Publications by authors named "Mignon Loh"

Background: B-cell acute lymphoblastic leukemia (B-cell ALL) is the most common childhood cancer. Despite a high overall cure rate, relapsed B-cell ALL remains a leading cause of cancer-related death among children. The addition of the bispecific T-cell engager molecule blinatumomab (an anti-CD19 and anti-CD3 single-chain molecule) to therapy for newly diagnosed standard-risk (as defined by the National Cancer Institute) B-cell ALL in children may improve outcomes.

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Genomic alterations of are common and associated with adverse clinical features in B-ALL. The relationship between the type of alteration, disease subtype and outcome are incompletely understood. Leukemia subtype and genomic alterations were determined using transcriptome and genomic sequencing and SNP microarray in 688 pediatric patients with B-ALL in St.

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Refractoriness to initial chemotherapy and relapse after remission are the main obstacles to curing T cell acute lymphoblastic leukemia (T-ALL). While tumor heterogeneity has been implicated in treatment failure, the cellular and genetic factors contributing to resistance and relapse remain unknown. Here we linked tumor subpopulations with clinical outcome, created an atlas of healthy pediatric hematopoiesis and applied single-cell multiomic analysis to a diverse cohort of 40 T-ALL cases.

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Children's Oncology Group study AALL1931 investigated the efficacy and safety of recombinant Erwinia asparaginase (JZP458) in patients with acute lymphoblastic leukemia/lymphoblastic lymphoma and hypersensitivity reactions/silent inactivation to Escherichia coli-derived asparaginases. Each pegylated Escherichia coli asparaginase dose remaining in a patient's treatment plan was replaced by intramuscular (IM) or IV JZP458 (6 doses) administered Monday/Wednesday/Friday (MWF). Three IM cohorts (1a [25 mg/m2 MWF], n = 33; 1b [37.

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Limited prognostic factors have been associated with overall survival (OS) post-relapse in childhood Acute Lymphoblastic Leukemia (ALL). Patients enrolled on 12 Children's Oncology Group frontline ALL trials (1996-2014) were analyzed to assess for additional prognostic factors associated with OS post-relapse. Among 16,115 patients, 2053 (12.

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Article Synopsis
  • The study investigates how genetic ancestry affects the biology and survival outcomes of children and young adults with T-cell Acute Lymphoblastic Leukemia (T-ALL), focusing on associations between ancestry, genomic subtypes, and overall and event-free survival rates.
  • Among 1309 patients, it was found that T-ALL molecular subtypes differed significantly based on genetic ancestry, with African ancestry patients having a higher prevalence of certain high-risk subtypes.
  • The research highlights that existing risk classification models may inaccurately assess patients of African ancestry, suggesting that incorporating genetic ancestry into cancer prognosis and treatment strategies is crucial for more accurate risk stratification.
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T-lineage acute lymphoblastic leukaemia (T-ALL) is a high-risk tumour that has eluded comprehensive genomic characterization, which is partly due to the high frequency of noncoding genomic alterations that result in oncogene deregulation. Here we report an integrated analysis of genome and transcriptome sequencing of tumour and remission samples from more than 1,300 uniformly treated children with T-ALL, coupled with epigenomic and single-cell analyses of malignant and normal T cell precursors. This approach identified 15 subtypes with distinct genomic drivers, gene expression patterns, developmental states and outcomes.

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Article Synopsis
  • Despite high cure rates for childhood acute lymphoblastic leukemia (ALL), it remains a major cause of cancer-related deaths in children, especially among those initially classified as standard-risk (SR).
  • Researchers analyzed genomic data from over 1,300 children with ALL to identify factors influencing relapse, focusing on comparing patients who relapsed against those who stayed in remission for five years.
  • Findings indicated that specific genomic subtypes and chromosomal alterations significantly affect relapse risk, highlighting the need for detailed genetic analysis to improve risk assessment and treatment strategies in childhood ALL.
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Purpose: Acute lymphoblastic leukemia (ALL) can occur across all age groups, with a strikingly higher cure rate in children compared with adults. However, the pharmacological basis of age-related differences in ALL treatment response remains unclear.

Methods: Studying 767 children and 309 adults with newly diagnosed B-cell ALL enrolled on frontline trials at St Jude Children's Research Hospital, MD Anderson Cancer Center, the Alliance for Clinical Trials in Oncology, and the ECOG-ACRIN Cancer Research Group, we determined the ex vivo sensitivity of leukemia cells to 21 drugs.

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Infants less than 1 year old diagnosed with KMT2A-rearranged (KMT2A-r) acute lymphoblastic leukemia (ALL) are at high risk of failure to achieve remission, relapse, and death due to leukemia, despite intensive therapies. Infant KMT2A-r ALL blasts are characterized by DNA hypermethylation. Epigenetic priming with DNA methyltransferase inhibitors increases the cytotoxicity of chemotherapy in preclinical studies.

