Additive effects of TPMT and NUDT15 on thiopurine toxicity in children with acute lymphoblastic leukemia across multiethnic populations

BACKGROUND

Thiopurines such as mercaptopurine (MP) are widely used to treat acute lymphoblastic leukemia (ALL). Thiopurine-S-methyltransferase (TPMT) and Nudix hydrolase 15 (NUDT15) inactivate thiopurines, and no-function variants are associated with drug-induced myelosuppression. Dose adjustment of MP is strongly recommended in patients with intermediate or complete loss of activity of TPMT and NUDT15. However, the extent of dosage reduction recommended for patients with intermediate activity in both enzymes is currently not clear.

METHODS

MP dosages during maintenance were collected from 1768 patients with ALL in Singapore, Guatemala, India, and North America. Patients were genotyped for TPMT and NUDT15, and actionable variants defined by the Clinical Pharmacogenetics Implementation Consortium were used to classify patients as TPMT and NUDT15 normal metabolizers (TPMT/NUDT15 NM), TPMT or NUDT15 intermediate metabolizers (TPMT IM or NUDT15 IM), or TPMT and NUDT15 compound intermediate metabolizers (TPMT/NUDT15 IM/IM). In parallel, we evaluated MP toxicity, metabolism, and dose adjustment using a Tpmt/Nudt15 combined heterozygous mouse model (Tpmt+/-/Nudt15+/-).

RESULTS

Twenty-two patients (1.2%) were TPMT/NUDT15 IM/IM in the cohort, with the majority self-reported as Hispanics (68.2%, 15/22). TPMT/NUDT15 IM/IM patients tolerated a median daily MP dose of 25.7 mg/m2 (interquartile range = 19.0-31.1 mg/m2), significantly lower than TPMT IM and NUDT15 IM dosage (P < .001). Similarly, Tpmt+/-/Nudt15+/- mice displayed excessive hematopoietic toxicity and accumulated more metabolite (DNA-TG) than wild-type or single heterozygous mice, which was effectively mitigated by a genotype-guided dose titration of MP.

CONCLUSION

We recommend more substantial dose reductions to individualize MP therapy and mitigate toxicity in TPMT/NUDT15 IM/IM patients.

Pharmacogenomics, Race, and Treatment Outcome in Pediatric Acute Myeloid Leukemia

Importance

Disparities in outcomes exist between Black and White patients with acute myeloid leukemia (AML), with Black patients experiencing poorer prognosis compared with their White counterparts.

Objective

To assess whether varying intensity of induction therapy to treat pediatric AML is associated with reduced disparities in treatment outcome by race.

Design, Setting, and Participants

A comparative effectiveness analysis was conducted of 86 Black and 359 White patients with newly diagnosed AML who were enrolled in the AML02 trial from 2002 to 2008 or the AML08 trial from 2008 to 2017. Statistical analysis was conducted from July 2023 through January 2024.

Interventions

Patients in AML02 were randomly assigned to receive standard low-dose cytarabine-based induction therapy or augmented high-dose cytarabine-based induction therapy, whereas patients in AML08 received high-dose cytarabine-based therapy.

Main Outcomes and Measures

Cytarabine pharmacogenomic 10-single-nucleotide variant (ACS10) scores were evaluated for association with outcome according to race and treatment arm.

Results

This analysis included 86 Black patients (mean [SD] age, 8.8 [6.5] years; 54 boys [62.8%]; mean [SD] leukocyte count, 52 600 [74 000] cells/µL) and 359 White patients (mean [SD] age, 9.1 [6.2] years; 189 boys [52.6%]; mean [SD] leukocyte count, 54 500 [91 800] cells/µL); 70 individuals with other or unknown racial and ethnic backgrounds were not included. Among all patients without core binding factor AML who received standard induction therapy, Black patients had significantly worse outcomes compared with White patients (5-year event-free survival rate, 25% [95% CI, 9%-67%] compared with 56% [95% CI, 46%-70%]; P = .03). By contrast, among all patients who received augmented induction therapy, there were no differences in outcome according to race (5-year event-free survival rate, Black patients, 50% [95% CI, 38%-67%]; White patients, 48% [95% CI, 42%-55%]; P = .78). Among patients who received standard induction therapy, those with low ACS10 scores had a significantly worse 5-year event-free survival rate compared with those with high scores (42.4% [95% CI, 25.6%-59.3%] and 70.0% [95% CI, 56.6%-83.1%]; P = .004); however, among patients who received augmented induction therapy, there were no differences in 5-year event-free survival rates according to ACS10 score (low score, 60.6% [95% CI, 50.9%-70.2%] and high score, 54.8% [95% CI, 47.1%-62.5%]; P = .43).

Conclusions and Relevance

In this comparative effectiveness study of pediatric patients with AML treated in 2 consecutive clinical trials, Black patients had worse outcomes compared with White patients after treatment with standard induction therapy, but this disparity was eliminated by treatment with augmented induction therapy. When accounting for ACS10 scores, no outcome disparities were seen between Black and White patients. Our results suggest that using pharmacogenomics parameters to tailor induction regimens for both Black and White patients may narrow the racial disparity gap in patients with AML.

Single-cell systems pharmacology identifies development-driven drug response and combination therapy in B cell acute lymphoblastic leukemia

Leukemia can arise at various stages of the hematopoietic differentiation hierarchy, but the impact of developmental arrest on drug sensitivity is unclear. Applying network-based analyses to single-cell transcriptomes of human B cells, we define genome-wide signaling circuitry for each B cell differentiation stage. Using this reference, we comprehensively map the developmental states of B cell acute lymphoblastic leukemia (B-ALL), revealing its strong correlation with sensitivity to asparaginase, a commonly used chemotherapeutic agent. Single-cell multi-omics analyses of primary B-ALL blasts reveal marked intra-leukemia heterogeneity in asparaginase response: resistance is linked to pre-pro-B-like cells, with sensitivity associated with the pro-B-like population. By targeting BCL2, a driver within the pre-pro-B-like cell signaling network, we find that venetoclax significantly potentiates asparaginase efficacy in vitro and in vivo. These findings demonstrate a single-cell systems pharmacology framework to predict effective combination therapies based on intra-leukemia heterogeneity in developmental state, with potentially broad applications beyond B-ALL.

Pediatric acute myeloid leukemia - novel approaches

PURPOSE OF REVIEW

Despite higher remission and survival rates than observed in adults, children with acute myeloid leukemia (AML) still suffer unacceptably high rates of treatment failure and late toxicities. Ongoing work aims to improve these long-term outcomes through improvements in the utilization of current therapies, the incorporation of novel chemotherapy agents, and improved use of current or novel cellular and immunotherapeutic approaches. In this review, we highlight recent advances and contextualize them within this evolving landscape.

RECENT FINDINGS

Novel agents such as the B-cell lymphoma 2 inhibitor venetoclax and the menin inhibitors have shown promising results with implications for large portions of the pediatric AML population. Older agents are being used in novel combinations (e.g. gemtuzumab ozogamicin) or are expanding into pediatrics after longer use in adults (e.g. Fms-like tyrosine kinase 3 inhibitors). Finally, immunotherapeutic approaches offer new options for patients with high-risk or relapsed disease.

SUMMARY

Recent findings have altered the landscape of pediatric AML therapy with exciting immediate and long-term implications. Ongoing studies may soon define this as standard as well. After many years in which few new therapies have become available for children with AML, recent and upcoming advances may soon dramatically alter the therapeutic landscape.

COVID-19 in Pediatric Patients With Acute Lymphoblastic Leukemia or Lymphoma

Importance

COVID-19 in pediatric patients with acute lymphoblastic leukemia or lymphoma (ALL/LLy) has not been described in detail and may affect chemotherapy administration and long-term outcomes.

Objective

To describe the clinical presentation of COVID-19 and chemotherapy modifications in pediatric patients with ALL/LLy.

Design, Setting, and Participants

This is a retrospective case series of patients at St Jude Children's Research Hospital and its affiliate sites with newly diagnosed ALL/LLy who were treated on the Total XVII protocol (NCT03117751) between March 30, 2020, and June 20, 2022. Participants included patients aged 1 to 18 years who were receiving protocol chemotherapy. Acute symptoms and chemotherapy modifications were evaluated for 60 days after the COVID-19 diagnosis, and viral clearance, adverse events, and second SARS-CoV-2 infections were followed up during the 27-month study period.

Exposures

SARS-CoV-2; all patients were screened at least weekly and at symptom onset and/or after known exposure to SARS-CoV-2.

Main Outcomes and Measures

Description of the spectrum of COVID-19 illness and chemotherapy modifications.

Results

Of 308 pediatric patients, 110 (36%) developed COVID-19 at a median age of 8.2 (IQR, 5.3-14.5) years. Sixty-eight patients (62%) were male. Most patients were in the continuation/maintenance phase of chemotherapy (101 [92%]). Severe disease was rare (7 [6%]) but was associated with older age, higher white blood cell counts at ALL/LLy diagnosis, lower absolute lymphocyte counts at COVID-19 diagnosis, abnormal chest imaging findings, and SARS-CoV-2 reinfection. Rare but serious thrombotic events included pulmonary embolism and cerebral venous sinus thrombosis (n = 1 for each). No multisystem inflammatory syndrome in children or death was seen. SARS-CoV-2 reinfection occurred in 11 patients (10%) and was associated with older age and with receiving standard or high-risk vs low-risk ALL/LLy therapy. Chemotherapy interruptions occurred in 96 patients (87%) and were longer for patients with severe disease, SARS-CoV-2 reinfection, and/or a COVID-19 diagnosis during the pre-Omicron variant period vs the post-Omicron period (after December 27, 2021).

