6-thioguanylic-acid and Leukopenia

A prospective randomized trial in patients with Crohn disease studied whether 6-thioguanine nucleotide (6-TGN) concentration-adapted azathioprine (AZA) therapy is clinically superior to a standard dose of 2.5 mg/kg/day AZA.. After 2 weeks of standard therapy, patients (n = 71) were randomized into standard (n = 32) or adapted-dose (n = 25) groups; 14 patients dropped out before randomization. In the adapted group, the AZA dose was adjusted to maintain 6-TGN concentrations between 250 and 400 pmol/8 x 10(8) erythrocytes (Ery). Response criteria were the number of patients in remission after 16 weeks without steroids (primary) and remission after 24 weeks, frequency of side effects, and quality of life (secondary).. After 16 weeks, 14 of 32 (43.8%) patients in the standard group vs 11 of 25 (44%) in the adapted group were in remission without steroids (intent-to-treat analysis). After 24 weeks, 43.8% vs 40% were in remission. No significant differences were found concerning quality of life, disease activity, 6-TGN concentrations, AZA dose, or dropouts due to side effects. Sixty-six patients had a wild-type thiopurine S-methyltransferase (TPMT) genotype, with TPMT activities of 8 to 20 nmol/(mL Ery x h). Five patients (dropouts after randomization) were heterozygous, with TPMT activities <8 nmol/(mL Ery x h). 6-Methyl mercaptopurine (6-MMP) concentrations >5700 pmol/8 x 10(8) Ery were not associated with hepatotoxicity.. Standard and adapted dosing with the provided dosing scheme led to identical 6-TGN concentrations and remission rates. Adapted dosing had no apparent clinical benefit for patients with TPMT activity between 8 and 20 nmol/(mL Ery x h). Additionally, 6-MMP monitoring had no predictive value for hepatotoxicity.

Topics: Adolescent; Adult; Aged; Chemical and Drug Induced Liver Injury; Crohn Disease; Dose-Response Relationship, Drug; Erythrocyte Indices; Female; Genotype; Guanine Nucleotides; Humans; Leukopenia; Male; Mercaptopurine; Methyltransferases; Middle Aged; Remission Induction; Thionucleotides; Thrombocytopenia

Although the relationship between NUDT15 and thiopurine-induced leukopenia has been proven in previous studies, no prominent factors explaining interindividual variations in its active metabolite, 6-thioguanine nucleotide (6-TGN), and clinical efficacy have been identified. In this study, the correlation between genotypes (thiopurine S-methyltransferase, NUDT15, and ITPA polymorphisms), 6-TGN concentrations, and clinical outcomes (efficacy and side effects) in patients with inflammatory bowel disease were investigated.. In total, 160 patients with inflammatory bowel disease were included, and the 3 genotyped genes and 6-TGN levels were measured by high-performance liquid chromatography. Statistical analyses and calculations were performed to determine their relationships.. ITPA genotypes and 6-TGN concentration were both associated with the clinical effectiveness of azathioprine (P = 0.036 and P = 4.6 × 10-7), with a significant correlation also detected between them (P = 0.042). Patients with ITPA variant alleles exhibited higher 6-TGN levels than those with the wild-type allele. In addition, the relationship between NUDT15 and leukopenia and neutropenia was confirmed (P = 1.79 × 10-7 and 0.002).. In summary, it is recommended that both ITPA and NUDT15 genotyping should be performed before azathioprine initiation. Moreover, the 6-TGN concentration should be routinely monitored during the later period of treatment.

