| BackgroundLeukemia is a malignant disease of the hematopoietic system and its incidence ranks the first among all malignant tumors in children,2/3 of which is contributed by acute lymphoblastic leukemia(ALL).Methotrexate(MTX),a folic acid antagonist,is one of the major drugs currently used to treat ALL.MTX inhibits the conversion of dihydrofolate to tetrahydrofolate by competitively inhibiting the activity of dihydrofolate reductase,and subsequently affects the intracellular DNA formation and induces cell apoptosis.While high dose of MTX penetrates the blood-brain and blood-testis barriers and shows a favorable preventive effect on the extramedullary relapse of leukemia,metabolic pathway of MTX in vivo,however,is complex and affected by many factors.Moreover,due to the poor selective effect on tumor cells,MTX may impair normal cells while killing tumor ones,with individual variation in efficacy and side effects,which greatly restrict the application of this drug in clinical practice.Currently it is believed that polymorphism in genes related to drug-metabolizing enzymes is mainly responsible for the different drug response and resistance developed among individuals,and no consistent conclusions have been reached yet.Objective1.Determine and explore the genotype distribution of genes,including glutathione S transferase P1(GSTP1),ATP binding cassette transporter B1(ABCB1),and methylenetetrahydrofolate reductase(MTHFR),in ALL children.2.Analyze the relationship between clinical adverse reactions and different genotypes of each genes,to understand the the association between the gene polymorphisms related to MTX and the probability of adverse reactions,providing a basis for better guidance on the clinical application of MTX.Methods1.Clinical data:A total of 47 ALL children with standard risk admitted to Children’s Medical Center of Qilu Hospital,Shandong University between Jun.2015 and Jun.2017 were selected,all patients were diagnosed by MICM classification,and detected by Minor residual disease(MRD)to determined the risk group.2.Determine gene polymorphism related to MTX:3ml peripheral blood samples were collected from the children with ALL and placed in EDTA anticoagulation tube,and DNA sequences were determined by polymerase chain reaction-microarray technique.3.The association between the gene polymorphisms related to MTX and the clinical adverse reactions:All children with ALL received CCCG-ALL-2015 regimen chemotherapy,followed by HDMTX regimen after induction therapy(VDLD,CAM regimen).Children were given intravenous injection of MTX 3g/m2 in 24hours every 14 days for 4 times.After the HDMTX treatment,all children received maintenance therapy with VD+6-MP+MTX,during which oral MTX 25mg/m2 was given each week.Blood routine,liver and kidney function,blood concentration of MTX was recorded regularly.The occurrence and severity of side effects in these children were evaluated and graded according to the WHO classification of chemotherapy side effects.The data were analyzed by IBM SPSS22.0 software.Results1.There were three subtypes,CC,TT,and CT,at locus 677 in MTHFR gene and frequencies of the three genotypes were 21.3%for CC,42.5%for TT,and 36.2 for CT in the present study.Relationships of the genotypes of MTHFR gene with the occurrence of high blood MTX concentration during HDMTX treatment and with the side effects such as abnormal liver function and bone marrow suppression during HDMTX treatment and maintenance therapy in ALL children were analyzed.The results showed that the risk of granulopenia in CC carriers was significantly reduced compared with that of CT+TT carriers during the HDMTX treatment in ALL children(χ2=4.812,P=0.028)and the risk of granulopenia in CT+ TT carriers was 1.181 times as high as that:in CC carriers(95%CI:1.018-1.370).2.There were three subtypes,AA,AG and GG,at locus 313 in GSTP1 gene and frequencies of genotypes of AA,AG,and GG were 70.2%,29.8%,and 0%,respectively,in the present study.Relationships of GSTP1 A313G genotypes with the occurrence of high blood MTX concentration during HDMTX treatment and with the side effects such as abnormal liver function and bone marrow suppression during HDMTX treatment and maintenance therapy in ALL children were analyzed.The results showed that polymorphism of A313G in GSTP1 gene was not significantly related to the occurrence of high blood drug concentration during HDMTX treatment and to granulopenia and abnormal liver function during HDMTX and maintenance therapy(P>0.05).3.There were three subtypes,CC,CT and TT,at locus 3435 in ABCB1 gene and frequencies of the three genotypes were 40.4%,42.6%,and 17%,respectively,in the present study.Relationships of the genotypes of ABCB1 gene with the occurrence of high blood MTX concentration during HDMTX treatment and with the side effects such as abnormal liver function and bone marrow suppression during HDMTX treatment and maintenance therapy in ALL children were analyzed.The results showed that polymorphism of C3435T in ABCB1 gene was not significantly related to the occurrence of high blood drug concentration during HDMTX treatment(P>0.05)and to granulopenia and abnormal liver function during HDMTX and maintenance therapy(P>0.05).4.Frequencies of the three genotypes,AA,AC,and CC at locus 1298 in MTHFR gene were 74.4%,21.3%,and 4.3%,respectively,in the present study.Relationships of the genotypes of MTHFR gene with the occurrence of high blood MTX concentration during HDMTX treatment and with the side effects such as abnormal liver function and bone marrow suppression during HDMTX treatment and maintenance therapy in ALL children were analyzed.It was found that polymorphism of A1298C in MTHFR gene was not significantly related to the occurrence of high blood drug concentration during HDMTX treatment(P>0.05)and to granulopenia and abnormal liver function during HDMTX and maintenance therapy(P>0.05).Conclusions1.Polymorphism distribution of C677T in MTHFR gene is associated with the occurrence of bone marrow suppression during HDMTX treatment in ALL children.Risk of bone marrow suppression in the CC carriers is significantly reduced compared with that of the CT+TT carriers in ALL children.2.MTHFR,ABCB1,and GSTP1 genes are not significantly related to the occurrence of delayed drug excretion during the HDMTX treatment.3.Distribution of polymorphisms of MTHFR A1298C,ABCBI C3435T,and GSTP1 A313G is not significantly related to the occurrence of drug-related adverse reactions in MTX-treated ALL children. |
PDF Full Text Request