Quantification of Plasma and Urine Thymidine and 2'-Deoxyuridine by LC-MS/MS for the Pharmacodynamic Evaluation of Erythrocyte Encapsulated Thymidine Phosphorylase in Patients with Mitochondrial Neurogastrointestinal Encephalomyopathy

Author(s)

Kipper, Karin ^{[1, 2]} ; Hecht, Max ^{[1, 2]} ; Antunes, Natalicia J. ^{[1, 3, 4]} ; Fairbanks, Lynette D. ^[5] ; Levene, Michelle ^[6] ; Ucar, Sema Kalkan ^[7] ; Schaefer, Andrew ^[8] ; Blakely, Emma L. ^[8] ; Bax, Bridget E. ^[6]

Affiliation

^[1] St Georges Univ London, Analyt Serv Int Ltd, Cranmer Terrace, London SW17 0RE - England

^[2] Univ Tartu, Inst Chem, 14a Ravila St, EE-50411 Tartu - Estonia

^[3] State Univ Campinas UNICAMP, Dept Pharmacol, Fac Med Sci, BR-13083881 Campinas, SP - Brazil

^[4] Queen Mary Univ London, Barts & London Sch Med & Dent, William Harvey Res Inst, Clin Pharmacol, London EC1M 6BQ - England

^[5] St Thomas Hosp, Purine Res Lab, London SE1 7EH - England

^[6] St Georges Univ London, Mol & Clin Sci, London SW17 0RE - England

^[7] Ege Univ, Div Inborn Error Metab, Med Fac, TR-35100 Izmir - Turkey

^[8] NHS Highly Specialised Serv Rare Mitochondrial Di, Newcastle Upon Tyne NE2 4HH, Tyne & Wear - England

• Document type: Journal article
• Source: JOURNAL OF CLINICAL MEDICINE; v. 9, n. 3 MAR 2020.
• Web of Science Citations: 0

Abstract

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an ultra-rare disorder caused by mutations in TYMP, leading to a deficiency in thymidine phosphorylase and a subsequent systemic accumulation of thymidine and 2'-deoxyuridine. Erythrocyte-encapsulated thymidine phosphorylase (EE-TP) is under clinical development as an enzyme replacement therapy for MNGIE. Bioanalytical methods were developed according to regulatory guidelines for the quantification of thymidine and 2'-deoxyuridine in plasma and urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for supporting the pharmacodynamic evaluation of EE-TP. Samples were deproteinized with 5% perchloric acid (v/v) and the supernatants analyzed using a Hypercarb column (30 x 2.1 mm, 3 mu m), with mobile phases of 0.1% formic acid in methanol and 0.1% formic acid in deionized water. Detection was conducted using an ion-spray interface running in positive mode. Isotopically labelled thymidine and 2'-deoxyuridine were used as internal standards. Calibration curves for both metabolites showed linearity (r > 0.99) in the concentration ranges of 10-10,000 ng/mL for plasma, and 1-50 mu g/mL for urine, with method analytical performances within the acceptable criteria for quality control samples. The plasma method was successfully applied to the diagnosis of two patients with MNGIE and the quantification of plasma metabolites in three patients treated with EE-TP. (AU)

• FAPESP's process: 16/22506-1 - Metabolism of dapaconazole
• Grantee: Natalícia de Jesus Antunes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral