Faculty Bibliography

PURPOSE: Acute pancreatitis is one of the common causes of asparaginase intolerance. The mechanism is unknown, and genetic predisposition to asparaginase-induced pancreatitis has not been previously identified. METHODS: To determine clinical risk factors for asparaginase-induced pancreatitis, we studied a cohort of 5,185 children and young adults with acute lymphoblastic leukemia, including 117 (2.3%) who were diagnosed with at least one episode of acute pancreatitis during therapy. A genome-wide association study was performed in the cohort and in an independent case-control group of 213 patients to identify genetic risk factors. RESULTS: Risk factors associated with pancreatitis included genetically defined Native American ancestry (P < .001), older age (P < .001), and higher cumulative dose of asparaginase (P < .001). No common variants reached genome-wide significance in the genome-wide association study, but a rare nonsense variant rs199695765 in CPA2, encoding carboxypeptidase A2, was highly associated with pancreatitis (hazard ratio, 587; 95% CI, 66.8 to 5166; P = 9.0 x 10-9). A gene-level analysis showed an excess of additional CPA2 variants in patients who did versus those who did not develop pancreatitis (P = .001). Sixteen CPA2 single-nucleotide polymorphisms were associated (P < .05) with pancreatitis, and 13 of 24 patients who carried at least one of these variants developed pancreatitis. Biologic functions that were overrepresented by common variants modestly associated with pancreatitis included purine metabolism and cytoskeleton regulation. CONCLUSION: Older age, higher exposure to asparaginase, and higher Native American ancestry were independent risk factors for pancreatitis in patients with acute lymphoblastic leukemia. Those who inherit a nonsense rare variant in the CPA2 gene had a markedly increased risk of asparaginase-induced pancreatitis.

Although there are high survival rates for children with acute lymphoblastic leukaemia, their outcome is often counterbalanced by the burden of toxic effects. This is because reported frequencies vary widely across studies, partly because of diverse definitions of toxic effects. Using the Delphi method, 15 international childhood acute lymphoblastic leukaemia study groups assessed acute lymphoblastic leukaemia protocols to address toxic effects that were to be considered by the Ponte di Legno working group. 14 acute toxic effects (hypersensitivity to asparaginase, hyperlipidaemia, osteonecrosis, asparaginase-associated pancreatitis, arterial hypertension, posterior reversible encephalopathy syndrome, seizures, depressed level of consciousness, methotrexate-related stroke-like syndrome, peripheral neuropathy, high-dose methotrexate-related nephrotoxicity, sinusoidal obstructive syndrome, thromboembolism, and Pneumocystis jirovecii pneumonia) that are serious but too rare to be addressed comprehensively within any single group, or are deemed to need consensus definitions for reliable incidence comparisons, were selected for assessment. Our results showed that none of the protocols addressed all 14 toxic effects, that no two protocols shared identical definitions of all toxic effects, and that no toxic effect definition was shared by all protocols. Using the Delphi method over three face-to-face plenary meetings, consensus definitions were obtained for all 14 toxic effects. In the overall assessment of outcome of acute lymphoblastic leukaemia treatment, these expert opinion-based definitions will allow reliable comparisons of frequencies and severities of acute toxic effects across treatment protocols, and facilitate international research on cause, guidelines for treatment adaptation, preventive strategies, and development of consensus algorithms for reporting on acute lymphoblastic leukaemia treatment.

Osteonecrosis is a dose-limiting toxicity in the treatment of pediatric acute lymphoblastic leukemia (ALL). Prior studies on the genetics of osteonecrosis have focused on patients >/=10 years of age, leaving the genetic risk factors for the larger group of children <10 years incompletely understood. Here, we perform the first evaluation of genetic risk factors for osteonecrosis in children <10 years. The discovery cohort comprised 82 cases of osteonecrosis and 287 controls treated on Children's Oncology Group (COG) standard-risk ALL protocol AALL0331 (NCT00103285, https://clinicaltrials.gov/ct2/show/NCT00103285), with results tested for replication in 817 children <10 years treated on COG protocol AALL0232 (NCT00075725, https://clinicaltrials.gov/ct2/show/NCT00075725). The top replicated single nucleotide polymorphisms (SNPs) were near bone morphogenic protein 7 [BMP7: rs75161997, P = 5.34 x 10(-8) (odds ratio [OR] 15.0) and P = .0498 (OR 8.44) in the discovery and replication cohorts, respectively] and PROX1-antisense RNA1 (PROX1-AS1: rs1891059, P = 2.28 x 10(-7) [OR 6.48] and P = .0077 [OR 3.78] for the discovery and replication cohorts, respectively). The top replicated nonsynonymous SNP, rs34144324, was in a glutamate receptor gene (GRID2, P = 8.65 x 10(-6) [OR 3.46] and P = .0136 [OR 10.8] in the discovery and replication cohorts, respectively). In a meta-analysis, the BMP7 and PROX1-AS1 variants (rs75161997 and rs1891059, respectively) met the significance threshold of <5 x 10(-8). Top replicated SNPs were enriched in enhancers active in mesenchymal stem cells, and analysis of annotated genes demonstrated enrichment in glutamate receptor and adipogenesis pathways. These data may provide new insights into the pathophysiology of osteonecrosis.

