Long-term neurotoxicity among childhood acute lymphoblastic leukaemia survivors enrolled between 1971 and 1998 in EORTC Children Leukemia Group studies.

Survival after childhood acute lymphoblastic leukemia (ALL) has increased over the last 40 years with an overall survival above 90%. Survivors may experience neurological late effects secondary to chemotherapy and radiotherapy. This observational retrospective study evaluated the cumulative incidence of neurological late effects among 890 childhood ALL survivors treated in EORTC CLG trials (58741, 58831/2 and 58881) between 1971 and 1998. Median follow-up was 19 years and interquartile range of the follow-up was 15-22 years. At 20 years from the end of treatment, approximately 66% of patients from the 58741 trial (accrual time: 1971-1978) and approximately 15% from the more recent trials had cognitive disturbance grade 1 or higher. Cumulative incidences at 20 years from treatment end of seizures, stroke and leukoencephalopathy were respectively 45%, 16% and 62% in study 58741, 13%, 2% and 5% in study 58831/2, and 8%, 2% and 3% in study 58881. Patients who were 10-17 years of age at diagnosis had a higher incidence of stroke and leukoencephalopathy as compared to those less than 6 years of age. Noteworthy, all neurological late effects continued to occur beyond 5 years after end of treatment. This retrospective study highlights the frequency of neurological late effects in survivors of childhood ALL. With the increase of the overall survival of ALL patients, the role and potential benefit of longitudinal neurological screening should be evaluated in further studies as these neurological late effects become an important public health challenge. This study is part of the larger EORTC CLG 58 Late Adverse Effects (LAE) study (ClinicalTrials.gov Identifier NCT01298388, date of registration February 16, 2011).

Socio-economic outcomes among long-term childhood acute lymphoblastic leukaemia survivors enrolled between 1971 and 1998 in EORTC CLG studies: Results of the 58LAE study.

OBJECTIVE: The objective of this study is to evaluate the socio-economic outcomes of survivors of childhood acute lymphoblastic leukaemia (ALL). METHODS: Childhood ALL adult survivors, enrolled in EORTC trials between 1971 and 1998 in France and Belgium, were invited to fill out a questionnaire with information about their socio-economic situation (living with a partner, having a university degree, having a job, working part time and history of having a paid job). The outcomes were compared with two matched control populations. RESULTS: Among 1418 eligible patients, 507 (35.8%) participated, including 39 (8%) and 61 (12%) patients who received a haematopoietic stem cell transplantation (HSCT) and a cranial radiotherapy (CRT), respectively. The median time to follow-up was 20 years, and median age was 25 years. Survivors showed a socio-economic level at least as good as controls. HCST and CRT were associated with a higher probability of not obtaining a bachelor degree (respectively OR = 3.49, 95% CI: 1.46-8.35 and OR = 2.31, 95% CI: 1.04-5.15), HSCT was associated with unemployment (OR = 2.89, 95% CI: 1.09-7.65) and having a relapse was associated with a higher probability of not having a partner (OR = 1.88, 95% CI: 1.01-3.51) adjusting for confounders. CONCLUSION: Childhood ALL survivors showed a high level of socio-economic participation. HCST and CRT were associated with poorer functioning.

Quality of life of long-term childhood acute lymphoblastic leukemia survivors: Comparison with healthy controls.

OBJECTIVE: Improved treatment landscape has led to better outcomes for paediatric acute lymphoblastic leukemia (ALL) survivors. As the number of survivors increase, we need to elucidate the long-term quality of life (QoL) and domains of complaints in these patients. Furthermore, the main priorities of these patients need to be clarified. We assessed long-term QoL outcomes of survivors of childhood ALL compared to matched population controls. METHODS: QoL data were collected from survivors recruited in France and Belgium between 2012 and 2017, including the Short Form Health Survey (SF-12) and the Quality of Life Systemic Inventory (QLSI). The Wilcoxon test was used to compare SF-12 scale scores between survivors and matched population controls. For the QLSI, comparisons were mainly descriptive. RESULTS: One hundred and eighty-six survivors (mean age: 27.6 years; range: 18.1-52.8) at follow-up completed QoL measures, amongst whom 180 were matched to controls. Overall, survivors had higher QoL on all SF12 scale scores, indicating that they had better functioning compared to controls. Statistically significant differences on the SF12 were observed for Vitality, Social Functioning, Role Limitations due to Emotional Problems and Mental Health scales. QLSI outcomes suggested that survivors were happier than controls with Couple and Social Relations. Controls were unhappiest compared to survivors with Money, Love life, Self-esteem, Nutrition and Paid Work. CONCLUSIONS: Our findings suggest that survivors of childhood ALL have better QoL outcomes on some domains compared to the general population, specifically around social and emotional functioning, and that they tend to prioritize their relationships more. Interventions for improving QoL outcomes, might build on existing positive experiences with family, friends and partners.

Fertility status among long-term childhood acute lymphoblastic leukaemia survivors enrolled between 1971 and 1998 in EORTC CLG studies: results of the 58 Late Adverse Effects study.

STUDY QUESTION: What are the fertility outcomes of male and female childhood acute lymphoblastic leukaemia (ALL) long-term survivors? SUMMARY ANSWER: We observed similar fertility outcomes in both male and female childhood ALL survivors compared with the general population, with the exception of a higher proportion of miscarriages among partners of male survivors. WHAT IS KNOWN ALREADY: Survival after childhood ALL is currently >90% and fertility impairments are among the main concerns of the long-term survivors. Few studies have focused on the fertility issues within this selected population and the existing data are difficult to interpret due to the different treatment regimens received by the patients, the small sample sizes and the unavailability of control data in many studies. STUDY DESIGN, SIZE, DURATION: Childhood ALL patients enrolled in European Organisation for Research and Treatment of Cancer (EORTC) studies between 1971 and 1998 in France and Belgium, <18 years old at diagnosis and alive and ≥18 years at follow-up were eligible. Among 1418 eligible survivors, 507 (35.8%) participated (277 females, 230 males). Controls from the general population matched one to one by age, province, level of urbanization and sex could be identified for 503 survivors. PARTICIPANTS/MATERIALS, SETTING, METHODS: Survivors and controls were invited to fill out a questionnaire including information about their menstrual cycles (for females), intention to have children, having children, use of medical help to become pregnant and occurrence of negative pregnancy outcomes (birth defect, miscarriage, medical abortion or stillbirth). The results were analysed separately for females and males. The association between age at diagnosis and fertility outcomes, adjusted by age at follow-up, study and country were investigated using logistic regression. MAIN RESULTS AND THE ROLE OF CHANCE: The median time since diagnosis was 20.1 years and the median age at follow-up was 25 years. There were 144 survivors (97 females, 47 males) who wanted to have children. Among these, craniospinal radiotheraphy (CRT) and haematopoietic stem cell transplantation (HSCT) were administered to 18% and 4%, respectively. Of these who tried to have children, 75% of females and 69% of males succeeded, compared with 72% and 61% of the controls, respectively. These differences were not statistically significant (P = 0.73 for females and P = 0.50 for males). Overall, fertility outcomes were comparable between survivors and controls, except that a higher proportion of miscarriages occurred in partners of male survivors (28.1% versus 5.9%, P = 0.021). Among female survivors, an older age at diagnosis (10-17 years) was associated with a greater risk of pregnancy problems (adjusted OR 5.61, P = 0.046). LIMITATIONS, REASONS FOR CAUTION: The interpretation of the incidence of miscarriage among the partners of male survivors is limited by the lack of data regarding the males' partners and by a possibly higher tendency to recall and disclose fertility issues among male survivors compared with male controls. WIDER IMPLICATIONS OF THE FINDINGS: Fertility outcomes were similar in childhood ALL survivors and controls, and the low proportion of patients treated with CRT or HSCT might explain this. Further studies should confirm the higher proportion of miscarriages in partners of male survivors. STUDY FUNDING/COMPETING INTEREST(S): This publication was supported by donations from the Fonds Cancer (FOCA) from Belgium and the KU Leuven from Belgium. G.R. has been awarded a fellowship by the EORTC Cancer Research Fund (ECRF). C.P. has been awarded a fellowship by Fonds Cancer (FOCA) from Belgium and the Kinderkankerfonds from Belgium (a non-profit childhood cancer foundation under Belgian law). No competing interests were declared. TRIAL REGISTRATION NUMBER: NCT01298388 (clinicaltrials.gov).

