Causal pathways in lymphoid leukemia: the gut microbiota, immune cells, and serum metabolites.

Background: We employed Mendelian randomization (MR) to investigate the causal relationship between the gut microbiota and lymphoid leukemia, further exploring the causal relationships among immune cells, lymphoid leukemia, and potential metabolic mediators. Methods: We utilized data from the largest genome-wide association studies to date, encompassing 418 species of gut microbiota, 713 types of immune cells, and 1,400 serum metabolites as exposures. Summary statistics for lymphoid leukemia, acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL) were obtained from the FinnGen database. We performed bidirectional Mendelian analyses to explore the causal relationships among the gut microbiota, immune cells, serum metabolites, and lymphoid leukemia. Additionally, we conducted a two-step mediation analysis to identify potential intermediary metabolites between immune cells and lymphoid leukemia. Results: Several gut microbiota were found to have causal relationships with lymphoid leukemia, ALL, and CLL, particularly within the Firmicutes and Bacteroidetes phyla. In the two-step MR analysis, various steroid hormone metabolites (such as DHEAS, pregnenolone sulfateprogestogen derivatives, and androstenediol-related compounds) were identified as potential intermediary metabolites between lymphoid leukemia and immune cells. In ALL, the causal relationship between 1-palmitoyl-2-docosahexaenoyl-GPE (16:0/22:6) and ALL was mediated by CD62L-plasmacytoid DC%DC (mediated proportion=-2.84%, P=0.020). In CLL, the causal relationship between N6,n6,n6-trimethyllysine and CLL was mediated by HLA DR+ CD8br AC (mediated proportion=4.07%, P=0.021). Conclusion: This MR study provides evidence supporting specific causal relationships between the gut microbiota and lymphoid leukemia, as well as between certain immune cells and lymphoid leukemia with potential intermediary metabolites.

Mycovirus-Containing Aspergillus flavus Alters Transcription Factors in Normal and Acute Lymphoblastic Leukemia Cells.

Transcription factors control genes to maintain normal hemopoiesis, and dysregulation of some factors can lead to acute lymphoblastic leukemia (ALL). Mycoviruses are known to alter the genetics of their fungal host. The present study evaluates the effects of the products of a mycovirus-containing Aspergillus flavus (MCAF), isolated from the home of a patient with ALL, on certain transcription factors of normal and ALL cell lines. Our published studies have shown that ALL patients have antibodies to MCAF, and that exposure of the mononuclear leukocytes of patients in complete remission to its products, unlike controls, results in the re-development of genetic and cell surface phenotypes characteristic of ALL. For the present study, normal, pre-B, and B-cell leukemia cell lines were exposed to the culture of MCAF. Pre- and post-exposure levels of PAX5, Ikaros, and NF-κB were assessed. Exposure to MCAF resulted in apoptosis, cell cycle changes, and complete downregulation of all transcription factors in normal cell lines. In acute leukemia cell lines, cellular apoptosis and alterations in the cell cycle were also noted; however, while there was downregulation of all tested transcription factors, residual levels were retained. The noted alterations in the transcription factors caused by MCAF are novel findings. The possible role of MCAF in leukemogenesis needs to be further investigated. Mycovirus-containing Aspergillus flavus was initially isolated from a leukemia patient's home. Our prior published studies have illuminated intriguing associations of this organism with leukemia. Unlike controls, patients diagnosed with acute lymphoblastic leukemia (ALL) harbor antibodies to this organism. Furthermore, the exposure of mononuclear cells from patients with ALL in complete remission to the products of this organism reproduced genetic and cell phenotypes characteristic of ALL. These findings underscore the potential role of environmental factors in leukemogenesis and hint at novel avenues for therapeutic intervention and preventive strategies.

Prediction of Bloodstream Infection in Pediatric Acute Leukemia by Microbiota and Volatile Organic Compounds Analysis.

