in both in vitro and in vivo cell line-based leukemia models. The goal of this study was to evaluate these lipopolymers in (i) PBMCs obtained from healthy donors to determine the potential impact on non-malignant cells, and (ii) primary leukemia patient cells to assess therapeutic efficacy. Methods: Target gene levels were determined by RT-qPCR and the effect of treatment on progenitor cells was assessed by measuring changes in colony forming ability. Results: At day 1 post-treatment, no changes in FLT3 mRNA levels were observed in all 6 PBMC samples with the 2 candidate lipopolymers (LeuFectB and LeuFectC) tested. Among 11 PBMC samples evaluated at day 2, only one sample showed a significant reduction in oncogene transcript levels on treatment with LeuFectB. The impact of lipopolymer/siRNA complex treatment on progenitor cells in the PBMC population was then assessed. Of the 7 PBMC samples tested, significant reduction in colony numbers was observed in one sample with LeuFectB and two samples with LeuFectC. On an average, the lipopolymer/siRNA complexes were well tolerated by normal healthy cells as changes observed in oncogene expression and colony forming ability were not consistent across the whole pool. Primary acute lymphoblastic leukemia (ALL) patient cells treated with complexes targeting STAT5A showed marked reduction in STAT5A transcript levels in 4 out of 7 samples with both the lipopolymers tested. The subsequent impact of STAT5A downregulation on the clonogenicity of leukemia stem cells was observed in the significant decrease in colony numbers seen in 3 samples (out of 8) with LeuFects. Additionally, combined downregulation of STAT5A and BCR-ABL genes in BCR-ABL+ ALL patient samples led to a notable decrease in cell proliferation and viability. Moreover,2 out of 3 acute myeloid leukemia (AML) patient samples harboring the FLT3-ITD mutation showed significant retardation in their colony forming ability on treatment with FLT3-targeting siRNA complexes. Collectively, the ALL and AML primary samples demonstrated promising preliminary results, suggesting a therapeutic effect on the stem cell population which is critical for mitigating relapse or prolonging remission. Conclusions: These findings provide further proof-of-concept for clinical translation of lipopolymer mediated siRNA therapy of leukemia, showing relative safety and selectivity of these lipopolymer/siRNA complexes.

Second primary B-ALL after exposure to lenalidomide for multiple myeloma: A US multicenter study.

7533 Background: Maintenance treatment (rx) with lenalidomide (R) improves overall survival (OS) in multiple myeloma (MM). We report a retrospective cohort of patients (pts) with second primary B-cell acute lymphoblastic leukemia (ALL) diagnosed after R-rx for MM. Methods: We included pts who were exposed to at least 1 yr of R for MM rx prior to ALL dx. After approval by institutional review board, data were collected by chart review at participating centers using Redcap. OS was the primary endpoint. We used BlueSky statistics v10.3.1 for analysis. Results: Analysis included 33 ALL pts diagnosed from 2014-2022 at 7 sites. 52% pts were female. Median follow up was 9.6 yrs (95%CI,7.6-11.8) from MM dx and 3.2 yrs (CI, 2.1-4.7) from ALL dx. Pt characteristics at MM dx are given in Table. Induction rx included: proteasome inhibitor (PI) +immunomodulatory drug (IMiD) (43%), PI+alkylator (24%), IMiD (18%) & others (15%). 50% pts received autologous stem cell transplantation (ASCT). Median OS from MM dx was 11.2 yrs (CI, 8.9-NR). Time from MM dx and initial R rx to ALL dx were 5.0 yrs (range, 2.4-18.5) and 4.4 yrs (2.2-10.6) respectively. Median duration of R exposure before ALL dx was 3.8 yrs (1.6-10.4). Table shows characteristics of pts at B-ALL dx and genetic classification based on karyotyping (n=30), ALL FISH (n=28), chromosomal microarray (n=5) and next-generation sequencing (n=5). 31 pts received ALL-directed rx while 1 pt was initially managed with close observation as the pt attained CR on stopping R ( Lakshman et al; ASH 2019 ). Rx was unknown in 1 pt. Initial rx included: hyper-CVAD+/- rituximab- 49%, pediatric inspired protocols-18%, reduced intensity rx for frail pts- 21% and others- 12%. Response to first line rx were: CR- 56%, CRi- 28%, induction failure- 16%. 32% pts attained measurable residual disease (MRD) negativity. 48% pts underwent SCT for ALL. 14 pts died during follow up. 3-yr OS from ALL-dx was 50% (CI, 33%-76%). 3 pts required rx for MM after ALL diagnosis (2 had allo-SCT for ALL before MM relapse). Conclusions: Most pts had standard risk MM and were exposed to R for several years prior to dx of B-ALL, characterized by high incidence of hypodiploid karyotype; IKZF1 loss and TP53 deletions/mutations were detected in a subset of pts.MRD-adapted timely discontinuation of R in standard risk MM may decrease risk of second primary ALL. [Table: see text]