Sociodemographic and Medical Determinants of Quality of Life in Long-Term Childhood Acute Lymphoblastic Leukemia Survivors Enrolled in EORTC CLG Studies.

BACKGROUND: due to increasing survival rates in childhood acute lymphoblastic leukemia (ALL), the number of survivors has been expanding. A significant proportion of these survivors can experience long-term emotional and psychosocial problems. However, the exact risk factors remain inconclusive. We investigated potential risk factors for decreased daily life quality and life challenges in long-term childhood ALL survivors enrolled between 1971 and 1998 in EORTC studies. METHODS: self-report questionnaires were collected from 186 survivors (109 females; mean age at diagnosis 5.62 years, range 0.2-14.7; median time since diagnosis of 20.5 years (12.9-41.6)), including the Short-Form Health Survey (SF-12) and Impact of Cancer-Childhood Survivors (IOC-CS). Multivariable linear regression models were used to assess the impact of gender, age at diagnosis, relapse/second neoplasm, National Cancer Institute (NCI) risk group and cranial radiotherapy on 2 subscales of the SF-12 (physical and mental health) and five subscales of the IOC-CS (life challenges, body and health, personal growth, thinking and memory problems and socializing). RESULTS: mental component scores of SF-12 were not significantly associated with any risk factor. Physical component scores were lower in relapsed, irradiated and NCI high-risk patients. Regarding IOC-CS negative impact subscales, life challenges was more negatively impacted by cancer in female, younger (i.e., <6 years) and relapsed patients. Regarding the positive impact scales, personal growth was more positively impacted in relapsed patients, whereas body and health, and socializing, were less positively impacted in these patients, compared to non-relapsed patients. Socializing was more positively impacted in older patients (>6 years). CONCLUSIONS: this study demonstrates that long-term outcomes can be both adverse and positive, depending on the patient's demographic and clinical characteristics. Younger, female, and relapsed patients might encounter more life challenges years after their disease, while physical challenges could occur more often in relapsed and high-risk patients. Finally, the positive effect on socializing in the older patients sheds new light on the importance of peer interactions for this subgroup. Specific individual challenges thus need specialized support for specific subgroups.

Prospective, real-time monitoring of pegylated Escherichia coli and Erwinia asparaginase therapy in childhood acute lymphoblastic leukaemia and non-Hodgkin lymphoma in Belgium.

Asparaginase (ASNase) is an important anti-leukaemic drug in the treatment of childhood acute lymphoblastic leukaemia (ALL) and non-Hodgkin lymphoma (NHL). A substantial proportion of patients develop hypersensitivity reactions with anti-ASNase neutralising antibodies, resulting in allergic reactions or silent inactivation (SI), and characterised by inactivation and rapid clearance of ASNase. We report results of a prospective, real-time therapeutic drug monitoring of pegylated Escherichia coli (PEG-)ASNase and Erwinia ASNase in children treated for ALL and NHL in Belgium. Erwinia ASNase was given as second-line after hypersensitivity to PEG-ASNase. In total, 286 children were enrolled in the PEG-ASNase cohort. Allergy was seen in 11·2% and SI in 5·2% of patients. Of the 42 patients treated with Erwinia ASNase, 7·1% experienced allergy and 2·4% SI. The median trough PEG-ASNase activity was high in all patients without hypersensitivity. After Erwinia administration significantly more day 3 samples had activities <100 IU/l (62·5% vs. 10% at day 2 (D2)). The median D2 activity was significantly higher for intramuscular (IM; 347 IU/l) than for intravenous Erwinia administrations (159 IU/l). This prospective, multicentre study shows that monitoring of ASNase activity during treatment of children with ALL and NHL is feasible and informative. Treatment with Erwinia ASNase warrants close monitoring and optimally adherence to a 2-day interval of IM administrations.

Long-term outcome evaluation of medium/high risk acute lymphoblastic leukaemia children treated with or without cranial radiotherapy in the EORTC 58832 randomized study.

