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P365 Serum adalimumab levels predict successful remission and safe de-intensification in inflammatory bowel disease patients in clinical practice

Aguas M.*1,2, Bosό V.3, Navarro B.1, Marqués-Miñana M.R.3, Bastida G.1,2, Beltrán B.1,2, Iborra M.1,2, Monte-Boquet E.3, Poveda-Andrés J.L.3, Nos P.1,2

1La Fe University and Politechnic Hospital, Gastroenterology, Valencia, Spain 2CIBEREHD, Networked Biomedical Research Center for Hepatic and Digestive Diseases, Valencia, Spain 3La Fe University and Polytechnic Hospital, Pharmacy, Medication Clinical Area, Valencia, Spain

Background

Little is known about the association between the pharmacokinetic features of adalimumab (ADL) and disease outcome in patients with inflammatory bowel disease (IBD).

Aims: To assess the association between random serum ADL levels and clinical and biochemical remission and between ADL levels and clinical decision making in daily practice. To determine the cut-off value for successful dose reduction in IBD patients treated with ADL.

Methods

We conducted a prospective cohort study (18 months) of IBD patients who received maintenance therapy with ADA (at least 12 weeks).

Results

Data were available for 157 serum samples from 87 patients. Serum ADL levels were associated with clinical remission: median 9.2 μg/ml vs 6.0 μg/ml for Crohn's disease patients with active disease (p=0.009) and 14.4 μg/ml vs 5.2 μg/ml for ulcerative colitis patients with active disease (p=0.002) (Fig. 1).

Figure 1. Receiver operating characteristic (ROC) curve. Serum ADA levels and remission of disease.

Serum ADL levels were 9.2 μg/ml for patients with a normal C-reactive protein (CRP) value (<5mg/l) and 5.2 μg/ml for patients with a high CRP value (p=0.002) (Fig. 2).

Figure 2. Receiver operating characteristic (ROC) curve. Serum ADA levels and normalization of C-reactive protein levels.

ADL levels were significantly associated with normal fecal calprotectin values (<80 ng/g) (10.8 μg/ml vs 7.6, respectively, p=0.038) (Fig. 3).

Figure 3. Receiver operating characteristic (ROC) curve. Serum ADA levels and fecal calprotectin <80 μg/g.

We analyzed the clinical decisions taken on the basis of serum ADA levels according to the cut-off values described in previous studies (8 μg/ml).

Figure 4. Decisions taken in clinical practice based on serum ADA levels: median serum ADA level for each decision group.

Figure 4 describes patients' drug levels according to the clinical decision taken. Serum ADL levels were significantly associated with successful de-intensification compared with the group in which doses remained unchanged (AUC 0.88; 95% CI: 0.81–0.95; p<0.001). The cut-off value for successful de-intensification was 12.2 μg/ml.

Conclusion

Higher ADL levels were significantly associated with clinical and biochemical remission. Our results, which were obtained under conditions of daily clinical practice, suggest that an ADL cut-off of 12.2 μg/ml is appropriate for successful dose reduction in IBD patients treated with ADL.