THE COST OF ACUTE LYMPHOBLASTIC LEUKEMIA TREATMENT IN CHILDREN USING COMBINED CHEMOTHERAPY AND IMMUNOTHERAPY: COMPARISON OF ESTIMATED AND REAL VALUES

Acute lymphoblastic leukemia is the most common pediatric cancer. The effectiveness of modern therapy protocols makes it possible to cure over 80% of children, and one of the advanced treatment methods is the use of monoclonal antibodies. Using the example of adult patients in the United States, the economic effectiveness of this innovative treatment strategy was proven, while no similar studies have been conducted in children with primary acute lymphoblastic leukemia. The aim of the study was to determine the real cost of therapy for children and adolescents with acute lymphoblastic leukemia according to the protocol using combined chemotherapy and immunotherapy at the stages of induction and consolidation. Materials and methods. The study included data from 54 patients (the study group) who received therapy using this method, taking into account indicators of direct medical and non-medical costs. The control group included 54 patient models corresponding to the initial estimated parameters when planning the protocol (body weight 30 kg, body surface area 1 m2). Research results. The median of real cost for providing medical care to one patient in the study group was 22% lower than the estimated cost. In its structure, the values of the median costs for inpatient stay, for instrumental and laboratory studies, as well as for drug therapy turned out to be lower. Since younger patients were included in the study group, the cost of drug therapy was recalculated to the calculated patient model, which equalized the median cost of drug therapy for the study and control groups. In a situation with equal characteristics of patients, as well as with the same cost of a day of inpatient stay, the median real cost of providing medical care to one patient in the study group corresponded to the estimated values. Conclusions. The median cost of medical care for patients with acute lymphoblastic leukemia according to the protocol using combined chemotherapy and immunotherapy in the study group was 22% lower than the estimated values. The actual practice of using the protocol for an average patient model with an equal cost of inpatient stay fully corresponded to the estimated values of the protocol.

Transcriptome analysis of primary adult B-cell lineage acute lymphoblastic leukemia identifies pathogenic variants and gene fusions, and predicts subtypes for in depth molecular diagnosis.

B-cell acute lymphoblastic leukemia (B-ALL) is classified into subgroups based on known driver oncogenes and molecular lesions, including translocations and recurrent mutations. However, the current diagnostic tests do not identify subtypes or oncogenic lesions for all B-ALL samples, creating a heterogeneous B-ALL group of unknown subtypes. We sorted primary adult B-ALL cells and performed transcriptome analysis by bulk RNA sequencing (RNA-seq). Transcriptomic analysis of an adult B-ALL cohort allowed the classification of four patient samples with subtypes that were not previously revealed by standard gene panels. The leukemia of two patients were of the DUX4 subtype and two were CRLF2+ Ph-like B-ALL. Furthermore, single nucleotide variant analysis detected the oncogenic NRAS-G12D, KRAS-G12D, and KRAS-G13D mutations in three of the patient samples, presenting targetable mutations. Additional oncogenic variants and gene fusions were uncovered, as well as multiple variants in the PDE4DIP gene across five of the patient samples. We demonstrate that RNA-seq is an effective tool for precision medicine in B-ALL by providing comprehensive molecular profiling of leukemia cells, identifying subtype and oncogenic lesions, and stratifying patients for appropriate therapy.