This retrospective study examined the longitudinal hospital outcomes (costs adjusted for inflation, hospital days, and admissions) associated with the treatment of pediatric, adolescent, and young adult acute lymphoblastic leukemia (ALL). Patients between one and 26 years of age with newly diagnosed ALL, who were treated at Primary Children's Hospital (PCH) in Salt Lake City, Utah were included. Treatment and hospitalization data were retrieved from system-wide cancer registry and enterprise data warehouse. PCH is a member of the Children's Oncology Group (COG) and patients were treated on, or according to, active COG protocols. Treatment-related hospital costs of ALL were examined by computing the average annual growth rates (AAGR). Longitudinal regressions identified patient characteristics associated with costs. A total of 505 patients (46.9% female) were included. The majority of patients had B-cell lineage ALL, 6.7% had T-ALL, and the median age at diagnosis was 4 years. Per-patient, first-year ALL hospitalization costs at PCH rose from $24,197 in 1998 to $37,924 in 2012. The AAGRs were 6.1, 13.0, and 7.6% for total, pharmacy, and room and care costs, respectively. Average days (AAGR = 5.2%) and admissions (AAGR = 3.8%) also demonstrated an increasing trend. High-risk patients had 47% higher costs per 6-month period in the first 5 years from diagnosis than standard-risk patients (P < 0.001). Similarly, relapsed ALL and stem cell transplantations were associated with significantly higher costs than nonrelapsed and no transplantations, respectively (P < 0.001). Increasing treatment-related costs of ALL demonstrate an area for further investigation. Value-based interventions such as identifying low-risk fever and neutropenia patients and managing them in outpatient settings should be evaluated for reducing the hospital burden of ALL.

Standard risk acute lymphoblastic leukemia (SR-ALL) has high cure rates, but requires 2-3 years of therapy. We aimed to (i) prospectively evaluate health-related quality of life (HRQOL) during and after SR-ALL therapy, and (ii) identify associated predictors. Parents of 160 SR-ALL patients enrolled on Children's Oncology Group (COG) therapeutic trial AALL0331 at 31 sites completed the Pediatric Quality of Life Inventory (PedsQL) 4.0 Generic Core Scales (physical, emotional and social functioning) and Family Assessment Device-General Functioning (FAD-GF) at 1, 6 and 12 months after diagnosis, and 3 months post-therapy. Mean PedsQL scores in physical, emotional and social functioning were impaired 1 month after diagnosis but steadily improved. Three months post-therapy, impaired physical and social functioning was observed in 27.8 and 25.8% of patients, respectively. In repeated-measures analysis, problematic family functioning predicted emotional (OR = 1.85, 95% CI 1.03-3.34) and social (OR = 1.99, 95% CI 1.21-3.27) impairment. Larger household size was associated with social impairment (OR = 1.21, 95% CI 1.02-1.45). Adverse neurological event(s) during therapy predicted post-therapy physical (OR = 5.17, 95% CI 1.61-16.63) and social (OR = 8.17, 95% CI 1.19-56.16) impairment. HRQOL 1 month after diagnosis was not predictive of HRQOL 3 months after therapy completion. In conclusion, children with SR-ALL experience considerable impairment in HRQOL at the end of induction, but rapidly improve. However, many still experience physical and social impairment 3 months post-therapy, suggesting a role for continued family and physical functioning support. Longer follow-up is needed to determine if post-therapy deficits change over time.

Treatment-related mortality is an important outcome in paediatric cancer clinical trials. An international group of experts in supportive care in paediatric cancer developed a consensus-based definition of treatment-related mortality and a cause-of-death attribution system. The reliability and validity of the system was tested in 30 deaths, which were independently assessed by two clinical research associates and two paediatric oncologists. We defined treatment-related mortality as death occurring in the absence of progressive cancer. Of the 30 reviewed deaths, the reliability of classification for treatment-related mortality was noted as excellent by clinical research associates (κ=0·83, 95% CI 0·60-1·00) and paediatric oncologists (0·84, 0·63-1·00). Criterion validity was established because agreement between the consensus classifications by clinical research associates and paediatric oncologists was almost perfect (0·92, 0·78-1·00). Our approach should allow comparison of treatment-related mortality across trials and across time.

