CD371-positive pediatric B-cell acute lymphoblastic leukemia: propensity to lineage switch and slow early response to treatment.

ABSTRACT: In the effort to improve immunophenotyping and minimal residual disease (MRD) assessment in acute lymphoblastic leukemia (ALL), the international Berlin-Frankfurt-Münster (iBFM) Flow Network introduced the myelomonocytic marker CD371 for a large prospective characterization with a long follow-up. In the present study, we aimed to investigate the clinical and biological features of CD371-positive (CD371pos) pediatric B-cell precursor ALL (BCP-ALL). From June 2014 to February 2017, 1812 pediatric patients with newly diagnosed BCP-ALLs enrolled in trial AIEOP-BFM ALL 2009 were evaluated as part of either a screening (n = 843, Italian centers) or validation cohort (n = 969, other iBFM centers). Laboratory assessment at diagnosis consisted of morphological, immunophenotypic, and genetic analysis. Response assessment relied on morphology, multiparametric flow cytometry (MFC), and polymerase chain reaction (PCR)-MRD. At diagnosis, 160 of 1812 (8.8%) BCP-ALLs were CD371pos. This correlated with older age, lower ETV6::RUNX1 frequency, immunophenotypic immaturity (all P < .001), and strong expression of CD34 and of CD45 (P < .05). During induction therapy, CD371pos BCP-ALLs showed a transient myelomonocytic switch (mm-SW: up to 65.4% of samples at day 15) and an inferior response to chemotherapy (slow early response, P < .001). However, the 5-year event-free survival was 88.3%. Among 420 patients from the validation cohort, 27 of 28 (96.4%) cases positive for DUX4-fusions were CD371pos. In conclusion, in the largest pediatric cohort, CD371 is the most sensitive marker of transient mm-SW, whose recognition is essential for proper MFC MRD assessment. CD371pos is associated to poor early treatment response, although a good outcome can be reached after MRD-based ALL-related therapies.

EBV-driven lymphoid neoplasms associated with pediatric ALL maintenance therapy.

The development of a second malignancy after the diagnosis of childhood acute lymphoblastic leukemia (ALL) is a rare event. Certain second malignancies have been linked with specific elements of leukemia therapy, yet the etiology of most second neoplasms remains obscure and their optimal management strategies are unclear. This is a first comprehensive report of non-Hodgkin lymphomas (NHLs) following pediatric ALL therapy, excluding stem-cell transplantation. We analyzed data of patients who developed NHL following ALL diagnosis and were enrolled in 12 collaborative pediatric ALL trials between 1980-2018. Eighty-five patients developed NHL, with mature B-cell lymphoproliferations as the dominant subtype (56 of 85 cases). Forty-six of these 56 cases (82%) occurred during or within 6 months of maintenance therapy. The majority exhibited histopathological characteristics associated with immunodeficiency (65%), predominantly evidence of Epstein-Barr virus-driven lymphoproliferation. We investigated 66 cases of post-ALL immunodeficiency-associated lymphoid neoplasms, 52 from our study and 14 additional cases from a literature search. With a median follow-up of 4.9 years, the 5-year overall survival for the 66 patients with immunodeficiency-associated lymphoid neoplasms was 67.4% (95% confidence interval [CI], 56-81). Five-year cumulative risks of lymphoid neoplasm- and leukemia-related mortality were 20% (95% CI, 10.2-30) and 12.4% (95% CI, 2.7-22), respectively. Concurrent hemophagocytic lymphohistiocytosis was associated with increased mortality (hazard ratio, 7.32; 95% CI, 1.62-32.98; P = .01). A large proportion of post-ALL lymphoid neoplasms are associated with an immunodeficient state, likely precipitated by ALL maintenance therapy. Awareness of this underrecognized entity and pertinent diagnostic tests are crucial for early diagnosis and optimal therapy.

Pneumocystis jirovecii pneumonia in paediatric acute lymphoblastic leukaemia: A report from the multi-international clinical trial AIEOP-BFM ALL 2009.

Pneumocystis jirovecii can cause life-threatening pneumonia (PjP), and patients with haematological malignancies are at high risk of this infection. Prophylactic measures have significantly decreased morbidity and mortality, but there is a paucity of contemporary data on the incidence and clinical course of PjP in well-defined and homogenous patient populations, such as children suffering from acute lymphoblastic leukaemia (ALL). In the multi-international trial AIEOP-BFM ALL2009, PjP was diagnosed in six children (incidence 1/1000) and was associated with insufficient prophylaxis in five of them. Although none of the patients died of PjP, the long-term impact of the infection is unclear.

