Children with acute lymphoblastic leukemia (ALL) have excellent outcomes, with >85% survival without relapse following contemporary therapies. Clinical and complete blood count (CBC) assessments are commonly used surveillance methods to detect relapses. We aimed to evaluate the efficacy of routine blood testing for detecting relapse using a systematic method of assessing normal and abnormal results.

This a retrospective, single center study included children aged 1-14 years diagnosed with ALL who completed therapy and were in complete remission. Demographic data, leukemia subtypes, risk stratification, treatment responses, and outcomes were also reviewed. CBC tests were evaluated, and abnormal results were categorized. The relapse groups were classified as asymptomatic and symptomatic relapses. The clinical outcomes of relapse and complications were analyzed. The sensitivity, specificity, positive predictive value, and negative predictive value of surveillance laboratory tests for predicting relapse after the end of treatment were evaluated.

In total, 187 patients underwent 2074 CBC tests. Ten patients underwent full surveillance, whereas the remaining patients underwent partial surveillance. The median number of surveillance blood draws per patient was 12. Relapse was observed in nine patients. Only three patients had asymptomatic relapses. Neutropenia, leukopenia, pancytopenia, thrombocytopenia, and anemia were observed in 98, 89, 10, 6, and 3 patients respectively. The sensitivity and specificity of neutropenia, leukopenia, thrombocytopenia, anemia, and pancytopenia were 11.11% and 47.9%, 0% and 50%, 33.3% and 98.31%, 0% and 99.4%, and 33.3% and 96.07%, respectively. No differences were observed between patients who had asymptomatic relapses and those whose clinical outcomes or consequences had symptomatic relapses.

Relapse after completion of therapy in ALL is rare. Regular blood count surveillance does not predict clinical outcomes or relapse. Prospective studies are required to assess appropriate risk-based surveillance and its effects on patient outcomes and quality of life.

Brain bases and progression of methotrexate-associated neurotoxicity and cognitive disturbances remain unknown. We tested whether brain abnormalities worsen in proportion to intrathecal methotrexate(IT-MTX) doses.

In this prospective, longitudinal study, we recruited 19 patients with newly diagnosed acute lymphoblastic leukemia 4-to-20 years of age and 20 matched controls. We collected MRI and neuropsychological assessments at a pre-methotrexate baseline and at week 9, week 22, and year 1 during treatment.

Patients had baseline abnormalities in cortical and subcortical gray matter(GM), white matter(WM) volumes and microstructure, regional cerebral blood flow, and neuronal density. Abnormalities of GM, blood flow, and metabolites worsened in direct proportions to IT-MTX doses. WM abnormalities persisted until week 22 but normalized by year 1. Brain injuries were localized to dorsal and ventral attentional and frontoparietal cognitive networks. Patients had cognitive deficits at baseline that persisted at 1-year follow-up.

Baseline abnormalities are likely a consequence of neuroinflammation and oxidative stress. Baseline abnormalities in WM microstructure and volumes, and blood flow persisted until week 22 but normalized by year 1, likely due to treatment and its effects on reducing inflammation. The cytotoxic effects of IT-MTX, however, likely contributed to continued, progressive cortical thinning and reductions in neuronal density, thereby contributing to enduring cognitive deficits.

Brain abnormalities at a pre-methotrexate baseline likely are due to acute illness. The cytotoxic effects of intrathecal MTX contribute to progressive cortical thinning, reductions in neuronal density, and enduring cognitive deficits. Baseline white matter abnormalities may have normalized via methotrexate treatment and decreasing neuroinflammation. Corticosteroid and leucovorin conferred neuroprotective effects. Our findings suggest that the administration of neuroprotective and anti-inflammatory agents should be considered even earlier than they are currently administered. The neuroprotective effects of leucovorin suggest that strategies may be developed that extend the duration of this intervention or adapt it for use in standard risk patients.

Despite the improvement in survival in acute lymphoblastic leukemia (ALL), there are still cases with evasion of chemotherapy-induced apoptosis. The IKK/NF-κB signaling pathway contributes to antiapoptotic gene expression. Pentoxifylline (PTX) inhibits IkB phosphorylation, blocking NF-κB and antiapoptotic activity.

We conducted a randomized, double-blind clinical trial on pediatric ALL patients undergoing induction therapy, assigning them to PTX or placebo group. Bone marrow aspirates were obtained on days 1, 8, 15, and 22. Apoptosis was assessed using Annexin-V/propidium iodide.

Results indicated that the PTX group exhibited higher apoptosis on day-8 (41.3% vs. 19.4%, p =0.029) and day-15 (35.0% vs. 14.2%, p <0.01). On day-8, the PTX group displayed an MRD of 0.25% vs. 18.2% (p <0.01) in placebo group; on day-15, the PTX group demonstrated an MRD of 0.09% vs. 1.4% (p =0.02). Patients achieving an MRD <0.01% on day-8 demonstrated a 3-year Overall Survival (OS) of 81.6% vs. 58.3% (p =0.03); on day-15, patients with MRD <0.01% had a 3-year OS of 77.9% vs. 54.5% (p =0.03). The PTX group achieved an MRD of <0.01% earlier on days-8 and 15, along with a higher apoptosis rate, indicating a more favorable therapeutic response. In the entire cohort, patients achieving MRD <0.01% on day-8 or 15 displayed superior OS.

Our study demonstrates that PTX enhances apoptosis and reduces MRD in pediatric acute lymphoblastic leukemia patients.

https://clinicaltrials.gov/, identifier NCT02451774.

Acute lymphoblastic leukemia (ALL) represents the predominant cancer in pediatric populations, though its occurrence in adults is relatively rare. Pre-treatment risk stratification is crucial for predicting prognosis. Important factors for assessment include patient age, white blood cell (WBC) count at diagnosis, extramedullary involvement, immunophenotype, and cytogenetic aberrations. Minimal residual disease (MRD), primarily assessed by flow cytometry following remission, plays a substantial role in guiding management plans. Over the past decade, significant advancements in ALL outcomes have been witnessed. Conventional chemotherapy has remarkably reduced mortality rates; however, its intensive nature raises safety concerns and has led to the emergence of treatment-resistant cases with recurrence of relapses. Consequently, The U.S. Food and Drug Administration (FDA) has approved several novel treatments for relapsed/refractory ALL due to their demonstrated efficacy, as indicated by improved complete remission and survival rates. These treatments include tyrosine kinase inhibitors (TKIs), the anti-CD19 monoclonal antibody blinatumomab, anti-CD22 inotuzumab ozogamicin, anti-CD20 rituximab, and chimeric antigen receptor (CAR) T-cell therapy. Identifying the variables that influence treatment decisions is a pressing necessity for tailoring therapy based on heterogeneous patient characteristics. Key predictive factors identified in various observational studies and clinical trials include prelymphodepletion disease burden, complex genetic abnormalities, and MRD. Furthermore, the development of serious adverse events following treatment could be anticipated through predictive models, allowing for appropriate prophylactic measures to be considered. The ultimate aim is to incorporate the concept of precision medicine in the field of ALL through valid prediction platform to facilitate the selection of the most suitable treatment approach.