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Juvenile myelomonocytic leukemia (JMML) is a hematologic malignancy of young children caused by mutations that increase Ras signaling output. Hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment, but patients with relapsed or refractory (advanced) disease have dismal outcomes. This phase II trial evaluated the safety and efficacy of trametinib, an oral MEK1/2 inhibitor, in patients with advanced JMML.

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Purpose: Many children treated for ALL develop long-term neurocognitive impairments. Increased risk of these impairments is associated with treatment and demographic factors. Exposure to anesthesia is an additional possible risk factor.

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Article Synopsis
  • Defining prognostic factors for T-lymphoblastic lymphoma (T-LL) is complex, as shown in the AALL1231 trial that included children and young adults with T acute lymphoblastic leukemia or T-LL, comparing standard therapy with the addition of bortezomib.
  • In the trial, 41% of patients provided bone marrow samples to measure minimal residual disease (MRD) after treatment, revealing that those with MRD levels below 0.1% had a significantly better event-free survival rate (89%) compared to those with MRD at or above 0.1% (64%).
  • Cox regression analysis indicated that having MRD levels at or above 0.1%
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  • Nijmegen breakage syndrome is linked to biallelic mutations in the NBN gene, increasing the risk of lymphoid cancers, including leukemia for heterozygous carriers.
  • A study of 4,325 pediatric B-cell acute lymphoblastic leukemia (B-ALL) patients discovered 25 unique damaging NBN variants, showing a significant increase in frequency compared to noncancer controls.
  • Functional assays confirmed 14 of these variants as having severe loss-of-function effects, but carriers of NBN variants had similar survival outcomes as those without such mutations, indicating they can safely undergo standard B-ALL therapies.
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Mutations in five canonical Ras pathway genes (NF1, NRAS, KRAS, PTPN11 and CBL) are detected in nearly 90% of patients with juvenile myelomonocytic leukemia (JMML), a frequently fatal malignant neoplasm of early childhood. In this report, we describe seven patients diagnosed with SH2B3-mutated JMML, including five patients who were found to have initiating, loss-of-function mutations in the gene. SH2B3 encodes the adaptor protein LNK, a negative regulator of normal hematopoiesis upstream of the Ras pathway.

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Osteonecrosis is a significant toxicity of acute lymphoblastic leukemia (ALL) therapy. In retrospective analyses, superior event-free survival was noted among affected adolescents in an earlier trial. We prospectively assessed osteonecrosis incidence, characteristics, and risk factors in patients 1-30 years with newly diagnosed high-risk B-ALL on COG AALL0232.

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Refractoriness to initial chemotherapy and relapse after remission are the main obstacles to cure in T-cell Acute Lymphoblastic Leukemia (T-ALL). Biomarker guided risk stratification and targeted therapy have the potential to improve outcomes in high-risk T-ALL; however, cellular and genetic factors contributing to treatment resistance remain unknown. Previous bulk genomic studies in T-ALL have implicated tumor heterogeneity as an unexplored mechanism for treatment failure.

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Purpose: Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric malignancy with myelodysplastic and myeloproliferative features. Curative treatment is restricted to hematopoietic stem-cell transplantation. Fludarabine combined with cytarabine (FLA) and 5-azacitidine (AZA) monotherapy are commonly used pre-transplant therapies.

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Purpose: Patients with Down syndrome (DS) and B-ALL experience increased rates of relapse, toxicity, and death. We report results for patients with DS B-ALL enrolled on Children's Oncology Group trials between 2003 and 2019.

Methods: We analyzed data for DS (n = 743) and non-DS (n = 20,067) patients age 1-30 years on four B-ALL standard-risk (SR) and high-risk trials.

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Hematologic malignancy is a risk factor for severe coronavirus disease 2019 (COVID-19) in adults; however, data specific to children with leukemia are limited. High-quality infectious adverse event data from the ongoing Children's Oncology Group (COG) standard-risk B acute lymphoblastic leukemia/lymphoma (ALL/LLy) trial, AALL1731, were analyzed to provide a disease-specific estimate of SARS-CoV-2 infection outcomes in pediatric ALL. Of 253 patients with reported infections, the majority (77.

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Chemotherapy-induced peripheral neuropathy (CIPN), a common condition in children with acute lymphoblastic leukemia, can be challenging to diagnose. Using data from Children's Oncology Group AALL0932 physical function study, we sought to determine if parent/guardian proxy-reported responses from the Pediatric Outcomes Data Collection Instrument could identify children with motor or sensory CIPN diagnosed by physical/occupational therapists (PT/OT). Four variables moderately discriminated between children with and without motor CIPN (c-index 0.

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The early thymic precursor (ETP) immunophenotype was previously reported to confer poor outcome in T-cell acute lymphoblastic leukemia (T-ALL). Between 2009 and 2014, 1256 newly diagnosed children and young adults enrolled in Children's Oncology Group (COG) AALL0434 were assessed for ETP status and minimal residual disease (MRD) using flow cytometry at a central reference laboratory. The subject phenotypes were categorized as ETP (n = 145; 11.

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