INTRODUCTION: Bloodstream infections (BSIs) cause treatment-related mortality in pediatric acute leukemia. We explored the potential of intestinal microbiota and fecal volatile organic compounds (VOCs) analyses to predict BSI. METHODS: In this case-control study, fecal samples of pediatric acute leukemia patients were collected. Microbiota composition and fecal VOC profiles of BSI cases and matched non-BSI controls were compared. RESULTS: In total, 6 patients were included, of which 1 developed BSI and 1 neutropenic fever. Both showed reduced microbial diversity and stability of Bacteroidetes. In the BSI case, Pantoea was identified 15 days before BSI. Significant differences in fecal VOC profiles were measured between the case and controls. CONCLUSION: Microbiota and fecal VOC could serve as biomarkers to predict BSI in pediatric leukemia.

Durable changes in the gut microbiome in survivors of childhood acute lymphoblastic leukemia.

There are limiteddata on long-term changes in the gut microbiome after acute lymphoblastic leukemia (ALL) therapy. We compared the gut microbial composition in stool samples of nine survivors of childhood ALL with 10 healthy sibling controls using 16S rRNA gene sequencing. Analysis of beta diversity within family units demonstrated a significant difference in bacterial strains between patients and healthy siblings. A significant difference in alpha diversity between patients and their healthy siblings was noted using Pielou's evenness. The composition of the gut microbiome differs between pediatric ALL survivors and healthy sibling controls for years after completion of therapy.

Healthcare-associated blood stream infections in hematological patients in Finland during the years 2006-2016.

OBJECTIVES: The aim was to identify the clinical characteristics, outcome, and antimicrobial susceptibility of healthcare-associated bloodstream infections (BSIs) in hematological patients. METHODS: This retrospectively collected laboratory-based surveillance data include 3404 healthcare-associated BSIs in 2296 patients with a hematological malignancy in hospitals participating in the Finnish Hospital Infection Program from January 1, 2006, to December 31, 2016. RESULTS: The most common underlying diseases were acute myelogenous leukemia (35%) and non-Hodgkin lymphoma (22%). Gram-positive organisms accounted for 60%-46% and gram-negative organisms for 24%-36% of BSIs in 2006-2016. The most common causative organism was coagulase-negative staphylococci (CoNS) (n = 731). The 7- and 28-day case fatality rates were 5.2% and 11.4%, respectively, and was highest in BSIs caused by Candida species (10.8% and 30.8%). The median age of patients increased from 59 years in 2006-2008 to 62 years in 2015-2016 (P < .01). Five percent of S aureus isolates were resistant to methicillin and five percent of Pseudomonas aeruginosa isolates were multidrug-resistant. Four percent of Klebsiella and seven percent of E coli isolates were resistant to ceftazidime. CONCLUSIONS: The proportion of gram-positive bacteria decreased and gram-negative bacteria increased over time. The case fatality rate was low and the median age of patients increased during the study.

Tisagenlecleucel infusion in patients with relapsed/refractory ALL and concurrent serious infection.

BACKGROUND: Tisagenlecleucel, an anti-CD19 chimeric antigen receptor T (CAR-T) cell therapy, has demonstrated durable efficacy and a manageable safety profile in pediatric and young adult patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) in the ELIANA pivotal trial and real-world experience. Experience from investigator-led studies prior to ELIANA suggests that infections and inflammatory conditions may exacerbate the severity of cytokine release syndrome (CRS) associated with CAR-T cell therapy, leading to extreme caution and strong restrictions for on-study and commercial infusion of tisagenlecleucel in patients with active infection. CRS intervention with interleukin (IL)-6 blockade and/or steroid therapy was introduced late in the course during clinical trials due to concern for potential negative effect on efficacy and persistence. However, earlier CRS intervention is now viewed more favorably. Earlier intervention and consistency in management between providers may promote broader use of tisagenlecleucel, including potential curative therapy in patients who require remission and recovery of hematopoiesis for management of severe infection. MAIN BODY: Patient 1 was diagnosed with B-ALL at 23 years old. Fourteen days before tisagenlecleucel infusion, the patient developed fever and neutropenia and was diagnosed with invasive Mucorales infection and BK virus hemorrhagic cystitis. Aggressive measures were instituted to control infection and to manage prolonged cytopenias during CAR-T cell manufacturing. Adverse events, including CRS, were manageable despite elevated inflammatory markers and active infection. The patient attained remission and recovered hematopoiesis, and infections resolved. The patient remains in remission ≥1 year postinfusion.Patient 2 was diagnosed with pre-B-ALL at preschool age. She developed severe septic shock 3 days postinitiation of lymphodepleting chemotherapy. After receiving tisagenlecleucel, she experienced CRS with cardiac dysfunction and extensive lymphadenopathy leading to renovascular compromise. The patient attained remission and was discharged in good condition to her country of origin. She remained in remission but expired on day 208 postinfusion due to cardiac arrest of unclear etiology. CONCLUSIONS: Infusion was feasible, and toxicity related to tisagenlecleucel was manageable despite active infections and concurrent inflammation, allowing attainment of remission in otherwise refractory pediatric/young adult ALL. This may lead to consideration of tisagenlecleucel as a potential curative therapy in patients with managed active infections.