We investigated the long-term outcome, the incidence of second neoplasms (SN) and the rate of late adverse effects (LAE) in children with central nervous system (CNS) negative medium/high-risk de novo acute lymphoblastic leukaemia (ALL), in first complete remission (CR1) at end of late intensification, randomized to receive no cranial radiotherapy (No CRT, n = 92) versus CRT (standard arm, n = 84) in the non-inferiority EORTC 58832 study (1983-1989). Median follow-up was 20 years (range 4-32 years). The 25-year disease-free survival rate (±SE) was 67·4 ± 4·9% without CRT and 70·2 ± 5·0% with CRT. The 25-year incidence of isolated (6·5 ± 2·6% vs. 4·8 ± 2·3%) and any CNS relapse {8·7 ± 2·9% vs. 11·9 ± 3·5%; hazard ratio (HR) 0·71 [95% confidence interval (CI) 0·28-1·79]; test of non-inferiority: P = 0·01} was not increased without CRT. The 25-year SN incidence in CR1 was 7·9 ± 4·6% vs. 11·0 ± 4·2%. The 25-year event-free and overall survival rates were quite similar in both arms [59·5 ± 6·3% vs. 60·5 ± 5·9%, HR 0·94 (95% CI 0·57-1·52), and 78·1 ± 4·3% vs. 78·5 ± 4·5%, HR 1·00 (95% CI 0·53-1·88)]. Omission of CRT was associated with dramatic decrease in CNS and endocrine LAE rates. In conclusion, our data suggest that, with proper systemic and intrathecal CNS prophylaxis, CRT could totally be omitted in CR1 without jeopardizing survival, while decreasing LAE in childhood ALL.

Prolonged versus standard native E. coli asparaginase therapy in childhood acute lymphoblastic leukemia and non-Hodgkin lymphoma: final results of the EORTC-CLG randomized phase III trial 58951.

Asparaginase is an essential component of combination chemotherapy for childhood acute lymphoblastic leukemia and non-Hodgkin lymphoma. The value of asparaginase was further addressed in a group of non-very high-risk patients by comparing prolonged (long-asparaginase) versus standard (short-asparaginase) native E. coli asparaginase treatment in a randomized part of the phase III 58951 trial of the European Organization for Research and Treatment of Cancer Children's Leukemia Group. The main endpoint was disease-free survival. Overall, 1,552 patients were randomly assigned to long-asparaginase (775 patients) or short-asparaginase (777 patients). Patients with grade ≥2 allergy to native E. coli asparaginase were switched to equivalent doses of Erwinia or pegylated E. coli asparaginase. The 8-year disease-free survival rate (±standard error) was 87.0±1.3% in the long-asparaginase group and 84.4±1.4% in the short-asparaginase group (hazard ratio: 0.87; P=0.33) and the 8-year overall survival rate was 92.6±1.0% and 91.3±1.2% respectively (hazard ratio: 0.89; P=0.53). An exploratory analysis suggested that the impact of long-asparaginase was beneficial in the National Cancer Institute standard-risk group with regards to disease-free survival (hazard ratio: 0.70; P=0.057), but far less so with regards to overall survival (hazard ratio: 0.89). The incidences of grade 3-4 infection during consolidation (25.2% versus 14.4%) and late intensification (22.6% versus 15.9%) and the incidence of grade 2-4 allergy were higher in the long-asparaginase arm (30% versus 21%). Prolonged native E. coli asparaginase therapy in consolidation and late intensification for our non-very high-risk patients did not improve overall outcome but led to an increase in infections and allergy. This trial was registered at www.clinicaltrials.gov as #NCT00003728.

Intellectual development of childhood ALL patients: a multicenter longitudinal study.

