Prospective Evaluation of Pharmacogenomics and Metabolite Measurements upon Azathioprine Therapy in Inflammatory Bowel Disease: An Observational Study.

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.

The analysis of factors associated with progression of isolated terminal ileal lesions.

OBJECTIVE: To assess the factors associated with the progression of isolated terminal ileal lesions (ITILs) at colonoscopy in Chinese patients. METHODS: Patients diagnosed with ITILs were enrolled. The ileoscopy was performed by two experienced gastroenterologists every 52 weeks. A logistic regression analysis was used to elucidate the factors associated with Crohn's disease (CD) and mucosal healing. A log rank test was used to assess the differences of the cumulative proportion of CD and mucosal healing in different groups at different times. RESULTS: (1) A total of 34 patients were included and no patient had taken nonsteroidal anti-inflammatory drug in the last 6 months; eight (23.5%) patients had a clinical diagnosis of CD, 14 (41.2%) patients achieved mucosal healing, and 12 (35.3%) patients showed no significant changes in the lesions at last follow-up. (2) The logistic regression analysis showed that only abdominal pain was a factor in the ITIL disease outcomes. (3) The cumulative proportion of CD in the abdominal pain group after 3 years was statistically higher than that in the non-abdominal pain group (42.7% vs. 6.2%, χ2 = 10.129, P = 0.001). However, the cumulative proportion of mucosal healing in the non-abdominal pain group was statistically higher than that in the abdominal pain group (73.3% vs. 5.6%, χ2 = 5.225, P = 0.022). (4) The numbers of lesions observed on the initial colonoscopy exams and the initial histologic findings were not related to the ITIL disease outcomes. CONCLUSIONS: Clinical symptoms may be related to ITIL disease outcomes. Patients with abdominal pain had a high likelihood of CD, whereas those without abdominal pain had a high likelihood of mucosal healing.

Should thiopurine methyltransferase genotypes and phenotypes be measured before thiopurine therapy in patients with inflammatory bowel disease?

BACKGROUND AND AIMS: Not all of the adverse effects to thiopurine therapy can be explained by thiopurine methyltransferase (TPMT) polymorphisms. This study was intended to evaluate the value of TPMT genotype and phenotype measurement during the first year of thiopurine therapy. METHODS: Consecutive patients with inflammatory bowel disease (IBD) who were receiving azathioprine or 6-mercaptopurine were followed up for 12 months. TPMT genotypes and phenotypes were examined in patients with IBD before thiopurine therapy and in unrelated healthy volunteers by polymerase chain reaction and high-performance liquid chromatography. RESULTS: A total of 199 patients and 300 healthy volunteers were included at 2 centers. Forty-seven of the 199 patients (23.62%) exhibited adverse effects during the entire course of thiopurine therapy. Two (1%) patients carrying TPMT*3C developed leucopenia at week 4 of azathioprine treatment. The TPMT*3C had a specificity of 100% (163/163) but a sensitivity of 5.56% (2/36) for predicting leucopenia. The calculated optimal cutoff activity for high TPMT activity and decreased TPMT activity was 4.75 U/mL red blood cells. The risk of leucopenia increased in the decreased TPMT group (odds ratio: 20.25; 95% confidence interval: 2.19-187.17; P = 0.004) and increased more during the initial 3 months of thiopurine therapy (odds ratio: 34.80; 95% confidence interval: 3.71-326.77; P = 0.001). Leucopenia occurred more frequently in the patients cotreated with 5-aminosalicylates than in those not cotreated (32.81% versus 11.11%, respectively, P < 0.001). CONCLUSIONS: The results of this study suggest that the value of TPMT genotyping before thiopurine therapy is limited in Chinese patients with IBD, considering the low sensitivity of predicting leucopenia, and that phenotyping is a more cost-effective tool that can be successfully used in patients. The coadministration of 5-aminosalicylates results in a high frequency of leucopenia in patients receiving azathioprine or 6-mercaptopurine.