Cancer Institute Acute Lymphoblastic Leukemia Consortium Protocol Research Articles

Venous Thromboembolism in Adolescents and Young Adults with Acute Lymphoblastic Leukemia Treated on a Pediatric-Inspired Regimen

Introduction Adolescent and young adult (AYA) patients (pts) with acute lymphoblastic leukemia (ALL) can be effectively treated with pediatric-inspired ALL regimens which incorporate asparaginase (ASP). Asparaginase is associated with increased venous thromboembolic (VTE) complications. We examined the incidence of and risk factors for VTE events as well as the impact of VTE events on outcomes of AYA pts treated on Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocols. Methods We identified pts aged 15-50 years diagnosed with Philadelphia chromosome negative (Ph-neg) ALL treated on 4 multicenter DFCI Consortium protocols (Pediatric 00-001, Pediatric 05-001, Adult 01-175, and Adult 06-254), or treated as per these protocols between 2000-2021. All regimens included an ASP containing induction, 30 weeks of continuous ASP exposure during consolidation and a continuation phase without ASP. The use of a pegylated vs non-pegylated ASP formulation varied between protocols. As ASP exposure is associated with both VTE and survival, it may confound the association between VTE and survival; thus, to ameliorate confounding, all survival associated outcomes were conducted on pts who remained on protocol for at least 1 year (encompassing ASP exposure). Overall survival (OS) and event free survival (EFS) were presented with Kaplan Meier curves and comparisons were made by the log-rank test. Cumulative incidence of VTE, relapse (CIR) and non-relapse mortality (NRM) were estimated by the cumulative incidence method with the appropriate competing risks, and comparisons were made by the Gray test. Cox regression analysis was fit to evaluate the effect of covariates on OS and EFS. Results Among 341 Ph-neg AYA ALL pts aged 15-50 years, 109 (32%) experienced one or more VTE events. The baseline characteristics did not differ between pts who experienced a VTE and those who did not experience a VTE, except for a higher rate of VTE among overweight/obese pts (BMI≥25 kg/m 2, n=56, 38%) vs normal BMI (n=53, 27%, p=0.04) and a lower rate of VTE in patients with hyperdiploid vs non-hyperdiploid karyotype (n=4, 12% vs n=105, 34%, p<0.01). Of the 109 pts with VTE, 9 (8%) experienced sinus vein thrombosis (2.6% in the overall cohort) and 19 (17%) experienced at least one additional VTE. Most initial VTE events occurred during consolidation (n=78, 72%), followed by induction (n=22, 20%), and continuation/follow-up (n=9, 8%). The 2-yr cumulative incidence of VTE was 32% (95% CI, 27%-37%) and was similar between patients who were treated with non-pegylated ASP vs. pegylated ASP (n=43, 30% vs n=65, 35%, p=0.35). The 2-yr cumulative incidence of VTE was higher in the BMI ≥ 25 kg/m 2 group compared to those with normal BMI (38% vs 28%, p=0.035, Figure 1) and was the only covariate associated with increased VTE risk in the univariate regression model (HR 1.49, 95% CI, 1.03-2.17). Among pts who completed ≥ 1 year of protocol therapy (n=220), the 4-year OS was 92%, and did not differ between pts who experienced VTE vs. not (94% vs 90%, p=0.99, Figure 2). Similarly, there were no differences in 4-year CIR (14% vs 11%, p=0.50), NRM (0% vs 3%, p=0.37), and EFS (86% vs 86%, p=0.79). In univariate analysis for OS, obese BMI (>30 kg/m 2), higher WBC, B-cell immunophenotype, and fewer weeks on ASP therapy were associated with worse OS; all remained predictive in the multivariable model. In the uni- and multivariable analysis for EFS, higher WBC and B-cell immunophenotype were associated with worse EFS. Notably, VTE was not associated with worse OS or EFS in all regression analyses. Conclusion Among AYAs treated on DFCI ALL Consortium protocols, VTE events were frequent, occurred mostly during consolidation phase and were more common among pts with overweight/obese BMI vs normal BMI. Sinus vein thrombosis was rare. VTE incidence did not impact CIR, NRM, EFS or OS, suggesting that VTE is a manageable toxicity.

Abstract 5216: The effect of polymorphisms in DAT1 and DRD4 on dietary intake during chemotherapy for childhood leukemia

Abstract Outcomes of acute lymphoblastic leukemia (ALL) are associated with both host and environmental factors. We hypothesized that there is also an interaction between them, with genetic variants influencing dietary choices. The dopamine transporter 1 (DAT1) and D4 subtype of the dopamine receptor (DRD4) genes are polymorphic, with a variable number of nucleotide repeats (VNTR) that affect dopaminergic neurotransmission, and reward circuitry for food cravings. Specifically, the 9-tandem repeats (9R) allele of DAT1 and the 7-tandem repeats (7R) allele of DRD4 are risk factors for eating disorders or undereating behavior in children. The goal of this study was to determine whether these polymorphisms are associated with altered dietary intake during therapy for childhood ALL. DNA was isolated from peripheral blood mononuclear cells collected from 439 children being treated on Dana Farber Cancer Institute ALL Consortium Protocol 05-001 (NCT00400946). Target alleles in DAT1 and DRD4 were determined using PCR product length analysis. Each subject was classified as having either zero or at least one copy of the target alleles. Dietary intake was previously determined using food frequency questionnaires collected at three timepoints: time of diagnosis, end of induction, and continuation therapy. As previously published dietary composition in fat and carbohydrate differed significantly among three timepoints. There was no significant difference between those with or without the target alleles in DAT1 or DRD4 in percent from fat or percent from carbohydrate at any of the three timepoints. However, significant differences were observed when dietary intake was compared to the Dietary Reference Intake (DRI). Notably, a greater portion of male participants with DAT1 9R polymorphism had fat consumption below the DRI at the time of diagnosis. On the contrary, significantly decreased portion of females with DAT1 9R had fat consumption below the DRI during continuation therapy. When compared to normative values, a significantly increased number of children had total calorie consumption below DRI during induction therapy. The DRD4 7R polymorphism was associated with fat intake below DRI during induction therapy in males. However, neither DAT1 nor DRD4 polymorphisms were related to variation in carbohydrates consumption. In addition, a greater portion of participants that carry both DAT1 and DRD4 polymorphism exhibited a trend toward undereating behavior in fat intake compared to the controls. Our results are the first to indicate that DAT1 and DRD4 polymorphisms are associated with altered dietary intake during chemotherapy for childhood ALL. Future study will further elucidate whether this modulation is associated with changes in their body weight, BMI, glucose level, and disease relapse. Citation Format: Jing Wen, Arul Duggimpudi, Shengguo Li, Elena Ladas, Kara M. Kelly, Peter D. Cole. The effect of polymorphisms in DAT1 and DRD4 on dietary intake during chemotherapy for childhood leukemia. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5216.

Feasibility of serial neurocognitive assessment using Cogstate during and after therapy for childhood leukemia.

Neurocognitive impairment is frequently observed among survivors of childhood acute lymphoblastic leukemia (ALL) within the domains of attention, working memory, processing speed, executive functioning, and learning and memory. However, few studies have characterized the trajectory of treatment-induced changes in neurocognitive function beginning in the first months of treatment, to test whether early changes predict impairment among survivors. If correct, we hypothesize that those children who are most susceptible to early impairment would be ideal subjects for clinical trials testing interventions designed to protect against treatment-related neurocognitive decline. In this pilot study, we prospectively assessed neurocognitive functioning (attention, working memory, executive function, visual learning, and processing speed), using the Cogstate computerized battery at six time points during the 2years of chemotherapy treatment and 1-year post-treatment (Dana-Farber Cancer Institute ALL Consortium protocol 11-001; NCT01574274). Forty-three patients with ALL consented to serial neurocognitive testing. Of the 31 participants who remained on study through the final time point, 1year after completion of chemotherapy, 28 (90%) completed at least five of six planned Cogstate testing time points. Performance and completion checks indicated a high tolerability (≥ 88%) for all subtests. One year after completion of treatment, 10 of 29 patients (34%) exhibited neurocognitive function more than 2 standard deviations below age-matched norms on one or more Cogstate subtests. Serial collection of neurocognitive data (within a month of diagnosis with ALL, during therapy, and 1-year post-treatment) is feasible and can be informative for evaluating treatment-related neurocognitive impairment.

Children with Acute Lymphoblastic Leukemia and Early Thrombosis Have Dysregulated Coagulation-Related Genes and Pathways

Introduction Thrombo-embolic events (TE) are a frequent complication of childhood acute lymphoblastic leukemia (ALL). Disease-specific mechanistic insights governing the development of TE in this disease remain unclear. Overexpression of coagulation-related genes (coagulome) and pathways have been identified in cancer-induced TE. We investigate whether coagulome dysregulation in newly-diagnosed children with ALL is associated with TE development. Methods We included patients aged 1-21 years old with newly-diagnosed ALL from September 3, 2015, to June 30, 2021, with available RNA-sequencing (RNAseq) data at diagnosis, either enrolled on the Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 16-001 or treated following the DFCI 11-001 protocol. RNAseq was performed through an optional study performed as part of the DFCI 16-001 clinical trial for patients who consented to it, or through the research oncogenomic program of the province of Quebec. The primary outcome was the occurrence of TE during ALL therapy requiring medical intervention (grade ≥2 as per the CTCAE version 5). TE were classified as early thrombosis (ET) if they occurred within 6 weeks from treatment start. Patients' characteristics were compared using Chi-Square or Fisher's exact test. Differential gene expression (DE) was performed to compare children with and without TE, adjusted for ALL phenotype (B- or T-cell lineage). The dysregulated genes were compared to a customized panel of 174 genes known to be implicated in cancer-related TE (coagulome and podoplanin) and in coagulation pathways. A secondary analysis, determined a priori, stratified children between ET and no TE, based on the hypothesis that the leukemia environment might predominantly affect early complications. Gene set enrichment analyses (GSEA) were performed on KEGG and gene ontology (GO) databases from the molecular signatures database (MSigDB). DE was considered for absolute fold change (FC) ≥2, and benjamini-Hochberg adjusted p-values (adj p) <0.05. Results We included 274 ALL patients (median age: 6.7 years [interquartile range, IQR: 3.7-12.0 years], 54% male, 81% B-ALL) of whom 49 (17.9%) experienced a TE (including 21 ET) at a median of 76 days (IQR: 27-155 days) following ALL diagnosis. Patients with TE were more likely to be ≥10 years old (57.1% vs. 31.6%, p<0.001) compared to those without TE. Sex, immunophenotype, mediastinal mass, central nervous system disease (CNS) involvement at diagnosis and risk status were otherwise not significantly different among the two groups. Three coagulation pathway-related genes were dysregulated in children with TE compared to those without TE. Glycoprotein 9 (GP9) and platelet factor 4 (PF4), implicated in von Willebrand-dependent platelet adhesion and platelet aggregation, were upregulated (log2FC = 2.1 and 1.5, respectively). Metalloproteinase-2 (MMP2), involved in collagenolysis and thrombus degradation, was downregulated (log2FC = -1.9). The KEGG olfactory transduction pathway was downregulated in the group with TE (normalized enrichment score (NES) = 1.55, adj p<0.001). In the secondary analysis stratified by timing of TE, patients with early TE were more likely to be ≥10 years (80.9% vs. 31.6%, p<0.001), have T-ALL (38.1% vs. 16.9%, p=0.002) and be CNS-positive at diagnosis (52.4% vs. 22.7%, p=0.004). Patients with ET showed overexpression of the GP9, PF4, integrin subunit beta 3 (ITGB3) and clusterin (CLU) genes involved in platelet aggregation and adhesion (log2FC = 3.3, 3.7, 2.7 and 1.6, respectively). The following GO pathways were significantly upregulated: blood coagulation (NES=1.73, adj p<0.001), platelet activation (NES=2.21, adj p<0.01), and platelet alpha granules (NES=2.48, adj p<0.001) while the KEGG olfactory transduction pathway was downregulated (NES=-1.70, adj p<0.001). Dysregulation of the olfactory transduction pathway has previously been described in cancer-associated TE in adults. Conclusion Our study identified coagulation-related genes and pathways that might be drivers of leukemia-induced thrombosis. Early TEs in childhood ALL were associated with significant upregulation of coagulation and platelet activation pathways, suggesting a role of the leukemia microenvironment in TE development. Additional studies are required to validate these observations that could be incorporated in future algorithms to predict TE risk in children with ALL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Adolescent and Young Adults with ALL Who Complete Therapy on DFCI Consortium ALL Trials Have Excellent Long-Term Overall Survival

Background: Adolescent and young adult (AYA) patients (pts) with acute lymphoblastic leukemia (ALL) or lymphoblastic lymphoma (LBL) have good outcomes when treated on pediatric regimens but still face worse survival compared to younger children (Siegel JAMA Onc 2018). Pediatric patients who do not complete ALL treatment, particularly planned asparaginase (ASP), have inferior oncologic outcomes (Silverman Blood 1997). In the CALBG 10403 trial of a pediatric-inspired regimen in AYAs 17-39 years (yrs), only 39% of pts completed planned treatment (Stock Blood 2019). We aimed to describe the prevalence of treatment failure, reasons for treatment non-completion, and their effect on survival among patients treated on Dana-Farber Cancer Institute (DFCI) ALL Consortium protocols. Methods: We identified Philadelphia chromosome negative (Ph-) pts aged 1-49 yrs treated on 4 sequential multi-center DFCI Consortium protocols between 2000 and 2018 (00-001, 05-001, 01-175, 06-254). Additional consecutive Ph- pts treated as per these protocols were identified by chart review. All pts were intended to receive 30 continuous weeks (wks) of ASP during consolidation. Treatment failure was defined as induction failure, induction death, relapse/progression on therapy, and remission death on therapy. Treatment non-completion was defined as transplant in first complete remission (CR), withdrawal due to toxicity or other reasons, loss to follow up, and ineligible status. Treatment completion was defined as no exit from treatment protocol before its completion, approximately 2 yrs from complete remission (CR). Per protocol, no patients were recommended for allogeneic hematopoietic stem cell transplant (HSCT) in CR1. ASP completion was defined as receiving at least 26 wks of ASP during consolidation (Silverman, Blood 2001). The protocols allowed for truncation of ASP for toxicity without exit from protocol. Median follow-up time was calculated using the reverse Kaplan Meier indicator. The chi square test was used to compare proportions between groups. Overall survival (OS) among groups was compared using the log rank test. Results: A total of 1,480 pts were identified: 1,149 children (< 15 yrs, median age 4.5 yrs) and 331 AYAs (15-49 yrs, median age 24 yrs). Median follow-up was 7.9 yrs. Treatment completion rate was lower among AYAs than children (61.3% vs. 89.9%, p < 0.001) (Table 1). This was driven by higher treatment failure rates among AYAs than children (19.9% vs. 5.5%) as well as higher treatment non-completion rates (19.0% vs. 4.6%), primarily driven by transplants in CR1 among AYAs. Treatment completion rates were lower among older (30-49 yrs) AYAs compared to younger (15-29 yrs) AYAs (50.5% vs. 65.7%, p = 0.009). Among 1235 pts who completed treatment, 1086 (87.9%) received ³26 weeks of ASP. ASP completion rate was lower among AYAs vs. children (79.2% vs. 89.6%, p < 0.001). A higher percentage of AYAs discontinued ASP because of toxicity than children (11.9% vs. 5.5%, p = 0.01). In a landmark analysis of patients who survived and had follow-up for at least 2 years from diagnosis, AYAs who completed treatment (with or without ASP completion) had an estimated 5-year OS of 92.7% (95% Confidence Interval (CI): 87.5%, 95.8%), while children who completed treatment had a 5-year OS of 97.9% (95% CI: 96.7%, 98.6%) (Log-rank test p = 0.002) (Figure 1). Patients alive at 2 years who failed or did not complete treatment had worse survival outcomes with a 5-year OS of 70.5% (95% CI: 53.9%, 82.1%) among AYAs and 76.1% (95% CI: 62.2%, 85.5%) among children (Log-rank test p = 0.598) Conclusions: AYAs in our cohort completed protocol treatment at higher rates than previously reported trials. Among AYAs who completed treatment protocol, oncologic outcomes were excellent (5-year OS above 90%) and comparable to (although statistically lower than) those of children. AYAs had higher treatment failure rates, likely due to more aggressive disease biology. AYAs had lower ASP completion rates and higher ASP discontinuation rates due to toxicity compared to children; the etiology and impact of that on survival will need to be further investigated. Introduction of novel agents to improve remission induction rates and prevent early relapse in AYAs might help further improve oncologic outcomes for this population. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Oral Mercaptopurine Adherence in Pediatric Acute Lymphoblastic Leukemia: A Survey Study From the Dana-Farber Cancer Institute Acute Lymphoblastic Leukemia Consortium.

Background: Oral chemotherapy nonadherence is a challenge in clinical oncology. During therapy for acute lymphoblastic leukemia (ALL), poor adherence to 6-mercaptopurine (6MP) increases relapse risk. Clinically significant nonadherence is reported in 30% of children treated for ALL on Children's Oncology Group (COG) trials. Whether nonadherence rates vary across regimens with different treatment schedules and modes of administration is unknown. Methods: We conducted an exploratory, cross-sectional survey study on parents of children (1-18 years) receiving continuation therapy on, or as per Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 11-001. Treatment required weekly visits to the clinic and 14 days of oral 6MP every 3 weeks. Survey assessed self-reported sociodemographics, medication-taking, chemotherapy comprehension, and 6MP adherence; adherence survey items were developed from published surveys. Patients were grouped as nonadherent if they endorsed missing one 6MP dose during the last cycle, or more than one dose during prior cycles, for nonmedical reasons. Results: Sixty-two families completed the surveys, all of whom had evaluable adherence data. In total, 25% of patients met the study definition of nonadherence. Twenty-three percent reported that it was "not easy" to follow administration guidelines around the dairy intake and 57% requested more teaching and educational resources. Conclusion: Self-reported nonadherence to oral 6MP in the DFCI ALL Consortium is high, with rates similar to those observed in the COG. This suggests that the additional contact during weekly infusions on the DFCI is insufficient to address barriers affecting oral chemotherapy adherence.

Ocular abnormalities at diagnosis and after the completion of treatment in children and adolescents with newly diagnosed acute lymphoblastic leukemia.

Ocular abnormalities (OA) in pediatric patients with acute lymphoblastic leukemia (ALL) are common findings both at diagnosis and later in follow-up. The frequency, predictors, and prognostic impact of OA in the context of recent ALL protocols are not well characterized. Single-center retrospective analysis of the medical records of 224 patients with ALL enrolled on Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 05-001. Overall, 217 (98%) patients had at least one ophthalmic exam. Retinal hemorrhages were the most frequent abnormalities at diagnosis (11%) and cataracts at later time points (13%). OA at diagnosis were associated with age ≥10years and with the severity of anemia and thrombocytopenia; they were also univariately associated with lower 5-year event-free survival (EFS) (high risk [HR]=3.09 [95% CI: 1.38-6.94]; p=.006), but not in a disease-free survival (DFS) model adjusted for end-induction minimal residual disease (p=.82). The cumulative incidence of cataract was 13.1% ± 2.8% at 43months from diagnosis; its development was associated with high presenting white blood cell count (≥50,000/μl) (p=.010), male sex (p=.036), higher risk group (p=.025), and cranial radiation (p=.004). Cataract was associated with decreased visual acuity. OA at diagnosis, present in 12% of patients, were associated with older age, anemia, and thrombocytopenia and did not carry a significant prognostic impact. Cataracts were detected in over 10% of patients and were associated with decreased visual acuity, thus supporting routine screening after completion of therapy, especially for those treated with high-risk protocols.