Conclusions and Relevance

In this case series of COVID-19 in pediatric patients with ALL/LLy, severe COVID-19 was rare, but chemotherapy administration was affected in most patients. Long-term studies are needed to establish the outcomes of COVID-19 in this population.

Genomic analysis of venous thrombosis in children with acute lymphoblastic leukemia from diverse ancestries

Venous thrombosis is a common adverse effect of modern therapy for acute lymphoblastic leukemia (ALL). Prior studies to identify risks of thrombosis in pediatric ALL have been limited by genetic screens of pre-identified genetic variants or genome- wide association studies (GWAS) in ancestrally uniform populations. To address this, we performed a retrospective cohort evaluation of thrombosis risk in 1,005 children treated for newly diagnosed ALL. Genetic risk factors were comprehensively evaluated from genome-wide single nucleotide polymorphism (SNP) arrays and were evaluated using Cox regression adjusting for identified clinical risk factors and genetic ancestry. The cumulative incidence of thrombosis was 7.8%. In multivariate analysis, older age, T-lineage ALL, and non-O blood group were associated with increased thrombosis while non-low-risk treatment and higher presenting white blood cell count trended toward increased thrombosis. No SNP reached genome-wide significance. The SNP most strongly associated with thrombosis was rs2874964 near RFXAP (G risk allele; P=4x10-7; hazard ratio [HR] =2.8). In patients of non-European ancestry, rs55689276 near the α globin cluster (P=1.28x10-6; HR=27) was most strongly associated with thrombosis. Among GWAS catalogue SNP reported to be associated with thrombosis, rs2519093 (T risk allele, P=4.8x10-4; HR=2.1), an intronic variant in ABO, was most strongly associated with risk in this cohort. Classic thrombophilia risks were not associated with thrombosis. Our study confirms known clinical risk features associated with thrombosis risk in children with ALL. In this ancestrally diverse cohort, genetic risks linked to thrombosis risk aggregated in erythrocyte-related SNP, suggesting the critical role of this tissue in thrombosis risk.

The PedAL/EuPAL Project: A Global Initiative to Address the Unmet Medical Needs of Pediatric Patients with Relapsed or Refractory Acute Myeloid Leukemia

The prognosis of children with acute myeloid leukemia (AML) has improved incrementally over the last few decades. However, at relapse, overall survival (OS) is approximately 40-50% and is even lower for patients with chemo-refractory disease. Effective and less toxic therapies are urgently needed for these children. The Pediatric Acute Leukemia (PedAL) program is a strategic global initiative that aims to overcome the obstacles in treating children with relapsed/refractory acute leukemia and is supported by the Leukemia and Lymphoma Society in collaboration with the Children's Oncology Group, the Innovative Therapies for Children with Cancer consortium, and the European Pediatric Acute Leukemia (EuPAL) foundation, amongst others. In Europe, the study is set up as a complex clinical trial with a stratification approach to allocate patients to sub-trials of targeted inhibitors at relapse and employing harmonized response and safety definitions across sub-trials. The PedAL/EuPAL international collaboration aims to determine new standards of care for AML in a first and second relapse, using biology-based selection markers for treatment stratification, and deliver essential data to move drugs to front-line pediatric AML studies. An overview of potential treatment targets in pediatric AML, focused on drugs that are planned to be included in the PedAL/EuPAL project, is provided in this manuscript.

Prognostic and Pharmacotypic Heterogeneity of Hyperdiploidy in Childhood ALL

PURPOSE

High hyperdiploidy, the largest and favorable subtype of childhood ALL, exhibits significant biological and prognostic heterogeneity. However, factors contributing to the varied treatment response and the optimal definition of hyperdiploidy remain uncertain.

METHODS

We analyzed outcomes of patients treated on two consecutive frontline ALL protocols, using six different definitions of hyperdiploidy: chromosome number 51-67 (Chr51-67); DNA index (DI; DI1.16-1.6); United Kingdom ALL study group low-risk hyperdiploid, either trisomy of chromosomes 17 and 18 or +17 or +18 in the absence of +5 and +20; single trisomy of chromosome 18; double trisomy of chromosomes 4 and 10; and triple trisomy (TT) of chromosomes 4, 10, and 17. Additionally, we characterized ALL ex vivo pharmacotypes across eight main cytotoxic drugs.

RESULTS

Among 1,096 patients analyzed, 915 had B-ALL and 634 had pharmacotyping performed. In univariate analysis, TT emerged as the most favorable criterion for event-free survival (EFS; 10-year EFS, 97.3% v 86.8%; P = .0003) and cumulative incidence of relapse (CIR; 10-year CIR, 1.4% v 8.8%; P = .002) compared with the remaining B-ALL. In multivariable analysis, accounting for patient numbers using the akaike information criterion (AIC), DI1.16-1.6 was the most favorable criterion, exhibiting the best AIC for both EFS (hazard ratio [HR], 0.45; 95% CI, 0.23 to 0.88) and CIR (HR, 0.45; 95% CI, 0.21 to 0.99). Hyperdiploidy and subgroups with favorable prognoses exhibited notable sensitivities to asparaginase and mercaptopurine. Specifically, asparaginase sensitivity was associated with trisomy of chromosomes 16 and 17, whereas mercaptopurine sensitivity was linked to gains of chromosomes 14 and 17.

CONCLUSION

Among different definitions of hyperdiploid ALL, DI is optimal based on independent prognostic impact and also the large proportion of low-risk patients identified. Hyperdiploid ALL exhibited particular sensitivities to asparaginase and mercaptopurine, with chromosome-specific associations.

Clinical and genomic characterization of an ATRA-insensitive acute promyelocytic leukemia variant with a FNDC3B::RARB fusion

The promyelocytic leukemia-retinoic acid receptor-α (PML::RARA) fusion is the hallmark of acute promyelocytic leukemia (APL) and is observed in over 95% of APL cases. RARA and homologous receptors RARB and RARG are occasionally fused to other gene partners, which differentially affect sensitivity to targeted therapies. Most APLs without RARA fusions have rearrangements involving RARG or RARB, both of which frequently show resistance to all-trans-retinoic acid (ATRA) and/or multiagent chemotherapy for acute myeloid leukemia (AML). We present a 13-year-old male diagnosed with variant APL with a novel FNDC3B::RARB in-frame fusion that showed no response to ATRA but responded well to conventional AML therapy. While FNDC3B has been identified as a rare RARA translocation partner in ATRA-sensitive variant APL, it has never been reported as a fusion partner with RARB and it is only the second known fusion partner with RARB in variant APL. We also show that this novel fusion confers an RNA expression signature that is similar to APL, despite clinical resistance to ATRA monotherapy.

Rituximab administration in pediatric patients with newly diagnosed acute lymphoblastic leukemia

Polyethylene glycol (PEG)-asparaginase (pegaspargase) is a key agent in chemotherapy for acute lymphoblastic leukemia (ALL), but recipients frequently experience allergic reactions. We hypothesized that by decreasing antibody-producing CD20-positive B cells, rituximab may reduce these reactions. Children and adolescents (aged 1-18 years) with newly diagnosed B-ALL treated on the St. Jude Total XVII study were randomized to induction therapy with or without rituximab on day 3 (cohort 1) or on days 6 and 24 (cohort 2). Patient clinical demographics, CD20 expression, minimal residual disease (MRD), rituximab reactions, pegaspargase allergy, anti-pegaspargase antibodies, and pancreatitis were evaluated. Thirty-five patients received rituximab and 37 did not. Among the 35 recipients, 16 (45.7%) experienced a grade 2 or higher reaction to rituximab. There were no differences between recipients and non-recipients in the incidence of pegaspargase reactions (P  >  0.999), anti-pegaspargase antibodies (P  =  0.327), or pancreatitis (P  =  0.480). CD20 expression on day 8 was significantly lower in rituximab recipients (P  <  0.001), but there were no differences in MRD levels on day 8, 15, or at the end of induction. Rituximab administration during induction in pediatric patients with B-ALL was associated with a high incidence of infusion reactions with no significant decrease in pegaspargase allergies, anti-pegaspargase antibodies, or MRD.

Ex vivo Drug Sensitivity Imaging-based Platform for Primary Acute Lymphoblastic Leukemia Cells

Resistance of acute lymphoblastic leukemia (ALL) cells to chemotherapy, whether present at diagnosis or acquired during treatment, is a major cause of treatment failure. Primary ALL cells are accessible for drug sensitivity testing at the time of new diagnosis or at relapse, but there are major limitations with current methods for determining drug sensitivity ex vivo. Here, we describe a functional precision medicine method using a fluorescence imaging platform to test drug sensitivity profiles of primary ALL cells. Leukemia cells are co-cultured with mesenchymal stromal cells and tested with a panel of 40 anti-leukemia drugs to determine individual patterns of drug resistance and sensitivity ("pharmacotype"). This imaging-based pharmacotyping assay addresses the limitations of prior ex vivo drug sensitivity methods by automating data analysis to produce high-throughput data while requiring fewer cells and significantly decreasing the labor-intensive time required to conduct the assay. The integration of drug sensitivity data with genomic profiling provides a basis for rational genomics-guided precision medicine. Key features Analysis of primary acute lymphoblastic leukemia (ALL) blasts obtained at diagnosis from bone marrow aspirate or peripheral blood. Experiments are performed ex vivo with mesenchymal stromal cell co-culture and require four days to complete. This fluorescence imaging-based protocol enhances previous ex vivo drug sensitivity assays and improves efficiency by requiring fewer primary cells while increasing the number of drugs tested to 40. It takes approximately 2-3 h for sample preparation and processing and a 1.5-hour imaging time. Graphical overview.

What is Next in Pediatric B-cell Precursor Acute Lymphoblastic Leukemia

Cure rates now exceed 90% in many contemporary trials for children with B-cell acute lymphoblastic leukemia (ALL). However, treatment remains suboptimal and therapy is toxic for all patients. New treatment options potentially offer the chance to reduce both treatment resistance and toxicity. Here, we review recent advances in ALL diagnostics, chemotherapy, and immunotherapy. In addition to describing recently published results, we also attempt to project the impact of these new developments into the future to imagine what B-ALL therapy may look like in the next few years.

Preclinical pharmacokinetic and pharmacodynamic evaluation of dasatinib and ponatinib for the treatment of T-cell acute lymphoblastic leukemia

LCK is a novel therapeutic target in ~40% of T-cell acute lymphoblastic leukemia (T-ALL), and dasatinib and ponatinib can act as LCK inhibitors with therapeutic effects. We herein report a comprehensive preclinical pharmacokinetic and pharmacodynamic evaluation of dasatinib and ponatinib in LCK-activated T-ALL. In 51 human T-ALL cases, these two drugs showed similar patterns of cytotoxic activity, with ponatinib being slightly more potent. Given orally in mice, ponatinib was associated with slower clearance with a longer T_max and higher AUC_0-24 h, although maximum pLCK inhibition was comparable between the two drugs. After establishing the exposure-to-response models, we simulated the steady-state pLCK inhibitory effects of each drug at currently approved dosages in humans: dasatinib at 140 mg and ponatinib at 45 mg once daily are both sufficient to achieve >50% pLCK inhibition for 13.0 and 13.9 h/day, respectively, comparable to pharmacodynamic profiles of these agents in BCR::ABL1 leukemias. Moreover, we developed a dasatinib-resistant T-ALL cell line model with LCK T316I mutation, in which ponatinib retained partial activity against LCK. In conclusion, we described the pharmacokinetic and pharmacodynamic profiles of dasatinib and ponatinib as LCK inhibitors in T-ALL, providing critical data for the development of human trials of these agents.

Clinical Impact of Minimal Residual Disease in Blood and Bone Marrow of Children with Acute Myeloid Leukemia

The prognostic significance of bone marrow minimal residual disease (MRD) in pediatric patients with acute myeloid leukemia (AML) is well-characterized, but the impact of blood MRD is not known. We therefore used flow-cytometric assessment of leukemia-specific immunophenotypes to measure levels of MRD in both blood and bone marrow of patients treated on the AML08 (NCT00703820) clinical trial. Blood samples were obtained at days 8 and 22 of therapy, whereas bone marrow samples were obtained at day 22. Among patients who were MRD-negative in the bone marrow at day 22, neither day 8 nor day 22 blood MRD was significantly associated with outcome. However, day 8 blood MRD was highly predictive of outcome among patients who were bone marrow MRD-positive at day 22. Although the measurement of blood MRD at day 8 cannot be used to detect day 22 bone marrow MRD-negative patients who are likely to relapse, our findings suggest that day 8 blood MRD can identify bone marrow MRD-positive patients who have a dismal prognosis and who may be candidates for the early use of experimental therapy.

Characterisation of children and adolescents with acute lymphoblastic leukaemia who presented without peripheral blood blasts at diagnosis

Of 1003 children with acute lymphoblastic leukaemia (ALL), 147 (14.7%) presented without peripheral blood blasts (PBB). While absence of PBB was not independently associated with survival outcomes when compared to those with PBB, patients without PBB had distinct genetic and clinical characteristics. Notably, we identified a novel genotype-phenotype relationship, in that the patients without PBB had a significantly higher incidence of hyperdiploid B-ALL, accounting for almost half of all patients without PBB (46.9% vs. 22.7%, p < 0.001). Further, absence of PBB was associated with decreased rates of leukaemia involvement of the central nervous system (p < 0.001).

Vaccines against SARS-CoV-2 are safe to administer in patients with antibodies to pegaspargase

OBJECTIVE

Allergic reactions to pegaspargase during ALL therapy are typically due to antibodies against polyethylene glycol (PEG), which is also used as a stabilizing agent in mRNA-based SARS-CoV-2 vaccines. To evaluate the safety of these vaccines in patients with anti-pegaspargase antibodies.

METHODS

We retrospectively reviewed the records of patients treated for ALL who had received SARS-CoV-2 vaccinations. All patients had antibodies against pegaspargase assayed during ALL therapy prospectively and in response to clinical allergies. Symptoms of intolerance to vaccination were gathered retrospectively from chart abstraction.

RESULTS

SARS-CoV-2 vaccination was well tolerated in all 78 patients with prior exposure to pegaspargase as part of their leukemia therapy. No reactions were observed in the 54 patients without a history of anti-pegaspargase antibodies or in 19 patients with antibodies who received mRNA vaccination. 1 patient who received the polysorbate containing Janssen vaccine experienced mild symptoms after vaccination not meeting the criteria of clinical allergy which spontaneously resolved within 25 minutes.

CONCLUSION

SARS-CoV-2 vaccination is safe in this population.

Pharmacotypes across the genomic landscape of pediatric acute lymphoblastic leukemia and impact on treatment response

Contemporary chemotherapy for childhood acute lymphoblastic leukemia (ALL) is risk-adapted based on clinical features, leukemia genomics and minimal residual disease (MRD); however, the pharmacological basis of these prognostic variables remains unclear. Analyzing samples from 805 children with newly diagnosed ALL from three consecutive clinical trials, we determined the ex vivo sensitivity of primary leukemia cells to 18 therapeutic agents across 23 molecular subtypes defined by leukemia genomics. There was wide variability in drug response, with favorable ALL subtypes exhibiting the greatest sensitivity to L-asparaginase and glucocorticoids. Leukemia sensitivity to these two agents was highly associated with MRD although with distinct patterns and only in B cell ALL. We identified six patient clusters based on ALL pharmacotypes, which were associated with event-free survival, even after adjusting for MRD. Pharmacotyping identified a T cell ALL subset with a poor prognosis that was sensitive to targeted agents, pointing to alternative therapeutic strategies. Our study comprehensively described the pharmacological heterogeneity of ALL, highlighting opportunities for further individualizing therapy for this most common childhood cancer.

Association of Inherited Genetic Factors With Drug-Induced Hepatic Damage Among Children With Acute Lymphoblastic Leukemia

Importance

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Hepatotoxic effects, including hyperbilirubinemia and elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, are common during all phases of therapy and are linked to several chemotherapeutic agents, including asparaginase, mercaptopurine, and methotrexate.

Objective

To determine which genetic variants were associated with hyperbilirubinemia and elevated ALT and AST levels in children, adolescents, and young adults treated for ALL.

Design, Setting, and Participants

This retrospective analysis of a multiethnic genome-wide association study was conducted between January 1, 2019, and April 15, 2022, including patients treated as part of Children's Oncology Group (COG) trials with centers in the United States, Canada, and Australia, which accrued data from December 29, 2003, to January 21, 2011 (AALL0232), and from January 22, 2007, to July 24, 2014 (AALL0434). Germline genotypes were interrogated using genome-wide arrays and imputed using a National Institutes of Health TOPMed Imputation server. Mixed-effects logistic regressions were used to account for multiple episodes for an individual patient. Genotype × treatment phase interaction was tested to uncover phase-specific genetic risk factors.

Exposures

Total duration of multiagent protocol chemotherapy ranging from 2.5 to 3.5 years.

Main Outcomes and Measures

The primary outcomes were National Cancer Institute Common Terminology Criteria for Adverse Events (version 4) hyperbilirubinemia of grade 3 or higher and elevated liver ALT and AST levels.

Results

A total of 3557 participants were included in the analysis (2179 [61.3%] male; median age, 11.1 [range, 1-30] years). Among 576 known variants associated with these liver function test results in the general population, UGT1A1 variant rs887829 and PNPLA3 variant rs738409 were associated with increased risk of hyperbilirubinemia (odds ratio [OR], 2.18 [95% CI, 1.89-2.53]; P = 6.7 × 10-27) and ALT and AST levels (OR, 1.27 [95% CI, 1.15-1.40]; P = 3.7 × 10-7), respectively, during treatment for ALL. Corresponding polygenic risk scores were associated with hepatotoxic effects across all therapy phases and were largely driven by UGT1A1 and PNPLA3 variants. Genome-wide association analysis revealed an age-specific variant near the CPT1A gene that was only associated with elevated ALT and AST levels among patients younger than 10 years (OR, 1.28 [95% CI, 1.18-1.39]; P = 8.7 × 10-10).

Conclusions and Relevance

These results suggest a strong genetic basis for interpatient variability in hyperbilirubinemia and aminotransferase level elevations during leukemia chemotherapy.

Top advances of the year: Pediatric oncology

Accelerated discovery and collaborative research continue to highlight the remarkable progress that has been made in the diagnosis and treatment of pediatric cancers. This manuscript highlights important discoveries on how precision oncology is being incorporated into the diagnosis and treatment of childhood cancer at the national level to identify promising new therapies using a tumor-agnostic approach. In addition, we have highlighted three articles that incorporate genomics and cell-free DNA to better classify, monitor and incorporate risk-based therapies for children with medulloblastoma. Finally, we highlighted the important role of monclonal antiobody therapy in the treatment of recurrent B-cell leukemia and newly diagnosed high-risk neuroblastoma.

The pediatric glucocorticoid toxicity index

OBJECTIVES

To develop a Pediatric glucocorticoid toxicity index (pGTI), a standardized, weighted clinical outcome assessment that measures change in glucocorticoid (GC) toxicity over time.

METHODS

Fourteen physician experts from 7 subspecialties participated. The physician experts represented multiple subspecialties in which GCs play a major role in the treatment of inflammatory disease: nephrology, rheumatology, oncology, endocrinology, genetics, psychiatry, and maternal-fetal medicine. Nine investigators were from Canada, Europe, or New Zealand, and 5 were from the United States. Group consensus methods and multi-criteria decision analysis were used. The pGTI is an aggregate assessment of GC toxicities that are common, important, and dynamic. These toxicities are organized into health domains graded as minor, moderate, or major and are weighted according to severity. The relative weights were derived by group consensus and multi-criteria decision analysis using the 1000Minds^TM software platform. Two quantitative scores comprise the overall toxicity profile derived from pGTI data: (1) the Cumulative Worsening Score; and (2) the Aggregate Improvement Score. The pGTI also includes a qualitative, unweighted record of GC side-effects known as the Damage Checklist, which documents less common toxicities that, although potentially severe, are unlikely to change with varying GC dosing.

RESULTS

One hundred and seven (107) toxicity items were included in the pGTI and thirty-two (32) in the Damage Checklist. To assess the degree to which the pGTI corresponds to expert clinical judgement, the investigators ranked 15 cases by clinical judgement from highest to lowest GC toxicity. Expert rankings were then compared to case ranking by the pGTI, yielding excellent agreement (weighted kappa 0.86). The pGTI was migrated to a digital environment following its development and initial validation. The digital platform is designed to ensure ease-of-use in the clinic, rigor in application, and accuracy of scoring. Clinic staff enter vital signs, laboratory results, and medication changes relevant to pGTI scoring. Clinicians record findings for GC myopathy, skin toxicity, mood dysfunction, and infection. The pGTI algorithms then apply the weights to these raw data and calculate scores. Embedded logic accounts for the impact of age- and sex-related reference ranges on several health domains: blood pressure, lipid metabolism, and bone mineral density. Other algorithms account for anticipated changes in the height Z-scores used in the growth domain, thereby addressing a concern unique to GC toxicity in children. The Damage Checklist ensures comprehensive measurement of GC toxicity but does not contribute to pGTI scoring, because the scored domains emphasize manifestations of GC toxicity that are likely to change over the course of a trial.

CONCLUSIONS

We describe the development and initial evaluation of a weighted, composite toxicity index for the assessment of morbidity related to GC use in children and adolescents. Developing the pGTI digital platform was essential for performing the nuanced calculations necessary to ensure rigor, accuracy, and ease-of-use in both clinic and research settings.

Dasatinib does not exacerbate dexamethasone-induced osteonecrosis in murine models of acute lymphoblastic leukemia therapy

INTRODUCTION

There are clinical reports that the incorporation of dasatinib may increase the frequency of osteonecrosis in acute lymphoblastic leukemia (ALL) treatment regimens. No rigorous testing of this hypothesis is available to guide clinicians.

METHODS

We tested whether oral dasatinib increased the frequency of dexamethasone-induced osteonecrosis in a murine model and tested its effects on dexamethasone's antileukemic efficacy in a murine BCR-ABL⁺ model of ALL.

RESULTS

Dasatinib did not change the frequency of osteonecrosis (p = .99) nor of arteriopathy (p = .36) in dexamethasone-treated mice when given at dosages that achieved clinically relevant steady-state dasatinib plasma concentrations of 53.1 ng/ml (95% CI: 43.5-57.3 ng/ml). These dasatinib exposures were not associated with increased dexamethasone plasma exposure in nonleukemia-bearing mice. These same dosages were not associated with any decrement in antileukemic efficacy of dexamethasone in a responsive BCR-ABL⁺ model of ALL.

CONCLUSIONS

Based on the results of our preclinical murine studies, we conclude that dasatinib is unlikely to increase the osteonecrotic effects of dexamethasone in ALL regimens.

Infectious Complications in Pediatric, Adolescent and Young Adult Patients Undergoing CD19-CAR T Cell Therapy

CD19-specific chimeric antigen receptor (CAR) T cell therapy has changed the treatment paradigm for pediatric, adolescent and young adult (AYA) patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, data on the associated infectious disease challenges in this patient population are scarce. Knowledge of infections presenting during treatment, and associated risk factors, is critical for pediatric cellular therapy and infectious disease specialists as we seek to formulate effective anti-infective prophylaxis, infection monitoring schemas, and empiric therapy regimens. In this work we describe our institutional experience in a cohort of 38 pediatric and AYA patients with CD19-positive malignancy treated with lymphodepleting chemotherapy (fludarabine/cyclophosphamide) followed by a single infusion of CD19-CAR T cells (total infusions, n=39), including tisagenlecleucel (n=19; CD19/4-1BB) or on an institutional clinical trial (n=20; CD19/4-1BB; NCT03573700). We demonstrate that infections were common in the 90 days post CAR T cells, with 19 (50%) patients experiencing a total of 35 infections. Most of these (73.7%) occurred early post infusion (day 0 to 28; infection density of 2.36 per 100 patient days-at-risk) compared to late post infusion (day 29 to 90; infection density 0.98 per 100 patient days-at-risk), respectively. Bacterial infections were more frequent early after CAR T cell therapy, with a predominance of bacterial blood stream infections. Viral infections occurred throughout the post infusion period and included primarily systemic reactivations and gastrointestinal pathogens. Fungal infections were rare. Pre-infusion disease burden, intensity of bridging chemotherapy, lymphopenia post lymphodepleting chemotherapy/CAR T cell infusion and development of CAR-associated hemophagocytic lymphohistiocytosis (carHLH) were all significantly associated with either infection density or time to first infection post CAR T cell infusion. A subset of patients (n=6) had subsequent CAR T cell reinfusion and did not appear to have increased risk of infectious complications. Our experience highlights the risk of infections after CD19-CAR T cell therapy, and the need for continued investigation of infectious outcomes as we seek to improve surveillance, prophylaxis and treatment algorithms.

Effects of zoledronic acid on osteonecrosis and acute lymphoblastic leukemia treatment efficacy in preclinical models

BACKGROUND

Osteonecrosis is a devastating side effect of acute lymphoblastic leukemia (ALL) therapy. Associations between bone density loss and osteonecrosis have sparked interest in using bisphosphonates to reduce this complication.

PROCEDURE

We assessed the impact of zoledronic acid (ZA) on the development of osteonecrosis in murine models when used either throughout therapy (continuous administration) or late in therapy after vascular lesions have developed but before osteonecrosis has occurred. Effects on bone density were measured using microcomputed tomography (μCT)-assessed tibial cortical thickness, while osteonecrosis was assessed histologically in the distal femur. Effects on antileukemic efficacy of chemotherapy were evaluated in both immunocompetent/syngeneic and patient-derived xenograft (PDX) models.

RESULTS

Continuous administration of ZA with chemotherapy prevented chemotherapy-associated bone loss (p < .001) and reduced osteonecrosis (p = .048). Late initiation of ZA diminished bone loss (p < .001) but had no impact on the development of osteonecrosis (p = .93). In the immunocompetent murine ALL model, mice treated with ZA and chemotherapy succumbed to leukemia sooner than mice treated with chemotherapy alone (p = .046). Analysis using PDX showed a nonsignificant decrease in survival with ZA (p = .17).

CONCLUSION

Our data indicate ZA may prevent osteonecrosis if begun with chemotherapy but showed no benefit when administered later in therapy. However, ZA may also reduce the antileukemic efficacy of chemotherapy.

Bone mineral density surveillance for childhood, adolescent, and young adult cancer survivors: evidence-based recommendations from the International Late Effects of Childhood Cancer Guideline Harmonization Group

Childhood, adolescent, and young adult cancer survivors are at increased risk of reduced bone mineral density. Clinical practice surveillance guidelines are important for timely diagnosis and treatment of these survivors, which could improve bone mineral density parameters and prevent fragility fractures. Discordances across current late effects guidelines necessitated international harmonisation of recommendations for bone mineral density surveillance. The International Late Effects of Childhood Cancer Guideline Harmonization Group therefore established a panel of 36 experts from ten countries, representing a range of relevant medical specialties. The evidence of risk factors for very low and low bone mineral density and fractures, surveillance modality, timing of bone mineral density surveillance, and treatment of very low and low bone mineral density were evaluated and critically appraised, and harmonised recommendations for childhood, adolescent, and young adult cancer survivors were formulated. We graded the recommendations based on the quality of evidence and balance between potential benefits and harms. Bone mineral density surveillance is recommended for survivors treated with cranial or craniospinal radiotherapy and is reasonable for survivors treated with total body irradiation. Due to insufficient evidence, no recommendation can be formulated for or against bone mineral density surveillance for survivors treated with corticosteroids. This surveillance decision should be made by the survivor and health-care provider together, after careful consideration of the potential harms and benefits and additional risk factors. We recommend to carry out bone mineral density surveillance using dual-energy x-ray absorptiometry at entry into long-term follow-up, and if normal (Z-score > -1), repeat when the survivor is aged 25 years. Between these measurements and thereafter, surveillance should be done as clinically indicated. These recommendations facilitate evidence-based care for childhood, adolescent, and young adult cancer survivors internationally.