Severe steroid-related neuropsychiatric symptoms during paediatric acute lymphoblastic leukaemia therapy-An observational Ponte di Legno Toxicity Working Group Study.

Steroids are a mainstay in the treatment of acute lymphoblastic leukaemia (ALL) in children and adolescents; however, their use can cause clinically significant steroid-related neuropsychiatric symptoms (SRNS). As current knowledge on SRNS during ALL treatment is limited, we mapped the phenotypes, occurrence and treatment strategies using a database created by the international Ponte di Legno Neurotoxicity Working Group including data on toxicity in the central nervous system (CNS) in patients treated with frontline ALL protocols between 2000 and 2017. Ninety-four of 1813 patients in the CNS toxicity database (5.2%) experienced clinically significant SRNS with two peaks: one during induction and one during intensification phase. Dexamethasone was implicated in 86% of SRNS episodes. The most common symptoms were psychosis (52%), agitation (44%) and aggression (31%). Pharmacological treatment, mainly antipsychotics and benzodiazepines, was given to 87% of patients while 38% were hospitalised due to their symptoms. Recurrence of symptoms was reported in 29% of patients and two previously healthy patients required ongoing pharmacological treatment at the last follow up. Awareness of SRNS during ALL treatment and recommendation on treatment strategies merit further studies and consensus.

Auer rod-positive acute leukemia with predominantly lymphoid immunophenotype: Report on 11 cases and review of literature.

BACKGROUND: Auer rods (AuRs) are prominent intracellular structures found almost exclusively in myeloid cell malignancies, such as acute myeloid leukemia (AML), chronic and juvenile myelomonocytic leukemia and myelodysplastic syndrome. Extremely rare AuRs have been reported in patients with acute lymphoblastic leukemia (ALL) or among ambiguous lineage leukemia patients with a dominantly lymphoblastic immunophenotype. PROCEDURE: We report diagnostic and follow-up data of an international cohort of 11 children suffering from leukemias with AuRs and with significant presence of T and myeloid markers, majority of whom categorized as early T-cell precursor (ETP, n = 7); or T-ALL (ETP status unknown, n = 2), ALAL (acute leukemia of ambiguous lineage, n = 1), and AML reclassified from ALAL (n = 1). We described other diagnostic details and treatment types and responses. Moreover, we summarize previously published data. RESULTS: Among the four patients who started and remained on ALL-type therapy, all were in the first complete remission, whereas both patients who started and remained on AML-type therapy relapsed and died. Of the patients who followed either a combined ALL/AML protocol (Interfant 06) or who switched from one of the two types of therapy to the other, one patient died, and the remaining four were in first complete remission at the most recent follow-up. We also searched for similar cases in the literature and found only three additional children with nonmyeloid leukemia and AuRs and 10 adults with this type of leukemia. CONCLUSIONS: Briefly, ALL- or combined ALL/AML-type therapy may be effective for treating AuR-positive leukemia patients with a lymphoid immunophenotype.

Deciphering the molecular complexity of the IKZF1plus genomic profile using Optical Genome Mapping.

Not available.

Effect of two additional doses of intrathecal methotrexate during induction therapy on serious infectious toxicity in pediatric patients with acute lymphoblastic leukemia.

Although initial central nervous system (CNS) involvement is rarely detected in childhood acute lymphoblastic leukemia (ALL), risk-adapted CNS-directed therapy is essential for all patients. Treatment intensity depends on the initial CNS status. In the AIEOP-BFM ALL 2009 trial, patients with cytomorphologic detection of leukemic blasts in initial cerebrospinal fluid were classified as CNS2 or CNS3 and received five intrathecal doses of methotrexate (MTX) in induction therapy compared to patients with CNS1 status (no blasts detected) who received three doses. The impact of additional intrathecal (IT) MTX on systemic toxicity in induction therapy is unknown. Between June 1st 2010 and February 28th 2017, a total of 6,136 ALL patients aged 1-17 years were enrolled onto the AIEOP-BFM ALL 2009 trial. The effect of three versus five doses of IT MTX during induction therapy on the incidence of severe infectious complications was analyzed. Among 4,706 patients treated with three IT MTX doses, 77 (1.6%) had a life-threatening infection during induction as compared to 59 of 1,350 (4.4%) patients treated with five doses (P<0.001; Odds Ratio 2.86 [95% Confidence Interval 1.99-4.13]). In a multivariate regression model, treatment with additional IT MTX proved to be the strongest risk factor for life-threatening infections (Odds Ratio 2.85 [1.96-4.14]). Fatal infections occurred in 16 (0.3%) and 38 (1.6%) patients treated with three or five IT MTX doses, respectively (P<0.001). As the relevance of additional intrathecal MTX in induction for relapse prevention in CNS2 patients is unclear, doses of intrathecal therapy have been reduced for these patients. (Clinicaltrials.gov identifiers: NCT01117441 and NCT00613457).

