Natalie Paterson
Genotype and Phenotype Testing to Predict Drug-Induced Toxicity in Pediatric Inflammatory Bowel Disease (IBD)
Overview: Inflammatory bowel disease (IBD) is a dysregulated immune response causing severe intestinal pain. The drug Azathioprine improves patients' outcomes but some children with IBD have a genetic predisposition that causes drug-toxicity. Using data from 40,000 IBD children, results showed that testing could potentially predict response to Azathioprine.Abstract: Inflammatory bowel disease (IBD) is a collective of chronic conditions characterized by a dysregulated immune response to tissue injury that causes inflammation, swelling, ulcers, and intense pain of the intestines. The immunomodulator Azathioprine serves to suppress patient’s overactive immune response, decreasing their disease symptoms, and helping improve their quality of life. Of children with IBD, 20% have a polymorphism in the gene that codes for the enzyme thiopurine methyltransferase (TPMT). Polymorphisms that result in low TPMT activity are correlated to decreased efficacy of Azathioprine metabolism which increases drug toxicity and can result in life-threatening myelosuppression (reduction of bone marrow). We hypothesize that genotype and phenotype tests for TPMT can be used to predict patient response to Azathioprine. To explore this, we utilized data from ImproveCareNow (ICN) which is a vast network containing anonymized data from over 40,000 pediatric IBD patients. We found 17% of patients in ICN are currently prescribed Azathioprine, 29.9% of those patients have been genotyped and 66.8% have been phenotyped. Treatment success was measured by remission status. We found that of the patients who failed treatment 25.8% had never completed genotype testing and 31.5% had never completed phenotype testing. Overall, these findings are informative and suggest a potential benefit of such tests but to draw statistically viable conclusions a clinical study is necessary.
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