Exposure to a mycovirus containing Aspergillus Flavus reproduces acute lymphoblastic leukemia cell surface and genetic markers in cells from patients in remission and not controls.

The etiology of acute lymphoblastic leukemia (ALL) remains unknown. A recent "two-hit" model for the occurrence of precursor B cell acute lymphoblastic leukemia propose that this disease arises through a two-step process, including predisposing genetic mutation and exposure to infections. While several genetic mutations are proposed, no infection category has been suggested. We have isolated a certain Aspergillus Flavus from residence of an ALL patient. This organism contains mycovirus and does not produce aflatoxin. The supernatant of culture of this mycovirus containing Aspergillus Flavus (SAF) was tested on the PBMCs of ALL patients in remission and controls. Cell surface phenotypes and genetic markers were examined. The effects of its combination with Epstein-Barr virus (EBV) was also investigated. For the SAF, positive and negative controls were aflatoxin and culture of Mycocladus corymbifer, respectively. Controls for ALL were sickle cell patients undergoing exchange transfusion. Incubation of the PMBCs from ALL patients in remission, or controls, with SAF resulted in re-development of ALL cell surface phenotypes and genetic markers in ALL patients in remission and not controls. These differentiating effects were not seen with aflatoxin or culture of Mycocladus Corymbifer. Addition of EBV did not alter effects of SAF. Currently, there are no techniques to discriminately reproduce characteristic leukemic genetic markers and cell surface phenotypes in cells from ALL patients in remission and not controls. These studies may provide a test for recognition of ALL patients in remission and new prospects for the investigation of leukemogenesis.

Elevated plasma phage load as a marker for intestinal permeability in leukemic patients.

Microbial translocation (MT) and altered gut microbiota have been described in acute leukemic patients and contribute to immune activation and inflammation. However, phage translocation has not been investigated in leukemia patients yet. We recruited 44 leukemic patients and 52 healthy adults and quantified the levels of 3 phages in peripheral blood, which were the most positive phages screened from fecal samples. The content of 16S rRNA in plasma was detected by qPCR to assess the intestinal mucosa of these patients. Spearman's rank correlation was used to analyze the relationship between phage load and the relevant clinical data. We found the most prevalent phages in fecal samples were λ phage, Wphi phage, and P22 phage, and λ phage had the highest detection rate in plasma (68%). Phage content was affected by chemotherapy and course of disease and correlated with the levels of CRP (r = 0.43, p = 0.003), sCD14 (r = 0.37, p = 0.014), and sCD163 (r = 0.44, p = 0.003). Our data indicate that plasma phage load is a promising marker for gut barrier damage and that gut phage translocation correlates with monocyte/macrophage activation and systemic inflammatory response in leukemic patients.

Gut microbial composition difference between pediatric ALL survivors and siblings.