Class II Human Leukocyte Antigen Variants Associate With Risk of Pegaspargase Hypersensitivity

We conducted the first human leukocyte antigen (HLA) allele and genome-wide association study to identify loci associated with hypersensitivity reactions exclusively to the PEGylated preparation of asparaginase (pegaspargase) in racially diverse cohorts of pediatric leukemia patients: St Jude Children's Research Hospital's Total XVI (TXVI, n = 598) and Children's Oncology Group AALL0232 (n = 2,472) and AALL0434 (n = 1,189). Germline DNA was genotyped using arrays. Genetic variants not genotyped directly were imputed. HLA alleles were imputed using SNP2HLA or inferred using BWAkit. Analyses between genetic variants and hypersensitivity were performed in each cohort first using cohort-specific covariates and then combined using meta-analyses. Nongenetic risk factors included fewer intrathecal injections (P = 2.7 × 10-5 in TXVI) and male sex (P = 0.025 in AALL0232). HLA alleles DQB1*02:02, DRB1*07:01, and DQA1*02:01 had the strongest associations with pegaspargase hypersensitivity (P < 5.0 × 10-5 ) in patients with primarily European ancestry (EA), with the three alleles associating in a single haplotype. The top allele HLA-DQB1*02:02 was tagged by HLA-DQB1 rs1694129 in EAs (r2  = 0.96) and less so in non-EAs. All single nucleotide polymorphisms associated with pegaspargase hypersensitivity reaching genome-wide significance in EAs were in class II HLA loci, and were partially replicated in non-EAs, as is true for other HLA associations. The rs9958628 variant, in ARHGAP28 (previously linked to immune response in children) had the strongest genetic association (P = 8.9 × 10-9 ) in non-EAs. The HLA-DQB1*02:02-DRB1*07:01-DQA1*02:01 associated with hypersensitivity reactions to pegaspargase is the same haplotype associated with reactions to non-PEGylated asparaginase, even though the antigens differ between the two preparations.

Fenofibrate reduces osteonecrosis without affecting antileukemic efficacy in dexamethasone-treated mice

Recent clinical trials in children with acute lymphoblastic leukemia (ALL) indicate that severe hypertriglyceridemia (>1000 mg/dL) during therapy is associated with an increased frequency of symptomatic osteonecrosis. Interventions to lower triglycerides have been considered, but there have been no preclinical studies investigating the impact of lowering triglycerides on osteonecrosis risk, nor whether such interventions interfere with the antileukemic efficacy of ALL treatment. We utilized our clinically relevant mouse model of dexamethasoneinduced osteonecrosis to determine whether fenofibrate decreased osteonecrosis. To test whether fenofibrate affected the antileukemic efficacy of dexamethasone, we utilized a BCR-ABL+ model of ALL. Serum triglycerides were reduced by fenofibrate throughout the period of treatment, with the most pronounced, 4.5-fold, decrease at week 3 (P<1x10-6). Both frequency (33% vs. 74%, P=0.006) and severity (median necrosis score of 0 vs. 75; P=6x10-5) of osteonecrosis were reduced with fenofibrate. Fenofibrate had no impact on BCR-ABL+ ALL survival (P=0.65) nor on the antileukemic properties of dexamethasone (P=0.49). These data suggest that lowering triglycerides with fenofibrate reduces dexamethasone- induced osteonecrosis while maintaining antileukemic efficacy, and thus may be considered for clinical trials.

Comprehensive analysis of dose intensity of acute lymphoblastic leukemia chemotherapy

Chemotherapy dosages are often compromised, but most reports lack data on dosages that are actually delivered. In two consecutive acute lymphoblastic leukemia trials that differed in their asparaginase formulation, native E. coli L-asparaginase in St. Jude Total 15 (T15, n=365) and pegaspargase in Total 16 (T16, n=524), we tallied the dose intensities for all drugs on the low-risk or standard-risk arms, analyzing 504,039 dosing records. The median dose intensity for each drug ranged from 61-100%. Dose intensities for several drugs were more than 10% higher on T15 than on T16: cyclophosphamide (P<0.0001 for the standard- risk arm), cytarabine (P<0.0001 for the standard-risk arm), and mercaptopurine (P<0.0001 for the low-risk arm and P<0.0001 for the standardrisk arm). We attributed the lower dosages on T16 to the higher asparaginase dosages on T16 than on T15 (P<0.0001 for both the low-risk and standard-risk arms), with higher dose-intensity for mercaptopurine in those with anti-asparaginase antibodies than in those without (P=5.62x10^{- 3} for T15 standard risk and P=1.43x10^-4 for T16 standard risk). Neutrophil count did not differ between protocols for low-risk patients (P=0.18) and was actually lower for standard-risk patients on T16 than on T15 (P<0.0001) despite lower dosages of most drugs on T16. Patients with low asparaginase dose intensity had higher methotrexate dose intensity with no impact on prognosis. The only dose intensity measure predicting a higher risk of relapse on both studies was higher mercaptopurine dose intensity, but this did not reach statistical significance (P=0.03 T15; P=0.07 T16). In these intensive multiagent trials, higher dosages of asparaginase compromised the dosing of other drugs for acute lymphoblastic leukemia, particularly mercaptopurine, but lower chemotherapy dose intensity was not associated with relapse.

Abstract CT146: Prognostic and therapeutic significance of leukemia subtypes in the context of risk-directed therapy based on minimal residual disease levels in pediatric acute lymphoblastic leukemia

Determination of prognostic and therapeutic implications of novel leukemia subtypes in children with acute lymphoblastic leukemia (ALL) treated with contemporary minimal residual disease (MRD)-directed therapy can improve outcome. In this study, we evaluated the clinical impact of identification of the full genomic spectrum of leukemia subtypes and MRD assessment to guide risk-directed therapy. A retrospective cohort study was conducted in 598 consecutive patients enrolled on Total Therapy Study 16 in a single center from October 29, 2007 to March 26, 2017, with a median follow-up of 7 years. High-hyperdiploid and ETV6-RUNX1 ALL were provisionally classified to be low-risk; TCF3-PBX1, hypodiploid&lt;44 chromosomes and T-ALL standard-risk; and BCR-ABL1, infant KMT2A-rearranged and ETP ALL high-risk. Single nucleotide polymorphism arrays, exome and transcriptome sequencing were used to identify novel leukemia subtypes. Final risk assignment was based on MRD levels measured in bone marrow samples on day 15 of induction and day 42 (end of induction). Patients with MRD≥1% on day 15 or 0.01% to &lt;1% on day 42 were assigned to standard-risk and those with MRD≥1% to high-risk group. MRD was determined in blood samples on day 8 for a research aim. The primary outcome was event-free survival. The secondary outcomes were relapse and overall survival. We identified 17 genetic subtypes, 8 of which were novel. Patients with ETV6-RUNX1, high-hyperdiploid and DUX4-rearranged B-ALL had the best 5-year event-free survival: 98.4%, 95.3%, and 95.0%, respectively. Those with TCF3-PBX1, PAX5alt, ETP, iAMP21, hypodiploid and T-ALL had intermediate rates (80.0% to 88.2%), while those with KMT2A-rearranged, BCR-ABL1, BCR-ABL1-like and ETV6-RUNX1-like ALL had the worst rates (64.1% to 76.2%). All but three of the 142 patients with day-8 blood MRD&lt;0.01% remained in continuous remission. Among novel subtypes, intensified therapy based on day-15 MRD≥1% improved outcome of patients with DUX4-rearranged, BCR-ABL1-like, and ZNF384-rearranged ALL, and achievement of day-42 MRD&lt;0.01% did not preclude relapse of those with PAX5alt, MEF2D-rearranged and ETV6-RUNX1-like ALL. Comprehensive genomic analyses identify novel subtypes, such as DUX4-rearranged, PAX5alt, BCR-ABL1-like, ETV6-RUNX1-like, M2F2D-rearranged and ZNF384-rearranged ALL, which have prognostic and therapeutic implications.

Citation Format: Sima Jeha, John K. Choi, Deqing Pei, Elaine Coustan-Smith, Hiroto Inaba, Jeffrey E. Rubnitz, Raul C. Ribiero, Tanja A. Gruber, Susana C. Raimondi, Seth E. Karol, Kathryn G. Roberts, Jun J. Yang, Cheng Cheng, James R. Downing, William E. Evans, Mary V. Relling, Dario Campana, Charles G. Mullighan, Ching-Hon Pui. Prognostic and therapeutic significance of leukemia subtypes in the context of risk-directed therapy based on minimal residual disease levels in pediatric acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT146.

Clinical significance of novel subtypes of acute lymphoblastic leukemia in the context of minimal residual disease-directed therapy

We evaluate clinical significance of recently identified subtypes of acute lymphoblastic leukemia (ALL) in 598 children treated with minimal residual disease (MRD)-directed therapy. Among the 16 B-ALL and 8 T-ALL subtypes identified by next generation sequencing, ETV6-RUNX1, high-hyperdiploid and DUX4-rearranged B-ALL had the best five-year event-free survival rates (95% to 98.4%); TCF3-PBX1, PAX5alt, T-cell, ETP, iAMP21, and hypodiploid ALL intermediate rates (80.0% to 88.2%); and BCR-ABL1, BCR-ABL1-like and ETV6-RUNX1-like and KMT2A-rearranged ALL the worst rates (64.1% to 76.2%). All but three of the 142 patients with day-8 blood MRD <0.01% remained in remission. Among new subtypes, intensified therapy based on day-15 MRD≥1% improved outcome of DUX4-rearranged, BCR-ABL1-like, and ZNF384-rearranged ALL, and achievement of day-42 MRD<0.01% did not preclude relapse of PAX5alt, MEF2D-rearranged and ETV6-RUNX1-like ALL. Thus, new subtypes including DUX4-rearranged, PAX5alt, BCR-ABL1-like, ETV6-RUNX1-like, MEF2D-rearranged and ZNF384-rearranged ALL have important prognostic and therapeutic implications.

