Diversity of cancer stem cells in acute lymphoblastic leukaemia

Phd ThesisFor many cancers research led to controversial results regarding frequency and identity of cancer stem cells, cells that self-renew and are able to reconstitute the full phenotype of the original malignancy. In some malignancies such as acute myeloid leukaemia the hierarchical stem cell model that suggests that only rare and immunophenotypically immature blasts exhibit stem cell characteristics, resembling the normal physiological haematopoietic hierarchy, has been well established. In contrast to that, the stochastic model states that all or at least a substantial proportion of malignant cells has stem cell potential whereby this is supported by extrinsic stimuli. Initially, several studies suggested that acute lymphoblastic leukaemia (ALL) also is organised in a hierarchy. However, using more immunocompromised mouse strains and refined transplantation techniques for in vivo xenotransplantation models, previous findings regarding frequency and restriction of stem cells to very early B-precursor cell stages have been challenged in more recent studies. In order to address the questions of identity and frequency of stem cells in ALL, a robust orthotopic mouse model with the most immunocompromised mouse strain currently available (NOD/scid IL2Rγnull; NSG) was established. Primary diagnostic patient ALLs or blasts harvested from engrafted mouse bone marrow were sorted for B-cell lineage differentiation markers CD10, CD19, CD20 or CD34 to purify candidate stem cell populations of different maturity. All transplanted cell populations, from the most immature CD34+CD19low stage to the already more differentiated stage of CD19+CD20high cells were able to reconstitute the original ALL in mouse bone marrow and followed a typical dissemination pattern with infiltration of the spleen. Furthermore, this more mature CD19+CD20high subpopulation proved self-renewal ability in serial transplantation experiments. To investigate, whether stem cells in ALL are a rare entity or more abundant, unsorted bulk leukaemia blasts were transplanted in limiting dilutions from 1 x 104 to 10 cells per mouse. Cell numbers required for engraftment varied between leukaemias but the leukaemia engrafted in mice when only 10 to 1,000 cells were transplanted. The limiting dilution experiments were repeated with sorted blast populations according to the surface antigens CD10, CD20 and CD34. Stem cell frequencies in all sorted populations were comparable and as few as 10 to 100 cells were sufficient to reconstitute the leukaemia in mice. Stem cells do not seem to be restricted to immature blast populations as in the hierarchical model but a broad spectrum of different blast immunophenotypes display stem cell capabilities. Furthermore, the frequency of stemness among unsorted bulk ALL cells as well as subpopulations of different maturity according to the blast immunophenotype is high and similar. The results from this thesis provide strong evidence for the stochastic cancer stem cell model in B precursor ALL.NHS: The North of England Children’s Cancer Research group (NECCR): Leukaemia and Lymphoma Research: The JGW Paterson foundation

Polymorphisms of methylenetetrahydrofolate reductase (MTHFR) and susceptibility to pediatric acute lymphoblastic leukemia in a German study population

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) has a major impact on the regulation of the folic acid pathway due to conversion of 5,10-methylenetetrahydrofolate (methylene-THF) to 5-methyl-THF. Two common polymorphisms (677C>T and 1298A>C) in the gene coding for MTHFR have been shown to reduce MTHFR enzyme activity and were associated with the susceptibility to different disorders, including vascular disease, neural tube defects and lymphoid malignancies. Studies on the role of these polymorphisms in the susceptibility to acute lymphoblastic leukemia (ALL) led to discrepant results. METHODS: We retrospectively evaluated the association of the MTHFR 677C>T and 1298A>C polymorphisms with pediatric ALL by genotyping a study sample of 443 ALL patients consecutively enrolled onto the German multicenter trial ALL-BFM 2000 and 379 healthy controls. We calculated odds ratios of MTHFR genotypes based on the MTHFR 677C>T and 1298A>C polymorphisms to examine if one or both of these polymorphisms are associated with pediatric ALL. RESULTS: No significant associations between specific MTHFR variants or combinations of variants and risk of ALL were observed neither in the total patient group nor in analyses stratified by gender, age at diagnosis, DNA index, immunophenotype, or TEL/AML1 rearrangement. CONCLUSION: Our findings suggest that the MTHFR 677C>T and 1298A>C gene variants do not have a major influence on the susceptibility to pediatric ALL in the German population

Anakoinosis: communicative reprogramming of tumor systems: for rescuing chemorefractory neoplasia

