Outcome In Childhood Acute Lymphoblastic Leukemia Research Articles

Invasive fungal diseases impact on outcome of childhood ALL – an analysis of the international trial AIEOP-BFM ALL 2009

In children with acute lymphoblastic leukemia (ALL), risk groups for invasive fungal disease (IFD) with need for antifungal prophylaxis are not well characterized, and with the advent of new antifungal compounds, current data on outcome are scarce. Prospectively captured serious adverse event reports of children enrolled in the international, multi-center clinical trial AIEOP-BFM ALL2009 were screened for proven/probable IFD, defined according to the updated EORTC/MSG consensus definitions. In a total of 6136 children (median age 5.2 years), 224 proven/probable IFDs (65 yeast and 159 mold) were reported. By logistic regression, the risk for proven/probable IFDs was significantly increased in children ≥12 years and those with a blast count ≥10% in the bone marrow on day 15 (P < 0.0001 each). Proven/probable IFDs had a 6-week and 12-week mortality of 10.7% and 11.2%, respectively. In the multivariate analysis, the hazard ratio for event-free and overall survival was significantly increased for proven/probable IFD, age ≥12 years, and insufficient response to therapy (P < 0.001, each). Our data define older children with ALL and those with insufficient treatment-response at high risk for IFD. As we show that IFD is an independent risk factor for event-free and overall survival, these patients may benefit from targeted antifungal prophylaxis.

Epigenetic Fine Mapping and Functional Dissection of Inherited Non-Coding Variation Impacting the Pharmacogenomics of Acute Lymphoblastic Leukemia Treatment

Acute lymphoblastic leukemia (ALL) is the most prevalent childhood cancer. Despite cure rates exceeding 90%, relapsed ALL is the 5th most common pediatric cancer. Although chemotherapeutic drug resistance remains the primary cause of treatment failure and relapse, it remains unclear to what extent non-coding inherited DNA sequence variants impact gene regulatory programs that contribute to differences in chemotherapeutic drug resistance and clinical outcome in childhood ALL. To address this knowledge gap we performed epigenetic fine mapping on inherited non-coding DNA sequence variants associated with ex vivo resistance to six antileukemic agents (dexamethasone, prednisolone, l-asparaginase, vincristine, 6-mercaptopurine and 6-thioguanine) in primary ALL cells from pediatric patients and inherited non-coding DNA sequence variants associated with clinical outcome (persistence of minimal residual disease and relapse) in pediatric patient cohorts using chromatin accessibility data from over 130 primary ALL cells, ALL cell lines and ALL xenografts. This analysis fine mapped over 1700 variants (sentinel variants and variants in high linkage disequilibrium; r2>0.8) to cis-regulatory elements in the ALL genome. To comprehensively dissect the functional effects of these fine mapped variants on gene regulatory activity we performed massively parallel reporter assays (MPRAs) in 10 human ALL cell lines of both B- and T-cell lineages. MPRAs utilized 23 DNA barcodes per variant allele and tested variants at bidirectional promoters using both sequence orientations. In total, 98,168 oligonucleotides each containing 175-bp of genomic sequence centered on each variant allele and a unique 10-bp barcode sequence were evaluated for gene regulatory activity. MPRA identified 558 variants with significant and concordant allele-specific activities in three or more ALL cell lines. Expression quantitative trait loci (eQTL) mapping and HiChIP three-dimensional promoter loop profiling identified candidate target genes for a subset of functional variants. We additionally evaluated the functional effects of top ranked variants using luciferase reporter assays and CRISPR/Cas9 genome editing. These variants were associated with the expression of B3GNT5, CACUL1, HERC1, KDM4C and VRK3. Notably, two of these functional variants (rs10411204 and rs1247117) impacted transcription factor (TF) consensus DNA motifs for AP-1 family TFs and PU.1. Collectively, these data suggest that many inherited non-coding variants associated with pharmacogenomic traits in childhood ALL have significant gene regulatory effects. Importantly, the identification of chemotherapeutic drug resistance-associated molecular pathways perturbed by inherited non-coding variants can improve our ability to circumvent drug resistance with novel therapeutic approaches.

PB1758: TWENTY-ONE YEARS’ EXPERIENCE OF THE EORTC 58951 PROTOCOL FOR THE TREATMENT OF CHILDHOOD ACUTE LYMPHOBLASTIC LEUKEMIA IN THE SOUTH OF TUNISIA