Topics: Azathioprine; Biomarkers; China; Guanine Nucleotides; Humans; Inflammatory Bowel Diseases; Leukopenia; Methyltransferases; Prognosis; Pyrophosphatases; Thionucleotides

This study aimed to investigate the influence of TPMT*3C, ITPA, NUDT15, and 6-thioguanine nucleotides (6-TGN) on azathioprine (AZA)-induced myelosuppression in Southwest China patients with autoimmune hepatitis (AIH). A total of 113 Chinese patients with AIH receiving AZA maintenance treatment were evaluated. The relevant clinical data of the patients were collected from the hospital information system. Genotyping of TPMT*3C(rs1142345), ITPA (rs1127354) and NUDT15(rs116855232) was conducted using a TaqMan double fluorescent probe. The concentration of 6-TGN was determined using UPLC-MS/MS. Among AIH patients treated with AZA, 40 (35.4%) exhibited different degrees of myelosuppression. The NUDT15 variant was associated with leukopenia (P = 8.26 × 10

Topics: Adult; Aged; Alleles; Azathioprine; China; Female; Genetic Association Studies; Guanine Nucleotides; Hepatitis, Autoimmune; Humans; Leukopenia; Male; Methyltransferases; Middle Aged; Mutation; Phenotype; Pyrophosphatases; Thionucleotides

NUDT15 R139C (rs116855232) is a recently identified genetic factor responsible for thiopurine-induced leukocytopenia and hair loss. In this study, we investigated the association of NUDT15 R139C with 6-thioguanine nucleotide (6-TGN) levels and thiopurine-induced leukocytopenia in Japanese patients with inflammatory bowel disease (IBD).. Two hundred and sixty-four subjects (103 healthy volunteers and 161 IBD patients treated with thiopurines) were enrolled. Genotyping for NUDT15 R139C was performed using Custom TaqMan® SNP genotyping assays.. The NUDT15 C/C, C/T, and T/T genotypes were 80.7, 18.2, and 1.1 %, respectively. The allelic frequency was 10.2 %. Among 161 IBD patients, there was no significant difference in 6-TGN levels among the NUDT15 genotypes. Forty-five patients (27.9 %) developed leukocytopenia (WBC <3000/μl), and the C/T and T/T genotypes were significantly associated with the development of leukocytopenia (P = 1.7 × 10(-5)). In these patients, 6-TGN levels were not significantly different between NUDT15 genotypes. NUDT15 R139C was significantly associated with early (<8 weeks) (P = 1.03 × 10(-4)) and late (>8 weeks) leukocytopenia (P = 4.3 × 10(-4)). The decrease in WBC count at 2 and 4 weeks was significantly higher in patients with the C/T or T/T genotypes as compared to the patients with the C/C genotype. All patients with the T/T genotype (n = 2) developed early severe hair loss and severe leukocytopenia (<1000/μl). The logistic regression analysis revealed that NUDT15 R139C was the sole genetic factor responsible for the thiopurine-induced leukocytopenia (P = 0.001).. These results suggest that NUDT15 R139C-related thiopurine-induced leukocytopenia is mediated by a 6-TGN-independent mechanism.

Topics: Adult; Alopecia; Case-Control Studies; Female; Gene Frequency; Genetic Predisposition to Disease; Guanine Nucleotides; Humans; Inflammatory Bowel Diseases; Leukocyte Count; Leukopenia; Male; Mercaptopurine; Middle Aged; Pyrophosphatases; Thionucleotides

Up to approximately 40% to 50% of patients discontinue thiopurine therapy during the course of inflammatory bowel disease (IBD). We investigated the role of the metabolite thiopurine in IBD treatment. This was a prospective study. IBD patients receiving azathioprine (AZA) were prospectively included. Thiopurine methyltransferase (TPMT) genotypes were examined before therapy, and thiopurine metabolite levels were examined at weeks 2, 4, 8, 12, 24, and 48. In total, 132 patients were included. The frequency of leucopenia increased at 6-thioguanine nucleotide (6-TGN) levels ≥420  pmol/8 × 10(8) RBC (odds ratio [OR] = 7.9; 95% confidence interval (95%CI): 3.5-18.0; P < 0.001) and increased more during the initial 12 weeks of thiopurine therapy (OR = 16.0; 95%CI: 5.7-44.9; P < 0.001). The patients with 6-TGN levels ≥420 pmol/8 × 10 RBC at weeks 4, 8, and 12 had an increased likelihood of leucopenia. Clinical response increased at 6-TGN levels ≥225 pmol/8 × 10(8) RBC (OR = 13.5; 95% CI: 3.7-48.9; P < 0.001) in Crohn disease (CD) patients. The CD patients with 6-TGN levels ≥225 pmol/8 × 10(8) RBC at weeks 8, 12, and 24 had an increased likelihood of successful clinical response. TPMT*3C had a specificity of 100%, but a sensitivity of 8% for predicting leucopenia.A 6-TGN level between 225 and 420 pmol/8 × 10(8) RBC could be a therapeutic window in patients receiving AZA therapy, and it could likely predict leucopenia in the initial 12 weeks of AZA therapy and a reasonable chance of successful clinical response in CD patients. The value of TPMT genotyping before thiopurine therapy is limited in Chinese patients with IBD, considering the low sensitivity of predicting leucopenia.