The survival rates of children with acute lymphoblastic leukemia (ALL) have improved over the years, but infections remain a significant cause of morbidity and mortality. Chemotherapy has a range of harmful side effects including the loss of protective antibodies against vaccine-preventable diseases. The objective of this study was to evaluate the serological status of pediatric ALL cases before and after intensive chemotherapy.

Children treated and followed for ALL at Dokuz Eylül University were included in this retrospective cross-sectional study. Antibody levels against hepatitis A, hepatitis B, and rubella were routinely assessed at both the time of diagnosis and 6 months after completion of chemotherapy. Measles, mumps, and varicella antibody levels were evaluated at only 6 months after treatment.

Seventy-eight children who completed chemotherapy for ALL were enrolled in the study. All participants had non-protective antibody levels for at least one of the diseases. The highest seropositivity rate was found for hepatitis A (55.1%) and the lowest for measles (17.9%) after chemotherapy. Overall, 50.7%, 30.6%, and 45.7% of the patients significantly lost their humoral immunity against hepatitis B, hepatitis A, and rubella, respectively. Patients in the higher-risk group for ALL had lower seropositivity rates than patients of the other risk groups. There were statistically significant relationships between the protective antibody rates for hepatitis A and varicella and the ages of the patients. Except for hepatitis A vaccination, pre-chemotherapy vaccination did not affect post-chemotherapy serology. On the other hand, all children with a history of varicella before diagnosis showed immunity after chemotherapy.

Patients with ALL, including those previously fully vaccinated, are at great risk of infection due to the decrease in protective antibody levels after chemotherapy. There is a need for routine post-chemotherapy serological testing and re-vaccination based on the results obtained.

Polymorphisms in NUDT15 may result in differences in mercaptopurine-induced toxicity. This study aimed to identify the frequency of the NUDT15 (c.415C>T; rs116855232) polymorphism and investigate the effect of this polymorphism on mercaptopurine-induced toxicity in a population of Syrian patients with childhood acute lymphoblastic leukemia (ALL).

This is a retrospective study that included children with ALL reaching at least 6 months of maintenance therapy. The NUDT15 genotyping was determined using standard targeted sequencing of polymerase chain reaction products. The odds ratio (OR) for the association between toxicity and genotype was evaluated.

A total of 92 patients were enrolled. The majority of the patients in the study population were low-risk (63.04%), followed by intermediate-risk (25%), and high-risk (11.96%). There were 5 patients (5.4%) with NUDT15 (c.415C>T; rs116855232) CT genotype, and 1 patient (1.08%) with NUDT15 TT genotype, with allele frequencies of C=0.962 and T=0.038. The mercaptopurine median dose intensity was 100%, 54.69%, and 5% for the genotypes CC, CT, and TT, respectively (P=0.009). Early onset leukopenia was significantly associated with the NUDT15 polymorphism (OR: 6.16, 95% CI: 1.11-34.18, P=0.037). There was no association between the NUDT15 genotype and hepatotoxicity.

Approximately 6.5% of the study population exhibited reduced NUDT15 activity. The mercaptopurine dose intensity was considerably low in NUDT15 rs116855232 TT genotype compared with CT and CC. The dosage of mercaptopurine should be adjusted according to the NUDT15 genotype in pediatric patients with ALL.

Information on the etiology and prognosis for leukemoid reaction (LR) in children is still limited and little is known about the factors that distinguish LR from hematological malignancy (HM).

This was a single-center, case-control study. Pediatric patients (<18 years) with a white blood cell (WBC) count of 50,000/μL or more were included in the study. Clinical information and laboratory test results were extracted from the electronic medical records. Patients were divided into the LR and HM groups. Logistic regression analysis was performed to investigate the factors that discriminated LR from HM.

We found 214 cases (115 cases in the LR group and 99 cases in the HM group) eligible for analysis. Approximately half of the LR cases were due to infectious diseases (n = 58, 50%); bacteremia and respiratory infections were the most common infections. Age younger than 2 years (odds ratio [95% confidence interval]) (2.154 [0.690-6.727]), presence of known underlying diseases (10.006 [3.119-32.102]), WBC count <60,555/μL (20.676 [6.357-67.251]), platelet count 118,000/μL or higher (15.059 [3.876-58.504]), lactate dehydrogenase (LDH) below 781 U/L (4.219 [1.378-12.915]), and C-reactive protein (CRP) ≥0.91 mg/dL (10.568 [2.736-40.825]) were identified as the predictive factors for LR by logistic regression analysis. Thirty-day mortality was higher in the LR group than in the HM group but the difference was not statistically significant (13% vs. 6%, p = 0.087).

Approximately half of the etiology of LR was infectious diseases and prognosis was poorer for LR than for HM. Age, presence of known underlying conditions, and laboratory tests, including WBC count, platelet count, LDH, and CRP, may be useful in distinguishing LR from HM.

The multidrug nature of anticancer treatment and different treatment protocols used in the studies are likely to be a major limitation in establishing real risk factors determining the occurrence of dental abnormalities. The authors aimed to establish a relationship between the duration and the dose of chemotherapy and the number of tooth adverse effects in the group receiving the same treatment. Of the 40 anticancer therapy recipients who attended the outpatient dental clinic, 7 leukemia survivors receiving the treatment according to the ALL IC-BFM 2002 protocol were selected. The study group consisted of four females and three males aged 92 to 207 months at the time of dental examination and 29 to 91 months at leukemia diagnosis. As a result of the clinical and radiological examination, dental abnormalities such as agenesis, tooth size reduction, root abnormalities, and taurodontia were identified, and the medical records of all survivors were reviewed in terms of drugs administered, their doses, and treatment schedules. No correlation was observed between the treatment duration of an intensive therapy, the entire therapy, and the number of tooth abnormalities. No relationship was also found between the number of dental abnormalities and the cumulative dose of vincristine, L-asparaginase, methotrexate, cyclophosphamide, cytarabine, and 6-mercaptopurine. The age at the onset of antineoplastic therapy is likely to be the strongest risk factor for toxic injury during tooth development.