Cryptic TCF3 fusions in childhood leukemia: Detection by RNA sequencing.

Acute lymphoblastic leukemia (ALL) is the most frequent malignancy in childhood and adolescence. In more than 60% of cases of this heterogeneous disease, a genetic marker is identified via cytogenetic or molecular analyses. TCF3 gene fusions occur in 5%-11% of ALL patients. In < 1%, the TCF3 alteration in ALL leads to a TCF3-HLF fusion gene. Even though this is a very rare event, the detection of a TCF3-HLF fusion gene is associated with a very poor prognosis with incurable relapses in almost all patients. The frequent TCF3-PBX1 fusion gene, which is detectable in 5%-10% of childhood B-cell precursor ALLs and ~3.8% of adult B-cell precursor ALLs, is associated with a rather good prognosis, that is, an observed event-free 5-year survival of approximately 85%. Thus, the distinction of the different partner genes fused to TCF3 is essential for risk assessment. To verify RNA sequencing as a tool for detection of known and unknown fusion genes, we screened 200 cases of pediatric B-cell precursor ALL with "targeted" RNA sequencing in a pilot project in comparison to classical cytogenetic analyses (chromosome R-banding analysis), fluorescence in situ hybridization, and PCR. We observed a TCF3 fusion gene in 6.5% (13/200) of the patients. Ten (5%) patients displayed a TCF3-PBX1 fusion gene, two (1%) patients a TCF3-FLI1 fusion gene, and one (0.5%) patient a TCF3-HLF fusion gene. For the TCF3 fusions, we obtained discrepant results with the different methods, which are described in the article. Taken together, translocations leading to TCF3 fusion genes might appear cryptic and may remain undetected by a single method.

Pre-existing antibodies against polyethylene glycol reduce asparaginase activities on first administration of pegylated E. coli asparaginase in children with acute lymphocytic leukemia.

Antibodies against polyethylene glycol (PEG) in healthy subjects raise concerns about the efficacy of pegylated drugs. We evaluated the prevalence of antibodies against PEG among patients with acute lymphoblastic leukemia (ALL) prior to and/or immediately after their first dose of pegylated E.coli asparaginase (PEG-ASNase). Serum samples of 701 children, 673 with primary ALL, 28 with relapsed ALL, and 188 adults with primary ALL were analyzed for anti-PEG IgG and IgM. Measurements in 58 healthy infants served as reference to define cut-points for antibody-positive and -negative samples. Anti-PEG antibodies were detected in ALL patients prior the first PEG-ASNase with a prevalence of 13.9% (anti-PEG IgG) and 29.1% (anti-PEG IgM). After administration of PEG-ASNase the prevalence of anti-PEG antibodies decreased to 4.2% for anti-PEG IgG and to 4.5% for anti-PEG IgM. Pre-existing anti-PEG antibodies did not inhibit PEG-ASNase activity but significantly reduced PEGASNase activity levels in a concentration dependent manner. Although pre-existing anti-PEG antibodies did not boost, pre-existing anti-PEG IgG were significantly associated with firstexposure hypersensitivity reactions (CTCAE grade 2) (p.

Can Machine Learning Models Predict Asparaginase-associated Pancreatitis in Childhood Acute Lymphoblastic Leukemia.