BACKGROUND: In childhood acute lymphoblastic leukemia (ALL), radiotherapy for CNS prophylaxis is not used in frontline therapy anymore. Standard treatment for ALL nowadays consists of polychemotherapy. Therefore, assessment of potential chemotherapy-induced cognitive side effects becomes important. Although neurotoxicity was demonstrated in cross-sectional studies, longitudinal studies remain scarce. PROCEDURE: We evaluated intellectual development of 94 pediatric ALL patients between 1990 and 1997, diagnosed before the age of 12 years, treated according to the European Organisation for Research and Treatment of Cancer Children's Leukemia Group 58881 protocol. Three assessments of the Wechsler Intelligence Scale for Children Revised were performed since diagnosis, according to age. Using repeated measures regression analysis, we investigated the effect of gender (low versus increased) risk group, parents' education, age at diagnosis, intelligence quotient (IQ) subscale (verbal (VIQ) versus performance (PIQ) intelligence), and test session. RESULTS: PIQ scores were lower than VIQ at baseline (-5.3 points on average, p = 0.0032), yet PIQ increased more strongly (PIQ: +3.9 points per test session; VIQ: +0.8, p = 0.0079), so this baseline difference disappeared (p = 0.0079). There were no clear effects of gender (girls: +0.6 points; p = 0.78) or risk group (low risk: +1.5 points; p = 0.49), but IQ scores were higher when one parent had followed higher education (+9.5 points, p < 0.0001). Finally, diagnosis at younger age predicted lower IQ scores (-1.3 points per year, p = 0.0009). CONCLUSION: Given that IQ scores did not decline, our findings demonstrate a stable pattern. However, the lower PIQ scores at baseline may indicate that performance functioning is vulnerable to acute neurotoxicity. Also, lower scores for younger patients highlight the stronger impact of the disease and/or treatment at younger age.Copyright © 2016 John Wiley & Sons, Ltd.

Unique long non-coding RNA expression signature in ETV6/RUNX1-driven B-cell precursor acute lymphoblastic leukemia.

Overwhelming evidence indicates that long non-coding RNAs have essential roles in tumorigenesis. Nevertheless, their role in the molecular pathogenesis of pediatric B-cell precursor acute lymphoblastic leukemia has not been extensively explored. Here, we conducted a comprehensive analysis of the long non-coding RNA transcriptome in ETV6/RUNX1-positive BCP-ALL, one of the most frequent subtypes of pediatric leukemia. First, we used primary leukemia patient samples to identify an ETV6/RUNX1 specific expression signature consisting of 596 lncRNA transcripts. Next, integration of this lncRNA signature with RNA sequencing of BCP-ALL cell lines and lncRNA profiling of an in vitro model system of ETV6/RUNX1 knockdown, revealed that lnc-NKX2-3-1, lnc-TIMM21-5, lnc-ASTN1-1 and lnc-RTN4R-1 are truly regulated by the oncogenic fusion protein. Moreover, sustained inactivation of lnc-RTN4R-1 and lnc-NKX2-3-1 in ETV6/RUNX1 positive cells caused profound changes in gene expression. All together, our study defined a unique lncRNA expression signature associated with ETV6/RUNX1-positive BCP-ALL and identified lnc-RTN4R-1 and lnc-NKX2-3-1 as lncRNAs that might be functionally implicated in the biology of this prevalent subtype of human leukemia.

Different outcome of T cell acute lymphoblastic leukemia with translocation t(11;14) treated in two consecutive children leukemia group EORTC trials.

Acute lymphoblastic leukemia of T cell lineage (T-ALL) is an aggressive malignant disease which accounts for 15 % of childhood ALL. T(11;14) is the more frequent chromosomal abnormality in childhood T-ALL, but its prognostic value remained controversial. Our aim was to analyze the outcome of childhood T-ALL with t(11;14) to know if the presence of this translocation is associated with a poor prognosis. We conducted a retrospective study from a series of 20 patients with t(11;14), treated in two consecutive trials from the European Organization for Research and Treatment of Cancer Children Leukemia Group over a 19-year period from 1989 to 2008. There were no significant differences between the 2 consecutive groups of patients with t(11;14) regarding the clinical and biological features at diagnosis. Among 19 patients who reached complete remission, 9 patients relapsed. We noticed 7 deaths all relapse- or failure-related. In the 58881 study, a presence of t(11;14) was associated with a poor outcome with an event-free survival at 5 years at 22.2 % versus 65.1 % for the non-t(11;14) T-ALL (p = 0.0004). In the more recent protocol, the outcome of T-ALL with t(11;14) reached that of non-t(11;14) T-ALL with an event-free survival at 5 years at 65.5 versus 74.9 % (p = 0.93). The presence of t(11;14) appeared as a poor prognostic feature in the 58881 trial whereas this abnormality no longer affected the outcome in the 58951 study. This difference is probably explained by the more intensive chemotherapy in the latest trial.