Multiparametric flow cytometry (MFC) has become a powerful tool in minimal residual disease (MRD) detection in B-lymphoblastic leukemia/lymphoma (B-ALL). In the setting of targeted immunotherapy, B-ALL MRD detection often relies on alterative gating strategies, such as the utilization of CD22 and CD24. It is important to depict the full diversity of normal cell populations included in the alternative B-cell gating methods to avoid false-positive results. We describe two CD22-positive non-neoplastic cell populations in the peripheral blood (PB), including one progenitor population of uncertain lineage and one mature B-cell population, which are immunophenotypic mimics of B-ALL.

Using MFC, we investigated the prevalence and phenotypic profiles of both CD22-positive populations in 278 blood samples from 52 patients with B-ALL; these were obtained pre- and post-treatment with CD19 and/or CD22 CAR-T therapies. We further assessed whether these two populations in the blood were exclusively associated with B-ALL or recent anticancer therapies, by performing the same analysis on patients diagnosed with other hematological malignancies but in long-term MRD remission.

The progenitor population and mature B-cell population were detected at low levels in PB of 61.5% and 44.2% of B-ALL patients, respectively. Both cell types showed distinctive and highly consistent antigen expression patterns that are reliably distinguishable from B-ALL. Furthermore, their presence is not restricted solely to B-ALL or recent therapy.

Our findings aid in building a complete immunophenotypic profile of normal cell populations in PB, thereby preventing misdiagnosis of B-ALL MRD and inappropriate management.

Data on survival outcomes in patients with acute lymphoblastic leukemia (ALL) originating from Nepal are limited. We aim to present the real-world data on treatment outcomes of patients with de novo ALL treated with pediatric ALL-Berlin-Frankfurt-Muenster (BFM)-95 protocol in Nepal.

We used the medical records of 103 consecutive patients with ALL treated in our center from 2013 to 2016 to evaluate the overall survival (OS) and relapse-free survival (RFS) and analyzed the effects of clinicopathologic factors on survival outcomes in patients with ALL.

The 3-year OS and RFS in the entire cohort was 89.4% (95% CI, 82.1 to 96.7) and 87.3% (95% CI, 79.8 to 94.7), with a mean OS and RFS of 79.4 months (95% CI, 74.2 to 84.5) and 76.6 months (95% CI, 70.8 to 82.4), respectively. Patients with prednisone good response (PGR) showed better mean OS and RFS, whereas complete marrow response on day 33 was associated with better mean OS alone. Patients with Philadelphia (Ph)-positive ALL showed worse mean RFS compared to those with Ph-negative status. On multivariate analysis, PGR (hazard ratio [HR], 0.11; 95% CI, 0.03 to 0.49; P = .004) and sagittal vein thrombosis (SVT; HR, 5.95; 95% CI, 1.30 to 27.18; P = .02) were the only independent predictors of OS and RFS, respectively. Adverse events on BFM-95 protocol included SVT (4.9%), peripheral neuropathy (7.8%), myopathy (20.4%), hyperglycemia (24.3%), intestinal obstruction (7.8%), avascular necrosis of femur (6.8%), and mucositis (46%).

BFM-95 protocol appears to be a safe and effective strategy in adolescent and young adults and adult Nepalese population with ALL with a low toxicity profile.

The survival of childhood leukemia has improved. We aimed to report the survival rate and the associated factors in children with acute leukemia during an 8-year follow-up.

This study investigates the 8-year survival rates of children with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) in Shiraz, the largest oncology center in Southern Iran. We also aimed to assess the independent factors associated with higher mortality in childhood leukemia.

Children 0-18 years with acute leukemia were followed from 2013 to 2021 in Shiraz, Iran. The 8-year overall survival (OS) and event-free survival (EFS) rates were estimated by the Kaplan-Meier method. Independent factors associated with survival were assessed by the Cox regression hazard modeling.

We included 786 children, with 43.5% female, and a mean age of 6.32 ± 4.62 years. Patients with AML compared to ALL experienced more relapse (34.6% vs. 22.5%, p = .01) and death (31.7% vs. 11.3%, p < .001). The cumulative 8-year OS and EFS were 81% (95% confidence interval (CI), 74.3% to 86.1%) and 68.3% (95% CI, 63.5% to 72.7%) in ALL patients and 63.5% (95% CI, 52.1% to 72.9%) and 43% (95% CI, 33.1% to 52.6%) in AML patients. Multivariable analysis revealed that hepatomegaly (hazard ratio = 4, 95% CI, 1.0 to 22.3, p = .05) was the main independent risk factor of death in ALL patients. No definite risk factor was defined for AML patients.

The survival of childhood leukemia has recently increased dramatically in low-middle income countries. Hepatomegaly was introduced as a potential risk factor for lower survival in ALL patients. Further multicenter studies are needed to confirm the validity of this association.

Worldwide, the incidence of cancer is on the rise. Current cancer treatments include chemotherapy, radiation therapy, and surgery. Chemotherapy and radiation treatment are typically associated with severe adverse effects and a decline in patients' quality of life. Anti-cancer substances derived from plants and animals need to be evaluated therapeutically as it is cost-effective, have fewer side effects, and can improve cancer patients' quality of life. Recently, bovine colostrum (BC) has attracted the interest of numerous researchers investigating its anti-cancer potential in humans. Dressings loaded with BC are beneficial in treating chronic wounds and diabetic foot ulcers. Lactoferrin, a glycoprotein with potent anti-oxidant, anti-inflammatory, anti-cancer, and anti-microbial effects, is abundant in BC. The BC pills successfully promote the regression of low-grade cervical intraepithelial neoplasia when administered intravaginally. The biological, genetic, and molecular mechanisms driving BC remain to be determined. Oral BC supplements are generally well-tolerated, but some flatulence and nausea may happen. To evaluate the therapeutic effects, long-term safety, and appropriate dosages of BC drugs, well-designed clinical trials are necessary. The purpose of this article is to emphasize the anti-cancer potential of BC and its constituents.