Asparaginase-associated pancreatitis (AAP) frequently affects children treated for acute lymphoblastic leukemia (ALL) causing severe acute and persisting complications. Known risk factors such as asparaginase dosing, older age and single nucleotide polymorphisms (SNPs) have insufficient odds ratios to allow personalized asparaginase therapy. In this study, we explored machine learning strategies for prediction of individual AAP risk. We integrated information on age, sex, and SNPs based on Illumina Omni2.5exome-8 arrays of patients with childhood ALL (N=1564, 244 with AAP 1.0 to 17.9 yo) from 10 international ALL consortia into machine learning models including regression, random forest, AdaBoost and artificial neural networks. A model with only age and sex had area under the receiver operating characteristic curve (ROC-AUC) of 0.62. Inclusion of 6 pancreatitis candidate gene SNPs or 4 validated pancreatitis SNPs boosted ROC-AUC somewhat (0.67) while 30 SNPs, identified through our AAP genome-wide association study cohort, boosted performance (0.80). Most predictive features included rs10273639 (PRSS1-PRSS2), rs10436957 (CTRC), rs13228878 (PRSS1/PRSS2), rs1505495 (GALNTL6), rs4655107 (EPHB2) and age (1 to 7 y). Second AAP following asparaginase re-exposure was predicted with ROC-AUC: 0.65. The machine learning models assist individual-level risk assessment of AAP for future prevention trials, and may legitimize asparaginase re-exposure when AAP risk is predicted to be low.

Effect of Blinatumomab vs Chemotherapy on Event-Free Survival Among Children With High-risk First-Relapse B-Cell Acute Lymphoblastic Leukemia: A Randomized Clinical Trial.

Importance: Blinatumomab is a CD3/CD19-directed bispecific T-cell engager molecule with efficacy in children with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL). Objective: To evaluate event-free survival in children with high-risk first-relapse B-ALL after a third consolidation course with blinatumomab vs consolidation chemotherapy before allogeneic hematopoietic stem cell transplant. Design, Setting, and Participants: In this randomized phase 3 clinical trial, patients were enrolled November 2015 to July 2019 (data cutoff, July 17, 2019). Investigators at 47 centers in 13 countries enrolled children older than 28 days and younger than 18 years with high-risk first-relapse B-ALL in morphologic complete remission (M1 marrow, <5% blasts) or with M2 marrow (blasts ≥5% and <25%) at randomization. Intervention: Patients were randomized to receive 1 cycle of blinatumomab (n = 54; 15 µg/m2/d for 4 weeks, continuous intravenous infusion) or chemotherapy (n = 54) for the third consolidation. Main Outcomes and Measures: The primary end point was event-free survival (events: relapse, death, second malignancy, or failure to achieve complete remission). The key secondary efficacy end point was overall survival. Other secondary end points included minimal residual disease remission and incidence of adverse events. Results: A total of 108 patients were randomized (median age, 5.0 years [interquartile range {IQR}, 4.0-10.5]; 51.9% girls; 97.2% M1 marrow) and all patients were included in the analysis. Enrollment was terminated early for benefit of blinatumomab in accordance with a prespecified stopping rule. After a median of 22.4 months of follow-up (IQR, 8.1-34.2), the incidence of events in the blinatumomab vs consolidation chemotherapy groups was 31% vs 57% (log-rank P < .001; hazard ratio [HR], 0.33 [95% CI, 0.18-0.61]). Deaths occurred in 8 patients (14.8%) in the blinatumomab group and 16 (29.6%) in the consolidation chemotherapy group. The overall survival HR was 0.43 (95% CI, 0.18-1.01). Minimal residual disease remission was observed in more patients in the blinatumomab vs consolidation chemotherapy group (90% [44/49] vs 54% [26/48]; difference, 35.6% [95% CI, 15.6%-52.5%]). No fatal adverse events were reported. In the blinatumomab vs consolidation chemotherapy group, the incidence of serious adverse events was 24.1% vs 43.1%, respectively, and the incidence of adverse events greater than or equal to grade 3 was 57.4% vs 82.4%. Adverse events leading to treatment discontinuation were reported in 2 patients in the blinatumomab group. Conclusions and Relevance: Among children with high-risk first-relapse B-ALL, treatment with 1 cycle of blinatumomab compared with standard intensive multidrug chemotherapy before allogeneic hematopoietic stem cell transplant resulted in an improved event-free survival at a median of 22.4 months of follow-up. Trial Registration: ClinicalTrials.gov Identifier: NCT02393859.

Frequency and prognostic impact of PAX5 p.P80R in pediatric acute lymphoblastic leukemia patients treated on an AIEOP-BFM acute lymphoblastic leukemia protocol.

