101. Quantification of Thioguanine in DNA Using Liquid Chromatography-Tandem Mass Spectrometry for Routine Thiopurine Drug Monitoring in Patients With Pediatric Acute Lymphoblastic Leukemia
- Author
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Hee Won Cho, Rihwa Choi, Soo-Youn Lee, Hong Hoe Koo, Hee Young Ju, Jisook Park, Eun Sang Yi, Mi Ryung Chun, Ji Won Lee, and Ju Kyung Hyun
- Subjects
Drug ,Male ,medicine.medical_specialty ,Adolescent ,media_common.quotation_subject ,Coefficient of variation ,Clinical Biochemistry ,Therapeutic drug monitoring ,030226 pharmacology & pharmacy ,Gastroenterology ,03 medical and health sciences ,0302 clinical medicine ,Liquid chromatography–mass spectrometry ,Interquartile range ,Tandem Mass Spectrometry ,Internal medicine ,TPMT ,Genotype ,Liquid chromatography-tandem mass spec- trometry ,medicine ,Humans ,Child ,Thioguanine ,media_common ,Clinical Chemistry ,medicine.diagnostic_test ,Thiopurine methyltransferase ,biology ,Thiopurine ,business.industry ,Biochemistry (medical) ,General Medicine ,DNA ,Methyltransferases ,Precursor Cell Lymphoblastic Leukemia-Lymphoma ,DNA-incorporated 6-thioguanine ,030220 oncology & carcinogenesis ,Child, Preschool ,biology.protein ,Female ,Original Article ,Drug Monitoring ,NUDT15 ,business ,Quantitative analysis (chemistry) ,Chromatography, Liquid - Abstract
Background We developed an assay to measure DNA-incorporated 6-thioguanine (DNA-TG) and validated its clinical applicability in Korean pediatric patients with acute lymphoblastic leukemia (ALL) in order to improve individualized thiopurine treatment and reduce the life-threatening cytotoxicity. Methods The DNA-TG assay was developed based on liquid chromatography-tandem mass spectrometry, with isotope-labeled TG-d3 and guanine-d3 as internal standards. This method was applied to 257 samples of pediatric ALL patients. The DNA-TG level was compared with erythrocyte TG nucleotide (RBC-TGN) level in relation to the TPMT and NUDT15 genotypes, which affect thiopurine metabolism, using Spearman’s rank test and repeated measure ANOVA. Results For DNA-TG quantification, a linearity range of 10.0-5,000.0 fmol TG/µg DNA; bias for accuracy of –10.4% –3.5%; coefficient of variation for intra- and inter-day precision of 3.4% and 5.8% at 80 fmol TG/µg DNA and of 4.9% and 5.3% at 800 fmol TG/µg DNA, respectively; and recovery of 85.7%–116.2% were achieved without matrix effects or carry-over. The median DNA-TG level in the 257 samples was 106.0 fmol TG/µg DNA (interquartile range, 75.8–150.9). There was a strong correlation between DNA-TG and RBC-TGN levels (ρ = 0.68, P < 0.0001). The DNA-TG/RBC-TGN ratio was significantly higher in NUDT15 intermediate metabolizers (*1/*2 and *1/*3) than in patients with wildtype alleles (P < 0.0001). Conclusions This simple and sensitive method for measuring DNA-TG level can improve therapeutic drug monitoring for thiopurine treatment.
- Published
- 2020