Risk factors for symptomatic venous thromboembolism during therapy for childhood acute lymphoblastic leukemia.

BACKGROUND: Symptomatic venous thromboembolism (VTE) is an unpredictable and life-threatening toxicity, which occurs early in childhood acute lymphoblastic leukemia (ALL) therapy. Approximately 5% of children will experience VTE which is treated with anticoagulation. Asparaginase and corticosteroids are etiologic factors for VTE, however other clinical factors may modify this risk. PROCEDURE: We sought to i) assess published pre-treatment VTE risk factors ii) identify early clinical factors that were associated with VTE and iii) determine whether single nucleotide polymorphisms (SNPs) associated with VTE in non-cancer patients contributed to VTE in children with ALL. We performed a detailed, retrospective analysis of 1021 ALL patients treated between 1998 and 2013. Individual patient records were reviewed to ascertain VTE incidence and document treatment-related clinical variables. RESULTS: The incidence of VTE was 5.1%. Extremes of weight at diagnosis (<5th or >95th centile) was an independent risk factor in multivariable analysis, when added to published risk factors of age ≥10 years and mediastinal mass. When factors during induction/consolidation were considered separately: bacteremia, elevated serum gamma-glutamyl transferase and bilirubin were associated with VTE occurrence. None of the SNPs associated with VTE in non-cancer populations were significantly associated with VTE in our cohort. CONCLUSION: We found two known risk factors (age ≥ 10 years and mediastinal mass) in a large cohort of children treated for ALL and identified other factors associated with VTE such as weight extremes at diagnosis, bacteremia, and abnormal liver function which warrant further study. These VTE risk factors may form the basis of future thromboprophylaxis trials.

Health-related quality of life of survivors of childhood acute lymphoblastic leukemia: a systematic review.

PURPOSE: Acute lymphoblastic leukemia (ALL) survivors are the largest group of childhood cancer survivors; however, their risk for late effects is high. Cancer-related late effects have the potential to compromise health-related quality of life (HRQL) long into survivorship. None of the reviews so far have focused on ALL solely, but described HRQL for all childhood cancers. We aimed to identify ALL survivors at risk for poor HRQL and identify possible risk factors. METHOD: Following PRISMA guidelines, we performed a systematic review, searching published literature in Pubmed, PsycInfo, Embase, and the Cochrane database including all publications up to December 16, 2016. Two independent reviewers (JV and ER) screened eligible articles and assessed article quality. RESULTS: We found 31 studies representing 4356 survivors and 901 proxies. Thirteen studies found worse, eight found no difference, and three better, overall HRQL scores compared with healthy controls or norms. ALL survivors typically had better overall HRQL scores than survivors of other childhood cancers. Clinical variables (e.g., treatment received) were not consistently associated with HRQL; however, experiencing worse late effects was associated with lower HRQL. Survivor and parent socio-demographic factors and psychological factors such as resilience and depression were also associated with HRQL. CONCLUSION: ALL survivors appeared to have worse or equivalent HRQL compared with controls, but better HRQL than survivors of other cancer types. However, studies reported a wide variability in HRQL and potential risk factors for poor HRQL. Measuring ALL survivors' HRQL longitudinally and comprehensively assessing potential risk factors might identify future avenues to intervene early.

Direct effects of Bmi1 on p53 protein stability inactivates oncoprotein stress responses in embryonal cancer precursor cells at tumor initiation.

Embryonal cancer can arise from postnatally persistent embryonal remnant or rest cells, which are uniquely characterized by the absence of p53 mutations. Perinatal overexpression of the MycN oncoprotein in embryonal cancer precursor cells causes postnatal rests, and later tumor formation through unknown mechanisms. However, overexpression of Myc in adult tissues normally activates apoptosis and/or senescence signals as an organismal defense mechanism against cancer. Here, we show that perinatal neuroblastoma precursor cells exhibited a transiently diminished p53 response to MycN oncoprotein stress and resistance to trophic factor withdrawal, compared with their adult counterpart cells from the TH-MYCN(+/+) transgenic mouse model of neuroblastoma. The adult stem cell maintenance factor and Polycomb group protein, Bmi1 (B-cell-specific Moloney murine leukemia virus integration site), had a critical role at neuroblastoma initiation in the model, by repressing p53 responses in precursor cells. We further show in neuroblastoma tumor cells that Bmi1 could directly bind p53 in a complex with other Polycomb complex proteins, Ring1A or Ring1B, leading to increased p53 ubiquitination and degradation. Repressed p53 signal responses were also seen in precursor cells for other embryonal cancer types, medulloblastoma and acute lymphoblastic leukemia. Collectively, these date indicate a general mechanism for p53 inactivation in some embryonal cell types and consequent susceptibility to MycN oncogenesis at the point of embryonal tumor initiation.

