No abstract

Pancreatitis occurs in approximately 4% of patients treated with the thiopurines azathioprine or mercaptopurine. Its development is unpredictable and almost always leads to drug withdrawal. We identified patients with inflammatory bowel disease (IBD) who had developed pancreatitis within 3 months of starting these drugs from 168 sites around the world. After detailed case adjudication, we performed a genome-wide association study on 172 cases and 2,035 controls with IBD. We identified strong evidence of association within the class II HLA region, with the most significant association identified at rs2647087 (odds ratio 2.59, 95% confidence interval 2.07-3.26, P = 2 × 10(-16)). We replicated these findings in an independent set of 78 cases and 472 controls with IBD matched for drug exposure. Fine mapping of the HLA region identified association with the HLA-DQA1*02:01-HLA-DRB1*07:01 haplotype. Patients heterozygous at rs2647087 have a 9% risk of developing pancreatitis after administration of a thiopurine, whereas homozygotes have a 17% risk.

IMPORTANCEUse of thiopurines may be limited by myelosuppression. TPMT pharmacogenetic testing identifies only 25% of at-risk patients of European ancestry. Among patients of East Asian ancestry, NUDT15 variants are associated with thiopurine-induced myelosuppression (TIM).OBJECTIVE To identify genetic variants associated with TIM among patients of European ancestry with inflammatory bowel disease (IBD). DESIGN, SETTING, AND PARTICIPANTSCase-control study of 491 patients affected by TIM and 679 thiopurine-tolerant unaffected patients who were recruited from 89 international sites between March 2012 and November 2015. Genome-wide association studies (GWAS) and exome-wide association studies (EWAS) were conducted in patients of European ancestry. The replication cohort comprised 73 patients affected by TIM and 840 thiopurine-tolerant unaffected patients. EXPOSURES Genetic variants associated with TIM.MAIN OUTCOMES AND MEASURES Thiopurine-induced myelosuppression, defined as a decline in absolute white blood cell count to 2.5 × 10 9 /L or less or a decline in absolute neutrophil cell count to 1.0 × 10 9 /L or less leading to a dose reduction or drug withdrawal. RESULTS Among 1077 patients (398 affected and 679 unaffected; median age at IBD diagnosis, 31.0 years [interquartile range, 21.2 to 44.1 years]; 540 [50%] women; 602 [56%] diagnosed as having Crohn disease), 919 (311 affected and 608 unaffected) were included in the GWAS analysis and 961 (328 affected and 633 unaffected) in the EWAS analysis. The GWAS analysis confirmed association of TPMT (chromosome 6, rs11969064) with TIM (30.5% [95/311] affected vs 16.4% [100/608] unaffected patients; odds ratio [OR], 2.3 [95% CI, 1.7 to 3.1], P = 5.2 × 10 −9 ). The EWAS analysis demonstrated an association with an in-frame deletion in NUDT15 (chromosome 13, rs746071566) and TIM (5.8% [19/328] affected vs 0.2% [1/633] unaffected patients; OR, 38.2 [95% CI, 5.1 to 286.1], P = 1.3 × 10 −8 ), which was replicated in a different cohort (2.7% [2/73] affected vs 0.2% [2/840] unaffected patients; OR, 11.8 [95% CI, 1.6 to 85.0], P = .03). Carriage of any of 3 coding NUDT15 variants was associated with an increased risk (OR, 27.3 [95% CI, 9.3 to 116.7], P = 1.1 × 10 −7 ) of TIM, independent of TPMT genotype and thiopurine dose.CONCLUSIONS AND RELEVANCE Among patients of European ancestry with IBD, variants in NUDT15 were associated with increased risk of TIM. These findings suggest that NUDT15 genotyping may be considered prior to initiation of thiopurine therapy; however, further study including additional validation in independent cohorts is required.

Introduction-Pharmacotherapyfor upper gastrointestinal bleeding has been diYcult to evaluate because clinical end points are infrequent and aVected by other factors. Aims-To evaluate whether blood in the stomach at endoscopy reflected severity of bleeding, predicted clinical outcomes, and could be altered by therapeutic agents. Methods-We studied 414 consecutive admissions with suspected upper gastrointestinal bleeding. Patients were randomised to receive lansoprazole 60 mg followed by 30 mg four times daily, tranexamic acid 2 g followed by 1 g four times daily, both drugs, or placebo for four days, until discharge or a clinical end point occurred. Logistic regression analysis was used to determine predictors of endoscopic changes and clinical outcomes, and to investigate the eVects of drug treatments on blood in the stomach. Results-Of 414 patients with suspected upper gastrointestinal bleeding, 379 were endoscoped. Upper gastrointestinal bleeding was confirmed in 316. Sixteen required surgery within 30 days and 16 died on the index admission. Trial treatments were evaluable on a per protocol basis in 228 patients. The amount of blood in the stomach was found to reflect initial risk, with significant associations with high risk categorisation (odds ratio 3.7 (95% confidence interval 1.5-9.4) for more than a trace v none/trace), age (1.5 (1.1-1.9) per decade), and initial pulse (1.02 (1.00-1.04) per beat), and to predict rebleeding (9.2 (4.6-18.7)) and surgery (8.2 (2.9-22.9)). Other stigmata were less significant in these respects. The amount of blood in the stomach at endoscopy was reduced significantly by both lansoprazole (0.22 (0.07-0.63)) and tranexamic acid (0.27 (0.09-0.81)), although there was no evidence of synergy. Conclusions-Blood in the stomach reflects clinical features in patients with acute upper gastrointestinal bleeding and is reduced by treatment with lansoprazole and tranexamic acid.

1. Gastric damage induced by low‐dose aspirin and the protective effect of enteric‐coating was assessed in healthy volunteers in a double‐blind placebo‐controlled cross‐over trial using Latin square design. Each was administered placebo, plain aspirin 300 mg daily, plain aspirin 600 mg four times daily, enteric‐coated aspirin 300 mg daily, or enteric‐ coated aspirin 600 mg four times daily for 5 days. Gastric damage was assessed endoscopically, and gastric mucosal bleeding measured. 2. Aspirin 300 mg daily and 600 mg four times daily caused significant increases in gastric injury compared with placebo. Gastric mucosal bleeding was significantly more with the high dose, with a trend towards increased gastric erosions, compared with the low dose. 3. Enteric‐coating of aspirin eliminated the injury caused by low dose aspirin and substantially reduced that caused by the higher dose. 4. All dosages and formulations caused similar inhibition of gastric mucosal prostaglandin E2 synthesis. 5. Serum thromboxane levels were suppressed equally with plain and enteric‐coated aspirin. 6. In this short‐term study in healthy volunteers, gastric toxicity from aspirin was largely topical, independent of inhibition of prostaglandin synthesis, and could be virtually eliminated by the use of an enteric‐ coated preparation.