Faculty Bibliography

We thank the research coordinators and following physicians at pediatric cancer centers for contributing data to this project: Prashant Hiwarkar and Jayashree Motwani, Birmingham Women's and Children's Hospital, UK; Kelly Malone, Children's Hospital of Colorado, USA; Mylene Bassal, Children's Hospital of Eastern Ontario, Canada; Yoav Messinger and Joanna Perkins, Children's Hospital of Minnesota, USA; Van Huynh, Children's Hospital of Orange County, USA; Richard Ho, Children's Hospital at Vanderbilt, USA; Joanne Chuah and Jessa Morales, Children's Hospital at Westmead, Australia; Donald Wells, Dell Children's Hospital, USA; Nicolas Boissel, Hospital Saint-Louis, France; Tannie Huang, Kaiser Permanente, USA; Stacey Marjerrison, McMaster Children's Hospital, Canada; William Carroll and Joanna Pierro, New York University Langone Medical Center, USA; Ajay Vora, Sheffield Children's Hospital, UK; Donna Lancaster, The Royal Marsden Hospital, UK; Lucie Šrámková, University Hospital Motol, Czech Republic; Chatchawin Assanasen, University of Texas Health Science Center, San Antonio, USA; Rupert Handgretinger, University of Tübingen, Germany.

BACKGROUND/OBJECTIVES/OBJECTIVE:Anthracyclines are used in induction therapy of pediatric acute lymphoblastic leukemia (ALL) and are known to generate oxidative stress; whether this translates into enhanced antileukemic activity or hemolytic effects in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency is unknown. DESIGN/METHODS/METHODS:Among 726 pediatric patients with newly diagnosed ALL treated at St. Jude Children's Research Hospital, 22 had deficient G6PD activity. We compared the prevalence of positive minimal residual disease (MRD) ≥1% at Day 15/Day 19 of induction or ≥0.01% at Day 42/Day 46 (end of induction) and the number of red blood cell (RBC) transfusions after daunorubicin in induction between patients with or without G6PD deficiency, adjusting for ALL risk group, treatment protocol, age, and gender. RESULTS:There was no difference in Day 15/19 (P = 1) or end of induction MRD (P = 0.76) nor in the number of RBC transfusions (P = 0.73); the lack of association with MRD was confirmed in a dataset of 1192 newly diagnosed male patients enrolled in a Children's Oncology Group trial (P = 0.78). CONCLUSION/CONCLUSIONS:We found no evidence that G6PD deficiency affects daunorubicin activity during induction treatment for ALL.

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Characterized by high levels of Native American ancestry, Hispanics are disproportionally affected by this cancer with high incidence and inferior survival, but the genetic basis for this disparity remains poorly understood because of a paucity of genome-wide investigation of ALL in Hispanics. Performing a genome-wide association study in 940 Hispanic children with ALL and 681 ancestry-matched non-ALL controls, we identified a novel susceptibility locus in the ERG gene (rs2836365; P = 3.76 × 10^-8, odds ratio [OR] = 1.56), with independent validation (P = 0.01, OR = 1.43). Imputation analyses pointed to a single causal variant driving the association signal at this locus overlapping with putative regulatory DNA elements. The effect size of the ERG risk variant rose sharply with increasing Native American genetic ancestry. The ERG risk genotype was under-represented in ALL with the ETV6-RUNX1 fusion (P < 0.0005) but enriched in the TCF3-PBX1 subtype (P < 0.05). Interestingly, ALL cases with germline ERG risk alleles were significantly less likely to have somatic ERG deletion (P < 0.05). Our results provide novel insights to genetic predisposition to ALL and its contribution to racial disparity in this cancer.