Topics: Adult; Aged; Azathioprine; China; Drug Monitoring; Female; Genetic Testing; Guanine Nucleotides; Humans; Immunosuppressive Agents; Inflammatory Bowel Diseases; Leukopenia; Male; Methyltransferases; Middle Aged; Pharmacogenetics; Predictive Value of Tests; Prospective Studies; Thionucleotides

It remains controversial whether 6-thioguanine nucleotide (6-TGN)-based dose adjusting can be beneficial in azathioprine (AZA) therapy. This study is designed to assess the role of 6-TGN concentrations in maintaining clinical remission in Chinese patients with Crohn's disease (CD).. We performed a prospective observational study and collected data of CD patients in the First Affiliated Hospital of Anhui Medical University from June 2013 to April 2014. Demographic material, CD activity index, 6-TGN concentration, and laboratory tests were recorded at baseline and at each visit. In addition, 6-TGN was measured when drug adverse effects occurred. All patients achieved maintenance stage were administered a stable AZA dose at least 3 months before enrollment and were followed up at least 12 months. Thiopurine S-methyltransferase (TPMT) genotype was measured before AZA treatment.. Sixty-nine patients receiving maintenance therapy were analyzed. A positive correlation was found between 6-TGN levels and AZA dose (r = 0.258, p = 0.032). The mean 6-TGN concentration was 302.06 ± 115.84 in the remission group vs. 264.94 ± 164.53 pmol/8 × 10(8) RBC in those with active disease (t = 0.847, p = 0.40), and 197.74 ± 66.54 pmol/8 × 10(8) RBC in patients who relapsed vs. 310.26 ± 122.38 pmol/8 × 10(8) RBC for those in sustained remission (t= -2.541, p = 0.013). In the leukopenia group, the 6-TGN concentration was 469.11 ± 115.53 pmol/8 × 10(8) RBC vs. 257.31 ± 83.74 pmol/8 × 10(8) RBC in the non-leukopenia group (t = 7.622, p < 0.001). There was a significant negative correlation between leukocyte count and 6-TGN concentration (r= -0.326, p = 0.006).. 6-TGN measurement is a helpful method of preventing disease relapse and avoiding leukopenia in individual azathioprine maintenance therapy.

Topics: Adult; Azathioprine; Crohn Disease; Drug Monitoring; Erythrocytes; Female; Guanine Nucleotides; Humans; Immunosuppressive Agents; Leukocyte Count; Leukopenia; Male; Methyltransferases; Prospective Studies; Thionucleotides; Young Adult

Thiopurine-related toxicity results in discontinuation of therapy in up to 30% of patients with inflammatory bowel disease. Although thiopurine S-methyltransferase (TPMT) is implicated in toxicity, not all toxicity can be attributed to TPMT polymorphisms. We investigated the effects of polymorphisms of genes involved in thiopurine and folate metabolism pathways on 6-thioguanine nucleotide levels and toxicity.. Retrospective clinical data and blood samples were collected from 132 pediatric patients with inflammatory bowel disease treated with azathioprine. Eighty-seven genetic polymorphisms of 30 genes were screened using the MassARRAY system, and 70 polymorphisms of 28 genes were selected for further analysis.. TPMT genotype (P < 0.001), concurrent use of mesalazine (P = 0.006), ABCC5 (rs2293001) (P < 0.001), ITPA (rs2236206 and rs8362) (P = 0.010 and P = 0.003), and ABCB1 (rs2032582) (P = 0.028) were all associated with the ratio of 6-thioguanine nucleotides to azathioprine dose. ADK (rs10824095) (P = 0.004, odds ratio [OR] = 6.220), SLC29A1 (rs747199) (P = 0.016, OR = 5.681), and TYMS (rs34743033) (P = 0.045, OR = 3.846) were associated with neutropenia. ABCC1 (rs2074087) (P = 0.022, OR = 3.406), IMPDH1 (rs2278294) (P = 0.027, OR = 0.276), and IMPDH2 (rs11706052) (P = 0.034, OR = 3.639) had a significant impact on lymphopenia.. This study describes genetic polymorphisms in genes whose products may affect pharmacokinetics and which may predict the relative likelihood of benefit or risk from thiopurine treatment. These findings may serve as a basis for personalized thiopurine therapy in pediatric patients with inflammatory bowel disease, although our data need to be validated in further studies.