BACKGROUND:Hereditary predisposition is rarely suspected for childhood acute lymphoblastic leukaemia (ALL). Recent reports of germline ETV6 variations associated with substantial familial clustering of haematological malignancies indicated that this gene is a potentially important genetic determinant for ALL susceptibility. Our aims in this study were to comprehensively identify ALL predisposition variants in ETV6 and to determine the extent to which they contributed to the overall risk of childhood ALL. METHODS:Whole-exome sequencing of an index family with several cases of ALL was done to identify causal variants for ALL predisposition. Targeted sequencing of ETV6 was done in children from the Children's Oncology Group and St Jude Children's Research Hospital front-line ALL trials. Patients were included in this study on the basis of their enrolment in these clinical trials and the availability of germline DNA. ETV6 variant genotypes were compared with non-ALL controls to define ALL-related germline risk variants. ETV6 variant function was characterised bioinformatically and correlated with clinical and demographic features in children with ALL. FINDINGS/RESULTS:We identified a novel non-sense ETV6 variant (p.Arg359X) with a high penetrance in an index family. Subsequent targeted sequencing of ETV6 in 4405 childhood ALL cases identified 31 exonic variants (four non-sense, 21 missense, one splice site, and five frameshift variants) that were potentially related to ALL risk in 35 cases (1%). 15 (48%) of 31 ALL-related ETV6 variants clustered in the erythroblast transformation specific domain and were predicted to be highly deleterious. Children with ALL-related ETV6 variants were significantly older at leukaemia diagnosis than those without (10·2 years [IQR 5·3-13·8] vs 4·7 years [3·0-8·7]; p=0·017). The hyperdiploid leukaemia karyotype was highly over-represented in ALL cases harbouring germline ETV6 risk variants compared with the wild-type group (nine [64%] of 14 cases vs 538 [27%] of 2007 cases; p=0·0050). INTERPRETATION/CONCLUSIONS:Our findings indicated germline ETV6 variations as the basis of a novel genetic syndrome associated with predisposition to childhood ALL. The development of recommendations for clinical interventions and surveillance for individuals harbouring ALL-related ETV6 variants are needed. FUNDING/BACKGROUND:US National Institutes of Health and American Lebanese Syrian Associated Charities.

The outcome for pediatric ALL patients that relapse is dismal. A hallmark of relapsed disease is acquired resistance to multiple chemotherapeutic agents, particularly glucocorticoids. In this study, we performed a genome-scale shRNA screen to identify mediators of prednisolone sensitivity in ALL cell lines. The incorporation of this data with an integrated analysis of relapse-specific genetic and epigenetic changes allowed us to identify the MAPK pathway as a mediator of prednisolone resistance in pediatric ALL. We show that knockdown of the specific MAPK pathway members MEK2 and MEK4 increased sensitivity to prednisolone through distinct mechanisms. MEK4 knockdown increased sensitivity specifically to prednisolone by increasing the levels of the glucocorticoid receptor. MEK2 knockdown increased sensitivity to all chemotherapy agents tested by increasing the levels of p53. Furthermore, we demonstrated that inhibition of MEK1/2 with trametinib increased sensitivity of ALL cells and primary samples to chemotherapy in vitro and in vivo. To confirm a role for MAPK signaling in patients with relapsed ALL, we measured the activation of MEK1/2 target ERK in matched diagnosis and relapse primary samples and observed increased pERK levels at relapse. Furthermore, relapse samples have an enhanced response to MEK inhibition compared to matched diagnosis samples in xenograft models. Altogether, our data indicate that inhibition of the MAPK pathway increases chemosensitivity to glucocorticoids and possibly other agents, and is an attractive target for prevention and/or treatment of relapsed disease.

Glucocorticoids are important therapy for acute lymphoblastic leukemia (ALL) and their major adverse effect is osteonecrosis. Our goal was to identify genetic and nongenetic risk factors for osteonecrosis. We performed a genome-wide association study of single nucleotide polymorphisms (SNPs) in a discovery cohort comprising 2285 children with ALL treated on the Children's Oncology Group AALL0232 protocol (NCT00075725 https://clinicaltrials.gov/ct2/show/NCT00075725), adjusting for covariates. The minor allele at SNP rs10989692 (near the glutamate receptor GRIN3A locus) was associated with osteonecrosis (hazard ratio = 2.03, P=3.59x10-7). The association was supported by two replication cohorts, including 361 children with ALL on St. Jude's Total XV protocol (NCT00137111 https://clinicaltrials.gov/ct2/show/NCT00137111) and 309 non-ALL patients from Vanderbilt University's BioVU repository treated with glucocorticoids (odds ratio = 1.87 and 2.26, P = 0.063 and 0.0074 respectively). In a meta-analysis, rs10989692 was also highest ranked (P = 2.68x10-8), and the glutamate pathway was the top ranked pathway (P = 9.8x10-4). Osteonecrosis-associated glutamate receptor variants were also associated with other vascular phenotypes including cerebral ischemia (OR = 1.64, P = 2.5x10-3) and arterial embolism and thrombosis (OR = 1.88, P = 4.2x10-3). In conclusion, osteonecrosis was associated with inherited variations near glutamate receptor genes. Further understanding this association may allow interventions to decrease osteonecrosis.