Evaluation of timing of first vaccination in children after hematopoietic allogeneic stem cell transplantation.

PURPOSE: Protective immunity to vaccine preventable infectious diseases might be lost over time following hematopoietic stem cell transplantation (HSCT). Limited data are available on the appropriate follow-up of vaccination schedules in pediatric HSCT patients. This study aims to ascertain whether the guidelines for vaccination recommended in our hospital are followed and to which extent of conformity they are used. METHODS: A 5-year survey, including all pediatric allogeneic HSCT patients, transplanted at the Ghent University hospital, Belgium. Data were collected from the patient's electronic (nursing and medical) charts. RESULTS: Data on vaccination schedules of 28 patients (54.9%) eligible for the recommended vaccinations were collected. Eleven patients (11/28; 39.3%) were vaccinated timely. In 14 out of 17 patients (82.4%) vaccination was postponed for medical reasons, while vaccination was postponed without medical reason in 17.6% (3/17). Vaccination data could not be retrieved in 43.1 (22/51) of patients. Vaccination was declined by the parents in one patient (2.0%). CONCLUSION: There is high level of agreement between the hospital guideline and the vaccination of pediatric HSCT patients. Health-care providers play a crucial role in effectively appropriate follow-up of vaccination schedules.

LIN28B overexpression defines a novel fetal-like subgroup of juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is a rare and aggressive stem cell disease of early childhood. RAS activation constitutes the core component of oncogenic signaling. In addition, leukemic blasts in one-fourth of JMML patients present with monosomy 7, and more than half of patients show elevated age-adjusted fetal hemoglobin (HbF) levels. Hematopoietic stem cell transplantation is the current standard of care and results in an event-free survival rate of 50% to 60%, indicating that novel molecular-driven therapeutic options are urgently needed. Using gene expression profiling in a series of 82 patient samples, we aimed at understanding the molecular biology behind JMML and identified a previously unrecognized molecular subgroup characterized by high LIN28B expression. LIN28B overexpression was significantly correlated with higher HbF levels, whereas patients with monosomy 7 seldom showed enhanced LIN28B expression. This finding gives a biological explanation of why patients with monosomy 7 are rarely diagnosed with high age-adjusted HbF levels. In addition, this new fetal-like JMML subgroup presented with reduced levels of most members of the let-7 microRNA family and showed characteristic overexpression of genes involved in fetal hematopoiesis and stem cell self-renewal. Lastly, high LIN28B expression was associated with poor clinical outcome in our JMML patient series but was not independent from other prognostic factors such as age and age-adjusted HbF levels. In conclusion, we identified elevated LIN28B expression as a hallmark of a novel fetal-like subgroup in JMML.

Childhood Acute Lymphoblastic Leukemia: Progress Through Collaboration.

PURPOSE: To review the impact of collaborative studies on advances in the biology and treatment of acute lymphoblastic leukemia (ALL) in children and adolescents. METHODS: A review of English literature on childhood ALL focusing on collaborative studies was performed. The resulting article was reviewed and revised by the committee chairs of the major ALL study groups. RESULTS: With long-term survival rates for ALL approaching 90% and the advent of high-resolution genome-wide analyses, several international study groups or consortia were established to conduct collaborative research to further improve outcome. As a result, treatment strategies have been improved for several subtypes of ALL, such as infant, MLL-rearranged, Philadelphia chromosome-positive, and Philadelphia chromosome-like ALL. Many recurrent genetic abnormalities that respond to tyrosine kinase inhibitors and multiple genetic determinants of drug resistance and toxicities have been identified to help develop targeted therapy. Several genetic polymorphisms have been recognized that show susceptibility to developing ALL and that help explain the racial/ethnic differences in the incidence of ALL. CONCLUSION: The information gained from collaborative studies has helped decipher the heterogeneity of ALL to help improve personalized treatment, which will further advance the current high cure rate and the quality of life for children and adolescents with ALL.

MYCN-driven regulatory mechanisms controlling LIN28B in neuroblastoma.