The role of daratumumab in relapsed/refractory CD38 positive acute leukemias—case report on three cases with a literature review

Primary refractory or relapsed T-cell acute lymphoblastic leukemia (T-ALL) and mixed phenotype myeloid/T-cell acute leukemia have dismal prognoses. New treatment approaches, preferably targeting specific leukemic aberrations to overcome resistance, are urgently needed. The bright expression of the CD38 antigen found in several cases of T-ALL led to an investigation into the role of anti-CD38 antibodies in the treatment of T-ALL. Here, we present three cases of resistant and relapsed T-ALL and myeloid/T-cell treated with daratumumab-based therapy, including venetoclax and bortezomib (Dara-Ven-Bor). All patients achieved complete remission, with minimal residual disease negativity within four weeks of treatment, allowing them to proceed to allogeneic hematopoietic cell transplantation. The toxicity of the triple schema was acceptable. Our patients and other cases reviewed here suggest that daratumumab combined with venetoclax and bortezomib may be a very effective and relatively safe salvage treatment, even in primary resistant T-ALL.

ALL-596 Primary Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia Among Adolescents and Young Adults Between 2017-2022 in Armenia

ALL-596 Primary Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia Among Adolescents and Young Adults Between 2017-2022 in Armenia

The impact of CAR-T therapy for outcomes in primary refractory acute lymphoblastic leukemia

The impact of CAR-T therapy for outcomes in primary refractory acute lymphoblastic leukemia

Opposing effects of KDM6A and JDP2 on glucocorticoid sensitivity in T-ALL.

Glucocorticoids (GCs) are the cornerstone of acute lymphoblastic leukemia (ALL) therapy. Although mutations in NR3C1, which encodes the GC receptor (GR), and other genes involved in GC signaling occur at relapse, additional mechanisms of adaptive GC resistance are uncertain. We transplanted and treated 10 primary mouse T-lineage acute lymphoblastic leukemias (T-ALLs) initiated by retroviral insertional mutagenesis with GC dexamethasone (DEX). Multiple distinct relapsed clones from 1 such leukemia (T-ALL 8633) exhibited discrete retroviral integrations that upregulated Jdp2 expression. This leukemia harbored a Kdm6a mutation. In the human T-ALL cell line CCRF-CEM, enforced JDP2 overexpression conferred GC resistance, whereas KDM6A inactivation unexpectedly enhanced GC sensitivity. In the context of KDM6A knockout, JDP2 overexpression induced profound GC resistance, counteracting the sensitization conferred by KDM6A loss. These resistant "double mutant" cells with combined KDM6A loss and JDP2 overexpression exhibited decreased NR3C1 mRNA and GR protein upregulation upon DEX exposure. Analysis of paired samples from 2 patients with KDM6A-mutant T-ALL in a relapsed pediatric ALL cohort revealed a somatic NR3C1 mutation at relapse in 1 patient and a markedly elevated JDP2 expression in the other. Together, these data implicate JDP2 overexpression as a mechanism of adaptive GC resistance in T-ALL, which functionally interacts with KDM6A inactivation.

Ex vivo Drug Sensitivity Imaging-based Platform for Primary Acute Lymphoblastic Leukemia Cells.

