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* = Presenting author

P305 Infliximab serum levels do not predict remission after the induction phase in Crohn's Disease patients

M. Chaparro*1, I. Guerra2, M. Iborra3, J.L. Cabriada4, L. Bujanda5, C. Taxonera6, V. García-Sánchez7, I. Marín-Jiménez8, M. Barreiro de-Acosta9, I. Vera10, M.D. Martín-Arranz11, B. Hernández-Breijo12, F. Mesonero13, L. Sempere14, F. Gomollón15, M. Mora16, M. Ramas1, A. Algaba2, B. Beltrán3, I. Moraleja4, A. Arbelaiz17, J.L. Mendoza6, E. Iglesias-Flores7, L. Menchén8, R. Ferreiro9, C. Suárez Ferrer10, S. Gómez Senent11, L. Guijarro12, P.M. Linares1, J.P. Gisbert1

1Hospital Universitario de La Princesa, IIS-IP and CIBERehd, Gastroenterology Unit, Madrid, Spain, 2Hospital Universitario de Fuenlabrada, Gastroenterology Unit, Madrid, Spain, 3Hospital Universitario La Fe and CIBERehd, Gastroenterology Unit, Valencia, Spain, 4Hospital Galdakao, Gastroenterology Unit, Vizcaya, Spain, 5Hospital de Donostia, Instituto Biodonostia, UPV/EHU and CIBEREHD, Gastroenterology Unit, Guipuzcoa, Spain, 6Hospital Clínico Universitario San Carlos and IdISSC, Gastroenterology Unit, Madrid, Spain, 7Hospital Universitario Reina Sofía, Gastroenterology Unit, Córdoba, Spain, 8Hospital General Universitario Gregorio Marañón, Gastroenterology Unit, Madrid, Spain, 9Complejo Hospitalario Universitario de Santiago, Gastroenterology Unit, Santiago de Compostela, Spain, 10Hospital Universitario Puerta de Hierro , Gastroenterology Unit, Madrid, Spain, 11Hospital Universitario La Paz , Gastroenterology Unit, Madrid, Spain, 12Universidad de Alcalá and CIBERehd, Systems Biology, Alcalá de Henares, Spain, 13Hospital Universitario Ramón y Cajal, Gastroenterology Unit, Madrid, Spain, 14Hospital General Universitario de Alicante, Gastroenterology Unit, Alicante, Spain, 15Hospital Clínico Universitario Lozano Blesa and CIBERehd, Gastroenterology Unit, Zaragoza, Spain, 16Hospital de Manises, Gastroenterology Unit, Valencia, Spain, 17Hospital de Donostia, Instituto Biodonostia, UPV/EHU and CIBEREHD, Gastroenterology Unit, San Sebastián, Spain


The correlation between IFX serum levels and remission achievement after the induction phase in Crohn's disease (CD) patients has not been studied.

Aims: 1) To evaluate the correlation between IFX levels and remission after the induction phase in CD patients. 2) To assess the accuracy of IFX serum levels to predict short-term remission.


CD patients with active disease (CDAI>150) naïve to anti-TNF treatment were included. Patients received IFX 5 mg/kg at weeks 0, 2, 6 and 14. Remission was defined as a CDAI score < 150, and response as a decrease of >70 points after 14 weeks of treatment. Clinical evaluation was assessed and blood samples were obtained at baseline and weeks 4, 8 and 14. IFX and antibodies to IFX (ATI) were measured using a homogeneous mobility shift assay (HMSA; Prometheus Lab, San Diego, Unites States). Correlation between IFX levels during the induction phase and response at week 14 was calculated. Receiver operating characteristic (ROC) curves were constructed and the area under the ROC curves (AUC) was calculated. Determination of predictive IFX concentration thresholds were based on the choice of the corresponding sensitivity and specificity pair determined from the ROC curves


Twenty-nine patients were included (58% female, 76% ileal or ileocolonic involvement, 48% inflammatory behaviour, 41% with previous surgery and 65% on concomitant immunosuppressants). At week 14, 72% of patients achieved remission, 14% partial response and 14% non-response. Female gender was more frequent among responders, CDAI score was lower, and time of evolution of the disease was shorter among patients that reached remission. Mean IFX concentration was similar between patients that reached remission at week 14 and those who did not: 35 vs. 42 μg/mL at week 4, 33 vs. 34 μ g/mL at week 8, and 5 vs. 8.4 μ g/mL at week 14, respectively. In the multivariate analysis adjusted by age, gender and time of evolution of the disease, IFX trough levels at week 14 were not associated with remission (odds ratio=0.75, 95% confidence interval=0.5-1.1). The AUCs for the IFX concentration to predict remission at week 14 were: 0.38 at week 4, 0.52 at week 8 and 0.37 at week 14. The corresponding figures for response instead of remission were 0.2 at week 4, 0.23 at week 8 and 0.15 at week 14. No concentration threshold was predictive of remission in any visit.


There was no association between IFX serum levels at weeks 4, 8 or 14 and clinical response or remission after the induction phase in CD patients. Therefore, IFX threshold concentration that predicts clinical response or remission at week 14 could not be determined