Background: Childhood acute lymphoblastic leukemia (ALL) is a hematologic malignancy with high rate of cure. Aims: We report the experience of the clinical hematology department of Sfax-Tunisia for the treatment of childhood ALL with the EORTC 58951 protocol. Methods: From January 2000 to December 2020, we retrospectively studied the outcome of childhood ALL aged less 16 years, treated with the EORTC 58951 pediatric protocol. For those patients we studied the leukemia characteristics (sex ratio, white blood cell counts WBC, blast’s phenotype, cytogenetic abnormalities) and response to treatment: response to prophase, remission rate, risk group stratification, treatment related mortality (TRM) (induction and post induction death) and survival (overall survival OS and event free survival. Results: From January 2000 to December 2020, 284 children were treated with the EORTC 58951 protocol. Medium age was 7 years (range: 1 to 15 years). Sex ratio M/F was 1.53. WBC counts more than 100 G/L were observed respectively in 41, 44 and 15% of cases. The blast’s phenotype was B in 70%. Cytogenetic abnormalities were noted in 37% of cases. A good response to prophase was noted in 80% and complete remission in 92% of cases. The EORTC risk group stratification was Low Risk (LR) in 5%, Average Risk1 (AR1) in 39%, Average Risk2 (AR2) in 25% and Very High Risk (VHR) in 31%. TRM was 10%: induction rate death was 6% and post-induction rate death was 4%. Twenty-eight patients from VHR group with sibling familial donor underwent allograft. The relapse rate was 29% of all patients in remission; 4% for LR group, 39% for AR1 group, 18% for AR2 group and 39% for VHR group. At a follow up of 126 months, OS and EFS at 10 years were respectively 61% and 56%. Summary/Conclusion: At diagnosis, childhood ALL in our study had poor characteristics particularly higher rate of T phenotype of blasts, higher rate of leukocytosis more than 100 G/L, higher rate of VHR therapeutic group and higher rate of cortico-resistant regarding occidental series. Despite the acceptable results concerning remission rate but survival rates remain lower than those observed in the literature, this is explained mainly by the high rate of relapse (29% vs ≃15%). It can be improved our results by detecting high risk patient with MRD study especially for AR1 risk group and doing allograft for VHR patients.

Longer Time Intervals From Symptom Onset to Diagnosis Affect the Overall Survival in Children With Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Early diagnosis and timely treatment are essential for effective cancer control and have been widely analyzed in childhood cancer. However, few studies have described the time to diagnosis and treatment in children with ALL. This study investigated delays in diagnosis and treatment initiation and their impact on survival. This retrospective cohort study included 419 patients 0 to 14 years old at a tertiary hospital between 2011 and 2015. The optimal cutoff values for delays were determined by X-tile software. The Kaplan-Meier method and Cox regression models were used to evaluate the impact of delays on survival. The median diagnosis, treatment, and total delays were 21 (interquartile range [IQR]: 11-35), 4 (IQR: 2-7), and 26 (IQR: 16-43) days, respectively. The results of multivariate analyses showed that diagnosis delay, risk stratification, and minimal residual disease level were independent predictors for treatment outcome in childhood ALL. These findings suggested that a longer time to diagnosis negatively affected the clinical outcome of childhood ALL. Reducing the time to diagnosis could help to improve survival in these patients.

Treatment outcomes for childhood acute lymphoblastic leukemia in low-middle income country before minimal residual disease risk stratification

BackgroundOutcome of childhood acute lymphoblastic leukemia (ALL) in low- and middle-income countries is lagging in many aspects including diagnosis, risk stratification, access to treatment and supportive care. Objectiveto report the outcome of childhood ALL at Ain Shams University Children’s Hospitals with the use of risk-based protocols before the implementation of minimal residual disease technology and to evaluate the use of double delayed intensification (DDI) in standard risk patients. MethodsTwo hundred and twenty patients with ALL diagnosed between January 2005 and December 2014 were included in the study. Patients were treated according to a modified CCG 1991 and 1961 for standard and high risk respectively. Patients were stratified into three risk groups: standard risk (SR), high-risk standard arm (HR-SA), and high-risk augmented arm (HR-AA). ResultsAmong the whole cohort, the 10-year event-free survival (EFS) and overall survival (OS) were 78.1% and 84.3% respectively. Patients with Pre-B immunophenotype (IPT) had significantly better outcome than T-cell IPT (EFS 82.0% versus 58.6%, p < 0.001; OS 86.9% versus 69%, p = 0.003 for Pre-B and T-cell respectively). Among the SR group, patients treated with single delayed intensification (SDI) had comparable EFS and OS rates when compared to patients treated with DDI with EFS 82.4% versus 87.5%, p = 0.825 and OS 88.2% versus 93.5%, p = 0.638 for SDI and DDI groups, respectively. ConclusionThe use of risk-based protocol with simple laboratory techniques resulted in acceptable survival outcome in resource limited settings. The use of double delayed intensification showed no survival advantage in patients with standard risk.

Update on Diagnosis of Childhood Acute Lymphoblastic Leukemia (ALL) in Indonesia

Update on Diagnosis of Childhood Acute Lymphoblastic Leukemia (ALL) in Indonesia

Outcomes in Older Adults with Acute Lymphoblastic Leukemia (ALL) Receiving Linker Protocol at a Single Center Institution