Resistance of acute lymphoblastic leukemia (ALL) cells to chemotherapy, whether present at diagnosis or acquired during treatment, is a major cause of treatment failure. Primary ALL cells are accessible for drug sensitivity testing at the time of new diagnosis or at relapse, but there are major limitations with current methods for determining drug sensitivity ex vivo. Here, we describe a functional precision medicine method using a fluorescence imaging platform to test drug sensitivity profiles of primary ALL cells. Leukemia cells are co-cultured with mesenchymal stromal cells and tested with a panel of 40 anti-leukemia drugs to determine individual patterns of drug resistance and sensitivity ("pharmacotype"). This imaging-based pharmacotyping assay addresses the limitations of prior ex vivo drug sensitivity methods by automating data analysis to produce high-throughput data while requiring fewer cells and significantly decreasing the labor-intensive time required to conduct the assay. The integration of drug sensitivity data with genomic profiling provides a basis for rational genomics-guided precision medicine. Key features Analysis of primary acute lymphoblastic leukemia (ALL) blasts obtained at diagnosis from bone marrow aspirate or peripheral blood. Experiments are performed ex vivo with mesenchymal stromal cell co-culture and require four days to complete. This fluorescence imaging-based protocol enhances previous ex vivo drug sensitivity assays and improves efficiency by requiring fewer primary cells while increasing the number of drugs tested to 40. It takes approximately 2-3 h for sample preparation and processing and a 1.5-hour imaging time. Graphical overview.

Миелодиспластический синдром, возникший после полихимиотерапии лейкоза. Последствие химиотерапии или проявление генетической нестабильности?

Great progress has been achieved in the treatment of oncological diseases; however, the problem of the occurrence of secondary malignant neoplasms remains actual, among which hematologic malignancies are common. The development of secondary tumors is of particular interest, because the individual predisposition of the body to malignant transformation of cells and the carcinogenic effect of antitumor therapy of primary cancer are possible etiological factors. The article presents a review of literature devoted to the cases of secondary malignant neoplasms that emerged after antitumor treatment. A clinical case of a secondary myelodysplastic syndrome developed after chemotherapy in the treatment of primary acute lymphoblastic leukemia is described.

Optimized Method for Cell Surface Protein Identification on Primary B-Cell Precursor Acute Lymphoblastic Leukemia Cells

Optimized Method for Cell Surface Protein Identification on Primary B-Cell Precursor Acute Lymphoblastic Leukemia Cells

High-grade desmoplastic infantile astrocytoma in a 1-year-old child with Down’s syndrome: a case report

BackgroundDown’s syndrome is the most common chromosomal abnormality in humans. It has been associated with central nervous system tumors such as primary acute lymphoblastic leukemia and germinomas, but desmoplastic infantile astrocytoma has not yet been reported with Down’s syndrome. Desmoplastic infantile astrocytoma is a rare intracranial tumor that mostly occurs in the first 2 years of life. It usually presents as a large, aggressive tumor with both solid and cystic components. Genetically, it has been linked to the BRAF V600E mutation. Despite the rapid growth pattern, it usually has a favorable prognosis after neurosurgical excision. The presence of this extremely rare, genetically linked tumor, and its combination with Down’s syndrome, the most common human genetic defect, makes this a very novel clinical presentation. It also raises a very research-worthy question of an undiscovered link between these two genetic disorders.Case presentationIn this case, we report a 1-year-old Pakistani origin male child with Down’s syndrome, who presented with progressive macrocephaly and developmental regression over the last 2 months. He was unable to sit by himself, and had lost his handgrip bilaterally. Down’s Syndrome was diagnosed soon after birth, based on typical facial features and presence of palmar crease, and later confirmed karyotypically for Trisomy 21. Upon presentation, initial blood tests did not show any abnormality. Magnetic resonance imaging of the brain was done, and showed a mixed intensity cystic mass with solid dural component posteriorly in the right parieto temporo occipital region. Craniotomy was performed, and about 85% of the tumor mass was excised. Histological examination and immunochemistry confirmed the suspected radiological diagnosis of desmoplastic infantile astrocytoma. After surgical excision, our patient gradually reacquired his previously regressed developmental milestones. Unfortunately, the remaining mass, which could not be excised due to its attachment to the highly vascular dura mater, showed regrowth on repeat brain magnetic resonance imaging. As his parents did not consent to further surgery, chemotherapy was offered as the next treatment option to prevent tumor regrowth.ConclusionsThis case report highlights the need for more case data and research to understand desmoplastic infantile astrocytoma, and their genetic correlation with Down’s syndrome. From a clinical standpoint, since desmoplastic infantile astrocytoma has a good postresection prognosis in a majority of early-diagnosed clinical cases, pediatricians, radiologists, and pathologists should consider desmoplastic infantile astrocytoma in their initial differential diagnosis in Down’s syndrome patients with macrocephaly and developmental regression during the first 2 years of life.