The epidemiology of infant acute lymphoblastic leukemia (ALL), hypodiploid ALL, and mixed-phenotype acute leukemia (MPAL) in Canada is unknown. The main objective was to describe the prevalence, prognostic factors, and outcomes of three rare and high-risk ALL subtypes in Canada. This is a retrospective study using the Cancer in Young People-Canada (CYP-C) database. Event-free survival (EFS) and overall survival (OS) were described by the Kaplan-Meier method and compared using the log-rank test. Among 2626 children aged 0-14 years diagnosed with B-cell acute lymphoblastic leukemia (B-ALL) between 2001 and 2018, 227 (8.6%) patients were identified to be infant ALL (n = 139), hypodiploid ALL (n = 43), or MPAL (n = 45). The 5-year EFS/OS was significantly worse in the infant ALL subgroup compared to that of hypodiploid ALL and MPAL. For the entire cohort, presenting White blood cells (WBCs) ≥50 × 10⁹/L was independently associated with worse EFS/OS.

Over the years, the Hispanic population living in the United States has consistently shown high incidence rates of childhood acute leukemias (AL). Similarly, high AL incidence was previously observed in Mexico City (MC). Here, we estimated the AL incidence rates among children under 15 years of age in MC during the period 2010-2017.

The Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia conducted a study gathering clinical and epidemiological information regarding children newly diagnosed with AL at public health institutions of MC. Crude age incidence rates (cAIR) were obtained. Age-standardized incidence rates worldwide (ASIRw) and by municipalities (ASIRm) were calculated by the direct and indirect methods, respectively. These were reported per million population <15 years of age; stratified by age group, sex, AL subtypes, immunophenotype and gene rearrangements.

A total of 903 AL cases were registered. The ASIRw was 63.3 (cases per million) for AL, 53.1 for acute lymphoblastic leukemia (ALL), and 9.4 for acute myeloblastic leukemia. The highest cAIR for AL was observed in the age group between 1 and 4 years (male: 102.34 and female: 82.73). By immunophenotype, the ASIRw was 47.3 for B-cell and 3.7 for T-cell. The incidence did not show any significant trends during the study period. The ASIRm for ALL were 68.6, 66.6 and 62.8 at Iztacalco, Venustiano Carranza and Benito Juárez, respectively, whereas, other municipalities exhibited null values mainly for AML.

The ASIRw for childhood AL in MC is among the highest reported worldwide. We observed spatial heterogeneity of rates by municipalities. The elevated AL incidence observed in Mexican children may be explained by a combination of genetic background and exposure to environmental risk factors.

There is a lack of consensus for safely discharging adolescent and young adults (AYA) with newly diagnosed acute lymphoblastic leukemia. From 2017 to 2019 we evaluated predefined early discharge criteria for 41 AYA patients during induction chemotherapy. Only 17% (7/41) of patients met criteria for early discharge. Two (29%) patients who were discharged early were readmitted, but not to the pediatric intensive care unit (PICU). This outcome was compared to a historic cohort at our institution of 73 patients who were discharged without predefined discharge criteria. Twenty-seven (37%, p = 0.7) patients were readmitted, but 13 (48%) were readmitted to the PICU (p = 0.004).

The therapy design of childhood acute lymphoblastic leukemia (ALL) has evolved over the past 60 years. The St. Jude Children's Research Hospital has developed 17 treatment protocols from 1962 to 2017, aiming to have the most effective and least toxic treatment form. This review summarizes each protocol's objectives, inclusion criteria, treatment phases, pharmacological agents, irradiation therapy, response criteria, risk stratification, type of relapse, and overall survival. The enhancement and successful application of preventive therapy for ALL and following a risk-stratified approach have progressively improved the cure rate of childhood ALL, with relatively few adverse sequelae. Moreover, St. Jude's scientific theme serves as a reminder of the principal factor of research directed to a catastrophic disease such as ALL.

In order to analyze the clinical characteristics of epileptic seizures in children with acute lymphoblastic leukemia (ALL) during treatment.

The clinical and imaging data of children diagnosed as ALL with epilepsy seizures from January 2013 to December 2020 were retrospectively analyzed.

A total of 2217 children with ALL were admitted during the study, of whom 229 (10.33%) had epileptic seizures after ALL treatment. Among them, 45 (19.65%) were in the high-risk group and 184 (80.35%) were in the low-risk group. Epileptic seizures mainly occurred in the induction remission period (24.02%), maintenance treatment period (25.33%) and after bone marrow transplantation (21.40%). The common causes were MTX-related demyelinating encephalopathy (34.06%) and reversible posterior encephalopathy syndrome (PRES) (25.3%). The first symptom was mainly convulsion (34.50%). The first attack had a comprehensive attack and partial attack. Most patients stop themselves. 30 cases (13.10%) had acute recurrence of epilepsy (recurrence within 3 months after the first attack), and 49 cases (25.76%) had neurological dysfunction after follow-up. 36 cases developed symptomatic epilepsy. Among the 130 children who completed the follow-up, 78 (60.00%) had no obvious neurological sequelae, and 52 (40.0%) had neurological sequelae. Among the 52 cases, there were 34 cases of mild sequelae and 18 cases of severe sequelae, including 8 cases of epilepsy combined with cognitive impairment.

Epileptic seizure is a common neurological complication during ALL treatment. The etiology and associated manifestations of the first epileptic seizure are diverse. Early neuroimaging and EEG examination are helpful for early diagnosis and treatment.

Downregulation of surface epitopes causes postimmunotherapy relapses in B-lymphoblastic leukemia (B-ALL). Here we demonstrate that mRNA encoding CD22 undergoes aberrant splicing in B-ALL. We describe the plasma membrane-bound CD22 Δex5-6 splice isoform, which is resistant to chimeric antigen receptor (CAR) T cells targeting the third immunoglobulin-like domain of CD22. We also describe splice variants skipping the AUG-containing exon 2 and failing to produce any identifiable protein, thereby defining an event that is rate limiting for epitope presentation. Indeed, forcing exon 2 skipping with morpholino oligonucleotides reduced CD22 protein expression and conferred resistance to the CD22-directed antibody-drug conjugate inotuzumab ozogamicin in vitro. Furthermore, among inotuzumab-treated pediatric patients with B-ALL, we identified one nonresponder in whose leukemic blasts Δex2 isoforms comprised the majority of CD22 transcripts. In a second patient, a sharp reduction in CD22 protein levels during relapse was driven entirely by increased CD22 exon 2 skipping. Thus, dysregulated CD22 splicing is a major mechanism of epitope downregulation and ensuing resistance to immunotherapy.