Epidural blood patch for post-dural puncture headaches in adult and paediatric patients with malignancies: a review

Many anaesthetists are hesitant to perform epidural blood patch in patients with cancer because of the potential risk of seeding the CNS with malignant cells. Recent evidence suggests that anaesthetists may view malignancy as a relative contraindication to epidural blood patch rather than an absolute contraindication. This review article summarises the clinical dilemma, reviews the existing literature, and proposes a treatment algorithm that includes the utilisation of for the management of post-dural puncture headache in the oncology population.

Ultrasound has limited diagnostic utility in children with acute lymphoblastic leukemia developing pancreatitis

PURPOSE

Acute pancreatitis (AP) due to chemotherapy-induced pancreatic injury is a common side effect of treatment for acute lymphoblastic leukemia (ALL), the most common childhood malignancy. The American College of Radiology recommends ultrasound (US) for initial imaging of AP in all populations to assess for ductal obstruction. However, US may be insensitive to diagnose and assess chemotherapy-associated AP.

METHODS AND MATERIALS

The institutional review board approved this retrospective study. Patients with ALL and AP were identified from protocol databases, using Common Terminology Criteria for Adverse Events (CTCAE) version 3. Chemotherapy dosing, amylase/lipase levels, clinical symptoms, and US/computed tomography (CT) reports within 10 days of diagnosis were recorded. All CT images were reviewed for revised Atlanta classification and CT severity index (CTSI).

RESULTS

Sixty-nine patients, aged 2-21 years, experienced 88 episodes of AP, undergoing 98 US and 44 CT. Seventy-two events (82%) occurred within 30 days of asparaginase administration. Sixty-nine episodes (78%) were initially diagnosed by the presence of abdominal pain and pancreatic enzyme elevation. Overall sensitivities for AP detection were 47% using US and 98% for CT. US sensitivity was greatest in CTCAE grade 4 (86%) and necrotizing pancreatitis (67%).

CONCLUSIONS

Most cases of AP in children with ALL can be diagnosed with clinical history and labs. US has limited sensitivity in detecting pancreatitis in this population. Imaging to diagnose AP in this patient population could be limited to clinically equivocal cases.

Team approach: Management of osteonecrosis in children with acute lymphoblastic leukemia

With current treatments for acute lymphoblastic leukemia (ALL), the overall prognosis for survival is favorable. Increasing emphasis is placed on recognizing and managing the long-term consequences of ALL and its treatment, particularly involving osteonecrosis. Early osteonecrosis diagnosis and management may improve outcomes and is best accomplished through coordinated teams that may include hematologic oncologists, radiologists, orthopedic surgeons, physical therapists, and the patient and their family. Magnetic resonance imaging is the "gold standard" for diagnosis of early-stage and/or multifocal osteonecrosis. Treatments for osteonecrosis in ALL patients are risk stratified and may include observation, corticosteroid or chemotherapy adjustment, and pharmaceutical or surgical approaches.

Pharmacogenomics and ALL treatment: How to optimize therapy

Inherited genetic variations may alter drug sensitivity in patients with acute lymphoblastic leukemia, predisposing to adverse treatment side effects. In this review, we discuss evidence from children and young adults with acute lymphoblastic leukemia to review the available pharmacogenomic data with an emphasis on clinically actionable and emerging discoveries, for example, genetic variants in thiopurine methyltransferase and NUDT15 that alter 6-mercaptopurine dosing. We also highlight the need for ongoing pharmacogenomic research to validate the significance of recent findings. Further research in young adults, as well as with novel therapeutics, is needed to provide optimal therapy in future trials.

Safety, pharmacokinetics, and pharmacodynamics of panobinostat in children, adolescents, and young adults with relapsed acute myeloid leukemia

BACKGROUND

Novel therapies are urgently needed for pediatric patients with relapsed acute myeloid leukemia (AML).

METHODS

To determine whether the histone deacetylase inhibitor panobinostat could be safely given in combination with intensive chemotherapy, a phase 1 trial was performed in which 17 pediatric patients with relapsed or refractory AML received panobinostat (10, 15, or 20 mg/m² ) before and in combination with fludarabine and cytarabine.

RESULTS

All dose levels were tolerated, with no dose-limiting toxicities observed at any dose level. Pharmacokinetic studies demonstrated that exposure to panobinostat was proportional to the dose given, with no associations between pharmacokinetic parameters and age, weight, or body surface area. Among the 9 patients who had sufficient (>2%) circulating blasts on which histone acetylation studies could be performed, 7 demonstrated at least 1.5-fold increases in acetylation. Although no patients had a decrease in circulating blasts after single-agent panobinostat, 8 of the 17 patients (47%), including 5 of the 6 patients treated at dose level 3, achieved complete remission. Among the 8 complete responders, 6 (75%) attained negative minimal residual disease status.

CONCLUSIONS

Panobinostat can be safely administered with chemotherapy and results in increased blast histone acetylation. This suggests that it should be further studied in AML.

Whole-joint magnetic resonance imaging to assess osteonecrosis in pediatric patients with acute lymphoblastic lymphoma

BACKGROUND

Osteonecrosis is a debilitating complication in children and adolescents with acute lymphoblastic leukemia or acute lymphoblastic lymphoma (LLy). An objective screening test to identify patients at risk for symptomatic, extensive joint involvement will help manage osteonecrosis.

METHODS

We performed a prospective, longitudinal pilot study with whole-joint magnetic resonance imaging (MRI) of shoulders, elbows, hips, knees, ankles, and hindfeet to evaluate the incidence and timing of osteonecrosis involving multiple joints in 15 patients with LLy aged 9-21 years at diagnosis.

RESULTS

Osteonecrosis affecting ≥30% of the epiphysis occurred in eight of 15 patients, with a high prevalence in hips (12 of 26 examined [46%]) and knees (10 of 26 [38%]) post reinduction I and in shoulders (seven of 20 [35%]) post reinduction II. Most osteonecrotic hips and knees with ≥30% epiphyseal involvement became symptomatic and/or underwent surgery (100% and 82%, respectively). All eight patients with ≥30% epiphyseal involvement had multijoint involvement. Seven of these patients had hip or knee osteonecrosis by the end of remission induction, and only these patients developed osteonecrosis that became symptomatic and/or underwent surgery in their hips, knees, shoulders, ankles, and/or feet; all of these joints were associated with epiphyseal abnormalities on post reinduction I imaging.

CONCLUSIONS

MRI screening in adolescent patients with LLy revealed osteonecrosis in multiple joints. Initial screening with hip and knee MRI at the end of induction may identify susceptible patients who could benefit from referrals to subspecialties, more extensive follow-up imaging of other joints, and early medical and surgical interventions.

Fluoroquinolone prophylaxis does not increase risk of neuropathy in children with acute lymphoblastic leukemia

Background

Fluoroquinolone antibiotics are frequently utilized in pediatric oncology patients as prophylaxis or step‐down therapy following broad spectrum beta‐lactam therapy for febrile neutropenia. Concerns regarding neurotoxicity limit the use of these agents. No studies have evaluated the association between fluoroquinolone use and neurotoxicity in pediatric oncology patients receiving other neurotoxic agents such as vincristine.

Methods

An observational cohort study comprising patients aged 0‐18 at diagnosis enrolled on a prospective study for treatment of acute lymphoblastic leukemia (ALL) at a pediatric comprehensive cancer center between October 2007 and November 2018. Data for neuropathic pain and sensory or motor neuropathy were collected prospectively, and a Cox proportional hazards regression model was used to evaluate associations between administration of fluoroquinolone antibiotics during induction therapy and subsequent development of vincristine‐induced peripheral neurotoxicity (VIPN).

Results

A total of 598 participants were enrolled, including 338 (57%) who received fluoroquinolones during induction therapy; of these 470 (79%) were diagnosed with VIPN and 139 (23%) were diagnosed with high‐grade (Grade 3+) VIPN. On unadjusted analyses, and analyses adjusted for age and race, there was no evidence of an association between fluoroquinolone exposure and subsequent VIPN (hazard ratio [HR] 0.8, 95% CI 0.5‐1.04, P = .08) or high‐grade VIPN (HR 1.1, 95% CI 0.4‐2.2, P = .87).

Conclusions

The results of this observational study do not show an association between exposure to fluoroquinolone antibiotics during induction therapy for ALL and subsequent development of vincristine‐induced peripheral neuropathies, and suggest that a large increase in VIPN is unlikely.

Higher plasma asparaginase activity after intramuscular than intravenous Erwinia asparaginase

It is unclear if dosing intervals for Erwinase can be extended with intramuscular (i.m.) versus intravenous (i.v.) dosing. Children with acute lymphoblastic leukemia received Erwinase at 30 000-42 000 IU/m² i.v. or i.m. I.m. Erwinase (n = 22) achieved activity above 0.1 IU/mL for longer than i.v. Erwinase (n = 33) (3.4 vs 2.9 days, P = 0.0007). With 30 000 IU/m² Monday, Wednesday, Friday, more patients achieved adequate concentrations over the weekend with i.m. vs i.v. dosing (P = 5 × 10^-36 ). A schedule with i.v. doses on Monday and Wednesday and i.m. doses on Friday of 30 000 IU/m² maintained activity > 0.1 IU/mL over the weekend in 80% of patients.