Introduction: Acute lymphoblastic leukemia (ALL) is an aggressive hematological cancer that has predominately been regarded as a pediatric disease. However, it is estimated that 16-31% of new cases occur in adult patients, with 17% of patients diagnosed being 55 years of age or older. While the clinical outcomes of childhood ALL are excellent with complete response (CR) rates of greater than 90% and overall cure rates of 80-90%, the adult population, particularly the elderly population, fair much worse with 5-year overall survival (OS) less than 15% and 5% for patients older than 60 and 70, respectively. A large part of the success of pediatric outcomes has to do with the intensive chemotherapy regimen and so several studies have addressed the role of pediatric-inspired regimens in the elderly. The superior results of these trials favor a pediatric-based approach in the adult population however it is felt that the omission of asparaginase is an important modification for older patients. The current standard of care at our institution for patients who are 50 years of age or older is the Linker protocol based on 2002 prospective cohort study by Linker et al. With an impressive CR rate of 93% and 5-year event free survival (EFS) of 52%, we sought to retrospectively determine if the benefit of this therapy outweighed its known significant toxicity. Since the original Linker study only included 8 patients over the age of 50, we felt that the favorable outcomes may be potentially overrepresented in a much older treated population. Methods : A centralized bone marrow database search was performed for all bone marrow biopsies from January 1, 2006 to June 1, 2016 using a free text search for "acute lymphoblastic leukemia" in the bone marrow report. This was cross-referenced with the pharmacy medication dispensary database using a free text search for "asparaginase". All patients who were aged 50 years or older, had a new diagnosis of ALL (B and T cell subtype included), initiated treatment with the Linker Protocol and diagnosed between January 1 2006 to June 1 2016 were included in the study. Patients were excluded if they had relapsed or refractory ALL, under the age of 50, treated with an alternative regimen or palliated. For this study, ALL was defined based on the 2016 WHO classification. Data collected included patients age, sex, comorbidities, presenting white blood cell count, CNS involvement and ALL immunophenotype and cytogenetics. Results: A total of 125 bone marrow reports and patient charts were reviewed, and 85 patients were excluded based on the above exclusion criteria. A further 21 patients were excluded because they were either treated outside of our center, charts were not available, wrongly diagnosed or outside the timeframe of the study. The remaining 19 patients were included in the study analysis with an average follow-up time of 66 months. The mean age at diagnosis was 61 (range 51-70) with a slight male predominance of 58% (11/19). 5% of patients (1/16) had CNS involvement, with 11% unknown. B-cell immunophenotype was observed in 84% (16/19) with the remaining 16% T-cell subtype (3/19). Philadelphia chromosome and MLL rearrangements were present in 26% and 11% of patients, respectively. Cytogenetics were normal in 16%(3/19), complex in 26%(5/19), demonstrated at least 1 abnormality in 26%(5/19) and unknown in 32%(6/19). Complete remission was observed in 74%(14/19) of patients with 16% undergoing allogeneic stem cell transplant. The mean OS was 57.8 months (95%CI, 30.2-85.4) with 5-year OS of 40%, Fig 1. The mean progression free survival (PFS) was 40 months (95% CI, 19.5-60.4) with 5-year PFS of 38%, Fig 2. In a subgroup analysis of patients aged 50-59 and 60-70, 5-year OS was 70% and 20%, respectively (P-value 0.092), Fig 3. Finally, 100% of patients (19/19) had documented infection during therapy, with 47%(9/19) requiring ICU admission. Conclusion: This retrospective single center study showed that the use of an intensified pediatric-inspired regimen including asparaginase in older patients with ALL is reasonable, resulting in an impressive CR rate and 5-year OS. The benefit, however, appears to be limited to those aged 50-59 while those over 60 years of age have dismal survival rates as reported in previous literature. Certainly, with 100% infection rates and almost half of patients requiring an ICU admission, toxicity needs to be considered and this treatment should be reserved for the fit elderly population. Disclosures No relevant conflicts of interest to declare.

The Adherence to MRD Time Points Is a Significantly Prognostic Predictor in an MRD-Directed Therapy for Childhood Acute Lymphoblastic Leukemia in Taiwan

