P169 Circulating eNAMPT predicts anti-TNF response in IBD patients: possible place in therapy of anti-eNAMPT antibody

Background extracellular Nicotinamide phosphoribosyltrasferase (eNAMPT) is a cytokine with paracrine and autocrine effects on different cell types. Importantly, eNAMPT levels are increased in patients suffering of Inflammatory Bowel Diseases (IBD). Biologic drugs have been found effective in many IBD patients; however, a large proportion of patients with severe disease fail to achieve remission due to lack of drug response, loss of response, drug intolerance, or severe side effects that require cessation of therapy. Therefore, there is a clinical need for predictive response biomarkers as well as for new therapeutic strategies. Methods First, we investigated the expression of NAMPT in biopsies, in stools and the secretion of eNAMPT in serum in four cohorts of IBD patients. Second, we investigated if circulating eNAMPT levels correlate with the clinical response to biologics (infliximab, adalimumab, ustekinumab, vedolizumab). Clinical response is defined as a reduction of >2 points in HBI (for CD) and in pMAYO (for UC) from baseline. Third, we have developed a monoclonal anti-eNAMPT antibody and we have evaluated its preclinical efficacy in acute and chronic preclinical models of IBD. Results We have determined the levels of circulating eNAMPT in three cohorts of patients that were not controlled by DMARDs and were treated with infliximab (IFX, cohort 1 and 3) or adalimumab (ADA, cohort 2). Notably, we confirmed a pronounced variability through the cohorts, identifying a group of patients with eNAMPT serum levels comparable with healthy adult populations and a group that showed elevated levels of eNAMPT. Performing a ROC curve analysis, a cutoff of 4.5 ng/ml can be extrapolated to discriminate these two populations. Noteworthy, 100% patients with levels of eNAMPT below 4.5 ng/ml were responsive to infliximab/adalimumab. In contrast, anti-TNF therapy failed either at 14 or 22 weeks in some patients with high circulating levels of eNAMPT, indicating that high systemic eNAMPT might be associated with an increased risk of resistance to anti-TNF therapy. Notably, we found also that eNAMPT levels in stools of IBD patients are elevated compared to healthy subjects. Then, we have developed and validated a candidate monoclonal antibody (called C269) which bind to eNAMPT, block is cytokine activity and reduces IBD symptoms, immune infiltrate and fibrosis in DSS and DNBS models. Conclusion Our data demonstrate that eNAMPT serum levels correlate with the clinical response to anti-TNF therapies suggesting that eNAMPT is not a simple by- stander of IBD, and that local and serum eNAMPT could be define as a biomarker to define the responsiveness to biologics. Notably, its neutralization might be a pharmacological strategy worth investigating.