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer with high cure rates leading to rising numbers of long-term survivors. Adult survivors of childhood ALL are at increased risk of obesity, cardiovascular disease, and other chronic illnesses. We hypothesize that ALL therapy is associated with long-term gut microbiome alterations that contribute to predisposition to chronic medical conditions. We conducted a pilot study to test whether differences can be detected between stool microbiota of pediatric ALL survivors and their siblings. Stool samples were collected from 38 individuals under age 19 who were at least 1 year after completion of therapy for ALL. Stool samples collected from 16 healthy siblings served as controls. 16S ribosomal RNA gene sequencing was performed on the stool samples. Comparing microbiota of survivors to sibling controls, no statistically significant differences were found in alpha or beta diversity. However, among the top 10 operational taxonomic units (OTUs) from component 1 in sparse partial least squares discriminant analysis (sPLS-DA) with different relative abundance in survivors versus siblings, OTUs mapping to the genus Faecalibacterium were depleted in survivors. Differences in gut microbial composition were found between pediatric survivors of childhood ALL and their siblings. Specifically, the protective Faecalibacterium is depleted in survivors, which is reminiscent of gut microbiota alteration found in adult survivors of childhood ALL and reported in obesity, suggesting that microbiota alterations in pediatric ALL survivors start in childhood and may play a role in predisposition to chronic illness in later years of survivorship.

Invasive Rhino-Orbito-Cerebral Mucormycosis in Pediatric Patient with Acute Leukemia.

BACKGROUND: Invasive fungal infections are a life-threatening complication of cancer treatments, especially in hemato-oncological patients. Mucormycosis is the third leading cause of invasive fungal infections after Aspergillus and Candida infections. The first clinical symptoms are usually non-specific, which can lead to a late diagnosis and delayed therapy. PURPOSE: The objective of this report is to summarize data in the literature about mucormycosis and to present a case report of a patient with acute lymphoblastic leukemia, who developed this infection at our center. Risk factors for the development of mucormycosis, clinical symptoms, radiology, laboratory results, and outcome were retrospectively evaluated. CASE: We describe a 6-years-old female patient with acute lymphoblastic leukemia. During the induction phase of therapy, the patient developed febrile neutropenia and did not respond to therapy with a combination of antibiotics and supportive treatment. Pansinusitis and orbitocellulitis developed. Examination of the biological material revealed that the etiological agent was a Rhizopus sp. The patient was treated with a combination of antimycotic drugs, but the infection disseminated to the central nervous system. She underwent radical surgical resection of the affected tissue. At this time, she is still under treatment with antimycotic and oncology agents, but is in remission of the main diagnosis and in good clinical condition. CONCLUSION: Mucormycosis is an invasive fungal infection with high morbidity and mortality. Early diagnosis and initiation of effective therapy using a combination of amphotericin B administration and surgery are necessary to obtain a favorable outcome. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.

Gastrointestinal toxicity during induction treatment for childhood acute lymphoblastic leukemia: The impact of the gut microbiota.

Intestinal mucositis is a common side effect of chemotherapy leading to diarrhea, abdominal pain and increased risk of infections. The intestinal microbiota has been recognized as a key regulator of mucosal immune responses. Therefore, we hypothesized that intestinal microbial changes would be associated with enterocyte loss and systemic inflammation during induction treatment for childhood acute lymphoblastic leukemia (ALL). We prospectively included 51 children newly-diagnosed with ALL treated in Denmark in 2015-2018. Plasma C-reactive protein (CRP), plasma citrulline (marker of functional enterocytes mass) measurements and fecal samplings were performed on treatment Days 1, 8, 15, 22 and 29. Moreover, intestinal mucositis was scored by a trained nurse/physician. Fecal samples in patients and 19 healthy siblings were analyzed by 16S rRNA gene sequencing (V3-V4 region). Bacterial alpha diversity was lower in patients compared to siblings. It decreased from Day 1 to Days 8-22 and increased on Day 29. Shannon alpha diversity index was correlated with CRP on Days 15-29 (rho = -0.33-0.49; p < 0.05) and with citrulline on Days 15 and 29 (although with p values <0.06, rho = 0.32-0.34). The abundance of unclassified Enterococcus species (spp.) was correlated with CRP on Days 22-29 (rho = 0.42-0.49; p < 0.009), while the abundance of unclassified Lachnospiraceae spp. was correlated with citrulline on days 8-15 (rho = 0.48-0.62, p < 0.001). Systemic inflammation, enterocyte loss and relative abundance of unclassified Enterococcus spp. reached a peak around Day 15. In conclusion, specific changes in the microbiota were associated with the severity of enterocyte loss and systemic inflammation during chemotherapy.