Topics: Adolescent; Anti-Inflammatory Agents, Non-Steroidal; Azathioprine; Colitis, Ulcerative; Crohn Disease; Dose-Response Relationship, Drug; Female; Genotype; Guanine Nucleotides; Humans; Immunosuppressive Agents; Inflammatory Bowel Diseases; Leukopenia; Male; Mesalamine; Methyltransferases; Polymorphism, Genetic; Retrospective Studies; Thionucleotides

Azathioprine (AZA) is frequently used in patients with inflammatory bowel disease (IBD). However, toxic adverse reactions frequently develop and limit the clinical benefits. Currently, the precise mechanisms underlying thiopurine-related toxicity are not well understood. To investigate the relationship between the extent of thiopurine metabolism and adverse reactions in Japanese IBD patients, we prospectively observed 48 IBD patients who received AZA. We analyzed the thiopurine S-methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) gene mutations and measured the concentrations of 6-thioguanine nucleotide (6-TGN) continuously for 52 weeks. All patients possessed wild-type TPMT gene sequences. The ITPA 94C>A mutation was detected in 19 patients (39.6%). Adverse reactions developed in 14 of the 48 patients (29.2%), including leukopenia in 10 patients (20.8%). In the leukopenia group, the percentages of patients with 94C>A were higher than those in the without-leukopenia group (70.0% vs. 31.6%, P < 0.05). The average concentrations of 6-TGN in the patients with 94C>A were generally higher than those in the patients without 94C>A, however, there were no significant differences. Only 3 out of 10 patients with leukopenia exhibited high 6-TGN levels (30.0%). No negative correlations between white blood cell (WBC) counts and 6-TGN concentrations were observed. The cumulative incidence of leukopenia were higher for patients with 94C>A. Seven out of 19 patients (36.8%) with the ITPA 94C>A mutation developed leukopenia; however, this mutation may not unequivocally increase the risk of developing leukopenia. In addition, there are factors other than increased 6-TGN levels that are involved in the onset of leukopenia.

Topics: Adult; Alleles; Azathioprine; Erythrocytes; Female; Genotype; Guanine Nucleotides; Humans; Immunosuppressive Agents; Incidence; Inflammatory Bowel Diseases; Japan; Leukopenia; Male; Methyltransferases; Middle Aged; Mutation; Pharmacogenetics; Prospective Studies; Pyrophosphatases; Thionucleotides; Young Adult