The mechanism(s) underlying downregulation of surface CD22 following CD22-directed immunotherapy remains underexplored. Our biochemical and correlative studies demonstrate that in B-ALL, CD22 expression levels are controlled by inclusion/skipping of CD22 exon 2. Thus, aberrant splicing of CD22 is an important driver/biomarker of de novo and acquired resistance to CD22-directed immunotherapies. See related commentary by Bourcier and Abdel-Wahab, p. 87. This article is highlighted in the In This Issue feature, p. 85.

The prognosis of relapsed/refractory (R/R) pediatric acute leukemia is extremely poor. We retrospectively reviewed 20 consecutive pediatric patients with R/R acute leukemia who underwent a first HLA-haploidentical peripheral blood stem cell transplantation following reduced-intensity conditioning (haplo-RIC-PBSCT) with very low-dose antithymocyte globulin (ATG) between 2012 and 2019. Of these 20 patients, 7 patients had acute lymphoblastic leukemia, and 13 had acute myeloid leukemia. At the time of haplo-RIC-PBSCT, 15 patients had active disease. The median follow-up duration for survivors was 56 months (range 22-108 months). Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus, short-term methotrexate, methylprednisolone, and ATG 1.25 mg/kg on day-2. The 2-year cumulative incidence of transplant-related mortality and relapse were 5.0% [95% confidence interval (CI) 0.7-30.5%)] and 57.8% (95% CI 37.4-79.6%), respectively. Among the 20 patients, 16 (80.0%) developed grade III-IV acute GVHD, and 2 developed severe chronic GVHD. The 2-year event-free survival and overall survival rates were 40.0% (95% CI 19.3-60.0%) and 50.0% (95% CI 27.1-69.2%), respectively. Although the sample size is small, the survival outcomes of the present study are encouraging.

Adolescent and young adult (AYA) patients 16-30 years old with high-risk acute lymphoblastic leukemia (HR-ALL) have inferior outcomes compared to younger HR-ALL patients. AALL0232 was a Phase 3 randomized Children's Oncology Group trial for newly diagnosed HR B-ALL (1-30 years). Between 2004 and 2011, 3154 patients enrolled with 3040 eligible and evaluable for induction. AYA patients comprised 20% of patients (16-21 years, n = 551; 22-30 years, n = 46). 5-year event-free survival and overall survival was 65.4 ± 2.2% and 77.4 ± 2.0% for AYA patients compared to 78.1 ± 0.9% and 87.3 ± 0.7% for younger patients (p < 0.0001). Five-year cumulative incidence of relapse was 18.5 ± 1.7% for AYA patients and 13.5 ± 0.7% for younger patients (p = 0.006), largely due to increased marrow relapses (14.0 ± 1.5% versus 9.1 ± 0.6%; p < 0.0001). Additionally, induction failure rate was higher in AYA (7.2 ± 1.1% versus 3.5 ± 0.4%; p < 0.001) and post-induction remission deaths were significantly higher in AYA (5.7 ± 1.0% versus 2.4 ± 0.3%; p < 0.0001). AALL0232 enrolled the largest number of AYA B-ALL patients to date, demonstrating significantly inferior survival and greater rates of treatment-related toxicities compared to younger patients. Although treatment intensification has improved outcomes in younger patients, they have not been associated with the same degree of improvement for older patients.

Prior studies have identified that survivors of childhood acute lymphoblastic leukemia (ALL) report poor health status. It is unknown how risk-stratified therapy impacts the health status of ALL survivors.

We estimated and compared the prevalence of self-reported poor health status among adult (≥18 years) survivors of childhood ALL diagnosed at age <21 years from 1970 to 1999 and sibling controls, excluding proxy reports. Therapy combinations defined treatment groups representative of 1970s therapy (70s), standard- and high-risk 1980s and 1990s therapy (80sSR, 80sHR, 90sSR, 90sHR), and relapse/bone marrow transplant (R/BMT). Log-binomial models, adjusted for clinical and demographic factors, compared outcomes between groups using prevalence ratios (PR) with 95% confidence intervals (CI).

Among 5,119 survivors and 4,693 siblings, survivors were more likely to report poor health status in each domain including poor general health (13.5% vs. 7.4%; PR = 1.92; 95% CI, 1.69-2.19). Compared with 70s, 90sSR and 90sHR were less likely to report poor general health (90sSR: PR = 0.75; 95% CI, 0.57-0.98; 90sHR: PR = 0.58; 95% CI, 0.39-0.87), functional impairment (90sSR: PR = 0.56; 95% CI, 0.42-0.76; 90sHR: PR = 0.63; 95% CI, 0.42-0.95), and activity limitations (90sSR: 0.61; 95% CI, 0.45-0.83; 90sHR: PR = 0.59; 95% CI, 0.38-0.91). An added adjustment for chronic conditions in multivariable models partially attenuated 90sSR risk estimates.

Risk-stratified ALL therapy has succeeded in reducing risk for poor general health, functional impairment, and activity limitations among more recent survivors of standard- and high-risk therapy.

Future research into the relationship between risk-stratified therapy, health status, and late health outcomes may provide new opportunities to further improve late morbidity among survivors.

Alterations in the IKZF1 gene drive B-cell acute lymphoblastic leukemia (B-ALL) but are not routinely used to stratify patients by risk because of inconsistent associations with outcomes. We describe a novel deletion in 22q11.22 that was consistently associated with very poor outcomes in patients with B-ALL with IKZF1 alterations.

To determine whether focal deletions within the λ variable chain region in chromosome 22q11.22 were associated with patients with B-ALL with IKZF1 alterations with the highest risk of relapse and/or death.

This cohort study included 1310 primarily high-risk pediatric patients with B-ALL who were taken from 6 independent clinical cohorts, consisting of 3 multicenter cohorts (AALL0232 [2004-2011], P9906 [2000-2003], and patients with Down syndrome who were pooled from national and international studies) and 3 single-institution cohorts (University of Utah [Salt Lake City], Children's Hospital of Philadelphia [Philadelphia, Pennsylvania], and St. Jude Children's Hospital [Memphis, Tennessee]). Data analysis began in 2011 using patients from the older studies first, and data analysis concluded in 2021.

Focal 22q11.22 deletions.

Event-free and overall survival was investigated. The hypothesis that 22q11.22 deletions stratified the prognostic effect of IKZF1 alterations was formulated while investigating nearby deletions in VPREB1 in 2 initial cohorts (n = 270). Four additional cohorts were then obtained to further study this association (n = 1040).