Temporal changes in gut microbiota profile in children with acute lymphoblastic leukemia prior to commencement-, during-, and post-cessation of chemotherapy.

BACKGROUND: Alteration in gut microbiota has been recently linked with childhood leukemia and the use of chemotherapy. Whether the perturbed microbiota community is restored after disease remission and cessation of cancer treatment has not been evaluated. This study examines the chronological changes of gut microbiota in children with acute lymphoblastic leukemia (ALL) prior to the start-, during-, and following cessation of chemotherapy. METHODOLOGY: We conducted a longitudinal observational study in gut microbiota profile in a group of paediatric patients diagnosed with ALL using 16 s ribosomal RNA sequencing and compared these patients' microbiota pattern with age and ethnicity-matched healthy children. Temporal changes of gut microbiota in these patients with ALL were also examined at different time-points in relation to chemotherapy. RESULTS: Prior to commencement of chemotherapy, gut microbiota in children with ALL had larger inter-individual variability compared to healthy controls and was enriched with bacteria belonging to Bacteroidetes phylum and Bacteroides genus. The relative abundance of Bacteroides decreased upon commencement of chemotherapy. Restitution of gut microbiota composition to resemble that of healthy controls occurred after cessation of chemotherapy. However, the microbiota composition (beta diversity) remained distinctive and a few bacteria were different in abundance among the patients with ALL compared to controls despite completion of chemotherapy and presumed restoration of normal health. CONCLUSION: Our findings in this pilot study is the first to suggest that gut microbiota profile in children with ALL remains marginally different from healthy controls even after cessation of chemotherapy. These persistent microbiota changes may have a role in the long-term wellbeing in childhood cancer survivors but the impact of these changes in subsequent health perturbations in these survivors remain unexplored.

Microbiota changes in a pediatric acute lymphocytic leukemia mouse model.

Hematological malignancies are the most common type of pediatric cancers, and acute lymphocytic leukemia (ALL) is the most frequently occurring hematological malignancy during childhood. A major cause of mortality in leukemia is bloodstream infection (BSI). The aim of the current study was to explore the gut microbiota in ALL and its potential functional alterations. High-throughput sequencing was used to characterize the bacterial and fungal microbiota in feces and their predicted functional characteristics in a xenotransplant pediatric ALL mouse model. Our work shows that gut microbiota significantly changes in leukemia, which may result in functional alterations. This study may provide potential therapeutic or preventive strategies of BSI in ALL.

Successful Management of Unusual Multiple Gut Colonization With Extremely Drug-resistant Bacteria in an Infant Undergoing Hematopoietic Cell Transplantation.

Enterobacterales represent a serious threat to transplant patients due to their increase frequency of carbapenem resistance and wide spreading. We present a case of an infant with acute lymphoblastic leukemia undergoing hematopoietic stem cell transplantation. Before transplantation an unusual double colonization of the gastrointestinal tract with extremely resistant Escherichia coli and Klebsiella pneumoniae strains producing metallo-beta-lactamase was diagnosed. Respective epidemiologic management was implemented, based on the strict reverse isolation in patient-protective environment, and intensified antimicrobial surveillance. After granulocyte recovery, no extremely drug-resistant strains were found, and no case of isolation and/or transmission of carbapenem-resistant bacteria has been identified in the transplant center during the following 6 months.

Successful Management of Hepatosplenic Infection Due to Saccharomyces cerevisiae in a Child With Acute Lymphoblastic Leukemia.

Saccharomyces cerevisiae is an emerging pathogen within the immunocompromised. We present a 4-year-old boy with acute lymphoblastic leukemia presenting with polymerase chain reaction-confirmed hepatosplenic S. cerevisiae infection and significant immune reconstitution symptoms. We explore the challenges of monitoring treatment efficacy using C-Reactive protein, ß-D-glucan, and imaging and the administration of chemotherapy alongside antifungals and steroids for control of immune reconstitution syndrome.

Invasive mucormycosis during treatment for acute lymphoblastic leukaemia-successful management of two life-threatening diseases.