Azathioprine (AZA) is associated with a high frequency of adverse reactions. We examined polymorphism of the thiopurine S-methyltransferase (TPMT) gene to determine whether the TPMT genotype would be a predictive marker for the development of adverse reactions to AZA.. The frequency of TPMT mutations was investigated in 147 Japanese inflammatory bowel disease (IBD) patients retrospectively. In these subjects, the presence of four mutant alleles (TPMT*2, *3B, *3C and *8) was determined by direct sequencing. The incidence of adverse reactions among patients carrying wild-type TPMT was investigated. The blood level of 6-thioguanine nucleotide (6-TGN) was measured and analyzed in 47 patients with wild-type TPMT. The results were analyzed in relation to the concomitant use of aminosalicylates (ASA).. Of the 147 patients, 144 (98.0%) were wild-type for TPMT (TPMT*1/*1) and three (2.0%) carried a mutant TPMT allele (TPMT*1/*3C). The incidence of adverse reactions was 33.3% (38/114) in the wild-type group. Leukopenia (WBC < or = 3000/microL) was seen in 15.8% of the patients with wild-type TPMT. 6-TGN levels varied among 47 patients with wild-type TPMT. The blood levels of 6-TGN were significantly higher in the patients receiving concomitant ASA treatment compared with those not receiving concomitant ASA treatment (P = 0.0033).. The frequency of TPMT gene mutations is low among Japanese IBD patients. The incidence of adverse reactions to AZA was high, even in patients carrying wild-type TPMT. It is concluded that determination of TPMT genotype may not be useful in Japanese IBD patients to predict adverse reactions to AZA.

Topics: Adult; Alopecia; Aminosalicylic Acids; Anti-Inflammatory Agents; Asian People; Azathioprine; Chemical and Drug Induced Liver Injury; Communicable Diseases; Female; Gastrointestinal Agents; Gastrointestinal Diseases; Gene Frequency; Genetic Predisposition to Disease; Genetic Testing; Guanine Nucleotides; Humans; Inflammatory Bowel Diseases; Japan; Leukopenia; Liver Diseases; Male; Methyltransferases; Phenotype; Polymorphism, Genetic; Predictive Value of Tests; Retrospective Studies; Thionucleotides; Young Adult

In the present study of 12 boys and 19 girls 2-16 years of age (median, 7 years) on oral 6-mercaptopurine (6MP) and methotrexate (MTX) maintenance therapy (MT) for non-B-cell acute lymphoblastic leukemia (ALL), we found that (a) during MT, 6-thioguanine nucleotides (6TGN) (the major cytotoxic metabolite of 6MP) accumulate in the erythrocytes (E-6TGN); (b) for patients receiving an unchanged dose of 6MP, no significant correlation could be demonstrated between the mean E-6TGN (mE-6TGN) and the dose of 6MP (r = -0.11, P = 0.28) (31 patients); (c) among 21 patients receiving 50-75 mg/m2 6MP, a variation of up to 3 orders of magnitude in mE-6TGN could be demonstrated, with the interindividual coefficient of variation (CV) in mE-6TGN for these patients being 0.31; (d) the median intraindividual CV in E-6TGN at an unchanged dose of 6MP was 0.11 (range, 0.04-0.18); and (e) the degree of myelodepression as measured by the mean white cell count was related to mE-6TGN (r = -0.55, P = 0.0006). These results indicate that E-6TGN could be a useful parameter for monitoring 6MP maintenance chemotherapy, although this needs to be explored in prospective studies.

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Child; Child, Preschool; Dose-Response Relationship, Drug; Erythrocytes; Female; Guanine Nucleotides; Humans; Leukopenia; Male; Mercaptopurine; Methotrexate; Monitoring, Physiologic; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Thionucleotides

Azathioprine metabolite concentrations were studied in 54 kidney transplant recipients. Thirty-seven of these patients were studied over a 6 month period to investigate the intrapatient variation in metabolite concentrations. All patients had stable functioning grafts and normal peripheral white blood cell counts. The metabolites measured were plasma 6-mercaptopurine and red blood cell 6-thioguanine nucleotide. There was no correlation between azathioprine dose and plasma 6-mercaptopurine concentration but there was a significant correlation between dose and red blood cell 6-thioguanine nucleotide concentration (rs = 0.41, P less than 0.005). The individual transplant recipient showed little variation in metabolite concentrations over several months. Using this group as a control we studied metabolite concentrations in patients with kidney transplants who developed leucopenia. Our preliminary findings indicate that elevated red cell 6-thioguanine nucleotide concentrations, above the control range, can be associated with bone marrow depression.

Topics: Adult; Allopurinol; Azathioprine; Dose-Response Relationship, Drug; Female; Guanine Nucleotides; Humans; Individuality; Kidney Transplantation; Leukocyte Count; Leukopenia; Male; Sex Factors; Thionucleotides