This study of 1310 patients with B-ALL (717 male [56.1%] and 562 female patients [43.9%]) found that focal 22q11.22 deletions are frequent (518 of 1310 [39.5%]) in B-ALL and inconsistent with physiologic V(D)J recombination. A total of 299 of 1310 patients with B-ALL had IKZF1 alterations. Among patients with IKZF1 alterations, more than half shared concomitant focal 22q11.22 deletions (159 of 299 [53.0%]). Patients with combined IKZF1 alterations and 22q11.22 deletions had worse outcomes compared with patients with IKZF1 alterations and wild-type 22q11.22 alleles in every cohort examined (combined cohorts: 5-year event-free survival rates, 43.3% vs 68.5%; hazard ratio [HR], 2.18; 95% CI, 1.54-3.07; P < .001; 5-year overall survival rates, 66.9% vs 83.9%; HR, 2.05; 95% CI, 1.32-3.21; P = .001). While 22q11.22 deletions were not prognostic in patients with wild-type IKZF1 , concomitant 22q11.22 deletions in patients with IKZF1 alterations stratified outcomes across additional risk groups, including patients who met the IKZF1plus criteria, and maintained independent significance in multivariate analysis for event-free survival (HR, 2.05; 95% CI, 1.27-3.29; P = .003) and overall survival (HR, 1.83; 95% CI, 1.01-3.34; P = .05).

This cohort study suggests that 22q11.22 deletions identify patients with B-ALL and IKZF1 alterations who have very poor outcomes and may offer a new genetic biomarker to further refine B-ALL risk stratification and treatment strategies.

The NCCN Guidelines for Acute Lymphoblastic Leukemia (ALL) focus on the classification of ALL subtypes based on immunophenotype and cytogenetic/molecular markers; risk assessment and stratification for risk-adapted therapy; treatment strategies for Philadelphia chromosome (Ph)-positive and Ph-negative ALL for both adolescent and young adult and adult patients; and supportive care considerations. Given the complexity of ALL treatment regimens and the required supportive care measures, the NCCN ALL Panel recommends that patients be treated at a specialized cancer center with expertise in the management of ALL This portion of the Guidelines focuses on the management of Ph-positive and Ph-negative ALL in adolescents and young adults, and management in relapsed settings.

One cause of poor outcomes in children of low-income countries affected by acute lymphoblastic leukaemia (ALL) is loss to follow-up due to abandonment of treatment. Assuming this type of loss to follow-up as independent censoring, as in standard Kaplan-Meier estimates, ignores the likely association of abandonment with biologic and socio-economic factors related to outcome. Moreover, when comparing treatment protocols adopted in different time periods, possible imbalances in patients' characteristics must be considered. We aim to compare the outcome of children enrolled in two subsequent protocols for ALL treatment (2000-2007 and 2008-2015) in Honduras, taking both dependent censoring due to abandonment of treatment and imbalances between patient characteristics into account.

Marginal structural models based on inverse probability of treatment and censoring (IPTC) weighting allow the estimation of potential event-free survival (EFS) as if no abandonment of treatment occurred and the whole cohort was exposed, or not, to both protocols. An Aalen additive model and a logistic-regression model were used to build abandonment and treatment weights, respectively.

The two protocols recruited 514 and 717 patients. Measured baseline covariates in both protocols were gender, age, white blood cell count, central nervous system involvement, tumour histology and socio-economic status. The potential EFS is slightly higher under the more recent protocol in the first 3 years but no difference is estimated in the long period [survival difference at 5 years (95% confidence interval) = 0.1% (-0.97%; 1.13%)]. Both protocols would allow reducing the event rate by 12-13% if there was no abandonment of treatment.

Using IPTC weighting, we found a similar potential effect of the two treatment protocols if the imbalance due to the different distribution of potential confounders and to abandonment of therapy was removed.

Asparaginase (Asp) is one of the most important drugs for treating acute lymphoblastic leukemia (ALL). However, off-protocol Asp administration (OPAA) or hypersensitivity may disturb its pharmacokinetic profile. In this retrospective study, we sought to determine whether OPAA and hypersensitivity to Escherichia coli asparaginase (E coli Asp) impaired extramedullary relapse prevention in a pediatric ALL cohort treated according to SCMC-ALL-2005 protocol from 2005 to 2014 at the Shanghai Children's Medical Center (SCMC). In total, 676 patients were enrolled in this study, including 369 with OPAA and 60 exhibiting hypersensitivity to E coli Asp. At the end of the most recent follow-up, 58 patients had extramedullary relapse. The 5-year cumulative extramedullary relapse incidence in patients with OPAA was 11.01%, whereas that in patients without OPAA was 5.28% (P = .0036). Moreover, the 5-year cumulative extramedullary relapse incidence in patients that exhibited hypersensitivity to E coli Asp was 16.48%, whereas that in patients without hypersensitivity was 7.59% (P = .0195). Concerning the relapse site, OPAA not only increased central nervous system (CNS) relapse but testicular relapse as well. Based on Fine and Gray multivariate analysis, OPAA and hypersensitivity to Asp were independent risk factors for extramedullary relapse. In conclusion, to prevent extramedullary relapse of ALL, adequate duration to administrate Asp was more important than the total dosage, and more attention should be paid to Asp inadequate due to hypersensitivity.

Deregulated activation of signaling through the RAS/RAF/mitogen-activated protein kinase/extracellular signal-regulated kinase (RAS/RAF/MEK/ERK) and signal transducer and activator of transcription (STAT) pathways is involved in numerous hematological malignancies, making it an attractive therapeutic target. This study aimed to assess the effect of the combination of ERK2 inhibitor VX-11e and STAT3 inhibitor STA-21 on acute lymphoblastic leukemia cell lines REH and MOLT-4.

REH and MOLT-4 cell lines were cultured with each drug alone and in combination. Cell viability, ERK activity, cell cycle distribution, apoptosis and oxidative stress induction were assessed by flow cytometry. Protein levels of STAT3, phospho-STAT3, protein tyrosine phosphatase 4A3 (PTP4A3), survivin, p53 and p21 were determined by western blotting.

VX-11e in combination with STA-21 significantly inhibited cell viability, induced G₀/G₁ cell-cycle arrest, enhanced production of reactive oxygen species, and induced apoptosis. These effects were associated with an increased level of p21 protein in REH cells and with reduced levels of phopho-STAT3, survivin and PTP4A3 proteins in MOLT-4 cells.

