Faculty Bibliography

Genetic alterations that activate NOTCH1 signaling and T cell transcription factors, coupled with inactivation of the INK4/ARF tumor suppressors, are hallmarks of T-lineage acute lymphoblastic leukemia (T-ALL), but detailed genome-wide sequencing of large T-ALL cohorts has not been carried out. Using integrated genomic analysis of 264 T-ALL cases, we identified 106 putative driver genes, half of which had not previously been described in childhood T-ALL (for example, CCND3, CTCF, MYB, SMARCA4, ZFP36L2 and MYCN). We describe new mechanisms of coding and noncoding alteration and identify ten recurrently altered pathways, with associations between mutated genes and pathways, and stage or subtype of T-ALL. For example, NRAS/FLT3 mutations were associated with immature T-ALL, JAK3/STAT5B mutations in HOXA1 deregulated ALL, PTPN2 mutations in TLX1 deregulated T-ALL, and PIK3R1/PTEN mutations in TAL1 deregulated ALL, which suggests that different signaling pathways have distinct roles according to maturational stage. This genomic landscape provides a logical framework for the development of faithful genetic models and new therapeutic approaches.

Remission induction therapy for acute lymphoblastic leukemia (ALL) includes medications that may cause hepatotoxicity, including asparaginase. We used a genome-wide association study (GWAS) to identify loci associated with elevated alanine transaminase (ALT) levels after induction therapy in children with ALL enrolled on St. Jude Children's Research Hospital (SJCRH) protocols. Germline DNA was genotyped using arrays and exome sequencing. Adjusting for age, body mass index, ancestry, asparaginase preparation and dosage, the PNPLA3 rs738409 (C>G) I148M variant, previously associated with fatty liver disease risk, had the strongest genetic association with ALT (P = 2.5x10-8 ). The PNPLA3 rs738409 variant explained 3.8% of the variability in ALT, and partly explained race-related differences in ALT. The PNPLA3 rs738409 association was replicated in an independent cohort of 2,285 patients treated on Children's Oncology Group protocol AALL0232 (P = 0.024). This is an example of a pharmacogenetic variant overlapping with a disease risk variant

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype characterized by genomic alterations that activate cytokine receptor and kinase signaling. We examined the frequency and spectrum of targetable genetic lesions in a retrospective cohort of 1389 consecutively diagnosed childhood B-ALL patients with high-risk clinical features and/or elevated minimal residual disease at the end of remission induction therapy. The Ph-like gene expression profile was identified in 341 of 1389 patients, 57 of which were excluded from additional analysis because of the presence of BCR-ABL1 (n=46) or ETV6-RUNX1 (n=11). Among the remaining 284 (20.4%) patients, overexpression and rearrangement of CRLF2 (IGH-CRLF2 or P2RY8-CRLF2) were identified in 124 (43.7%), with concomitant genomic alterations activating the JAK-STAT pathway (JAK1, JAK2, IL7R) identified in 63 patients (50.8% of CRLF2-rearranged cases). Of the remaining patients, using RT-PCR or transcriptome sequencing, we identified targetable ABL-class fusions (ABL1, ABL2, CSF1R and PDGFRB) in 14.1% of Ph-like ALL cases, EPOR rearrangements or JAK2 fusions (8.8%), alterations activating other JAK-STAT signaling genes (IL7R, SH2B3, JAK1; 6.3%) and other kinases (FLT3, NTRK3, LYN; 4.6%), and mutations involving the Ras pathway (KRAS, NRAS, NF1, PTPN11; 6%). We identified eight new rearrangement partners for four kinase genes previously reported to be rearranged in Ph-like ALL. The current findings provide support for the precision-medicine testing and treatment approach for Ph-like ALL that has been implemented in Children's Oncology Group ALL trials.

The causes of individual relapses in children with acute lymphoblastic leukemia (ALL) remain incompletely understood. We evaluated the contribution of germline genetic factors to relapse in 2225 children treated on Children's Oncology Group trial AALL0232. We identified 302 germline single nucleotide polymorphisms (SNPs) associated with relapse after adjusting for treatment and ancestry and 715 additional SNPs associated with relapse in an ancestry-specific manner. We tested for replication of these relapse-associated SNPs in external data sets of antileukemic drug pharmacokinetics and pharmacodynamics and an independent clinical cohort. 224 SNPs were associated with rapid drug clearance or drug resistance, and 32 were replicated in the independent cohort. The adverse risk associated with black and Hispanic ancestries was attenuated by addition of the 4 SNPs most strongly associated with relapse in these populations [for blacks: model without SNPs hazard ratio (HR)=2.32, P=2.27 x 10-4, model with SNPs HR=1.07, P=0.79; for Hispanics: model without SNPs HR=1.7, P=8.23 x 10-5, model with SNPs HR=1.31, P=0.065]. Relapse SNPs associated with asparaginase resistance or allergy were overrepresented among SNPs associated with relapse in the more asparaginase intensive treatment arm (20/54 in Capizzi-methorexate arm vs 8/54 in high-dose methotrexate arm, P=0.015). Inherited genetic variation contributes to race-specific and treatment-specific relapse risk.Leukemia accepted article preview online, 18 January 2017. doi:10.1038/leu.2017.24.

Purpose Children with acute lymphoblastic leukemia (ALL) are generally instructed to take mercaptopurine (6-MP) in the evening and without food or dairy products. This study examines the association between 6-MP ingestion habits and 6-MP adherence, red cell thioguanine nucleotide (TGN) levels, and risk of relapse in children with TMPT wild-type genotype. Methods Participants included 441 children with ALL receiving oral 6-MP for maintenance. Adherence was monitored over 48,086 patient-days using the Medication Event Monitoring System; nonadherence was defined as adherence rate < 95%. 6-MP ingestion habits examined included: takes 6-MP with versus never with food, takes 6-MP with versus never with dairy, and takes 6-MP in the evening versus morning versus varying times. Results Median age at study was 6 years (range, 2 to 20 years); 43.8% were nonadherent. Certain 6-MP ingestion habits were associated with nonadherence (taking 6-MP with dairy [odds ratio (OR), 1.9; 95% CI, 1.3 to 2.9; P = .003] and at varying times [OR, 3.4; 95% CI, 1.8 to 6.3; P = .0001]). After adjusting for adherence and other prognosticators, there was no association between 6-MP ingestion habits and relapse risk (6-MP with food: hazard ratio [HR], 0.7; 95% CI, 0.3 to 1.9; P = .5; with dairy: HR, 0.3; 95% CI, 0.07 to 1.5; P = .2; taken in evening/night: HR, 1.1; 95% CI, 0.2 to 7.8; P = .9; at varying times: HR, 0.3; 95% CI, 0.04 to 2.7; P = .3). Among adherent patients, there was no association between red cell TGN levels and taking 6-MP with food versus without (206.1 +/- 107.1 v 220.6 +/- 121.6; P = .5), with dairy versus without (220.1 +/- 87.8 v 216.3 +/- 121.3; P =.7), or in the evening/night versus morning/midday versus varying times (218.8 +/- 119.7 v 195.5 +/- 82.3 v 174.8 +/- 93.4; P = .6). Conclusion Commonly practiced restrictions surrounding 6-MP ingestion might not influence outcome but may hinder adherence. Future recommendations regarding 6-MP intake during maintenance therapy for childhood ALL should aim to simplify administration.

Adequate exposure to oral 6-mercaptopurine (6MP) during maintenance therapy for childhood acute lymphoblastic leukemia (ALL) is critical for sustaining durable remissions; the accuracy of self-reported 6MP intake is unknown. We aimed to directly compare self-report to electronic monitoring (Medication Event Monitoring System [MEMS]), and identify predictors of over-reporting in a cohort of 416 children with ALL in first remission over 4 study months per patient (1,344 patient-months for the cohort) during maintenance therapy. Patients were classified as "perfect reporters" (self-report=MEMS), "over reporters" (self-report>MEMS by >/=5 days/month for >/=50% of study months), and "others" (all patients not meeting criteria for perfect- or over-reporter). Multivariable logistic regression examined sociodemographic and clinical characteristics, 6MP dose-intensity, TPMT genotype, TGN levels, and 6MP non-adherence (MEMs-based adherence rate <95%) associated with the over-reporter phenotype; generalized estimating equations (GEE) compared 6MP intake by self-report and MEMS over the study period. Self-reported 6MP intake exceeded MEMS at least some of the time in 84% of patients. Fifty (12%) patients were classified as perfect reporters, 98 (23.6%) as over-reporters, 2 (0.5%) as under-reporters, and 266 (63.9%) as others. Multivariable logistic regression technique identified the following variables associated with the over-reporter phenotype: i) non-white race: Hispanic, odds ratio (OR)=2.4, 95%CI, 1.1-5.1, p=0.02; Asian, OR=3.1, 95%CI, 1.2-8.3, p=0.02; African-American, OR=5.4, 95%CI, 2.3-12.8, p=0.0001; ii) paternal education

PMCID:5383868

PMID: 28153823

ISSN: 1528-0020

CID: 2437172