Personalized therapy in pediatric high-risk B-cell acute lymphoblastic leukemia

Although cure rates for pediatric acute lymphoblastic leukemia (ALL) have now risen to more than 90%, subsets of patients with high-risk features continue to experience high rates of treatment failure and relapse. Recent work in minimal residual disease stratification and leukemia genomics have increased the ability to identify and classify these high-risk patients. In this review, we discuss this work to identify and classify patients with high-risk ALL. Novel therapeutics, which may have the potential to improve outcomes for these patients, are also discussed.

A quality improvement project to improve pediatric medical provider sleep and communication during night shifts

QUALITY PROBLEM OR ISSUE

Night-shift medical providers frequently experience limited sleep resulting in fatigue, often because of paging activity. Streamlined medical-specific communication interventions are known to improve sleep and communication among these providers.

INITIAL ASSESSMENT

We found that non-urgent paging communication occurred frequently during night-shifts, leading to provider sleep disturbances within our institution. We tested a quality improvement (QI) intervention to improve paging practices and determined its effect on provider sleep.

CHOICE OF SOLUTION

We used a Plan-Do-Study-Act QI model aimed at improving clinician sleep and paging communications.

IMPLEMENTATION

We initially conducted focus groups of nurses and physician trainees to inform the creation of a standardized paging intervention. We collected actigraphy and sleep log data from physicians, nurse practitioners, and physician trainees and performed electronic collection of paging frequency data.

EVALUATION

Data were collected between December 2015 and March 2017 from pediatric residents, pediatric hematology/oncology (PHO) fellows, hospitalist medicine nocturnists and nurses working during night-shift hours in PHO inpatient units. We collected baseline data before implementation of the QI intervention and at 1 month post-implementation. Although objective measures and provider reports demonstrated improved medical-specific communication paging practices, provider sleep was not affected.

LESSONS LEARNED

Provider-based standardization of paging communication was associated with improved medical-specific communication between nurses and providers; however, provider sleep was not affected. The strategies used in this intervention may be transferable to other clinics and institutions to streamline medical-specific communication.

Venetoclax in combination with cytarabine with or without idarubicin in children with relapsed or refractory acute myeloid leukaemia: a phase 1, dose-escalation study

BACKGROUND

Outcomes for children with relapsed or refractory acute myeloid leukaemia remain poor. The BCL-2 inhibitor, venetoclax, has shown promising activity in combination with hypomethylating agents and low-dose cytarabine in older adults for whom chemotherapy is not suitable with newly diagnosed acute myeloid leukaemia. We aimed to determine the safety and explore the activity of venetoclax in combination with standard and high-dose chemotherapy in paediatric patients with relapsed or refractory acute myeloid leukaemia.

METHODS

We did a phase 1, dose-escalation study at three research hospitals in the USA. Eligible patients were aged 2-22 years with relapsed or refractory acute myeloid leukaemia or acute leukaemia of ambiguous lineage with adequate organ function and performance status. During dose escalation, participants received venetoclax orally once per day in continuous 28-day cycles at either 240 mg/m2 or 360 mg/m2, in combination with cytarabine received intravenously every 12 h at either 100 mg/m2 for 20 doses or 1000 mg/m2 for eight doses, with or without intravenous idarubicin (12 mg/m2) as a single dose, using a rolling-6 accrual strategy. The primary endpoint was the recommended phase 2 dose of venetoclax plus chemotherapy and the secondary endpoint was the proportion of patients treated at the recommended phase 2 dose who achieved complete remission or complete remission with incomplete haematological recovery. Analyses were done on patients who received combination therapy. The study is registered with ClinicalTrials.gov (NCT03194932) and is now enrolling to address secondary and exploratory objectives.

FINDINGS

Between July 1, 2017, and July 2, 2019, 38 patients were enrolled (aged 3-22 years; median 10 [IQR 7-13]), 36 of whom received combination therapy with dose escalation, with a median follow-up of 7·1 months (IQR 5·1-11·2). The recommended phase 2 dose of venetoclax was found to be 360 mg/m2 (maximum 600 mg) combined with cytarabine (1000 mg/m2 per dose for eight doses), with or without idarubicin (12 mg/m2 as a single dose). Overall responses were observed in 24 (69%) of the 35 patients who were evaluable after cycle 1. Among the 20 patients treated at the recommended phase 2 dose, 14 (70%, 95% CI 46-88) showed complete response with or without complete haematological recovery, and two (10%) showed partial response. The most common grade 3-4 adverse events were febrile neutropenia (22 [66%]), bloodstream infections (six [16%]), and invasive fungal infections (six [16%]). Treatment-related death occurred in one patient due to colitis and sepsis.

INTERPRETATION

The safety and activity of venetoclax plus chemotherapy in paediatric patients with heavily relapsed and refractory acute myeloid leukaemia suggests that this combination should be tested in newly diagnosed paediatric patients with high-risk acute myeloid leukaemia.

FUNDING

US National Institutes of Health, American Lebanese Syrian Associated Charities, AbbVie, and Gateway for Cancer Research.

Long-Term Functional Outcomes Among Childhood Survivors of Cancer Who Have a History of Osteonecrosis

BACKGROUND

Glucocorticoids used to treat childhood leukemia and lymphoma can result in osteonecrosis, leading to physical dysfunction and pain. Improving survival rates warrants research into long-term outcomes among this population.

OBJECTIVE

The objective of this study was to compare the physical function and quality of life (QOL) of survivors of childhood cancer who had an osteonecrosis history with that of survivors who had no osteonecrosis history and with that of people who were healthy (controls).

DESIGN

This was a cross-sectional study.

METHODS

This study included St Jude Lifetime Cohort Study participants who were ≥ 10 years from the diagnosis of childhood leukemia or lymphoma and ≥ 18 years old; 135 had osteonecrosis (52.5% men; mean age = 27.7 [SD = 6.08] years) and 1560 had no osteonecrosis history (52.4% men; mean age = 33.3 [SD = 8.54] years). This study also included 272 people who were from the community and who were healthy (community controls) (47.7% men; mean age = 35.1 [SD = 10.46] years). The participants completed functional assessments and questionnaires about QOL.

RESULTS

Survivors with osteonecrosis scored lower than other survivors and controls for dorsiflexion strength (mean score = 16.50 [SD = 7.91] vs 24.17 [SD = 8.61] N·m/kg) and scored lower than controls for flexibility with the sit-and-reach test (20.61 [SD = 9.70] vs 23.96 [SD = 10.73] cm), function on the Physical Performance Test (mean score = 22.73 [SD = 2.05] vs 23.58 [SD = 0.88]), and mobility on the Timed "Up & Go" Test (5.66 [SD = 2.25] vs 5.12 [SD = 1.28] seconds). Survivors with hip osteonecrosis requiring surgery scored lower than survivors without osteonecrosis for dorsiflexion strength (13.75 [SD = 8.82] vs 18.48 [SD = 9.04] N·m/kg), flexibility (15.79 [SD = 8.93] vs 20.37 [SD = 10.14] cm), and endurance on the 6-minute walk test (523.50 [SD = 103.00] vs 572.10 [SD = 102.40] m).

LIMITATIONS

Because some eligible survivors declined to participate, possible selection bias was a limitation of this study.

CONCLUSIONS

Survivors of childhood leukemia and lymphoma with and without osteonecrosis demonstrated impaired physical performance and reported reduced QOL compared with controls, with those requiring surgery for osteonecrosis most at risk for impairments. It may be beneficial to provide strengthening, flexibility, and endurance interventions for patients who have pediatric cancer and osteonecrosis for long-term function.

Integrative genomic analyses reveal mechanisms of glucocorticoid resistance in acute lymphoblastic leukemia

Identification of genomic and epigenomic determinants of drug resistance provides important insights for improving cancer treatment. Using agnostic genome-wide interrogation of mRNA and miRNA expression, DNA methylation, SNPs, CNAs and SNVs/Indels in primary human acute lymphoblastic leukemia cells, we identified 463 genomic features associated with glucocorticoid resistance. Gene-level aggregation identified 118 overlapping genes, 15 of which were confirmed by genome-wide CRISPR screen. Collectively, this identified 30 of 38 (79%) known glucocorticoid-resistance genes/miRNAs and all 38 known resistance pathways, while revealing 14 genes not previously associated with glucocorticoid-resistance. Single cell RNAseq and network-based transcriptomic modelling corroborated the top previously undiscovered gene, CELSR2. Manipulation of CELSR2 recapitulated glucocorticoid resistance in human leukemia cell lines and revealed a synergistic drug combination (prednisolone and venetoclax) that mitigated resistance in mouse xenograft models. These findings illustrate the power of an integrative genomic strategy for elucidating genes and pathways conferring drug resistance in cancer cells.

Asparaginase formulation impacts hypertriglyceridemia during therapy for acute lymphoblastic leukemia

BACKGROUND

Glucocorticoids and asparaginase, used to treat acute lymphoblastic leukemia (ALL), can cause hypertriglyceridemia. We compared triglyceride levels, risk factors, and associated toxicities in two ALL trials at St. Jude Children's Research Hospital with identical glucocorticoid regimens, but different asparaginase formulations. In Total XV (TXV), native Escherichia coli l-asparaginase was front-line therapy versus the pegylated formulation (PEG-asparaginase) in Total XVI (TXVI).

PROCEDURE

Patients enrolled on TXV (n = 498) and TXVI (n = 598) were assigned to low-risk (LR) or standard/high-risk (SHR) treatment arms (ClinicalTrials.gov identifiers: NCT00137111 and NCT00549848). Triglycerides were measured four times and were evaluable in 925 patients (TXV: n = 362; TXVI: n = 563). The genetic contribution was assessed using a triglyceride polygenic risk score (triglyceride-PRS). Osteonecrosis, thrombosis, and pancreatitis were prospectively graded.