Our findings provide a rationale for combined inhibition of RAS/RAF/MEK/ERK and STAT3 pathways in order to enhance anticancer effects against acute lymphoblastic leukemia cells.

Childhood acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. The onset of obesity during childhood ALL has been well established and is associated with inferior survival rates and increased treatment-related toxicities. This pilot study sought to determine if a dietary intervention is feasible and minimizes weight gain during the initial phases of treatment for ALL.

Participants were recruited from four institutions, fluent in English or Spanish, between 5 and 21 years old, and enrolled within 3 days of starting induction therapy. Participants were counseled for 6 months to follow a low glycemic diet. Dietary and anthropometric data were collected at diagnosis, end of induction, and end of month 6 (NCT03157323).

Twenty-three of 28 participants (82.1%) were evaluable and included in the analysis. Dietary changes targeted by the nutrition intervention were successful; sugar intake declined (P = .003), whereas vegetable intake increased (P = .033). The majority of participants were able to adhere to the dietary principles prescribed: ≥70.0% reduced glycemic load and ≥60.0% increased fiber intake and decreased sugar intake. Importantly, we did not observe an increase in body mass index z-score during induction or over the 6-month intervention period. Most families found the nutrition intervention easy to follow (60%) and affordable (95%) despite simultaneous initiation of treatment for ALL.

A 6-month nutrition intervention initiated during the initial phase of treatment for childhood ALL is feasible and may prevent weight gain. Our preliminary findings need to be confirmed in a larger clinical trial.

Being overweight or obese (OW/OB) during B-cell acute lymphoblastic leukemia (B-ALL) induction is associated with chemoresistance as quantified by minimal residual disease (MRD). We hypothesized that caloric and nutrient restriction from diet/exercise could lessen gains in fat mass (FM) and reduce postinduction MRD. The Improving Diet and Exercise in ALL (IDEAL) trial enrolled patients 10 to 21 years old, newly diagnosed with B-ALL (n = 40), in comparison with a recent historical control (n = 80). Designed to achieve caloric deficits ≥20% during induction, reduce fat intake/glycemic load, and increase activity, IDEAL's end points were FM gain (primary), MRD ≥0.01%, and adherence/feasibility. Integrated biology explored biomarkers of OW/OB physiology. IDEAL intervention did not significantly reduce median FM change from baseline overall (+5.1% [interquartile range [IQR], 15.8] vs +10.7% [IQR, 16.0]; P = .13), but stratified analysis showed benefit in those OW/OB (+1.5% [IQR, 6.6] vs +9.7% [IQR, 11.1]; P = .02). After accounting for prognostic factors, IDEAL intervention significantly reduced MRD risk (odds ratio, 0.30; 95% confidence interval, 0.09-0.92; P = .02). The trial exceeded its adherence (≥75% of overall diet) and feasibility (≥80% completed visits) thresholds. Integrated biology found the IDEAL intervention increased circulating adiponectin and reduced insulin resistance. The IDEAL intervention was feasible, decreased fat gain in those OW/OB, and reduced MRD. This is the first study in any hematologic malignancy to demonstrate potential benefit from caloric restriction via diet/exercise to augment chemotherapy efficacy and improve disease response. A prospective, randomized trial is warranted for validation. These trials were registered at www.clinicaltrials.gov as #NCT02708108 (IDEAL trial) and #NCT01317940 (historical control).

Our aim was to determine impairments in physical functions, activity limitations, and participation restrictions with the International Classification of Functioning, Disability and Health version for Children and Youth (ICF-CY) framework in children with acute lymphoblastic leukemia (ALL) receiving treatment. Physical functions were assessed in terms of pain level, fatigue level, handgrip strength, and motor proficiency. Fine motor activities and lower extremity performance were assessed to determine activity limitations. Participation was assessed with a patient-reported questionnaire. Thirty children with ALL (mean age: 8.45 ± 3.33 years) were included. Pain and fatigue level were mild. Poor handgrip strength was found; their mean handgrip strength was 60% of the normative. Fifty-six percent of the children had below-average motor performance. Participation scores were considerably high, except for sport and physical functioning sub-score. Participation level was positively associated with bilateral coordination and duration after diagnosis, while negatively correlated with pain and fatigue level (p ˂ 0.05).Conclusion: The ICF-CY-based evaluation was useful to understand children's limitations in everyday life. Children with ALL need supportive interventions during treatments in terms of physical functioning and participation in activities. Children with ALL with higher pain and fatigue, poor bilateral coordination, and who were in earlier period after diagnosis had higher risk for participation restriction. What is Known: • Children with ALL had physical functioning limitations on treatments. • Participation restrictions were described in children with ALL off treatment. What is New: • The ICY-CY-based health and functioning evaluation allows health care professionals to globally determine limitations of everyday life in children with ALL on treatment. • Impairments in physical functions, pain severity, fatigue severity, and duration after diagnosis are associated with participation to everyday life in children with ALL on treatment.

Osteonecrosis of the femoral head (ONFH) is a potentially severe toxicity associated with glucocorticoid treatment for pediatric hematologic malignancy. We examined clinical outcomes of THA in adolescents and young adults treated for hematologic malignancies who developed advanced ONFH.

In a single-institution cohort, we retrospectively reviewed medical records and imaging for perioperative complications, reoperations, functional assessment at last follow-up, and radiological outcomes. Twenty-seven patients (41 hips) underwent THA (bilateral in 14 patients). There were 11 males. Median (interquartile range [IQR]) age at primary diagnosis was 14.9 years [1.8-18.9]. The median (IQR) age at THA was 19.8 years [14.6-30.3]. Mean (range) post-THA follow-up was 111.5 months (65.4-165.8).

Perioperative complications included one intraoperative calcar fracture that was secured with a cerclage wire and one posterior hip dislocation that occurred 6 days postoperatively, requiring closed reduction. One hip required a revision 21.1 months post-THA due to a fractured ceramic liner. The radiographic review was available for 38 of 41 hips and demonstrated none with loosening, subsidence, or osteolysis; nine developed periacetabular stress shielding. Incidence of stress shielding was associated with increased postoperative pain (P = .0130). There was a significant functional improvement in range of motion (ROM), pain, use of supports, participation in school, work, and sports, and use of pain medication from preoperative to postoperative clinical visits (P < .001).

Total hip arthroplasty in adolescents and young adults offers symptomatic and functional improvement in patients with ONFH. We found it to be safe with low perioperative complication rates even in patients undergoing active treatment for malignancy.