A 5-year-old patient treated for acute lymphoblastic leukaemia (ALL) developed proven pulmonary invasive fungal disease (IFD) due to Actinomucor elegans. While completing ALL treatment according to AIEOP ALL protocol 2009 for further 15 months, antifungal treatment with liposomal amphotericin B and intermittent additional posaconazole was continued until immune reconstitution 7 months after the end of ALL treatment. Repeated imaging guided treatment decisions. Twenty-six and 19 months after the end of ALL treatment and antifungal treatment, respectively, the patient is still in the first complete remission and shows no signs of active invasive fungal disease (IFD).

Long-Term Risk of Infections After Treatment of Childhood Leukemia: A Population-Based Cohort Study Using Administrative Health Data.

PURPOSE: Infections are a frequent complication during childhood leukemia treatment. Little is known about the infectious risk in survivors. We compared the relative rate (RR) of infections after treatment completion between pediatric leukemia survivors and the general population. METHODS: We performed a retrospective, population-based cohort study of children diagnosed with leukemia between 1992 and 2015 in Ontario, Canada, who were alive and relapse free 30 days after treatment completion (index date). Leukemia survivors were matched 5:1 with the general population by year of birth, sex, and rural status and stratified by initial treatment, including and excluding hematopoietic stem-cell transplantation (HSCT). The primary outcome was time to infections, as identified using validated diagnostic codes from administrative databases. Individuals were censored at the earliest of death, first relapse, loss to follow-up, or end of study. RESULTS: A total of 2,204 leukemia survivors were included and matched with 11,020 controls. The rate of infections was elevated after treatment completion compared with controls (RR, 1.51; 95% CI, 1.45 to 1.57) and at less than 1 year (RR, 1.77; 95% CI, 1.69 to 1.86); 1 to 4.99 years (RR, 1.66; 95% CI, 1.62 to 1.71), and 5 or more years (RR, 1.29; 95% CI, 1.22 to 1.36) from the index date. Among those whose initial treatment excluded HSCT, the rate remained elevated more than 5 years from the index date (RR, 1.29; 95% CI, 1.23 to 1.35). Infection-related death was significantly increased in leukemia survivors both among the entire cohort (hazard ratio, 149.3; 95% CI, 20.4 to 1,091.9) and among those without HSCT (hazard ratio, 92.7; 95% CI, 12.4 to 690.7). CONCLUSION: A significant association was found between a history of leukemia therapy and an increased risk of infections. Additional study is needed to establish which exposures in patients with leukemia lead to late infections.

Bacterial translocation in acute lymphocytic leukemia.

Bloodstream infection (BSI) is the major cause of mortality in acute lymphocytic leukemia (ALL). Causative pathogens in BSI originate from the gut microbiota due to an increase in intestinal permeability, a process known as bacterial translocation (BT). The gut microbiota in physiological conditions is controlled by a large number of immune cells as part of the gut-associated lymphoid tissue (GALT).The aim of the current study was to investigate the mechanism of bacterial translocation in leukemia by identifying and characterizing alterations in the GALT in leukemic mouse model. Our studies revealed a severe impairment of the GALT characterized by a loss of lymphatic cells in ALL, which eventually led to BSI. We identified differentially expressed genes in the intraepithelium and the lamina propria, which may contribute to BT and to the impairment of lymphocyte migration.

Invasive fusariosis masquerading as extramedullary disease in rapidly progressive acute lymphoblastic leukemia.

Invasive fusariosis (IF) most commonly occurs in patients with hematologic malignancies and severe neutropenia, particularly during concomitant corticosteroid use. Breakthrough infections can occur in high-risk patients despite Aspergillus-active antifungal prophylaxis. We describe a patient with rapid acute lymphoblastic leukemia (ALL) progression who presented with multifocal skin nodules thought to be choloromatous disease. These lesions were ultimately diagnosed as IF and the patient had two simultaneously active disease processes. This case highlights the importance of pathologic diagnosis of new skin lesions in ALL patients, even during leukemia progression, and demonstrates that IF can occur despite normal neutrophil counts and Aspergillus-active prophylaxis.