Rawiporn Tiyasirichokchai. Association between NUDT15 genotypes and 6-MP toxicity in childhood acute Lymphoblastic leukemia. Master's Degree(Clinical Pathology). Mahidol University. Mahidol University Library and Knowledge Center. : Mahidol University, 2018.
Association between NUDT15 genotypes and 6-MP toxicity in childhood acute Lymphoblastic leukemia
Abstract:
NUDT15 is the dephosphatase enzyme that plays an important role in dephosphorylation of (d)GTP and 6-thio-(d)GTP to (d)GMP and 6-thio-(d)GMP. It has been reported that NUDT15 variant is associated with 6-MP dose intolerance in ALL patients. Therefore, the aims of this study were to investigate the association between NUDT15 genetic polymorphisms and 6MP-induced myelotoxicity. Onehundred children with RAMA ALL 001 protocol were recruited for collecting DNA and clinical data in the first 6 months of maintenance phase. NUDT15 genotyping was classified into four diplotypes (NUDT15* 1: wild-type, NUDT15* 3: rs116855232, NUDT15* 6: rs554405994 and NUDT15* 2: rs116855232, rs554405994) . The results showed that all NUDT15 heterozygous and homozygous diplotypes were associated with leukopenia grade 3 (P = 0.023) or 4 (P = 0.041) and neutropenia grade 3 (P = 0.017) or grade 4 (P = 3.12x10-5) in the first 8 weeks while the grade 3 thrombocytopenia was related to those diplotypes in week 9-24. In addition, the median of WBC (WT 2,100/mm3 vs. Var 1,200/mm3, P = 0.008), ANC (WT 809/mm3 vs. Var 127/mm3, P= 2.13x10-4) and platelet count (WT 168,000/mm3 vs. Var 121,000/mm3, P = 0.009) in NUDT15 variant was significantly lower than wild-type group. Moreover, the dose intensity of NUDT15 variants is less than wildtype with P= 0.056 (dose intensity of WT 66.67% vs. heterozygous variant 48.8% vs. homozygous variant 16.67% ) in week 9-24. The multivariate analysis showed that infections were associated with leukopenia (P = 0.013), neutropenia (P = 0.010) in week 9-24 and thrombocytopenia ( P = 0. 039) in the first 8 weeks. In addition, NUDT15 variants had a significant difference of 6-MP dose tolerance lower than wild-type patients in the younger age group (age 1-9.9 years) with P = 0.009 unlike the age 10-15 years group. This finding suggested that NUDT15 variants particularly influenced 6MP-induced myelotoxicity in ALL children therefore the identification of NUDT15 polymorphisms should be done for pre-emptive 6-MP or thiopurine drug administration and 6-MP dose adjustment would be concerned in NUDT15 variants