PURPOSE/OBJECTIVE:Children and young adults with hypodiploid B-lymphoblastic leukemia (B-ALL) fare poorly and hematopoietic stem cell transplantation (HSCT) is often pursued in first complete remission (CR1). We retrospectively reviewed the outcomes of children and young adults with hypodiploid B-ALL who were enrolled in recent Children's Oncology Group (COG) trials to evaluate the impact of HSCT on outcome. PATIENTS AND METHODS/METHODS:Cytogenetic analyses and DNA index were performed at COG-approved laboratories, and hypodiploidy was defined as modal chromosome number less than 44 and/or DNA index less than 0.81. Minimal residual disease (MRD) was determined centrally using flow cytometry at two reference laboratories. Patients with hypodiploid ALL came off protocol therapy postinduction and we retrospectively collected details on their subsequent therapy and outcomes. Event-free survival (EFS) and overall survival (OS) were estimated for the cohort. RESULTS:Between 2003 and 2011, 8,522 patients with National Cancer Institute standard-risk and high-risk B-ALL were enrolled in COG AALL03B1 ( ClinicalTrials.gov identifier: NCT00482352). Hypodiploidy occurred in 1.5% of patients (n = 131), 98.3% of whom achieved CR after induction therapy. Five-year EFS and OS were 52.2% ± 4.9% and 58.9% ± 4.8%, respectively. Outcomes for patients undergoing CR1 HSCT were not significantly improved: 5-year EFS and OS were 57.4% ± 7.0% and 66.2% ± 6.6% compared with 47.8% ± 7.5% and 53.8% ± 7.6%, respectively ( P = .49 and .34, respectively) for those who did not undergo transplantation. Patients with MRD of 0.01% or greater at the end of induction had 5-year EFS and OS of 26.7% ± 9.3% and 29.3% ± 10.1%, respectively, and HSCT had no significant impact on outcomes. CONCLUSION/CONCLUSIONS:Children and young adults with hypodiploid B-ALL continue to fare poorly and do not seem to benefit from CR1 HSCT. This is especially true for patients with MRD of 0.01% or greater at the end of induction. New treatment strategies are urgently needed for these patients.

Recent genomic studies have identified chromosomal rearrangements defining new subtypes of B-progenitor acute lymphoblastic leukemia (B-ALL), however many cases lack a known initiating genetic alteration. Using integrated genomic analysis of 1,988 childhood and adult cases, we describe a revised taxonomy of B-ALL incorporating 23 subtypes defined by chromosomal rearrangements, sequence mutations or heterogeneous genomic alterations, many of which show marked variation in prevalence according to age. Two subtypes have frequent alterations of the B lymphoid transcription-factor gene PAX5. One, PAX5alt (7.4%), has diverse PAX5 alterations (rearrangements, intragenic amplifications or mutations); a second subtype is defined by PAX5 p.Pro80Arg and biallelic PAX5 alterations. We show that p.Pro80Arg impairs B lymphoid development and promotes the development of B-ALL with biallelic Pax5 alteration in vivo. These results demonstrate the utility of transcriptome sequencing to classify B-ALL and reinforce the central role of PAX5 as a checkpoint in B lymphoid maturation and leukemogenesis.

The efficacy of asparaginase in acute lymphoblastic leukemia (ALL) is dependent on depletion of asparagine, an essential amino acid for ALL cells. The target level of plasma asparaginase activity to achieve asparagine depletion has been between 0.05 and 0.4 IU/mL. COG AALL07P4 examined the asparaginase activity and plasma and CSF asparagine concentration of pegaspargase when given intravenously in the treatment of NCI high risk ALL. Matched plasma asparaginase/asparagine levels of the clearance of 54 doses of pegaspargase given in induction or consolidation demonstrated that all patients who had a plasma asparaginase level >0.02 IU/mL had undetectable plasma asparagine. No difference was observed in CSF asparagine levels associated with matched plasma asparaginase levels of 0.02-0.049 versus 0.05-0.22 IU/mL (p = .25). Our data suggest that a plasma asparaginase activity level of 0.02 IU/mL can effectively deplete plasma asparagine. The data also indicate that the 95% CI for plasma asparagine depletion after a pegaspargase dose is 22-29 days. Clinical trial registration: clinicaltrials.gov identifier NCT00671034.