Whole-transcriptome analysis in acute lymphoblastic leukemia: a report from the DFCI ALL Consortium Protocol 16-001

AbstractThe molecular hallmark of childhood acute lymphoblastic leukemia (ALL) is characterized by recurrent, prognostic genetic alterations, many of which are cryptic by conventional cytogenetics. RNA sequencing (RNA-seq) is a powerful next-generation sequencing technology that can simultaneously identify cryptic gene rearrangements, sequence mutations and gene expression profiles in a single assay. We examined the feasibility and utility of incorporating RNA-seq into a prospective multicenter phase 3 clinical trial for children with newly diagnosed ALL. The Dana-Farber Cancer Institute ALL Consortium Protocol 16-001 enrolled 173 patients with ALL who consented to optional studies and had samples available for RNA-seq. RNA-seq identified at least 1 alteration in 157 patients (91%). Fusion detection was 100% concordant with results obtained from conventional cytogenetic analyses. An additional 56 gene fusions were identified by RNA-seq, many of which confer prognostic or therapeutic significance. Gene expression profiling enabled further molecular classification into the following B-cell ALL (B-ALL) subgroups: high hyperdiploid (n = 36), ETV6-RUNX1/-like (n = 31), TCF3-PBX1 (n = 7), KMT2A-rearranged (KMT2A-R; n = 5), intrachromosomal amplification of chromosome 21 (iAMP21) (n = 1), hypodiploid (n = 1), Philadelphia chromosome (Ph)-positive/Ph-like (n = 16), DUX4-R (n = 11), PAX5 alterations (PAX5 alt; n = 11), PAX5 P80R (n = 1), ZNF384-R (n = 4), NUTM1-R (n = 1), MEF2D-R (n = 1), and others (n = 10). RNA-seq identified 141 nonsynonymous mutations in 93 patients (54%); the most frequent were RAS-MAPK pathway mutations. Among 79 patients with both low-density array and RNA-seq data for the Philadelphia chromosome-like gene signature prediction, results were concordant in 74 patients (94%). In conclusion, RNA-seq identified several clinically relevant genetic alterations not detected by conventional methods, which supports the integration of this technology into front-line pediatric ALL trials. This trial was registered at www.clinicaltrials.gov as #NCT03020030.

Performance of Next Generation Sequencing for Minimal Residual Disease Detection for Pediatric Patients with Acute Lymphoblastic Leukemia: Results from the Prospective Clinical Trial DFCI 16-001

Performance of Next Generation Sequencing for Minimal Residual Disease Detection for Pediatric Patients with Acute Lymphoblastic Leukemia: Results from the Prospective Clinical Trial DFCI 16-001

Orthopedic toxicities among adolescents and young adults treated in DFCI ALL Consortium Trials

AbstractAdolescent and young adult patients with acute lymphoblastic leukemia (ALL) have superior outcomes when treated on pediatric regimens. Pediatric ALL regimens rely heavily on corticosteroids and asparaginase and are known to increase the risk of osteonecrosis (ON) and fractures in children, particularly adolescents. Orthopedic toxicity among young adults treated on pediatric-inspired regimens is not well described. Here, we report the symptomatic orthopedic toxicities of patients aged 15 to 50 years treated on sequential Dana-Farber Cancer Institute ALL Consortium protocols. Among 367 patients with a median age of 23 years (range, 15-50 years; 68% aged <30 years), 60 patients were diagnosed with ON (5-year cumulative incidence, 17%; 95% confidence interval [CI], 13-22), and 40 patients experienced fracture (5-year cumulative incidence, 12%; 95% CI, 8-15). Patients aged <30 years were significantly more likely to be diagnosed with ON (5-year cumulative incidence, 21% vs 8%; P = .004). Patients treated more recently on pegaspargase-based protocols were significantly more likely to be diagnosed with ON compared with those treated on earlier trials with native Escherichia coli asparaginase (5-year cumulative incidence, 24% vs 5%; P < .001). Of the 54 ON events for which adequate information was available, surgery was performed in 25 (46%). Patients with ON had superior overall survival (OS) compared with those without (multivariable OS hazard ratio, 0.15; 95% CI, 0.05-0.46; P = .001; ON included as a time-varying exposure). Increased rates of orthopedic toxicity in late-generation protocols may be driven by the pharmacokinetic drug interaction between pegaspargase and dexamethasone, leading to higher dexamethasone exposure.

Frequency and Prognostic Significance of Recurrent Gene Mutations in Pediatric B-ALL: Report from the DFCI ALL Consortium

The application of next-generation sequencing (NGS) approaches to leukemia markedly expanded our understanding of the molecular landscape of pediatric acute lymphoblastic leukemia (ALL), but NGS integration into clinical care and therapeutic decision making is still limited. The prognostic impact of discovered mutations in uniformly treated patients with newly diagnosed B-ALL is not well characterized, and there is no consensus regarding the clinical significance of many of these findings. We investigated the frequency of mutations affecting common molecular pathways in pediatric B-ALL that are potentially druggable with targeted therapies, to define the prognostic role of these mutations, as measured by end-induction minimal residual disease (MRD) and event-free survival (EFS). We analyzed 159 patients (median age 6 years, range 1-18) with newly diagnosed Ph-negative B-ALL treated between 2005-2015 according to the Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocols 05-001 and 11-001. Diagnostic leukemia samples were sequenced using a validated clinical NGS panel. We focused on mutations affecting the following pathways: Ras (NRAS, KRAS, PTPN11, NF1 and BRAF), cell cycle regulation (CCND3, CDKN2A/B and RB1), PI3K signaling (PTEN, PIK3CA, PIK3R1, PIK3C2B, MTOR, TSC1 and TSC2), Polycomb repressive complex 2 (PRC2) (EED, EZH2 and SUZ12), and JAK/STAT signaling (CRLF2, JAK2, JAK3, MPL, SH2B3 and SOCS1). Additionally, we analyzed mutations affecting CREBBP, FLT3, PAX5, SETD2 and TP53. Mutations occurring in the ExAC database at a frequency greater than 0.01% were excluded. A Fisher exact test and Wilcoxon rank sum test were used for categorical and continuous variables. High end-induction MRD, defined as &amp;gt; 10-3, was assessed by an Ig-TCR PCR assay. EFS was estimated using Kaplan and Meier method and tested between groups using a log-rank test. Induction death/failure, relapse or death were considered as events. Overall, 108 of the 159 patients (68%) carried at least one mutation in the studied genes. Most common mutations were in the Ras pathway (47%), CREBBP (9%), JAK pathway (8%), FLT3 (8%), PI3K pathway (5%), PAX5 (4%), SETD2 (4%), TP53 (4%), cell cycle regulation (3%) and PRC2 complex (3%). We investigated the distribution of mutations among common cytogenetic groups: ETV6-RUNX1, high hyperdiploidy (HHD) (51-65 chromosomes), hypodiploidy (&amp;lt;45 chromosomes), KMT2A-rearranged, TCF3-PBX1, and intra-amplification chromosome 21 (iAMP21). There was a strong association between TP53 and hypodiploidy (43% vs 2%; p=0.001). Ras pathway and FLT3 mutations were enriched in HHD (67% vs 39%; p=0.004) and (17% vs 4%; p=0.016), respectively. FLT3 mutations were mutually exclusive with ETV6-RUNX1 (12% vs. 0%, p=0.038), and Ras pathway mutations were rare in this subgroup (p=0.018). PAX5 mutations were enriched in children &amp;gt;10 years of age (p=0.035). There were no associations with sex. Ras pathway mutations were associated with high end-induction MRD (68% vs 42%; p=0.045), and this association was stronger for clonal (variant allele frequency (VAF) &amp;gt;25%) mutations (n=33) (63% vs 19%; p=0.0002). Focusing on HHD, CREBBP mutations frequently co-occurred with clonal Ras pathway mutations (83% vs 17%; p=0.032). Among HHD patients with evaluable MRD (n=33), 7 patients had high MRD, and 3 of these had CREBBP mutations (p=0.052). The analyzed cohort was enriched for higher risk ALL disease (Table 1). The 5-year EFS was 80%±3% among these 159 patients. Overall, no EFS difference was observed based on Ras pathway (p=0.35). Among HHD ALL, the presence of CREBBP or clonal Ras pathway mutations was significantly associated with inferior 5-yr EFS (50%±20% vs 97%±3%; p=0.0006, Figure 1) and (70%±13% vs 100%; p=0.007, Figure 2), respectively. In conclusion, our findings provide insight into the prognostic significance of the most common mutations in pediatric HHD B-ALL in a uniformly treated cohort of patients as part of the DFCI ALL Consortium. The presence of CREBBP and clonal Ras pathway mutations may be associated with upfront chemotherapy resistance as demonstrated by high end-induction MRD. Further analysis of Ras pathway mutations segregated by VAF is warranted. Future trials may integrate these findings into risk stratification of HHD ALL. With prospective continued clinical use of NGS assays, we will further clarify the role of mutations and their contribution to disease outcomes in B-ALL. Disclosures Mar: Blueprint Medicines Corporation: Current Employment, Current equity holder in publicly-traded company. Stegmaier:Novartis: Research Funding; Auron Therapeutics: Consultancy. Silverman:Takeda: Other: advisory board; Servier: Other: advisory board; Syndax: Other: advisory board.

Orthopedic Toxicity Among Adolescents and Young Adults Treated on DFCI ALL Consortium Trials

Orthopedic Toxicity Among Adolescents and Young Adults Treated on DFCI ALL Consortium Trials

Refining risk classification in childhood B acute lymphoblastic leukemia: results of DFCI ALL Consortium Protocol 05-001

AbstractDana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 05-001 tested a new risk stratification system in children and adolescents with newly diagnosed acute lymphoblastic leukemia (ALL). At study entry, B-ALL patients were classified as standard risk (SR) or high risk (HR) based on age, white blood cell (WBC) count, and central nervous system status. After achieving complete remission (CR), patients with high end-induction minimal residual disease (MRD) (≥10−3 by polymerase chain reaction analysis of patient-specific antigen receptor rearrangements) and/or adverse cytogenetics (KMT2A rearrangement or hypodiploidy) were reclassified as very high risk (VHR) and received intensified therapy. IKZF1 deletion status was retrospectively evaluated by multiplex ligation-dependent probe amplification. Between 2005 and 2011, 678 Philadelphia chromosome-negative B-ALL patients aged 1 to 18 years enrolled; 651 achieved CR and 648 received a final risk group. Among all 678 patients, 5-year event-free survival (EFS) was 87% (95% confidence interval [CI], 84-89) and overall survival 93% (95% CI, 90-94). Five-year disease-free survival of SR patients (N = 407) was 94% (95% CI, 91-96), HR (N = 176) was 84% (95% CI, 77-88), and VHR (N = 65) was 79% (95% CI, 67-87). IKZF1 deletion was present in 62 of 385 (16%) assessed patients and was associated with inferior 5-year EFS (63%; 95% CI, 49%-74% vs 88%; 95% CI, 84%-91%; P < .001), and higher 5-year cumulative incidence of relapse, including among those with low MRD (24% vs 8%, P = .001). In multivariable analysis, age ≥15 years, WBC ≥50 × 109/L, IKZF1 deletion, and MRD ≥10−4 was each associated with inferior outcome. In conclusion, risk-stratified therapy on DFCI 05-001 resulted in favorable outcomes for B-ALL patients, including those with VHR features. IKZF1 deletion was an independent predictor of inferior outcome. This trial was registered at www.clinicaltrials.gov as #NCT00400946.

A thymidylate synthase polymorphism is associated with increased risk for bone toxicity among children treated for acute lymphoblastic leukemia.

Bone fractures and osteonecrosis frequently complicate therapy for childhood acute lymphoblastic leukemia (ALL). Bone toxicity has been associated with exposure to corticosteroids and methotrexate (MTX) and age greater than 10 years. We tested whether common genetic polymorphisms were associated with bone toxicity during treatment for ALL. A total of 615 of 794 children enrolled on Dana Farber Cancer Institute ALL Consortium protocol 05-001 (NCT00400946) met eligibility criteria for inclusion in this analysis. Nineteen candidate polymorphisms were selected a priori, targeting genes related to glucocorticoid metabolism, oxidative damage, and folate physiology. Polymorphisms were genotyped using either PCR-based allelic discrimination or PCR product length analysis. Twenty percent of subjects were homozygous for two 28 bp repeats (2R/2R, where 2R is two 28-nucleotide repeats within the 5' untranslated region [UTR] of the thymidylate synthase [TS] gene) within the 5' UTR of the gene for TS. This 2R/2R genotype was associated with increased risk of osteonecrosis among children younger than 10 years at diagnosis (multivariable hazard ratio [HR] 2.71; 95%confidence interval [CI] 1.23-5.95; P = 0.013), and with bone fracture among children ≥ 10 years (multivariable HR 2.10; 95%CI 1.11-3.96; P = 0.022). No significant association was observed between TS genotype and red blood cell (RBC) folate, RBC MTX, or relapse risk. A common genetic variant is associated with increased risk of osteonecrosis among children younger than 10 years at diagnosis and with bone fractures among older children. These findings suggest that children and adolescents with the 2R/2R TS genotype should be closely monitored for the development of bone toxicity during therapy for ALL, and support a clinical trial testing the efficacy of protective interventions specifically in this vulnerable population.

Excellent Outcome of Children with Down Syndrome (DS) and Acute Lymphoblastic Leukemia (ALL) Treated on Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocols 00-001 and 05-001

▪BackgroundChildren with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) are shown to have increased therapy-related morbidity and mortality. Hence, therapy modifications and/or dose-reductions are common treatment strategies for this patient (pt) population. Dana-Farber Cancer Institute (DFCI) ALL Consortium protocols have used same risk-stratified treatment for children with and without DS and ALL.Aim:To define the toxicity profile and outcome of children with DS and de novo ALL treated on DFCI ALL Consortium therapy protocols 00-001 and 05-001 using therapy identical to non-DS patients.Methods:Demographic, clinical and outcome data of DS and non-DS patients enrolled on the DFCI ALL protocols 00-001 (2000-2004) and 05-001 (2005-2011) were analyzed. Risk categorization and protocol therapy have previously been described (J Clin Oncol 2013; 31:1202-10; Lancet Oncol 2015;16:1677-90). On both protocols, DS ALL pts were treated identically to non-DS pts without any dose reduction or modification, except for the option for DS ALL pts to receive 3 doses of leucovorin after IT methotrexate. Fisher’s exact test was used to compare toxicities in the DS and non-DS pts and Gray test was used to compare the cumulative incidence of fracture and osteonecrosis. Overall survival (OS) was defined as time from registration to death. Event-free survival (EFS) was defined as time from registration to first event (defined as induction failure, relapse, second malignant neoplasm (SMN) or death due to any cause). Induction failure and induction death were included as events at time zero. Disease-free survival (DFS) was defined as time from complete remission (CR) to relapse, SMN or death. Pts without an event were censored at the last known follow-up. The Kaplan-Meier method was used for survival estimation and Greenwood’s formula for calculation of 95% confidence interval (CI) of survival estimates. Outcome of DS patients was also examined using Ponte di Legno (PdL) risk group [Low risk (LR) was defined as age at diagnosis ≤ 6 yr. and white cell count < 10X109/L and, remainder as high risk (HR)].(Blood 2014;123:70-7). Two-sided p values <0.05 were considered significant.Results:Of 1286 eligible pts aged 1-18 yrs. with de novo ALL enrolled on protocols 00-001 and 05-001, 38 (3%) had DS. There was no difference in demographic or presenting clinical features between DS and non-DS ALL pts except immunophenotype (absence of T-ALL in DS vs 11.7% in non-DS, p=0.017) and presence of high hyperdiploidy (51-65 chromosomes) (8.8% in DS vs 25.1% in non-DS, p=0.027) (Table 1). Two DS-ALL pts withdrew from the study after achieving CR. There was no difference in the CR rates (DS: 100% vs non-DS: 95.2%, p=0.47) or proportion of pts with low end of induction minimal residual disease (MRD) between DS and non-DS groups (p=0.73). Toxicities were comparable except DS pts had significantly higher rates of ≥Grade 3 mucositis (data available for protocol 05-001 only) (DS: 52.0% vs. non-DS: 12.0%, p<0.001), non-CNS thrombosis/bleed (18.4% vs. 8.2%; p=0.036), and seizure (15.8% vs. 4.7%, p=0.010). DS pts also had marginally higher rate of bacterial and fungal infections (55.3% vs. 41.3%, p=0.096) (Table 2). All 38 DS pts achieved a CR and there were 4 relapses with 1 death due to disease. There were no treatment-related deaths in DS-ALL pts. With a median follow-up of 6.2 yrs. the 5-yr EFS, DFS, and OS of DS pts were similar to non-DS pts (90.7% [81.1-100.0] vs. 83.7% [81.7-85.9]; 90.7% [81.1-100.0] vs. 87.4% [85.5-89.3]; 97.1% [91.8-100.0] vs. 91.4% [89.8-93.0]), with the 95% CI overlapping for each comparison (Figures 1a and 1b). There was no difference in outcomes of DS-ALL PdL LR pts (n=13) compared to PdL HR pts (n=25) (5-yr EFS 90.0% [73.2-100.0]. vs. 91.0% [79.9-100.0]; 5-yr OS 100.0% [100.0-100.0] vs. 95.8% [88.2-100.0]).Conclusion:DS pts treated on DFCI ALL Consortium protocols without dose reduction or modifications achieved similar outcomes to non-DS pts. DS pts had a higher frequency of mucositis, infection, and seizures, but did not experience any treatment-related deaths. Other than a higher risk of thrombotic complications, they did not develop excessive toxicity to asparaginase. The low rates of relapse and toxicity-related mortality support the approach of unified therapy protocol for DS and non-DS ALL pts with emphasis on supportive care interventions to prevent toxicities. [Display omitted] [Display omitted] [Display omitted] DisclosuresAsselin:Jazz Pharmaceuticals: Consultancy, Speakers Bureau; Sigma Tau Pharamceuticals: Consultancy.

Randomized Study of Pegasparagase (SS-PEG) and Calaspargase Pegol (SC-PEG) in Pediatric Patients with Newly Diagnosed Acute Lymphoblastic Leukemia or Lymphoblastic Lymphoma: Results of DFCI ALL Consortium Protocol 11-001

▪Background: E.coli L-asparaginase (L-ASP) is an important component of treatment for childhood acute lymphoblastic leukemia (ALL), but the optimal preparation and dosing remain to be determined. Pegaspargase (SS-PEG) is a pegylated L-ASP formulation commonly used in frontline therapy. Calaspargase pegol (SC-PEG) is a novel formulation that uses the same ASP enzyme and PEG moiety as SS-PEG but a different linker molecule that is more hydrolytically stable, leading to a longer half-life. On Dana-Farber Cancer Institute (DFCI) ALL Consortium protocols, patients (pts) typically receive a single dose SS-PEG during induction, and then 15 doses every 2-weeks (wks) during post-induction in order to maintain therapeutic serum asparaginase activity (SAA), defined as ≥ 0.1 IU/mL, for 30 consecutive wks. We hypothesized that SC-PEG could be administered less frequently than SS-PEG during post-induction therapy with a similar SAA and toxicity profile.Methods: Between 2012-2015, pts aged 1-21 years with newly diagnosed ALL or lymphoblastic lymphoma (LL) were eligible to enroll on DFCI ALL Consortium Protocol 11-001. Pts were randomized at study entry to receive either SS-PEG (N=120) or SC-PEG (N=119), each given intravenously (IV) at a dose of 2500 IU/m2. Both groups received a single dose during multi-agent remission induction. Post-induction, pts assigned to SS-PEG received 15 doses every 2-wks and those assigned to SC-PEG received 10 doses every 3-wks along with other risk-stratified chemotherapy. Serum samples were obtained 4, 11, 18 and 25 days after the induction dose to determine SAA and prior to each post-induction dose (2 wks after each SS-PEG and 3 wks after each SC-PEG dose) to determine nadir SAA (NSAA) by a validated biochemical assay. Pts were switched to Erwinia asparaginase for Grade 2 or higher allergy or for silent inactivation (defined as 2 consecutive non-detectable NSAA). Asparaginase was permanently discontinued for pancreatitis and held for thrombosis (but re-started once the clot improved). End-induction minimal residual disease (MRD) was assessed in ALL pts by IGH/TCRPCR assay, with low MRD defined as < 0.001.Results: 239 eligible pts were enrolled (230 ALL and 9 LL). There were no significant differences in presenting characteristics between randomized arms. SAA during induction and NSAA during post-induction are displayed in Figure 1. SAA was similar for the two preparations at 4, 11 and 18 days after the induction dose, with SAA ≥ 0.1 IU/mL in ≥ 95% of pts at these time points on both arms. 25 days after the induction dose, SAA was higher with SC-PEG (median 0.298 IU/mL vs 0.056 for SS-PEG), with significantly more pts on SC-PEG arm with SAA ≥ 0.1 IU/mL (88% vs 15%, p<0.0001). Post-induction NSAA was similar between arms, with median NSAA ≥ 1.0 IU/mL (10-times higher than goal NSAA) at 7, 13, 19 and 25 wks after beginning the 30-wk post-induction asparaginase treatment. NSAA was ≥ 0.1 IU/mL in ≥ 98% of pts on both arms at each time point. Two pts on the SC-PEG arm (1.7%) and none on the SS-PEG arm met criteria for silent inactivation. There was no significant difference in rates of ASP-related allergy (p=1.00), pancreatitis (p=1.00), thrombosis (p=0.22) or infections (p=0.86) during induction or post-induction treatment (Table 1). Of 230 evaluable pts, 97% achieved CR, with no difference in proportion of pts with low end-induction MRD by randomized arm (91% SC-PEG vs 90% SS-PEG, p=1.00).Conclusion: During remission induction, a single dose of SC-PEG (2500 IU/m2) leads to more sustained SAA without excess toxicity or significant difference in the proportion of pts with low end-induction MRD. During post-induction therapy, SC-PEG can be given less frequently (every 3-wks) than SS-PEG (every 2-wks) with similar NSAA and toxicity. The high NSAA observed during post-induction therapy with each preparation suggests that a longer dosing interval and/or reduced dose may be feasible while still maintaining NSAA ≥ 0.1 IU/mL. Longer follow-up is necessary to determine event-free survival by randomized arm. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Dietary intake and childhood leukemia: The Diet and Acute Lymphoblastic Leukemia Treatment (DALLT) cohort study

ObjectiveChildren with acute lymphoblastic leukemia (ALL) are at elevated risk for nutrition-related morbidity both during and after therapy. We present the demographic characteristics and nutrient intake at study entry of a prospective cohort in which evaluating dietary intake in children diagnosed with ALL was investigated. MethodsDietary intake data were collected for participants enrolled on the Dana-Farber Cancer Institute ALL Consortium Protocol. Dietary intake was assessed with a food frequency questionnaire and was compared with the dietary reference intake by ALL risk group (standard and high risk). ResultsDietary intake data were collected from 81% of participants (n = 640). We found that 27% of participants were overweight/obese. Intake of total calories and other nutrients exceeded the dietary reference intake in up to 79% of children. This was evident in both risk groups and was pronounced among younger children. For micronutrients, dietary intake of calcium, vitamin D (females only), and zinc differed significantly between patients with standard-risk and those with high-risk ALL. ConclusionsThis study was successful in collecting dietary intake data at the time of cancer diagnosis in a multicenter setting in a pediatric population at high-risk for nutrition-related morbidity. We identified “at-risk” dietary intakes, which vary by sex and ALL risk group; such patients may benefit from future dietary interventions.

Impact of Socioeconomic Status on Timing of Relapse and Overall Survival for Children Treated on Dana-Farber Cancer Institute ALL Consortium Protocols (2000-2010).

Population-based evidence suggests that lower socioeconomic status (SES) negatively impacts the overall survival (OS) of children with leukemia; however, the relationships between SES and treatment-related mortality, relapse, and timing of relapse remain unclear. We examined OS, event-free survival (EFS) and cumulative incidence (CI) and timing of relapse by community-level poverty for 575 children aged 1-18 years with newly diagnosed acute lymphoblastic leukemia (ALL) treated on consecutive phase III multicenter Dana-Farber Cancer Institute ALL Consortium Protocols between 2000 and 2010. Children were categorized into high- and low-poverty areas for the analysis using aggregate U.S. Census data linked to zip code. Children living in high-poverty areas experienced a 5-year OS of 85% as compared with 92% for those in low-poverty areas (P = 0.02); poverty remained marginally significant (P = 0.07) after adjustment for immunophenotype, age, and white blood cell count. There were no differences detected in EFS or CI relapse by poverty area. However, 92% of the relapses observed in children from high-poverty areas occurred <36 months from complete remission, compared to 48% of those in children from low-poverty areas (P = 0.008). U.S. children with ALL living in high-poverty areas have a higher risk of early relapse when compared with those living in low-poverty areas despite uniform treatment. This may in part explain decreased OS observed in these children. This finding highlights disparities in childhood cancer outcomes by SES despite uniform treatment. Further investigations of the mechanistic pathways underlying this finding are needed.

Higher Incidence of Treatment-Related Toxicities in Non-Hispanic Patients Undergoing Therapy for Newly Diagnosed Pediatric Acute Lymphoblastic Leukemia on Dana-Farber Cancer Institute ALL Consortium Protocol 05-001