THE COURSE OF TOXIC HEPATITIS IN LEUKEMIC PATIENTS AT THE STAGE OF SUPPORT THERAPY.

One of the main tasks in the treatment of acute leukemia is to prevent the development of complications of chemotherapy, as well as the timely choice of the correct tactics for the treatment of complications. Because forced breaks associated with complications negatively affect the end result of leukemia treatment. Practice shows that one of the organs affected by chemotherapy is the liver, and its damage directly depends on the toxicity and duration of chemotherapy. Our task was to conduct research work in this area, and to study toxic liver lesions in patients with leukemia. Before that, we carried out similar work at the stages of induction and consolidation of treatment of acute leukemia in children. And this period of research work is devoted to the supportive stage of therapy in patients. Objective: To study the frequency of toxic liver damage in children with acute leukemia during support therapy, to choose treatment tactics according to the severity of toxic hepatitis. The study group included 51 children with primary acute lymphoblastic leukemia who completed the induction stage with complete remission and retained this result for the entire period of consolidation. The age of the patients ranged from 2.5 years to 15 years. Of these, there were 28 boys and 23 girls. The patients were from Baku and the regions of the republic. Treatment of acute lymphoblastic leukemia was carried out according to two branches of the Moscow – Berlin – 2015 program: B and T İmRG. The protocols of maintenance therapy of these branches do not differ, and both begin with the 31st week of the general program, end on the 104th. Each protocol consists of 8 stages of a combination of chemotherapy drugs Metotreksat + 6-Mercaptopurine, which last for 6 weeks and alternate with two-week courses of reinduction - Deksametazon + Vinkristin. Before the start of maintenance therapy, all patients with leukemia confirmed the preservation of the previously achieved remission, and the functional and organic state of the liver. With positive results, the continuation of leukemia treatment began. And when the symptoms of toxic hepatitis were detected, the severity was determined. According to this indicator, 3 forms of flow were issued: light, medium-heavy and heavy forms. The tactics of conducting therapy of each form were chosen by us. Of 51 patients, 42 had toxic hepatitis (82%). It was mild in 12 patients (23.5%), moderate in 26 children (50.9%), and severe in 4 children (7.8%). In the mild form of hepatitis, patients were prescribed intravenous administration of Riboksin + Aevit (orally) for 10-14 days, or alternatively, per os Ursobil + Aevit. This combination made it possible to restore all clinical and laboratory parameters in patients within 14-21 days, and at the same time, without interrupting chemotherapy. Moderate and severe forms of hepatitis occurred mainly during the period of reinduction (54.7%). The administration of intravenous adeomethionine (Heptral) in the form of monotherapy for 8-12 days allowed continuous reinduction courses. Following him, the administration of an oral combination of Ursobil + Lipoic acid + Aevit for 14-21 days allowed to preserve the long-term effect. In severe hepatitis, chemotherapy was suspended, and patients were prescribed intravenous adeomethionine (Heptral) in combination with oral Ursobil + Aevit for 10-14 days, and along with this detoxification therapy was carried out in parallel. Such treatment gave an improvement in clinical and laboratory parameters. Subsequently, intensive therapy was suspended, and chemotherapy was started accompanied by Ursobil + Aevit + Lipoic acid for the next two weeks. This choice of therapy allowed us to preserve the restored indicators for a long time. There were no deaths or severe complications from toxic hepatitis in any case.

Selective Expansion of NKG2C+ Adaptive NK Cells Using K562 Cells Expressing HLA-E.