RESULTS

The largest increase in triglycerides occurred in TXVI SHR patients treated with dexamethasone and PEG-asparaginase (4.5-fold increase; P <1 × 10^-15 ). SHR patients treated with PEG-asparaginase (TXVI) had more severe hypertriglyceridemia (>1000 mg/dL) compared to native l-asparaginase (TXV): 10.5% versus 5.5%, respectively (P = .007). At week 7, triglycerides did not increase with dexamethasone treatment alone (LR patients) but did increase with dexamethasone plus asparaginase (SHR patients). The variability in triglycerides explained by the triglyceride-PRS was highest at baseline and declined with therapy. Hypertriglyceridemia was associated with osteonecrosis (P = .0006) and thrombosis (P = .005), but not pancreatitis (P = .4).

CONCLUSION

Triglycerides were affected more by PEG-asparaginase than native l-asparaginase, by asparaginase more than dexamethasone, and by drug effects more than genetics. It is not clear whether triglycerides contribute to thrombosis and osteonecrosis or are biomarkers of the toxicities.

Diabetes mellitus among adult survivors of childhood acute lymphoblastic leukemia: A report from the St. Jude Lifetime Cohort Study

BACKGROUND

Greater than one-half of children who are treated for acute lymphoblastic leukemia (ALL) develop ≥1 treatment-related medical conditions in their lifetime, many of which are known risk factors for diabetes mellitus. In the current study, the authors evaluated the prevalence and risk factors of diabetes mellitus among clinically assessed adult survivors of childhood ALL METHODS: The authors performed a retrospective evaluation of data from survivors of ALL and community controls who were enrolled in the St. Jude Lifetime Cohort Study between October 1, 2007, and June 30, 2016. Participants were adults with ≥10 years of survival of childhood ALL and community controls who completed clinical and laboratory evaluations. Data for the current analysis were abstracted from medical records. Exposures evaluated herein included chemotherapy and radiation exposures and medical history, including drug-induced diabetes mellitus.

RESULTS

Of 1360 eligible adults who were ≥10-year survivors of childhood ALL, a total of 1044 completed the evaluations; these individuals had a mean age of 33.97±9.14 years and 50.86% were male. The 368 controls, 45.65% of whom were male, had a mean age of 35.33±10.21 years. Type 2 diabetes mellitus (T2DM) was found in approximately 7.47% of survivors and 3.80% of controls (odds ratio [OR], 2.07; 95% CI, 1.11-3.87). In adjusted models, among survivors, older age (OR, 1.05 for each additional year; 95% CI, 1.02-1.08), body mass index ≥30 kg/m² (OR, 7.40; 95% CI, 2.61-20.97), and drug-induced diabetes mellitus occurring during ALL therapy (OR, 4.67; 95% CI, 2.53-8.61) were found to be associated with T2DM.

CONCLUSIONS

Adult survivors of childhood ALL are at an increased risk of T2DM. Adult survivors of childhood ALL who are of older age, with an overweight or obese body mass index, and/or who developed drug-induced diabetes mellitus during treatment should be closely monitored for T2DM during long-term follow-up.

Antibodies Predict Pegaspargase Allergic Reactions and Failure of Rechallenge

PURPOSE

Pegaspargase (PEG-ASP) has largely replaced native Escherichia coli asparaginase (L-ASP) in the treatment of acute lymphoblastic leukemia because of its longer half-life and lower immunogenicity. Risk factors for allergic reactions to PEG-ASP remain unclear. Here, we identify risk factors for reactions in a front-line acute lymphoblastic leukemia trial and assess the usefulness of serum antibodies for diagnosing allergy and predicting rechallenge outcome.

PATIENTS AND METHODS

PEG-ASP was administered to 598 patients in St Jude's Total XVI study. Results were compared with Total XV study (ClinicalTrials.gov identifiers: NCT00549848 and NCT00137111), which used native L-ASP. Serum samples (n = 5,369) were analyzed for anti-PEG-ASP immunoglobulin G by enzyme-linked immunosorbent assay. Positive samples were tested for anti-polyethylene glycol (PEG) and anti-L-ASP. We analyzed potential risk factors for reactions and associations between antibodies and reactions, rechallenge outcomes, and PEG-ASP pharmacokinetics.

RESULTS

Grade 2 to 4 reactions were less common in the Total XVI study with PEG-ASP (81 [13.5%] of 598) than in the Total XV study with L-ASP (169 [41.2%] of 410; P = 1.4 × 10-23). For Total XVI, anti-PEG, not anti-L-ASP, was the predominant component of anti-PEG-ASP antibodies (96%). In a multivariable analysis, more intrathecal therapy (IT) predicted fewer reactions (P = 2.4 × 10-5), which is consistent with an immunosuppressant contribution of IT. Anti-PEG-ASP was associated with accelerated drug clearance (P = 5.0 × 10-6). Failure of rechallenge after initial reactions was associated with anti-PEG-ASP (P = .0078) and was predicted by the occurrence of angioedema with first reaction (P = .01).

CONCLUSION

Less IT therapy was the only independent clinical risk factor for reactions to PEG-ASP. PEG, and not L-ASP, is the major antigen that causes allergic reactions. Anti-PEG-ASP has utility in predicting and confirming clinical reactions to PEG-ASP as well as in identifying patients who are most likely to experience failure with rechallenge.

Bloodstream infections exacerbate incidence and severity of symptomatic glucocorticoid-induced osteonecrosis

BACKGROUND

Osteonecrosis is a common toxicity associated with glucocorticoid (e.g., dexamethasone and prednisone) treatment of children with acute lymphoblastic leukemia (ALL), but risk factors are incompletely defined. Infections are also a common complication of ALL therapy. Lipopolysaccharide (LPS) is used experimentally to mimic infection-related systemic effects. To our knowledge, the contribution of systemic infections to the risk of glucocorticoid-induced osteonecrosis has not been investigated.

PROCEDURE

Patients with ALL on St. Jude Total Therapy XV (n = 365) were assessed for documented bacteremia prior to development of osteonecrosis, which was confirmed by MRI, and graded using the National Cancer Institute's Common Terminology for Adverse Events (version 3.0). In a preclinical model, Balb/cJ mice treated with dexamethasone plus or minus LPS were assessed for frequency and severity of osteonecrosis and arteriopathy.

RESULTS

We found that patients with ALL who experienced bacteremia had a higher frequency of symptomatic osteonecrosis (≥grade 2) than those who did not (OR: 1.88; 95% CI, 1.03-3.41, P = 0.038). LPS exacerbated experimental dexamethasone-induced osteonecrosis. Mice treated with dexamethasone plus LPS had a higher incidence of osteonecrosis (P = 0.00086) and arteriopathy (P = 0.0047) than did those treated with dexamethasone alone, and the severity of osteonecrosis (P = 0.00045) and arteriopathy (P = 0.0048) was also more pronounced with the addition of LPS treatment. The increase in osteonecrosis was not explained by any alteration of dexamethasone pharmacokinetics by LPS.

CONCLUSIONS

These data identify systemic infection during ALL therapy as a novel risk factor in the development of glucocorticoid-induced osteonecrosis.

No evidence that G6PD deficiency affects the efficacy or safety of daunorubicin in acute lymphoblastic leukemia induction therapy

BACKGROUND/OBJECTIVES

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

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

We found no evidence that G6PD deficiency affects daunorubicin activity during induction treatment for ALL.

Safety and activity of venetoclax in combination with high-dose cytarabine in children with relapsed or refractory acute myeloid leukemia

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Background: Venetoclax is an orally available BCL-2 antagonist with demonstrated activity in adults with newly diagnosed or relapsed acute myeloid leukemia (AML). Here, we describe the first use of venetoclax 1) in combination with high-dose cytarabine and idarubicin 2) in patients 2-22 years old with relapsed AML. Methods: Patients with relapsed AML or AML refractory to at least two courses of induction therapy were enrolled in this Phase 1 study with a rolling-six design. All patients received venetoclax (240 or 360 mg/m2) on days 1-28 and low-dose (LD: 100 mg/m2 every 12 hours x 20 doses) or high-dose (HD: 1000 mg/m2 every 12 hours x 8 doses) cytarabine beginning on day 8 (Table). Patients who had previously received < 270 mg/m2 of doxorubicin equivalents also received idarubicin 12 mg/m2 on day 8 in dose level 4; other patients were enrolled on the expansion cohort at dose level 3. Non-hematologic CTCAE grade 3 or higher toxicities were intensity limiting (ILT), excluding those anticipated with HD cytarabine. Results: Among 18 evaluable patients, a single ILT (prolonged hematological suppression beyond day 50) was observed (Table). Toxicities were consistent with the underlying cytotoxic chemotherapy, with 14 patients experiencing a total of 40 grade 3 toxicities including 6 documented infections and 23 episodes of febrile neutropenia. There was 1 grade 4 fungal sepsis. The recommended phase 2 dose of venetoclax was 360 mg/m2 (max 600 mg) when combined with HD cytarabine or HD cytarabine/idarubicin. Of the 12 patients with > 50% reduction in blasts following the 7-day venetoclax window therapy, end-of-cycle marrow responses included 7 CR/CRi and 3 PR. Minimal residual disease negative remissions occurred in 4 patients. BH3 profiling of samples and a phase 2 expansion of both dose levels 3 and 4 to further characterize the promising activity of these combinations are underway. Conclusions: Venetoclax combined with cytarabine or cytarabine/idarubicin is active and well tolerated in pediatric patients with relapsed/ refractory AML. Clinical trial information: NCT03194932. [Table: see text]