FBXW7 regulates glucocorticoid response in T-cell acute lymphoblastic leukaemia by targeting the glucocorticoid receptor for degradation.

Loss of function mutation in FBXW7, an E3 ubiquitin ligase, is associated with good prognosis and early glucocorticoid treatment response in childhood T-cell acute lymphoblastic leukemia (T-ALL) by unknown mechanisms. Here, we show that FBXW7 targets the glucocorticoid receptor α (GRα) for ubiquitylation and proteasomal degradation in a manner dependent on glycogen synthase kinase 3 ß-mediated phsophorylation. FBXW7 inactivation caused elevated GRα levels, and enhanced the transcriptional response to glucocorticoids. There was significant enhancement of GR transcriptional responses in FBXW7-deficient cell lines and primary T-ALL samples, in particular, for those pro-apoptotic regulatory proteins, BIM and PUMA. Reduced FBXW7 expression or function promoted glucocorticoid sensitivity, but not sensitivity to other chemotherapeutic agents used in T-ALL. Moreover, this was a general feature of different cancer cell types. Taken together, our work defines GRα as a novel FBXW7 substrate and demonstrates that favorable patient prognosis in T-ALL is associated with FBXW7 mutations due to enhanced GRα levels and steroid sensitivity. These findings suggest that inactivation of FBXW7, a putative tumor suppressor protein, may create a synthetic lethal state in the presence of specific anticancer therapies.

Long-term outcomes in children with high-risk neuroblastoma treated with autologous stem cell transplantation.

We retrospectively analysed the outcomes of children transplanted for high-risk neuroblastoma (NB) at a single institution predominantly transplanted with total body irradiation and chemotherapy. The aims of this study were to determine the prognostic impact of clinical and biological features and to document long-term health outcomes. Forty patients were transplanted with a single unpurged autograft. Fourteen patients died from disease progression and two from late complications of treatment. Twenty-three patients are alive at a median of 4.6 years from diagnosis. Kaplan-Meier estimates of overall survival at 2, 5 and 10 years are 76+/-7.0, 60.2+/-8.4 and 54.7+/-9.3% following transplant. Response to induction therapy was significantly associated with survival (P<0.01). Long-term complications included growth (100%) and pubertal failure (83%), hearing impairment (73%), orthopaedic complications (63%), renal impairment (47%) and thyroid abnormalities (36%). Intrinsic and acquired resistance to chemotherapy remains the major obstacle to improving outcomes in high-risk NB. Although patients with chemo-sensitive disease are less likely to experience a relapse, substantial therapy-related toxicities result in poor long-term health outcomes for survivors.

Adeno-associated virus and lentivirus vectors mediate efficient and sustained transduction of cultured mouse and human dorsal root ganglia sensory neurons.

Peripheral nervous system (PNS) sensory neurons are directly involved in the pathophysiology of numerous inherited and acquired neurological conditions. Therefore, efficient and stable gene delivery to these postmitotic cells has significant therapeutic potential. Among contemporary vector systems capable of neuronal transduction, only those based on herpes simplex virus have been extensively evaluated in PNS neurons. We therefore investigated the transduction performance of recombinant adeno-associated virus type 2 (AAV) and VSV-G-pseudotyped lentivirus vectors derived from human immunodeficiency virus (HIV-1) in newborn mouse and fetal human dorsal root ganglia (DRG) sensory neurons. In dissociated mouse DRG cultures both vectors achieved efficient transduction of sensory neurons at low multiplicities of infection (MOIs) and sustained transgene expression within a 28-day culture period. Interestingly, the lentivirus vector selectively transduced neurons in murine cultures, in contrast to human cultures, in which Schwann and fibroblast-like cells were also transduced. Recombinant AAV transduced all three cell types in both mouse and human cultures. After direct microinjection of murine DRG explants, maximal transduction efficiencies of 20 and 200 transducing units per neuronal transductant were achieved with AAV and lentivirus vectors, respectively. Most importantly, both vectors achieved efficient and sustained transduction of human sensory neurons in dissociated cultures, thereby directly demonstrating the exciting potential of these vectors for gene therapy applications in the PNS.