Backgrounds and Purposes Minimal residual disease (MRD) monitoring has been proved to be the most important prognostic predictor in childhood acute lymphoblastic leukemia (ALL). The nationwide TPOG-ALL-2013 protocol (TPOG-2013), adapted from the St. Jude Total Therapy XV Study and Total Therapy XVI Study, was launched since January 2013. This is the first MRD-directed protocol for treatment of childhood ALL in Taiwan. Here, we report the improved treatment outcomes and the impacts of adherence to MRD time points. Patients and Methods Totally, 402 patients aged between 1-18 years and diagnosed before December 31, 2018, who had MRD monitoring at the major central laboratory (Chang Gung Memorial Hospital-Linkou), were enrolled with the last follow-up on June 30, 2019. According to TPOG-2013, two MRD measurements were scheduled on days 15-19 of induction (MRD1 time point, TP1) and days 35-42, end of induction (MRD2 time point, TP2) to make the definitive risk stratification to guide subsequent therapy. The methodologies of MRD measurement included multicolor flow cytometry for leukemia-associated immunophenotypes (LAIP) (82.3% of TPOG-2013 cohort), qPCR assay for clonally rearranged antigen-receptor genes (Ig/TCR) if no LAIP (12.5%). Since January 2018, reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR) was applied to patients carrying fusion transcripts (5.2%) of TCF3-PBX1, ETV6-RUNX1, BCR-ABL1, KMT2A-AFF1 (AF4) and KMT2A-MLLT3. The clinical features and outcomes of patients treated with TPOG-2013 were compared with those of 1,300 patients treated with the previous TPOG-ALL-2002 protocol (TPOG-2002), which did not integrate the MRD monitoring. Results The median follow-up time of the 402 patients of TPOG-2013 cohort was 32.5 months (range, 1.0-79.2 months). There were no significant differences in gender, age, WBC counts, and lineage at diagnosis between the patients treated with TPOG-2002 and TPOG-2013. However, based on the MRD data, the percentages of patients assigned to each risk group of TPOG-2013 was statistically differed from those of TPOG-2002 (P&lt; 0.0001). The 5-year event-free survival (EFS) (% ± SE) was significantly improved from 78.1 ± 1.2 of TPOG-2002 to 85.4 ± 2.5 of TPOG-2013 (P&lt; 0.0001). Further, the cumulative incidences (% ± SE) of isolated CNS relapse and any CNS relapse significantly decreased from 4.0 ± 0.5 to 0.3 ± 0.3 (P= 0.001) and from 5.8 ± 0.7 to 1.2 ± 0.9 (P= 0.001), respectively. The issue of non-adherence to MRD monitoring emerged since the implementation of MRD-directed TPOG-2013. For further analysis, 321 (80%) patients with exact adherence (EA) to both TPs were assigned as MRD EA group; 80 (20%) patients who were non-adherence (NA) to either one of TPs as MRD NA group; and one patient died between the two TPs was excluded for the comparative outcome analysis. The rate of non-adherence decreased significantly from 26.5% in 2013 to 2.4% in 2018. The major causes of non-adherence for both TPs were delaying MRD monitoring due to neutropenic fever and documented infections. In MRD EA group, 12.5% of patients were upgraded to higher-risk treatment groups based on their MRD results. The MRD NA group had older age (≥ 10 years), lower standard-risk and lower incidence of ETV6-RUNX1 compared with MRD EA group. There were significant differences in outcomes between MRD EA and MRD NA groups: the 5-year EFS were 89.4 ± 2.4 and 71.9 ± 7.4, respectively (P= 0.0005), overall survival (OS) were 90.9 ± 2.1 and 75.6 ± 5.8, respectively (P= 0.0003), and the cumulative incidence of isolated CNS relapse were 0 and 1.4 ± 1.3, respectively (P= 0.048) (Figure 1). In multivariate analysis, older age (≥ 10 years), higher WBC count (≥ 50 × 109/L) at diagnosis and MRD non-adherence were independent predictors for inferior EFS. In addition to these three factors, a higher-risk classification also predicted an inferior OS (Figure 2). Conclusions Contemporary MRD-directed therapy has improved the treatment outcomes of childhood ALL in Taiwan. The adherence to MRD time points remains a significantly prognostic predictor in the era of MRD-guided treatment. Disclosures No relevant conflicts of interest to declare.

Impact of asparaginase discontinuation on outcome in childhood ALL: A report from the Children’s Oncology Group (COG).

10005 Background: Asparaginase (ASP) is an important component of acute lymphoblastic leukemia (ALL) treatment, but is often discontinued due to toxicity. For allergic reactions, but not other toxicities, Erwinia Asparaginase (EA) is often substituted. The majority of treatment protocols use discrete, discontinuous periods of asparagine depletion. In the context of such protocols, the impact of EA substitution or complete ASP discontinuation is unknown. Methods: Patients age 1-30.99 years enrolled on frontline COG trials for B-ALL [standard risk (NCI SR): AALL0331; high risk (NCI HR) AALL0232] were included. The number of prescribed pegaspargase (PEG) doses varied by trial, risk strata, and randomization (Table). Maintenance therapy did not contain ASP. Landmark analyses starting at Maintenance compared event free survival (EFS) between those receiving all prescribed doses of PEG vs. those switched to EA but receiving all doses vs. those not receiving all ASP doses. Results: This study included 5,195 AALL0331 and 3,001 AALL0232 patients. The cumulative incidence of PEG discontinuation was 12.2±4.6% on AALL0331 and 25.4%±0.8% on AALL0232. In multivariable analyses adjusted for patient and disease variables, NCI HR patients who did not receive all prescribed ASP doses had inferior EFS [hazard ratio (HR) 1.5, 95% confidence interval (95CI) 1.2-1.9; p=0.002] compared to those receiving all prescribed PEG doses. Patients with EA substitution who completed their courses were not at increased risk (HR 1.1, 95CI 0.7-1.6; p=0.69). Sensitivity analyses excluding patients discontinuing ASP due to pancreatitis or thrombosis yielded similar results. NCI SR patients who discontinued ASP were not at elevated risk (HR 1.2, 95CI 0.9-1.6; p=0.23), except when analyses were restricted to NCI SR patients with slow early response (HR 1.7, 95CI 1.1-2.7; p=0.03). Conclusions: Discontinuation of ASP doses is associated with significantly inferior EFS and must be balanced against the risks of ASP re-challenge. Our results also illustrate the potentially severe consequences of EA shortages. Prescribed pegasparagase doses. [Table: see text]

The Effectiveness of Clinical Pharmacist Intervention in Reducing Drug Related Problems of Childhood Acute Lymphoblastic Leukemia Patient in Tangerang District General Hospital, Indonesia

ABSTRACT This study aimed to evaluate the clinical pharmacist interventions in reducing drug-related problems (DRPs) in childhood acute lymphoblastic leukemia (ALL) patients in the Tangerang District General Hospital, Banten, Indonesia. This study used a prospective analysis of patients with a pre-post design between January-March 2017. The Pharmaceutical Care Network Europe (PCNE) (V6.2) pre-post study system was used to identify the DRPs of 138 patients. The Pharmacist interventions were addressed to physicians, patients, and other health professions to determine the effectiveness of pharmacist interventions before and after the intervention. The number of identified DRPs was 177 problems and the identified types of DRP was 164 types. The pharmacist interventions significantly decreased the DRPs from 177 to 10 DRPs (p 0.05) to the decreased of the number and type of DRPs. Clinical pharmacist interventions able to reduce the number and type of DRPs and can improve treatment outcomes in childhood ALL.

Long-term results of the risk-stratified treatment of childhood acute lymphoblastic leukemia in China.

Long-term follow-up data for childhood acute lymphoblastic leukemia (ALL) are scarce in China because of lacking population-based and hospitalized registry system. This retrospective study, conducted at Shanghai's Children's Medical Center in China (SCMC), aimed to investigate the long-term results of childhood ALL and to identify prognostic factors. The Pediatric Oncology Network Database, designed by St. Jude Children's Research Hospital, USA, were used to collect data for the enrolled patients starting in 2005. From 2005 to 2014, 1085 evaluable patients with ALL aged 1 to 18years old were enrolled and treated using SCMC-ALL-2005 risk-stratified protocol. Complete remission was achieved in 95.6% of patients. At 5 and 10years, the event-free survival rate was 68.3±1.4% and 64.6±1.6%, and the overall survival rate was 80.0±1.2% and 76.3±1.6%, respectively. The 5-year event-free survival rates were 81.8±2.0%, 67.0±1.9%, and 14.3±4.0% for patients in low-risk, intermediate-risk, and high-risk groups, respectively. The cumulative risk of relapse was 24.5% at 10years. Induction failure conferred worse prognosis. Patients younger than 1year of age at diagnosis, intermediate-risk/high-risk group, male gender, and positive minimal residual disease (MRD) results at day 55, both in the univariate and multivariate analysis, were associated with significantly worse prognosis (P<.05). Patients with positive MRD at both day 35 and day 55 were related to a significantly poor outcome (P<.0001), but not for patients with negitive MRD at day 35. The overall outcomes for ALL patients treated with protocol SCMC-ALL-2005 in SCMC are lower than in developed countries. Factors including age, gender, risk group and MRD results at day 55 were associated with treatment outcomes in childhood ALL.

Cyclin dependent kinase inhibitor 2A/B gene deletions are markers of poor prognosis in Indian children with acute lymphoblastic leukemia.

Cyclin dependent kinase inhibitor 2A/B (CDKN2A/B) genes are implicated in many malignancies including acute lymphoblastic leukemia (ALL). These tumor suppressor genes, with a key regulatory role in cell cycle are located on chromosome 9p21.3. Previous studies involving CDKN2A/B gene deletions have shown mixed associations with survival outcome in childhood ALL. Hundred and four newly diagnosed children with ALL (1-14 years) were enrolled in this study. Genomic DNA from pretreatment bone marrow/peripheral blood samples of these children was investigated for copy number alterations in CDKN2A/B genes using multiplex ligation dependent probe amplification assay. Immunophenotype subtyping and cytogenetic and molecular analysis of ALL was performed at start of induction chemotherapy in all children. Children were monitored for response to prednisolone (Day 8), complete morphological remission, and minimal residual disease at the end of induction. The minimum postinduction follow-up period was 6 months. CDKN2A/B deletions were seen in 19.8% (18/91) of B lineage acute lymphoblastic leukemia (B-ALL) and 38.5% (5/13) of T lineage acute lymphoblastic leukemia (T-ALL). Monoallelic CDKN2A/B deletions were found in 61.1% of total deletions in B-ALL while all the children with T-ALL harbored biallelic deletions. The prevalence of CDKN2A/B gene deletions was found to be significantly higher in older children (P=0.002), in those with higher leukocyte count (P=0.037), and in National Cancer Institute high risk group patients (P=0.001) in the B-ALL subgroup. Hazard ratio was significantly high for children with CDKN2A/B deletions in total cohort (P=0.004). Children with CDKN2A/B deletion had significantly lesser event free survival (P=0.03). CDKN2A/B deletions were significantly more prevalent in T-ALL subgroup and were found to have higher hazard ratio and lesser event free survival in total cohort in our study.

DNA variants in DHFR gene and response to treatment in children with childhood B ALL: revisited in AIEOP-BFM protocol.