Background/Objectives: Nelarabine (Nel) is a T-cell specific agent, FDA approved for patients who have failed at least two regimens. COG AALL0434 evaluated the safety and efficacy of Nel when incorporated into COG augmented BFM (ABFM) chemotherapy in newly diagnosed patients with T-ALL. Design/Methods: AALL0434 enrolled 1,895 patients (2007-2014) and included a 2 x 2 pseudo-factorial randomization using the ABFM regimen. Patients were randomized to receive escalating dose methotrexate with pegaspargase (CMTX) or High Dose MTX (HDMTX). Intermediate and high-risk patients with T-ALL were randomized to +/-six 5-day courses of Nel 650 mg/m²/day during Consolidation (2), Delayed Intensification (1) and Maintenance (3). The intermediate and high risk patients received prophylactic (1200 cGy) or therapeutic (1800 cGy, CNS3) cranial irradiation. Patients with induction failure were non-randomly assigned to HDMTX+Nel. Results: For all randomized patients, the 4-year disease-free survival (DFS) and overall survival (OS) rates were 84.3 +/-1.1% and 90.2 +/-0.9%. The 4-year DFS rate for patients with T-ALL randomized to Nel (N=323) vs no Nel (N=336) was 88.9 +/-2.2% vs 83.3 +/-2.5%, (p=0.0332). Among patients with T-ALL randomized to CMTX the 4-year DFS for Nel (N=147) vs no Nel (N=151) was 92.2 +/-2.8% vs 89.8 +/-3.0%, p=0.3825. For those randomized to HDMTX, 4-year DFS was 86.2 +/-3.2% with Nel (N=176) vs 78.0 +/-3.7% without Nel (N=185), p=0.024. Differences between DFS in a 4-arm comparison were highly significant (P = 0.002), with no significant interactions between MTX and Nel randomizations (p=0.41). Patients with induction failure (N=43) assigned to HDMTX/Nel had a 4-year DFS of 54.8 +/-8.9%. Overall toxicity and neurotoxicity were acceptable and not significantly different between all four arms. Conclusions: COG AALL0434 showed outstanding overall outcomes for patients with T-cell malignancy with Nel improving DFS for children and young adults with T-ALL

Purpose Early intensification with methotrexate (MTX) is a key component of acute lymphoblastic leukemia (ALL) therapy. Two different approaches to MTX intensification exist but had not been compared in T-cell ALL (T-ALL): the Children's Oncology Group (COG) escalating dose intravenous MTX without leucovorin rescue plus pegaspargase escalating dose, Capizzi-style, intravenous MTX (C-MTX) regimen and the Berlin-Frankfurt-Muenster (BFM) high-dose intravenous MTX (HDMTX) plus leucovorin rescue regimen. Patients and Methods COG AALL0434 included a 2 × 2 randomization that compared the COG-augmented BFM (ABFM) regimen with either C-MTX or HDMTX during the 8-week interim maintenance phase. All patients with T-ALL, except for those with low-risk features, received prophylactic (12 Gy) or therapeutic (18 Gy for CNS3) cranial irradiation during either the consolidation (C-MTX; second month of therapy) or delayed intensification (HDMTX; seventh month of therapy) phase. Results AALL0434 accrued 1,895 patients from 2007 to 2014. The 5-year event-free survival and overall survival rates for all eligible, evaluable patients with T-ALL were 83.8% (95% CI, 81.2% to 86.4%) and 89.5% (95% CI, 87.4% to 91.7%), respectively. The 1,031 patients with T-ALL but without CNS3 disease or testicular leukemia were randomly assigned to receive ABFM with C-MTX (n = 519) or HDMTX (n = 512). The estimated 5-year disease-free survival ( P = .005) and overall survival ( P = .04) rates were 91.5% (95% CI, 88.1% to 94.8%) and 93.7% (95% CI, 90.8% to 96.6%) for C-MTX and 85.3% (95% CI, 81.0%-89.5%) and 89.4% (95% CI, 85.7%-93.2%) for HDMTX. Patients assigned to C-MTX had 32 relapses, six with CNS involvement, whereas those assigned to HDMTX had 59 relapses, 23 with CNS involvement. Conclusion AALL0434 established that ABFM with C-MTX was superior to ABFM plus HDMTX for T-ALL in approximately 90% of patients who received CRT, with later timing for those receiving HDMTX.