Adaptive natural killer (NK) cells expressing self-specific inhibitory killer-cell immunoglobulin-like receptors (KIRs) can be expanded in vivo in response to human cytomegalovirus (HCMV) infection. Developing a method to preferentially expand this subset is essential for effective targeting of allogeneic cancer cells. A previous study developed an in vitro method to generate single KIR+ NK cells for enhanced targeting of the primary acute lymphoblastic leukemia cells; however, the expansion rate was quite low. Here, we present an effective expansion method using genetically modified K562-HLA-E feeder cells for long-term proliferation of adaptive NK cells displaying highly differentiated phenotype and comparable cytotoxicity, CD107a, and interferon-γ (IFN-γ) production. More importantly, our expansion method achieved more than a 10,000-fold expansion of adaptive NK cells after 6 weeks of culture, providing a high yield of alloreactive NK cells for cell therapy against cancer.

P423: ADAPTING CRISPR CAS9 DROPOUT SCREENS TO IN VIVO PDX MODELS OF ACUTE LEUKEMIAS

Background: Acute leukemias require better treatment and targeted therapies represent interesting future therapeutic options. Such therapies precisely inhibit molecules with essential function, also called vulnerabilities or dependencies, so that leukemia cells die once the target is inhibited. Aims: Here, we aimed at identifying therapeutic targets on a patient individual level and in the surrounding of a living organism. Towards this aim, we established CRISPR Cas9 dropout screens in PDX models of acute leukemias in vivo. Methods: Primary patient acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) samples were transplanted into immunocompromised NSG mice and re-passaged to develop serially transplantable PDX models. To overcome limited transduction efficiency inherent to PDX leukemia cells, lentiviruses were used. Results: We first elaborated on the maximum library size to be used in PDX models in vivo. As only a limited number of PDX cells home into mice, library size is limited to ensure the coverage of the library. We used, screening sgRNAs as genetic barcodes in Cas9 negative samples to determine the maximum library size upon next generation sequencing (NGS); a regular distribution of all sgRNAs recovered from mice at the end of the experiments indicated a suitable library size. We found that PDX ALL models tolerated a larger library compared to PDX AML models that might reflect lower intra-sample heterogeneity and higher leukemia stem cell frequency in ALL compared to AML. To perform knockout screens, a split-construct for Cas9 was used to reduce plasmid size and optimize lentiviral transduction efficiency into PDX cells; concomitantly split-GFP was used to enrich cells expressing both Cas9 split plasmids by flow cytometry. A customized library consisting of 146 target genes combined with positive and negative control genes was designed at 5 sgRNAs per gene using the CLUE platform (www.crispr-clue.de) (Becker et al., Nucleic Acids Res. 2020) and cloned into a lentiviral vector backbone. The sgRNA library vectors include either a puromycin-resistance cassette or an H-2Kk surface marker, each combined with a BFP fluorescent marker. This allows to determine transduction efficiency by FACS-based detection of BFP and to enrich the transduced PDX cells either by puromycin selection or by H-2Kk-MACS selection. Input samples were collected after library transduction and enrichment to >90% CRISPR/Cas9 sgRNA library positive cells, while remaining cells were injected into immunocompromised NSG mice, grown in vivo and re-isolated at advanced disease stage. Analysis of input and endpoint samples using NGS enabled to determine the frequency of sgRNAs and bioinformatically compare the abundance of different sgRNAs between the control and the samples of interest using MAGeCK (Model-based Analysis of Genome-wide CRISPR-Cas9 Knockout). A significant sgRNA dropout was characterized by a p-value below 0.05 and a FDR below 0.1. The screening experiments led to the top 10 depleted dropout genes for ALL and AML PDX samples. Besides individual dropouts of the different samples, also shared dropouts were detected. Especially sample overlapping dropouts might represent interesting starting points for new therapeutic options. Summary/Conclusion: In summary, we have established a CRISPR Cas9 screening pipeline, which allows investigating therapeutic targets on a patient-individual level in ALL PDX models and, for the first time, in AML PDX models in vivo.

Abstract 722: Metals in primary teeth and childhood acute lymphoblastic leukemia: A pilot study

Abstract Background: Acute lymphoblastic leukemia (ALL) is the most common childhood cancer, but few environmental risk factors have been confirmed, mostly due to imprecise self-reported questionnaire data. This highlights the need for epidemiological studies to employ novel exposure assessment methods to objectively measure early life exposures. Many metals are considered known or probable human carcinogens, primarily based on studies of adult cancers. We seek to determine the association between pre- and postnatal uptake of metals and ALL risk. Methods: Children with and without ALL were recruited from Texas Children’s Hospital. Each participant donated 2-5 primary teeth for analysis. Using laser ablation-inductively coupled plasma-mass spectrometry, we measured 8 metals (arsenic, cadmium, chromium, copper, lead, manganese, magnesium, zinc) and calcium in teeth from 61 children with ALL and 6 without. In teeth, dentin and enamel form at different times, creating visible growth rings, which allowed us to objectively measure metal uptake for every week from up to 20 weeks before birth to 55 weeks after birth. At each timepoint, the ratio of metal to calcium was calculated to normalize the data. For each metal, we calculated the average prenatal uptake (i.e., 20 weeks before birth to birth) and average postnatal uptake (i.e., first week after birth to last available measurement). The average metal uptake in cases were compared to controls. To identify more specific window(s) of susceptibility, we used distributed lag regression, allowing us to incorporate data measured at all timepoints. Results: Compared to children without ALL, children with ALL on average had higher prenatal uptake of chromium (0.50 vs 0.43; p=0.07), manganese (1,969 vs 1,888; p=0.20), and lead (0.04 vs 0.02; p=0.03) and lower prenatal uptake of cadmium (0.01 vs 0.02; p=0.0004), copper (0.07 vs 0.10; p=0.19), magnesium (0.24 vs 0.29; p=0.35), and zinc (22 vs 24; p=0.01). Average prenatal uptake of arsenic was similar between cases and controls (0.01 vs 0.01; p=0.13). A similar pattern was observed with postnatal uptake of metals. Using distributed lag regression, prenatal uptake of manganese 10 to 20 weeks before birth was significantly associated (p<0.05) with risk of ALL, but a significantly protective association was observed starting at ~5 weeks after birth. While no other metals had a significant association with ALL, there was suggestive evidence that pre- and postnatal uptake of lead and chromium were positively associated with ALL, while pre- and postnatal uptake of zinc and copper were inversely associated. Conclusion: Using a novel exposure method to measure metal uptakes at specific windows of susceptibility in primary teeth samples, our results suggest certain metals may contribute to the etiology of ALL. A larger study is needed to draw more definitive conclusions about early-life uptake of metals and risk of ALL. Citation Format: Thanh Hoang, Manish Arora, Christine Austin, Paul C. Curtin, Philip J. Lupo, Michael E. Scheurer. Metals in primary teeth and childhood acute lymphoblastic leukemia: A pilot study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 722.

Second malignant neoplasms after treatment of 1487 children and adolescents with acute lymphoblastic leukemia-A population-based analysis of the Austrian ALL-BFM Study Group.

Second malignant neoplasms (SMN) after primary childhood acute lymphoblastic leukemia (ALL) are rare. Among 1487 ALL patients diagnosed between 1981 and 2010 in Austria, the 10‐year cumulative incidence of an SMN was 1.1% ± 0.3%. There was no difference in the 10‐year incidence of SMNs with regard to diagnostic‐, response‐ and therapy‐related ALL characteristics except for a significantly higher incidence in patients with leukocytes ≥50.0 G/L at ALL diagnosis (2.1% ± 1.0% vs. 0% for 20.0–50.0 G/L, and 1.0% ± 0.3% for < 20.0 G/L; p = 0.033). Notably, there was no significant difference in the incidence of SMNs between patients with or without cranial radiotherapy (1.2% ± 0.5% vs. 0.8% ± 0.3%; p = 0.295). Future strategies must decrease the incidence of SMNs, as this event still leads to death in one‐third (7/19) of the patients.

