P029 Expression of miR-21 in mucosal biopsies give clues to anti-TNF treatment non-response in IBD children and adults

Abstract

Abstract Background The use of anti-tumor necrosis factor (TNF) treatment has improved the treatment of IBD patients. However, approximately 30% of patients fail to respond to TNF inhibitors, and up to 50% of the patients who initially benefited from treatment with TNF inhibitors lose the response over time. Thus, identifying predictors of non-response and deciding on a treatment strategy according to biomarker profiles could enhance overall IBD disease management. MicroRNA-21 (miR-21) has been found to confer drug resistance to e.g. trastuzumab, 5-fluorouracil, and cisplatin. In this study, we hypothesized that miR-21 may play a role in anti-TNF drug resistance and therefore, miR-21 levels may be a predictive biomarker of anti TNF response in IBD. Methods Archived formalin-fixed, paraffin-embedded (FFPE) mucosal biopsies of IBD patients (30 adults and 27 children) were used in this study. All biopsies were collected at the time of initiation of biologics. Patients were stratified into three groups according to treatment response: Responders, Primary non-responders (PNR), and Secondary non-responders (SNR). Responders were treated with anti-TNF for a minimum of 3 years and did not experience loss of response thereafter. PNRs lost response during the first year of treatment. SNRs were treated for a minimum of 3 years with subsequent loss of response. MiR-21 expressions were quantified using Quantitative Real-Time PCR (miRCURY LNA RT Kit, Qiagen). Expression of miR-27a was used as the endogenous reference microRNA based on previous studies. Results In adults, responders had less miR-21 expression compared to PNRs and SNRs (relative median of miR-21 expression in folds [IQR]: 3.45[3.36 - 4.2], 5.05 [3.61 - 6.88], and 7.58 [6.21 - 8.2] in responders, PNRs, and SNRs respectively, p=0.04 and p=<0.01). In children, however, responders had an increased miR-21 expression compared to PNRs and SNRs (relative median of miR-21 expression in folds [IQR]: 19.94[15.88–24.59], 9.79[7.69– 14.44], and 10.58[5.66–12.91] in responders, PNRs, and SNRs respectively, p=0.03 and p=0.01). Expression of MiR-21 was found to be higher in children than adults (relative median of miR-21 expression in folds [IQR]: 4.65[3.45–7.21], and 13.6[8.37–19.05], respectively, p=<0.01). Conclusion Higher miR-21 expression indicates a higher response rate in children, whereas higher miR-21 expression could predict resistance to anti-TNF treatment in adults. MiR-21 expression could potentially be used as a predictive biomarker for anti-TNF treatment response in IBD patients with varying measures for children and adults.