Disruptive technologies, such as communicative reprogramming (anakoinosis) with cellular therapies in situ for treating refractory metastatic cancer allow patient care to accelerate along a totally new trajectory and highlight what may well become the next sea change in the care of patients with many types of advanced neoplasia. Cellular therapy in situ consisted of repurposed drugs, pioglitazone plus all-trans retinoic acid or dexamethasone or interferon-alpha (dual transcriptional modulation) combined with metronomic low-dose chemotherapy or low-dose 5-azacytidine, plus/minus classic targeted therapy. The novel therapeutic tools for specifically designing communication processes within tumor diseases focus on redirecting (1) rationalizations of cancer hallmarks (constitution of single cancer hallmarks), (2) modular events, (3) the 'metabolism' of evolutionary processes (the sum of therapeutically and intrinsically inducible evolutionary processes) and (4) the holistic communicative context, which determines validity and denotation of tumor promoting communication lines. Published data on cellular therapies in situ (6 histologic tumor types, 144 patients, age 0.9-83 years) in castration-resistant prostate cancer, pretreated renal clear cell carcinoma, chemorefractory acute myelocytic leukemia, multiple myeloma > second-line, chemorefractory Hodgkin lymphoma or multivisceral Langerhans cell histiocytosis, outline the possibility for treating refractory metastatic cancer with the hope that this type of reprogrammed communication will be scalable with minimal toxicity. Accessibility to anakoinosis is a tumor inherent feature, and cellular therapy in situ addresses extrinsic and intrinsic drug resistance, by redirecting convergent organized communication tools, while been supported by quite different pattern of (molecular-)genetic aberrations

The ability to cross the blood-cerebrospinal fluid barrier is a generic property of acute lymphoblastic leukemia blasts

Prevention of central nervous system (CNS) relapse is critical for cure of childhood Bcell precursor acute lymphoblastic leukaemia (BCP-ALL). Despite this, mechanisms of CNS infiltration are poorly understood and the timing, frequency and properties of BCP-ALL blasts entering the CNS compartment are unknown. We investigated the CNS-engrafting potential of BCP-ALL cells xenotransplanted into immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mice. CNS engraftment was seen in 23/29 diagnostic samples (79%), 2/2 from patients with overt CNS disease and 21/27 (78%) from patients thought to be CNS-negative by diagnostic lumbar puncture. Histological findings mimic human pathology and demonstrate that leukaemic cells primarily transit the blood-cerebrospinal-fluid barrier sitting in close proximity to the dural sinuses – the site of recently discovered CNS lymphatics. Retrieval of blasts from the CNS showed no evidence for chemokine receptor-mediated selective trafficking. The high frequency of infiltration and lack of selective trafficking led us to postulate that CNS tropism is a generic property of leukaemic cells. To test this we performed serial dilution experiments, CNS engraftment was seen in 5/6 mice following transplantation of as few as 10 leukaemic cells. Finally, clonal tracking techniques confirmed the polyclonal nature of CNS infiltrating cells with multiple clones engrafting in both the CNS and periphery. Overall, these findings suggest that sub-clinical seeding of the CNS is likely to be present in the majority of BCP-ALL patients at original diagnosis and efforts to prevent CNS relapse should concentrate on augmenting effective eradication of disease from this site, rather than targeting entry mechanisms

Serum neurofilament light chain (sNfL) values in a large cross-sectional population of children with asymptomatic to moderate COVID-19

Background!#!Serum neurofilament light chain (sNfL) is an established biomarker of neuro-axonal damage in multiple neurological disorders. Raised sNfL levels have been reported in adults infected with pandemic coronavirus disease 2019 (COVID-19). Levels in children infected with COVID-19 have not as yet been reported.!##!Objective!#!To evaluate whether sNfL is elevated in children contracting COVID-19.!##!Methods!#!Between May 22 and July 22, 2020, a network of outpatient pediatricians in Bavaria, Germany, the Coronavirus antibody screening in children from Bavaria study network (CoKiBa), recruited healthy children into a cross-sectional study from two sources: an ongoing prevention program for 1-14 years, and referrals of 1-17 years consulting a pediatrician for possible infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We determined sNfL levels by single molecule array immunoassay and SARS-CoV-2 antibody status by two independent quantitative methods.!##!Results!#!Of the 2652 included children, 148 (5.6%) were SARS-CoV-2 antibody positive with asymptomatic to moderate COVID-19 infection. Neurological symptoms-headache, dizziness, muscle aches, or loss of smell and taste-were present in 47/148 cases (31.8%). Mean sNfL levels were 5.5 pg/ml (SD 2.9) in the total cohort, 5.1 (SD 2.1) pg/ml in the children with SARS-CoV-2 antibodies, and 5.5 (SD 3.0) pg/ml in those without. Multivariate regression analysis revealed age-but neither antibody status, antibody levels, nor clinical severity-as an independent predictor of sNfL. Follow-up of children with pediatric multisystem inflammatory syndrome (n = 14) showed no association with sNfL.!##!Conclusions!#!In this population study, children with asymptomatic to moderate COVID-19 showed no neurochemical evidence of neuronal damage