PAX5 is a member of the paired box (PAX) family of transcription factors involved in B-cell development. PAX5P80R has recently been described as a distinct genetic B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) subtype with a favorable prognosis in adults. In contrast, an unfavorable outcome has been observed in children. Our aim was to determine the frequency of PAX5P80R in childhood BCP-ALL treated according to the Associazione Italiana Ematologia ed Oncologia Pediatrica-Berlin-Frankfurt-Muenster (AIEOP-BFM) ALL 2000 protocol and to evaluate its clinical significance within this study cohort. The analyses included 1237 patients with ALL treated in the AIEOP-BFM ALL 2000 trial with complete information for copy number variations (CNVs) of IKZF1, PAX5, ETV6, RB1, BTG1, EBF1, CDKN2A, CDKN2B, and ERG. A customized TaqMan genotyping assay was used to screen for PAX5P80R . Sanger sequencing was used to confirm PAX5P80R -positive results as well as to screen for second variants in PAX5. Agilent CGH + SNP arrays (e-Array design 85 320; Agilent Technologies) were performed in PAX5P80R -positive patients to verify additional CNVs. Almost 2% (20/1028) of our BCP-ALL cohort were PAX5P80R -positive. White blood cell counts higher than 50 000/µl as well as male sex were significantly (P < .05) associated with PAX5P80R . Most of the PAX5P80R -positive cases were 10 years of age or older. PAX5P80R -positive samples were enriched for deletions affecting PAX5, IKZF1, CDKN2A, and CDKN2B. Compared to PAX5P80R -wildtype BCP-ALL, PAX5P80R -positive patients showed a significantly reduced 5-year overall survival (P = .042). Further studies should evaluate the interaction of PAX5P80R with other genetic aberrations to further stratify intermediate risk pediatric BCP-ALL.

International cooperative study identifies treatment strategy in childhood ambiguous lineage leukemia.

Despite attempts to improve the definitions of ambiguous lineage leukemia (ALAL) during the last 2 decades, general therapy recommendations are missing. Herein, we report a large cohort of children with ALAL and propose a treatment strategy. A retrospective multinational study (International Berlin-Frankfurt-Münster Study of Leukemias of Ambiguous Lineage [iBFM-AMBI2012]) of 233 cases of pediatric ALAL patients is presented. Survival statistics were used to compare the prognosis of subsets and types of treatment. Five-year event-free survival (EFS) of patients with acute lymphoblastic leukemia (ALL)-type primary therapy (80% ± 4%) was superior to that of children who received acute myeloid leukemia (AML)-type or combined-type treatment (36% ± 7.2% and 50% ± 12%, respectively). When ALL- or AML-specific gene fusions were excluded, 5-year EFS of CD19+ leukemia was 83% ± 5.3% on ALL-type primary treatment compared with 0% ± 0% and 28% ± 14% on AML-type and combined-type primary treatment, respectively. Superiority of ALL-type treatment was documented in single-population mixed phenotype ALAL (using World Health Organization and/or European Group for Immunophenotyping of Leukemia definitions) and bilineal ALAL. Treatment with ALL-type protocols is recommended for the majority of pediatric patients with ALAL, including cases with CD19+ ALAL. AML-type treatment is preferred in a minority of ALAL cases with CD19- and no other lymphoid features. No overall benefit of transplantation was documented, and it could be introduced in some patients with a poor response to treatment. As no clear indicator was found for a change in treatment type, this is to be considered only in cases with ≥5% blasts after remission induction. The results provide a basis for a prospective trial.

Implementation of RNA sequencing and array CGH in the diagnostic workflow of the AIEOP-BFM ALL 2017 trial on acute lymphoblastic leukemia.

Risk-adapted therapy has significantly contributed to improved survival rates in pediatric acute lymphoblastic leukemia (ALL) and reliable detection of chromosomal aberrations is mandatory for risk group stratification. This study evaluated the applicability of panel-based RNA sequencing and array CGH within the diagnostic workflow of the German study group of the international AIEOP-BFM ALL 2017 trial. In a consecutive cohort of 117 children with B cell precursor (BCP) ALL, array analysis identified twelve cases with an IKZF1plus profile of gene deletions and one case of masked hypodiploidy. Genetic markers BCR-ABL1 (n = 1), ETV6-RUNX1 (n = 25), and rearrangements involving KMT2A (n = 3) or TCF3 (n = 3) were assessed by established conventional techniques such as karyotyping, FISH, and RT-PCR. Comparison of these results with RNA sequencing analysis revealed overall consistency in n=115/117 cases, albeit with one undetected AFF1-KMT2A fusion in RNA sequencing and one undetected ETV6-RUNX1 fusion in conventional analyses. The combined application of RNA sequencing, FISH, and CGH+SNP array reliably detected all genetic markers necessary for risk stratification and will be used as the diagnostic standard workflow for BCP-ALL patients enrolled in the AIEOP-BFM ALL 2017 study. Prospectively, consistent collection of genome-wide CGH+SNP array as well as RNA sequencing data will be a valuable source to elucidate new prognostic lesions beyond established markers of pediatric ALL. In this respect, RNA sequencing identified various gene fusions in up to half of the IKZF1plus (n = 6/12) and B-other (n = 19/36) cases but not in cases with hyperdiploid karyotypes (n = 35). Among these fusions, this study reports several previously undescribed in frame PAX5 fusions, including PAX5-MYO1G and PAX5-NCOA6.