Level IV, case series study. See Instructions for authors for a complete description of levels of evidence.

Symptomatic methotrexate-related central neurotoxicity, 'MTX neurotoxicity', is a severe toxicity experienced during acute lymphoblastic leukemia (ALL) therapy with potential long-term neurologic complications. Risk factors and long-term outcomes require further study. We conducted a systematic, retrospective review of 1251 consecutive Australian children enrolled on BFM or COG-based protocols between 1998-2013. Clinical risk predictors for MTX neurotoxicity were analyzed using regression. A genome-wide association study (GWAS) was performed on 48 cases and 537 controls. The incidence of MTX neurotoxicity was 7.6% (n=95/1251), at a median of 4 months from ALL diagnosis and 8 days after intravenous or intrathecal MTX. Grade 3 elevation of serum aspartate aminotransferase (P=0.005, OR 2.31 (1.28-4.16)) in induction/consolidation was associated with MTX neurotoxicity, after accounting for the only established risk factor, age a10 years. Cumulative incidence of CNS relapse was increased in children where intrathecal MTX was omitted following symptomatic MTX neurotoxicity (n=48) compared to where intrathecal MTX was continued throughout therapy (n=1174) (P=0.047). Five-year CNS relapsefree survival was 89.2%±4.6% when intrathecal MTX was ceased compared to 95.4%±0.6% when intrathecal MTX was continued. Recurrence of MTX neurotoxicity was low (12.9%) for patients whose intrathecal MTX was continued after their first episode. The GWAS identified SNPs associated with MTX neurotoxicity near genes regulating neuronal growth, neuronal differentiation and cytoskeletal organization (P>1E-06). In conclusion, increased serum aspartate aminotransferase and age a10 years at diagnosis were independent risk factors for MTX neurotoxicity. Our data do not support cessation of intrathecal MTX after a first MTX neurotoxicity event.

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.

Hematotoxicity monitoring in children with acute lymphoblastic leukemia (ALL) is critical to preventing life-threatening infections and drug discontinuation. The primary drug that causes hematotoxicity in ALL children is 6-mercaptopurine (6-MP). Genetic variability of the drug-metabolizing enzymes of 6-MP, thiopurine S-methyltransferase (TPMT), is one factor that might increase the susceptibility of children to hematotoxicity. The present study aimed to determine the variability in TPMT genotypes and phenotypes and its association with the occurrence of hematotoxicity in ALL children in maintenance therapy.

A cross-sectional study was conducted at Cipto Mangunkusumo and Dharmais National Cancer Hospital, Jakarta, Indonesia, from June 2017 to October 2018. We included ALL patients, 1-18 years, who were receiving at least one month of 6-MP during maintenance therapy according to the Indonesian protocol for ALL 2013. Direct sequencing was used to determine TPMT*3A, *3B, and *3C genotypes, and LC-MS/MS analysis was performed to measure the plasma concentrations of 6-MP and its metabolites. Association analysis between the TPMT genotype and hematotoxicity was evaluated using the unpaired t-test or Mann-Whitney's test.

The prevalence of neutropenia, anemia, and thrombocytopenia in ALL children during maintenance therapy was 51.9%, 44.3%, and 6.6%, respectively. We found a low frequency of TPMT*3C, which is 0.95%. No association was found between hematotoxicity and TPMT genotypes or age, nutritional status, serum albumin levels, risk stratification, the daily dose of 6-MP, and cotrimoxazole co-administration. However, hematotoxicity was associated with 6-methylmercaptopurine (6-MeMP) plasma concentrations and the ratio 6-MeMP/6-thioguanine (6-TGN). We also found no association between TPMT genotypes and TPMT phenotypes.

The 6-MeMP/6-TGN ratio is associated with hematotoxicity in ALL children during maintenance therapy but is not strong enough to predict hematotoxicity.

Nearly all international regimens for pediatric acute lymphoblastic leukemia (ALL) incorporate intravenous "high-dose" methotrexate (HDMTX, ≥1 g/m² ) to penetrate the central nervous system. Dosing is routinely adjusted for body surface area (BSA), but limited data describe the pharmacokinetics of HDMTX, particularly in obese and/or large patients. To understand the impact of body size (BSA) and body fat percentage (BFP) on HDMTX pharmacokinetics, we performed a secondary analysis of 36 children and adolescents 10-21 years old treated for newly diagnosed ALL and who were enrolled in a prospective study examining body composition. All patients received 5 g/m² of HDMTX infused over 24 hours. Plasma methotrexate concentrations were measured at 24, 42, and 48 hours. At 48 hours, ≥0.4 μmol/L was defined as "delayed elimination," necessitating prolonged supportive care. BFP was measured using dual-energy x-ray absorptiometry. A nonparametric population pharmacokinetic model was constructed with subsequent simulations to explore effects of BSA and BFP extremes. Despite standard BSA-adjusted dosing, we found significant intrapatient variability in mean MTX concentration (38%; range, 1.2%-86%). BSA and BFP were not linearly associated with increased area under the curve (AUC, P = 0.74 and P = 0.12), but both larger size (BSA) and greater obesity (BFP) were associated with an approximately 2-fold higher risk for delayed elimination at 48 hours. HDMTX AUC was not associated with toxicity. MTX pharmacokinetics vary among and even within patients despite BSA-adjusted dosing. Obesity and large size are identified as new risk factors for delayed elimination, requiring further investigation.

DYRK1A is a serine/threonine kinase encoded on human chromosome 21 (HSA21) that has been implicated in several pathologies of Down syndrome (DS), including cognitive deficits and Alzheimer's disease. Although children with DS are predisposed to developing leukemia, especially B cell acute lymphoblastic leukemia (B-ALL), the HSA21 genes that contribute to malignancies remain largely undefined. Here, we report that DYRK1A is overexpressed and required for B-ALL. Genetic and pharmacologic inhibition of DYRK1A decreased leukemic cell expansion and suppressed B-ALL development in vitro and in vivo. Furthermore, we found that FOXO1 and STAT3, transcription factors that are indispensable for B cell development, are critical substrates of DYRK1A. Loss of DYRK1A-mediated FOXO1 and STAT3 signaling disrupted DNA damage and ROS regulation, respectively, leading to preferential cell death in leukemic B cells. Thus, we reveal a DYRK1A/FOXO1/STAT3 axis that facilitates the development and maintenance of B-ALL.