Jassada BuaboonnamPariwan SripatanatadasakulAjjima TreesuconWaraporn GlomglaoPreeyanun SiraprapapatNattee NarkbunnamNassawee VathanaChayamon TakpraditKamon PhuakpetBunchoo PongtanakulSasima TongsaiPhakatip SinlapamongkolkulKleebsabai SanpakitFaculty of Medicine, Thammasat UniversityFaculty of Medicine, Siriraj Hospital, Mahidol University2020-01-272020-01-272019-01-01Pediatrics International. Vol.61, No.8 (2019), 754-7581442200X132880672-s2.0-85070782863https://repository.li.mahidol.ac.th/handle/20.500.14594/52311© 2019 Japan Pediatric Society Background: 6-Mercaptopurine (6-MP) is considered the backbone of therapy in the maintenance phase of acute lymphoblastic leukemia (ALL). Gene polymorphisms involved in thiopurine degradation are predictors of toxicity in patients treated with 6-MP. We investigated the effects of nucleoside diphosphate linked moiety X (nudix) type motif 15 (NUDT15) polymorphism NUDT15c.415C>T on neutropenia incidence, dose adjustment for 6-MP, and survival rates in Thai children with ALL. Methods: Children diagnosed with ALL who received 6-MP in the maintenance phase of treatment, in 2005–2016, were retrospectively enrolled. Results: The subjects consisted of 102 patients (median age, 5.2 years; 58 boys). On genetic testing 78, 22, and two patients were normal (CC), heterozygous (CT), and homozygous (TT), respectively. The incidence of neutropenia at 3 months was significantly higher in the CT/TT than CC polymorphism groups (OR, 12; 95%CI: 3.781–38.085, P < 0.001). The mean dose of 6-MP at 3, 6, and 12 months was significantly lower in the CT/TT versus the CC group (P < 0.001). The 5 year overall survival (OS) rate for CC was 80.4%, and for CT/TT, 95.5% (P = 0.34). The 5 year event-free survival (EFS) for CC and CT/TT was 75.1% and 85.7%, respectively (P = 0.17). After adjusted risk classification, no significant differences were observed for OS or EFS between the CC and CT/TT groups. Conclusion: Patients harboring the CT/TT polymorphism of NUDT15 had a significantly higher incidence of neutropenia during the first 3 months of maintenance, resulting in significantly lower doses of 6-MP.Mahidol UniversityMedicineArticleSCOPUS10.1111/ped.13905