Therapeutic Drug Monitoring of Asparaginase: Intra-individual Variability and Predictivity in Children With Acute Lymphoblastic Leukemia Treated With PEG-Asparaginase in the AIEOP-BFM Acute Lymphoblastic Leukemia 2009 Study.

BACKGROUND: Therapeutic drug monitoring (TDM) can identify patients with subtherapeutic asparaginase (ASNase) activity [silent inactivation (SI)] and prospectively guide therapeutic adaptation. However, limited intra-individual variability is a precondition for targeted dosing and the diagnosis of SI. METHODS: In the AIEOP-BFM acute lymphoblastic leukemia (ALL) 2009 trial, 2771 children with ALL were included and underwent ASNase-TDM in a central laboratory in Münster. Two biweekly administrations of pegylated ASNase during induction and a third dose during reinduction or the high-risk block, which was administered several weeks later, were monitored. We calculated (1) the incidence of SI; and (2) the predictivity of SI for SI after the subsequent administration. ASNase activities monitored during induction were categorized into percentiles at the respective sampling time points. These percentiles were used to calculate the intra-individual range of percentiles as a surrogate for intrapatient variability and to evaluate the predictivity of ASNase activity for the subsequent administration. RESULTS: The overall incidence of SI was low (4.9%). The positive predictive value of SI identified by one sample was ≤21%. Confirmation of SI by a second sample indicated a high positive predictive value of 100% for biweekly administrations, but not for administration more than 17 weeks later. Sampling and/or documentation errors were risks for misdiagnosis of SI. High intra-individual variability in ASNase activities, with ranges of percentiles over more than 2 quartiles and low predictivity, was observed in approximately 25% of the patients. These patients were likely to fail dose individualization based on TDM data. CONCLUSIONS: To use TDM as a basis for clinical decisions, standardized clinical procedures are required and high intra-individual variability should be taken into account. Details of the treatment are available in the European Clinical Trials Database at https://www.clinicaltrialsregister.eu/ctr-search/trial/2007-004270-43/DE.

THROMBOTECT - a randomized study comparing low molecular weight heparin, antithrombin and unfractionated heparin for thromboprophylaxis during induction therapy of acute lymphoblastic leukemia in children and adolescents.

Thromboembolism is a serious complication of induction therapy for childhood acute lymphoblastic leukemia. We prospectively compared the efficacy and safety of antithrombotic interventions in the consecutive leukemia trials ALL-BFM 2000 and AIEOP-BFM ALL 2009. Patients with newly diagnosed acute lymphoblastic leukemia (n=949, age 1 to 18 years) were randomized to receive low-dose unfractionated heparin, prophylactic low molecular weight heparin (enoxaparin) or activity-adapted antithrombin throughout induction therapy. The primary objective of the study was to determine whether enoxaparin or antithrombin reduces the incidence of thromboembolism as compared to unfractionated heparin. The principal safety outcome was hemorrhage; leukemia outcome was a secondary endpoint. Thromboembolism occurred in 42 patients (4.4%). Patients assigned to unfractionated heparin had a higher risk of thromboembolism (8.0%) compared with those randomized to enoxaparin (3.5%; P=0.011) or antithrombin (1.9%; P<0.001). The proportion of patients who refused antithrombotic treatment as allocated was 3% in the unfractionated heparin or antithrombin arms, and 33% in the enoxaparin arm. Major hemorrhage occurred in eight patients (no differences between the groups). The 5-year event-free survival was 80.9±2.2% among patients assigned to antithrombin compared to 85.9±2.0% in the unfractionated heparin group (P=0.06), and 86.2±2.0% in the enoxaparin group (P=0.10). In conclusion, prophylactic use of antithrombin or enoxaparin significantly reduced thromboembolism. Despite the considerable number of patients rejecting the assigned treatment with subcutaneous injections, the result remains unambiguous. Thromboprophylaxis - for the present time primarily with enoxaparin - can be recommended for children and adolescents with acute lymphoblastic leukemia during induction therapy. Whether and how antithrombin may affect leukemia outcome remains to be determined.