Background: Risk-adapted treatment strategies have contributed to excellent outcomes in pediatric acute lymphoblastic leukemia (ALL); however, treatment-associated acute and long-term toxicities persist. Therapy-associated toxicities of note in pediatric ALL are related to a treatment backbone that relies heavily on corticosteroids (prednisone and dexamethasone) and asparaginase (ASP). The most frequently observed toxicities include, but are not limited to, serious infection, pancreatitis, thrombosis and bony morbidities including osteonecrosis (ON) and fracture. Previous studies suggest that children of racial and ethnic minorities are at higher risk for treatment-associated toxicities. We assessed the incidence of treatment-related toxicities in Hispanic and non-Hispanic patients undergoing treatment for pediatric ALL.Patients and Methods: Retrospective cohort study investigating the incidence of treatment-related toxicities including infection, allergy to ASP, pancreatitis, thrombosis and bony morbidities in Hispanic and non-Hispanic children and adolescents with newly diagnosed ALL undergoing therapy on Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 05-001. The ethnicity of each patient was designated at the time of study enrollment by research coordinators. Descriptive statistics were calculated, mean +/- SD for continuous variables and frequency and percentages for categorical variables. Toxicity rates were based on number of patients. Comparison between groups was done by Chi-square test or FisherÕs exact test and p -value < 0.05 was considered significant.Results: Between 2005 and 2011, 794 children and adolescents (ages 1 - 18 years) were enrolled on Protocol 05-001, 730 of whom were evaluable for this investigation: 150 Hispanic (18%), 580 non-Hispanic (73%). Sixty-four patients did not have ethnicity documented. There was no significant difference in disease-risk group, age or gender between the two groups. Weight was significantly higher in Hispanic patients (31.9 ± 24.4 kg in Hispanic and 26.9 ± 18.7 kg in non-Hispanic, p = 0.021). There was no significant difference in the incidence of ASP-related toxicities (allergy, pancreatitis, thrombosis) between Hispanic and non-Hispanic patients. There was no significant difference in the overall incidence of infection between the two groups (42% in Hispanic and 50% in non-Hispanic, p = 0.081). Non-Hispanic patients had significantly higher rates of opportunistic infection (Pneumocystis pneumonia) than Hispanic patients (0.7% in Hispanic and 4% in non-Hispanic, p = 0.041). A similar difference in the incidence of bacteremia between the two groups approached, but did not reach statistical significance (p = 0.052). The overall incidence of fracture in all patients was 14.5% and was significantly higher in non-Hispanic patients (6% in Hispanic and 16.7% in non-Hispanic, p < 0.001). The overall incidence of ON was 8.9% and was significantly higher in non-Hispanic patients (3.3% in Hispanic and 10.3% in non-Hispanic, p = 0.007). (Table 1)Conclusion: The incidence of opportunistic infections and bony morbidities was significantly higher in non-Hispanic patients undergoing treatment for pediatric ALL on the DFCI ALL Consortium Protocol 05-001. The risk for, and impact of therapy-related toxicities varies by a patientÕs treatment tolerance, perhaps as a function of age and gender or as a result of disease biology or genetic polymorphisms affecting drug metabolism. Additionally, non-biologic factors such as medication adherence and nutritional status may also contribute to toxicity incidence in patients undergoing treatment for pediatric ALL. Prospective studies to further investigate our findings are warranted.TableAll Patients, (N = 730)Non-Hispanic, (N = 580)Hispanic, (N = 150)p -valueOverall Infection353/730 (48.4%)290/580 (50%)63/150 (42%)0.081Bacteremia289/730 (39.6%)240/580 (41.4%)49/150 (9.3%)0.052Opportunistic Infection24/730 (3.3%)23/580 (4%)1/150 (0.7%)0.041Fracture106/730 (14.5%)97/580 (16.7%)9/150 (6%)<0.001Osteonecrosis65/730 (8.9%)60/580 (10.3%)5/150 (3.3%)0.007Thrombosis*36/730 (4.9%)26/580 (4.5%)10/150 (6.7%)0.271Pancreatitis*78/730 (10.7%)60/580 (10.3%)18/150 (12%)0.559ASP Allergy*76/730 (10.4%)57/580 (9.8%)19/150 (12.7%)0.310*ASP-related toxicity DisclosuresNo relevant conflicts of interest to declare.

Homozygosity for the 2R Tandem Repeat Polymorphism in the Thymidylate Synthase (TS) Promoter Is Associated with Increased Risk for Bony Morbidity Among Children Treated for Acute Lymphoblastic Leukemia on DFCI Protocol 05-001

Introduction: Both fractures and avascular necrosis (AVN) of bone frequently complicate therapy for childhood acute lymphoblastic leukemia (ALL), resulting in significant pain and loss of function. Risk of bony morbidity has been associated with age >10 years and exposure to crucial components of leukemia therapy including corticosteroids, asparaginase, and methotrexate. To further define risk factors, we tested whether 19 common genetic polymorphisms were associated with bony morbidity among 637 children treated for ALL on Dana Farber Cancer Institute ALL Consortium protocol 05-001.Methods: Genomic DNA was isolated from peripheral blood or bone marrow collected at the time of remission. Nineteen candidate polymorphisms were selected a priori, targeting common variants within genes related to glucocorticoid metabolism, oxidative damage, and folate physiology. Single nucleotide polymorphisms were detected using PCR-based allelic discrimination assays. The number of 28bp nucleotide repeats within the 5' untranslated region of the gene for thymidylate synthase (TS) was assessed by PCR-product length analysis. The incidence of AVN and fracture were estimated by the cumulative incidence method identifying death and relapse as competing risks. Because the incidence of bony morbidity differed significantly between children above and below the age of 10 years, relationships between polymorphisms and bony morbidity were explored within these two age subgroups separately. Comparisons at the 0.10 significance level were modeled univariately and were considered in multivariable modeling using competing risks regression. Multivariable models for bony morbidity included sex, WBC at diagnosis, race, final risk group, and asparaginase randomization. Blood was collected during treatment for analysis of serum and RBC folate by HPLC.Results: Of the 637 patients tested, 627 achieved a complete remission and received post-induction therapy, of which 61 (9.7%) experienced AVN and 138 (22.0%) had ≥1 fracture. Both AVN and fracture were more common among those ≥10 years of age (22.9% AVN, 30.7% fracture) than younger children (5.5% AVN, p<0.0001 and 19.2% fracture, p=0.002). Homozygosity for the 2R TS polymorphism was observed in 129 (20.6%) of the 626 patients tested. This 2R/2R genotype was associated with a greater 5-year estimated incidence of AVN (11.6%; 95% CI 6.1-18.9%) than among those with 2R/3R or 3R/3R genotypes (4.1%, 95% CI 2.4-6.5%; p=0.0037; Figure [A]) among children < age 10, but not among older children. The increased risk of AVN in younger children remained significant in the multivariable risk regression model (adjusted hazard ratio 2.92; 95% CI 1.36-6.28; p=0.0059). Among children over age 10, this polymorphism was associated with an increased risk of bony fracture (multivariable HR 2.13; 95% CI 1.13-3.99; p=0.019; Figure [B]). No significant association was observed between bony morbidity and the other tested polymorphisms, including PAI-1 (rs6092), ABCB1 (rs1045642), and the vitamin D receptor Fok1 restriction site (rs228570) which have been previously linked to risk of AVN. Samples were available for analysis of serum and RBC folate at diagnosis (n=367), remission (n=347), 15 months post-remission (n=251), and at the conclusion of therapy (n=247). No significant association was observed between TS genotype and serum or RBC folate at any time point.Conclusions: Homozygosity for the 2R polymorphism in TS was associated with increased risk of bony morbidity among children treated for ALL. Interestingly, the impact of the polymorphism differed between those above the age of 10 years (associated with risk of fracture) and younger children (risk for AVN), suggesting that the pathophysiology of bony morbidity differs between these two age groups. This is the first report identifying a genetic risk factor for AVN specifically among children younger than 10 years, a group where AVN is significantly less frequent. This result suggests young children with ALL and the 2R/2R genotype should be monitored more closely for the development of AVN during therapy for ALL. [Display omitted] DisclosuresSilverman:Seattle Genetics, Inc.: Research Funding.