LIN28B has been identified as an oncogene in various tumor entities, including neuroblastoma, a childhood cancer that originates from neural crest-derived cells, and is characterized by amplification of the MYCN oncogene. Recently, elevated LIN28B expression levels were shown to contribute to neuroblastoma tumorigenesis via let-7 dependent de-repression of MYCN. However, additional insight in the regulation of LIN28B in neuroblastoma is lacking. Therefore, we have performed a comprehensive analysis of the regulation of LIN28B in neuroblastoma, with a specific focus on the contribution of miRNAs. We show that MYCN regulates LIN28B expression in neuroblastoma tumors via two distinct parallel mechanisms. First, through an unbiased LIN28B-3'UTR reporter screen, we found that miR-26a-5p and miR-26b-5p regulate LIN28B expression. Next, we demonstrated that MYCN indirectly affects the expression of miR-26a-5p, and hence regulates LIN28B, therefore establishing an MYCN-miR-26a-5p-LIN28B regulatory axis. Second, we provide evidence that MYCN regulates LIN28B expression via interaction with the LIN28B promoter, establishing a direct MYCN-LIN28B regulatory axis. We believe that these findings mark LIN28B as an important effector of the MYCN oncogenic phenotype and underline the importance of MYCN-regulated miRNAs in establishing the MYCN-driven oncogenic process.

Novel biological insights in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive type of blood cancer that accounts for about 15% of pediatric and 25% of adult acute lymphoblastic leukemia (ALL) cases. It is considered as a paradigm for the multistep nature of cancer initiation and progression. Genetic and epigenetic reprogramming events, which transform T-cell precursors into malignant T-ALL lymphoblasts, have been extensively characterized over the past decade. Despite our comprehensive understanding of the genomic landscape of human T-ALL, leukemia patients are still treated by high-dose multiagent chemotherapy, potentially followed by hematopoietic stem cell transplantation. Even with such aggressive treatment regimens, which are often associated with considerable acute and long-term side effects, about 15% of pediatric and 40% of adult T-ALL patients still relapse, owing to acquired therapy resistance, and present with very dismal survival perspectives. Unfortunately, the molecular mechanisms by which residual T-ALL tumor cells survive chemotherapy and act as a reservoir for leukemic progression and hematologic relapse remain poorly understood. Nevertheless, it is expected that enhanced molecular understanding of T-ALL disease biology will ultimately facilitate a targeted therapy driven approach that can reduce chemotherapy-associated toxicities and improve survival of refractory T-ALL patients through personalized salvage therapy. In this review, we summarize recent biological insights into the molecular pathogenesis of T-ALL and speculate how the genetic landscape of T-ALL could trigger the development of novel therapeutic strategies for the treatment of human T-ALL.

CD200/BTLA deletions in pediatric precursor B-cell acute lymphoblastic leukemia treated according to the EORTC-CLG 58951 protocol.

DNA copy number analysis has been instrumental for the identification of genetic alterations in B-cell precursor acute lymphoblastic leukemia. Notably, some of these genetic defects have been associated with poor treatment outcome and might be relevant for future risk stratification. In this study, we characterized recurrent deletions of CD200 and BTLA genes, mediated by recombination-activating genes, and used breakpoint-specific polymerase chain reaction assay to screen a cohort of 1154 cases of B-cell precursor acute lymphoblastic leukemia uniformly treated according to the EORTC-CLG 58951 protocol. CD200/BTLA deletions were identified in 56 of the patients (4.8%) and were associated with an inferior 8-year event free survival in this treatment protocol [70.2% ± 1.2% for patients with deletions versus 83.5% ± 6.4% for non-deleted cases (hazard ratio 2.02; 95% confidence interval 1.23-3.32; P=0.005)]. Genetically, CD200/BTLA deletions were strongly associated with ETV6-RUNX1-positive leukemias (P<0.0001), but were also identified in patients who did not have any genetic abnormality that is currently used for risk stratification. Within the latter population of patients, the presence of CD200/BTLA deletions was associated with inferior event-free survival and overall survival. Moreover, the multivariate Cox model indicated that these deletions had independent prognostic impact on event-free survival when adjusting for conventional risk criteria. All together, these findings further underscore the rationale for copy number profiling as an important tool for risk stratification in human B-cell precursor acute lymphoblastic leukemia. This trial was registered at www.ClinicalTrials.gov as #NCT00003728.