We have previously reported an association of dihydrofolate reductase promoter polymorphisms with reduced event-free survival in childhood acute lymphoblastic leukemia (ALL) patients treated with Dana Farber Cancer Institute protocol. Here, we assessed whether these associations are applicable to other protocol, based on different methotrexate doses. Genotypes for six tag polymorphisms and resulting haplotypes were analyzed for an association with ALL outcome. The association was found with the polymorphisms A-680C, A-317G and C-35T in high-risk group patients. Carriers of haplotype *1 had a remarkably higher risk of events compared with noncarriers and a lower probability of event-free survival (21.4 vs 81.3%). The role of DHFR variants in predicting the outcome of childhood ALL extends beyond single-treatment protocol and can be useful biomarker in personalizing treatment.

Role of BIRC5 Gene as a Prognostic Marker in Pediatric Acute Lymphoblastic Leukemia

Background and objectives: Acute lymphoblastic leukaemia (ALL) is the most common malignancy diagnosed in children. Survivin, a small inhibitor-of-apoptosis protein (IAP) encoded by the baculoviral inhibitor of apoptosis repeat-Containing 5 (BIRC5) gene, plays critical roles in malignancy by preventing apoptosis through blocking caspase activity. The aim of this study was to assess the prognostic role of BIRC5 gene in paediatric ALL. Subjects and methods: The present study was carried out on 42 children with the’ novo ALL who were followed up for two years and 10 apparently healthy children of matched age and sex (controls). Each child was subjected to complete history taking, clinical examination, laboratory investigations the form of CBC, Leishman-stained peripheral blood smears, Lactate dehydrogenase (LDH), Bone marrow (BM) aspiration and examination of Leishman-stained smears, Immunophenotyping on BM samples for routine panel of ALL determined by flow cytometer and quantitative determination of survivin gene expression by real time PCR on BM samples. Results: Patients with ALL had a significantly higher BIRC5 expression than did the control group (P=0.0004). There was a significant increase in survivin gene expression level in T-ALL when compared to common BALL and pre B-ALL (P=0.001). A significant positive correlation was found between survivin expression and LDH, uric acid and white blood cells (WBCs) (r=0.47, P=0.002; r=0.31, P=0.05, r=0.62, P=0.001), respectively. A significant higher survivin expression levels, LDH and WBCs was found in children with unfavorable outcome. 94.5% of ALL patients with high survivin expression had an unfavorable outcome while, in ALL children with low survivin expression, only 25% had an unfavorable outcome (P=0.001). Conclusion: BIRC5 gene expression was correlated with unfavorable outcome of childhood ALL. So, its measurement at diagnosis may detect a high risk ALL subgroup.

Clinical impact of minimal residual disease in children with different subtypes of acute lymphoblastic leukemia treated with Response-Adapted therapy.

To determine the clinical significance of minimal residual disease (MRD) in patients with prognostically relevant subtypes of childhood acute lymphoblastic leukemia (ALL), we analyzed data from 488 patients treated in St. Jude Total Therapy Study XV with treatment intensity based mainly on MRD levels measured during remission induction. MRD levels on day 19 predicted treatment outcome for patients with hyperdiploid >50 ALL, NCI standard-risk B-ALL or T-cell ALL, while MRD levels on day 46 were prognostic for patients with NCI standard-risk or high-risk B-ALL. Patients with t(12;21)/(ETV6-RUNX1) or hyperdiploidy >50 ALL had the best prognosis; those with a negative MRD on day 19 had a particularly low risk of relapse: 1.9% and 3.8%, respectively. Patients with NCI high-risk B-ALL or T-cell ALL had an inferior outcome; even with undetectable MRD on day 46, cumulative risk of relapse was 12.7% and 15.5%, respectively. Among patients with NCI standard-risk B-ALL, the outcome was intermediate overall but was poor if MRD was ≥1% on day ≥19 or MRD was detectable at any level on day 46. Our results indicate that the clinical impact of MRD on treatment outcome in childhood ALL varies considerably according to leukemia subtype and time of measurement.

Treatment of Childhood Acute Lymphoblastic Leukemia: Prognostic Factors and Clinical Advances.

While the majority of children and adolescents with newly diagnosed childhood acute lymphoblastic leukemia (ALL) will be cured, as many as 20% of patients will experience relapse. On current treatment regimens, the intensity of upfront treatment is stratified based upon prognostic factors with the aim of improving cure rates (for those at the highest risk of relapse) and minimizing treatment-related morbidity (for lower-risk patients). Here we review advances in the understanding of prognostic factors and their application. We also highlight novel treatment approaches aimed at improving outcomes in childhood ALL.

Prognostic significance of cytokine receptor-like factor 2 alterations in acute lymphoblastic leukemia: a meta-analysis.