Primary acute lymphoblastic leukemia cells are susceptible to microtubule depolymerization in G1 and M phases through distinct cell death pathways

Microtubule targeting agents (MTAs) are widely used cancer chemotherapeutics which conventionally exert their effects during mitosis, leading to mitotic or postmitotic death. However, accumulating evidence suggests that MTAs can also generate death signals during interphase, which may represent a key mechanism in the clinical setting. We reported previously that vincristine and other microtubule destabilizers induce death not only in M phase but also in G1 phase in primary acute lymphoblastic leukemia cells. Here, we sought to investigate and compare the pathways responsible for phase-specific cell death. Primary acute lymphoblastic leukemia cells were subjected to centrifugal elutriation, and cell populations enriched in G1 phase (97%) or G2/M phases (80%) were obtained and treated with vincristine. We found death of M phase cells was associated with established features of mitochondrial-mediated apoptosis, including Bax activation, loss of mitochondrial transmembrane potential, caspase-3 activation, and nucleosomal DNA fragmentation. In contrast, death of G1 phase cells was not associated with pronounced Bax or caspase-3 activation but was associated with loss of mitochondrial transmembrane potential, parylation, nuclear translocation of apoptosis-inducing factor and endonuclease G, and supra-nucleosomal DNA fragmentation, which was enhanced by inhibition of autophagy. The results indicate that microtubule depolymerization induces distinct cell death pathways depending on during which phase of the cell cycle microtubule perturbation occurs. The observation that a specific type of drug can enter a single cell type and induce two different modes of death is novel and intriguing. These findings provide a basis for advancing knowledge of clinical mechanisms of MTAs.

Acute lymphoblastic leukemia-derived extracellular vesicles affect quiescence of hematopoietic stem and progenitor cells

Patient-derived xenografted (PDX) models were generated through the transplantation of primary acute lymphoblastic leukemia (ALL) cells into immunodeficient NSG mice. We observed that ALL cells from mouse bone marrow (BM) produced extracellular vesicles (EVs) with specific expression of inducible heat shock protein HSP70, which is commonly activated in cancer cells. Taking advantage of this specific expression, we designed a strategy to generate fluorescent HSP70-labeled ALL EVs and monitor the impact of these EVs on endogenous murine BM cells ex vivo and in vivo. We discovered that hematopoietic stem and progenitor cells (HSPC) were mainly targeted by ALL EVs, affecting their quiescence and maintenance in the murine BM environment. Investigations revealed that ALL EVs were enriched in cholesterol and other metabolites that contribute to promote the mitochondrial function in targeted HSPC. Furthermore, using CD34+ cells isolated from cord blood, we confirmed that ALL EVs can modify quiescence of human HSPC. In conclusion, we have discovered a new oncogenic mechanism illustrating how EVs produced by proliferative ALL cells can target and compromise a healthy hematopoiesis system during leukemia development.

Changes in five-year survival for people with acute leukaemia in South Australia, 1980-2016.

To examine population changes in 5-year survival for people in South Australia diagnosed with acute leukaemia during 1980-2016, by socio-demographic characteristics. Retrospective analysis of South Australian Cancer Registry data for the period 1980-2016. All South Australian residents diagnosed with primary acute lymphoblastic leukaemia (ALL) or acute myeloid leukaemia (AML) during 1980-2016. 5-year disease-specific survival and disease-specific mortality. Crude 5-year disease-specific survival was 58% (95% CI, 54-61%) for the 1035 people diagnosed with ALL during 1980-2016, and 18% (95% CI, 17-20%) for the 2814 people diagnosed with AML. Survival improved steadily across the study period: from 44% (95% CI, 35-52%) for people with ALL diagnosed during 1980-1984 to 69% (95% CI, 63-75%) for those diagnosed during 2010-2016; and from 9% (95% CI, 5-15%) to 23% (95% CI, 20-26%) for people diagnosed with AML. Disease-specific mortality increased with age, but was not influenced by socio-economic status or remoteness of residence. After adjusting for other factors, rates of change in risk of leukaemia-related death were greater for younger than older patients with ALL (for interaction: P=0.004) or AML (P=0.005), but were not significantly influenced by socio-economic status or remoteness. Five-year survival for people with acute leukaemia in South Australia continuously improved during 1980-2016, and socio-economic status and remoteness did not influence survival. It improved markedly for younger patients (under 50 years of age). However, survival is still relatively poor, especially for people over 50 years with AML.