Immunogenicity of Anti-TNF in IBD Patients Aged Over 60 Years

The GEMINI 1 and 2 studies showed that in the induction phase, VDZ levels were higher in responders than in non responders.No clinical study has reported yet the value of an early measurement of VDZ trough levels for predicting long-term remission or the need for optimisation.The aim of the study was to determine the VDZ trough levels at W2 or W6 which would predict sustained clinical remission and the lack of need for optimisation at W10.A prospective, observational study which included all patients with IBD for whom VDZ treatment was initiated with a minimum follow-up of 28 weeks.All patients had failed two lines of anti-TNF.The patients received VDZ by infusion (300 mg) at W0, W2, W6 and then every 8 weeks.If there was no clinical response at W10, the patient received a VDZ infusion at W10 and then every 4 weeks.Before each infusion, VDZ trough levels were measured using ELISA assay (Theradiag (France), range: 0.2-60 µg/ml).These results were obtained on a blind basis in relation to clinical response and the clinicians did not have the results of these assays until the end of the study.34 patients were included in this prospective study and 29 were followed up for at least 28 weeks.(Median age: 51 years, M/F sex ratio: 36%, Crohn's disease (CD): 65%.Thirty eight percent of patients exhibited sustained remission without optimisation of VDZ.The clinical characteristics of the patients, duration of the disease and duration of previous anti-TNF treatment were comparable for both groups: sustained remission and treatment failure except that more CD patients were unresponsive (78% vs 45%, p=0.06).Mean trough levels of VDZ were equivalent at W2 between the sustained remission and treatment failure groups (33.4 vs 27.4 µg/ml, p=0.2).However, at W6, these levels were higher in case of sustained remission (41.7 vs 21.0 µg/mL p< 0.05).The investigation of a predictive threshold for sustained remission at W6 was analysed using a ROC curve (area under the curve: 0.84).A cut-off of 40.1 µg/mL for VDZ at W6 was predictive of sustained remission with a sensitivity of 100% and a specificity of 70%.Ten patients had optimisation of VDZ at W10 and 40% of patients exhibited a clinical response.Delta VDZ (VDZ level after 4W minus VDZ level before optimisation) was 0.1 µg/ml in case of response versus 5.1 in case of non-response (p<0.05).For the first time we report that