Cytokine receptor-like factor 2 (CRLF2) has been shown to play a role in the pathogenesis of acute lymphoblastic leukemia (ALL). Studies have examined the relationship between CRLF2 alterations such as over-expression or deregulation and clinical outcome in childhood ALL, but the results are conflicting. This meta-analysis aimed to explore the association between CRLF2 alterations and survival of pediatric patients with ALL. Electronic databases updated to March 2014 were searched for relevant studies. A meta-analysis was made of twelve studies including 5945 patients to evaluate the prognostic significance of CRLF2 alterations on survival in childhood ALL. Hazards ratios (HRs) with 95% confidence intervals (CIs) were pooled across the studies using a fixed-effects model. CRLF2 over-expression in childhood ALL was associated with poor prognosis in terms of relapse-free survival (RFS; HR=1.70, 95% CI=1.28-2.24, P=0.000), event-free survival (EFS; HR=1.78, 95% CI=1.05-3.01, P=0.032), and overall survival (OS; HR=2.28, 95% CI=1.42-3.65, P=0.001). The combined data also suggested that CRLF2 deregulation in childhood ALL was correlated with poor EFS (HR=1.95, 95% CI=1.46-2.61, P=0.000), RFS (HR=2.20, 95% CI=1.53-3.18, P=0.000), and OS (HR=1.89, 95% CI=1.24-2.87, P=0.003). Subgroup analysis on multivariate HRs showed that CRLF2 deregulation independently predicted a poor prognosis for childhood ALL. The present meta-analysis reveals that both CRLF2 over-expression and deregulation are associated with poor prognosis in pediatric patients with ALL.

Polymorphisms in the ABCB1 gene and effect on outcome and toxicity in childhood acute lymphoblastic leukemia.

The membrane transporter P-glycoprotein, encoded by the ABCB1 gene, influences the pharmacokinetics of anti-cancer drugs. We hypothesized that variants of ABCB1 affect outcome and toxicity in childhood acute lymphoblastic leukemia (ALL). We studied 522 Danish children with ALL, 93% of all those eligible. Risk of relapse was increased 2.9-fold for patients with the 1199GA variant versus 1199GG (P=0.001), and reduced 61% and 40%, respectively, for patients with the 3435CT or 3435TT variants versus 3435CC (overall P=0.02). The degree of bone marrow toxicity during doxorubicin, vincristine and prednisolone induction therapy was more prominent in patients with 3435TT variant versus 3435CT/3435CC (P=0.01/P<0.0001). We observed more liver toxicity after high-dose methotrexate in patients with 3435CC variant versus 3435CT/TT (P=0.03). In conclusion, there is a statistically significant association between ABCB1 polymorphisms, efficacy and toxicity in the treatment of ALL, and ABCB1 1199G>A may be a new possible predictive marker for outcome in childhood ALL.

ARID5B Regulates Leukemia Sensitivity to Antimetabolites in Children with Acute Lymphoblastic Leukemia Via Effects on Cell Cycle Progression

▪Acute lymphoblastic leukemia (ALL) in children is a prototype of cancer that can be cured by chemotherapy alone. However, the molecular mechanisms for anti-leukemic drug sensitivity and genetic basis of inter-patient variability in treatment response are not fully understood. Taking a genome-wide approach, we recently identified genetic variants in the ARID5B gene that strongly predispose children to developing ALL and also a high risk of relapse following therapy (J Clin Oncol 2012 30:751, Nat Genet 2009 41:1001). To understand the mechanisms by which ARID5B is linked to treatment outcome in childhood ALL, we sought to 1) characterize ARID5B expression in different genetic subtypes of ALL, 2) determine the effects of ARID5B expression on cytotoxicity of chemotherapeutic agents commonly used in ALL therapy, and 3) describe molecular pathways linking ARID5B to anti-leukemic drug sensitivity. In 567 children with newly diagnosed ALL treated at St. Jude Children’s Research Hospital (GSE33315), ARID5B expression was highest in cases with hyperdiploid karyotype (>50 chromosomes) and lowest in T-cell ALL and cases with MLL rearrangements. This pattern was validated in an independent cohort of 106 children from the Dutch Childhood Oncology Group (GSE13351). In 59 patients treated on the Children’s Oncology Group (COG) CCG1961 trial, lower ARID5B expression was associated with higher rates of relapse (P=0.01, GSE7440). Importantly, when we compared matched newly-diagnosed vs. relapsed ALL blasts from a cohort of 60 patients enrolled in COG trials (GSE28460), ARID5B expression was further downregulated at disease recurrence (P=0.0009). shRNA-mediated ARID5B knockdown in 3 ALL cell lines (Nalm6, SEM, and UOCB-1) substantially increased resistance to antimetabolites (an average of 5.16 and 35.3-fold increase in IC50 for methotrexate [MTX] and 6-mercaptopurine [6MP], respectively), with minimal effects on glucocorticoids, vincristine, asparaginase, and daunorubicin. Because cytotoxic effects of MTX and 6MP are highly dependent on the rate of cell proliferation, we postulate that ARID5B directly influences cell cycle entry. In all 3 cell lines, ARID5B knockdown led to significant blockade at the G1/S checkpoint, increasing the percent of cells in G0/G1 phase. At the molecular level, downregulation of ARID5B resulted in higher levels of p21 and reduction in phosphorylated Rb, consistent with the retention at G0/G1 phase. ARID5B expression was restricted to nucleus but affected both nuclear and cytoplasmic p21 expression in a time-dependent fashion. Interestingly, there was a highly significant negative correlation between p21 expression and MTX- and 6MP-induced apoptosis in all 3 ALL cell lines. Taken together, we hypothesize that lower expression of ARID5B impairs ALL cell cycling by upregulating p21, contributing to resistance to MTX and 6MP and eventually leukemia relapse. Finally, we compared global gene expression in ARID5B knockdown vs. control ALL cells, and via the Connectivity Map analysis we identified histone deacetylase (HDAC) inhibitors as promising agents for overcoming ARID5B-related drug resistance. Indeed, ARID5B knockdown cells were significantly more sensitive to panobinostat than controls, suggesting HDAC inhibitors as potential therapeutic options for patients with ARID5B-deficient and drug resistant ALL. DisclosuresNo relevant conflicts of interest to declare.

