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Background: Methotrexate is an important component of curative therapy in childhood acute lymphoblastic leukemia (ALL), but the role of genetic variation influencing methotrexate clearance and transport in toxicity susceptibility in children with ALL is not well established. Therefore, we evaluated the association between suspected methotrexate pharmacogenomic variants and methotrexate-related neurotoxicity., Methods: This study included children (aged 2-20 years) diagnosed with ALL (2005-2019) at six treatment centers in the southwest United States. Clinical information was abstracted from medical records. Suspected neurotoxic events occurring within 21 days of intravenous and/or intrathecal methotrexate delivered between the end of induction and start of maintenance therapy were independently reviewed by at least two pediatric oncologists. Germline DNA was genotyped and 97 methotrexate pharmacogenomic variants of interest with at least grade 3 evidence were identified using the Pharmacogenomics Knowledge Base. Associations between variants and neurotoxicity were assessed by logistic regression. Data were randomly split (80/20) and random forest was constructed to estimate the ability of the variants to correctly classify neurotoxicity., Results: Of the 763 patients included in the study, 8.2% (n = 63) developed methotrexate-associated neurotoxicity. In logistic models, none of the 97 available pharmacogenomic variants reached adjusted statistical significance. However, two variants, rs17222723 (odds ratio [OR] = 2.83 [ref. = T allele], 95% confidence interval [CI]: 1.20-6.15) in ABCC2 and rs1045642 (OR = 0.66 [ref. = minor A allele], 95% CI: 0.44-0.98) in ABCB1, were nominally associated (p-value < 0.05) with neurotoxicity susceptibility. The addition of pharmacogenomic variants did not improve the predictive performance of random forest model (AUC = 0.73) compared to clinical information alone (AUC = 0.74)., Conclusion: Overall, our results suggest that associations between neurotoxicity susceptibility and methotrexate pharmacogenomic variants are generally modest and these variants do not significantly improve neurotoxicity risk stratification among children with ALL., (© 2024 Pharmacotherapy Publications, Inc.)

Mitochondrial myopathy, lactic acidosis and sideroblastic anemia (MLASA) is a rare mitochondrial disorder that has previously been associated with mutations in PUS1 and YARS2. In the present report, we describe a 6-year old male with an MLASA plus phenotype. This patient had features of MLASA in the setting of developmental delay, sensorineural hearing loss, epilepsy, agenesis of the corpus callosum, failure to thrive, and stroke-like episodes. Sequencing of the mitochondrial genome identified a novel de novo, heteroplasmic mutation in the mitochondrial DNA (mtDNA) encoded ATP6 gene (m.8969G>A, p.S148N). Whole exome sequencing did not identify mutations or variants in PUS1 or YARS2 or any known nuclear genes that could affect mitochondrial function and explain this phenotype. Studies of fibroblasts derived from the patient revealed a decrease in oligomycin-sensitive respiration, a finding which is consistent with a complex V defect. Thus, this mutation in MT-ATP6 may represent the first mtDNA point mutation associated with the MLASA phenotype., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: The purpose of this research was to investigate the relationship between glutathione S-transferase (GST) polymorphisms and survival, and chemotherapy-related toxicity in 278 glioma patients., Experimental Design: We determined genetic variants for GSTM1, GSTT1, and GSTP1 enzymes by PCR and restriction fragment length polymorphisms. We conducted Kaplan-Meier and Cox-proportional hazard analyses to examine whether the GST polymorphisms are related to overall survival, and logistic regression analysis to explore whether the GST polymorphisms are associated with toxicity., Results: For patients with anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic oligoastrocytoma, and anaplastic ependymoma (n = 78), patients with GSTP1*A/*A-M1 null genotype survived longer than did the rest of the group (median survival "not achieved," and 41 months, respectively; P = 0.06). Among patients treated with nitrosoureas (n = 108), those with GSTP1*A/*A and GSTM1 null genotype were 5.7 times (95% confidence interval, 0.9-37.4) more likely to experience an adverse event secondary to chemotherapy, compared with the others., Conclusions: In patients with anaplastic astrocytoma, anaplastic oligodendroglioma, and anaplastic oligoastrocytoma, combination of germ-line GSTP1*A/*A and GSTM1 null genotype confers a survival advantage. Patients with this genotype also have an increased risk of adverse events secondary to chemotherapy that primarily comprised nitrosourea alkylating agents.