Trypsin-encoding PRSS1-PRSS2 variations influence the risk of asparaginase-associated pancreatitis in children with acute lymphoblastic leukemia: a Ponte di Legno toxicity working group report.

Asparaginase-associated pancreatitis is a life-threatening toxicity to childhood acute lymphoblastic leukemia treatment. To elucidate genetic predisposition and asparaginase-associated pancreatitis pathogenesis, ten trial groups contributed remission samples from patients aged 1.0-17.9 years treated for acute lymphoblastic leukemia between 2000 and 2016. Cases (n=244) were defined by the presence of at least two of the following criteria: (i) abdominal pain; (ii) levels of pancreatic enzymes ≥3 × upper normal limit; and (iii) imaging compatible with pancreatitis. Controls (n=1320) completed intended asparaginase therapy, with 78% receiving ≥8 injections of pegylated-asparaginase, without developing asparaginase-associated pancreatitis. rs62228256 on 20q13.2 showed the strongest association with the development of asparaginase-associated pancreatitis (odds ratio=3.75; P=5.2×10-8). Moreover, rs13228878 (OR=0.61; P=7.1×10-6) and rs10273639 (OR=0.62; P=1.1×10-5) on 7q34 showed significant association with the risk of asparaginase-associated pancreatitis. A Dana Farber Cancer Institute ALL Consortium cohort consisting of patients treated on protocols between 1987 and 2004 (controls=285, cases=33), and the Children's Oncology Group AALL0232 cohort (controls=2653, cases=76) were available as replication cohorts for the 20q13.2 and 7q34 variants, respectively. While rs62228256 was not validated as a risk factor (P=0.77), both rs13228878 (P=0.03) and rs10273639 (P=0.04) were. rs13228878 and rs10273639 are in high linkage disequilibrium (r2=0.94) and associated with elevated expression of the PRSS1 gene, which encodes for trypsinogen, and are known risk variants for alcohol-associated and sporadic pancreatitis in adults. Intra-pancreatic trypsinogen cleavage to proteolytic trypsin induces autodigestion and pancreatitis. In conclusion, this study finds a shared genetic predisposition between asparaginase-associated pancreatitis and non-asparaginase-associated pancreatitis, and targeting the trypsinogen activation pathway may enable identification of effective interventions for asparaginase-associated pancreatitis.

Expression of CD56 defines a distinct subgroup in childhood T-ALL with inferior outcome. Results of the ALL-BFM 2000 trial.

This study reports the prognostic impact of the expression of the natural killer cell marker CD56 in a large series of risk-adapted paediatric patients with T cell acute lymphoblastic leukaemia (T-ALL; n = 493) treated within the ALL-Berlin-Frankfurt-Münster (BFM) 2000 protocol. The immunophenotype was analysed centrally at diagnosis using flow cytometry and correlated with clinical parameters and outcome. CD56 expression was detected in 7·1% and early T-cell precursor (ETP) phenotype in 6·7% of all T-ALL patients. The percentage of ETP in the CD56+ T-ALL cohort was 4-fold higher than in the whole cohort. CD56+ T-ALL frequently expressed the progenitor marker CD34 and myeloid antigens CD13 and CD33. The 5-year event-free survival (EFS) rates for the European Group for the Immunological classification of Leukaemias/World Health Organization subgroups and the ETP phenotype were not statistically different. By contrast, patients with CD56 expression had a significantly reduced EFS (60 ± 8%) and overall survival (60 ± 8%) at 5 years, with a hazard ratio of 2·46 (P = 0·002) and 2·99 (P < 0·001), respectively. Moreover, CD56 expression in combination with the minimal residual disease (MRD)-based high risk assignment defined a population with a 'very-high' risk probability of relapse in the ALL-BFM 2000 trial. The CD56 marker has the potential to augment MRD-based risk stratification and may serve as a molecular target for antibody-based treatment strategies in childhood T-ALL.