Next Generation Amplicon Sequencing of Immunoglobulin Heavy Chain Gene Rearrangaments for Minimal Residual Disease (MRD) Stratification in Childhood Acute Lymphoblastic Leukemia (ALL): A Comparison with Classical qPCR-Based Technique

▪IntroductionMRD is an important predictor of outcome in childhood ALL. Since 2000, MRD detected by quantitative PCR (qPCR) for immunoglobulin and T-cell receptor gene rearrangements with a minimal sensitivity of 1E-04 has been used for risk group stratification in pediatric BFM trials. Next generation sequencing (NGS) permits rapid parallel sequencing of large numbers of DNA segments. It can overcome most of the limitations of qPCR: it allows highly specific molecular detection of MRD without laborious optimization of patient-specific assays. Moreover it enables not only monitoring of malignant clone but also shows the picture of entire immune background.AimsTo develop an assay for immunoglobulin heavy chain (IgH) rearrangements detection on Ion Torrent PGM/Ion Proton platforms and compare the MRD levels with qPCR at BFM stratification timepoints.MethodsTwo round PCR was used for library preparation. Libraries were created from 450ng (equivalent of 70,000 DNA copies) of bone marrow DNA and 50ng of Human Genomic DNA (Roche). In the first round of PCR rearranged IgH genes were amplified using IGH FR3 BIOMED-2 primers (van Dongen, Leukemia 2003). In the second round the sequencing adapters and multiplex identifiers were added. Sequencing was performed on Ion Torrent PGM/Ion Proton sequencers using a 200bp chemistry. We developed a bioinformatics algorithm for detection of reads with known clonal V-D-J rearrangements within the resulting fastq files.For validation of the assay we sequenced 1E-1 to 1E-5 dilutions of diagnostic samples from 2 patients in multiplicates. The results show that the assay gives reproducible quantitative results up to 1E-4 dilution.ResultsWe sequenced 183 samples from 67 patients (52×day 15, 65×day 33, 66×day 78) with childhood ALL treated according to AIEOP-BFM ALL 2000 protocol with the median coverage 587,406 reads per sample. Eighty-three (45.4%) samples were negative by both methods. Fifteen (8.2%) samples were positive by NGS and negative by qPCR and 14 (7.7%) samples were positive by qPCR and negative by NGS. All the discordant samples had MRD levels below the sensitivity of both methods. The overall correlation of all double positive and double negative samples was very good (R2=0.93). If risk group stratification based on NGS results would be performed, 8 patients would be classified as intermediate risk (IR) instead of standard risk (SR) (one of whom relapsed) and 8 patients as SR instead of IR. One patient would be relocated from IR to slow early responders (SER) group, and two patients from SER to IR (one of them relapsed). One patient who relapsed would be classified as high risk (HR) instead of SER. All 5 patients who were MRD negative at d15 by NGS remained MRD negative in later timepoints and none of them relapsed.DiscussionWe present a cost-effective and widely adoptable NGS-based method that provides clinically relevant results in childhood ALL. NGS has a great potential to reduce the laboriousness associated with patient-specific qPCR analysis and to speed up the process of MRD detection. The sensitivity of both methods is comparable when ~500ng of DNA is used. The majority of the differences were in the samples with MRD levels below 1E-4 and most of treatment stratification changes occurred between SR/IR. However, the different stratification mostly concerned patients who did not relapse. The sensitivity of NGS could be improved if more DNA was analyzed. However, the benefit of increased MRD sensitivity is questionable due to possible overtreatment of patients with very low MRD loads after induction treatment. “Online” identification of d15 MRD negative patients reported as having an excellent prognosis previously is possible only by NGS, because optimization of patient-specific qPCR takes several weeks.The addition of 10% polyclonal DNA seems to solve the problem of MRD overestimation by NGS in samples with B-cell aplasia. At present, the main drawback of the Ig/TCR-exploring NGS methods is lack of standardization both in the experimental setting and in data analysis. Therefore, recently a European network, the EuroClonality NGS Consortium, has been formed to standardize the whole workflow of analytics, pre-analytics and bioinformatics not only for MRD quantification but also for clonality assessment in lymphoid neoplasms and for repertoire analysis.Supported by IGA NT14343, IGA NT12397, IGA NT13462-4 and GAUK 394214. DisclosuresNo relevant conflicts of interest to declare.