Dexamethasone vs prednisone in induction treatment of pediatric ALL: results of the randomized trial AIEOP-BFM ALL 2000.

Induction therapy for childhood acute lymphoblastic leukemia (ALL) traditionally includes prednisone; yet, dexamethasone may have higher antileukemic potency, leading to fewer relapses and improved survival. After a 7-day prednisone prephase, 3720 patients enrolled on trial Associazione Italiana di Ematologia e Oncologia Pediatrica and Berlin-Frankfurt-Münster (AIEOP-BFM) ALL 2000 were randomly selected to receive either dexamethasone (10 mg/m(2) per day) or prednisone (60 mg/m(2) per day) for 3 weeks plus tapering in induction. The 5-year cumulative incidence of relapse (± standard error) was 10.8 ± 0.7% in the dexamethasone and 15.6 ± 0.8% in the prednisone group (P < .0001), showing the largest effect on extramedullary relapses. The benefit of dexamethasone was partially counterbalanced by a significantly higher induction-related death rate (2.5% vs 0.9%, P = .00013), resulting in 5-year event-free survival rates of 83.9 ± 0.9% for dexamethasone and 80.8 ± 0.9% for prednisone (P = .024). No difference was seen in 5-year overall survival (OS) in the total cohort (dexamethasone, 90.3 ± 0.7%; prednisone, 90.5 ± 0.7%). Retrospective analyses of predefined subgroups revealed a significant survival benefit from dexamethasone only for patients with T-cell ALL and good response to the prednisone prephase (prednisone good-response [PGR]) (dexamethasone, 91.4 ± 2.4%; prednisone, 82.6 ± 3.2%; P = .036). In patients with precursor B-cell ALL and PGR, survival after relapse was found to be significantly worse if patients were previously assigned to the dexamethasone arm. We conclude that, for patients with PGR in the large subgroup of precursor B-cell ALL, dexamethasone especially reduced the incidence of better salvageable relapses, resulting in inferior survival after relapse. This explains the lack of benefit from dexamethasone in overall survival that we observed in the total cohort except in the subset of T-cell ALL patients with PGR. This trial was registered at www.clinicaltrials.gov (BFM: NCT00430118, AIEOP: NCT00613457).

Therapeutic Drug Monitoring of Asparaginase Activity-Method Comparison of MAAT and AHA Test Used in the International AIEOP-BFM ALL 2009 Trial.

BACKGROUND: In the international AIEOP-BFM ALL 2009 trial, asparaginase (ASE) activity was monitored after each dose of pegylated Escherichia coli ASE (PEG-ASE). Two methods were used: the aspartic acid ß-hydroxamate (AHA) test and medac asparaginase activity test (MAAT). As the latter method overestimates PEG-ASE activity because it calibrates using E. coli ASE, method comparison was performed using samples from the AIEOP-BFM ALL 2009 trial. METHODS: PEG-ASE activities were determined using MAAT and AHA test in 2 sets of samples (first set: 630 samples and second set: 91 samples). Bland-Altman analysis was performed on ratios between MAAT and AHA tests. The mean difference between both methods, limits of agreement, and 95% confidence intervals were calculated and compared for all samples and samples grouped according to the calibration ranges of the MAAT and the AHA test. RESULTS: PEG-ASE activity determined using the MAAT was significantly higher than when determined using the AHA test (P < 0.001; Wilcoxon signed-rank test). Within the calibration range of the MAAT (30-600 U/L), PEG-ASE activities determined using the MAAT were on average 23% higher than PEG-ASE activities determined using the AHA test. This complies with the mean difference reported in the MAAT manual. With PEG-ASE activities >600 U/L, the discrepancies between MAAT and AHA test increased. Above the calibration range of the MAAT (>600 U/L) and the AHA test (>1000 U/L), a mean difference of 42% was determined. Because more than 70% of samples had PEG-ASE activities >600 U/L and required additional sample dilution, an overall mean difference of 37% was calculated for all samples (37% for the first and 34% for the second set). CONCLUSIONS: Comparison of the MAAT and AHA test for PEG-ASE activity confirmed a mean difference of 23% between MAAT and AHA test for PEG-ASE activities between 30 and 600 U/L. The discrepancy increased in samples with >600 U/L PEG-ASE activity, which will be especially relevant when evaluating high PEG-ASE activities in relation to toxicity, efficacy, and population pharmacokinetics.