To Örebro University

Background: Inter-individual differences in drug clearance are common in inflammatory bowel disease (IBD) patients treated with biologics. Associations between inflammatory markers, clinical features, and drug levels may indicate that the inflammatory immune response influences the pharmacokinetics of biologics. We assessed the impact of inflammatory and immunity-related proteins on drug levels in IBD.

Methods: Serum samples from 144 IBD patients initiating biologics in a prospective multicentre cohort were analysed using AFIAS-3 (Boditech Med Inc. Korea). The primary outcome was drug levels after the end of induction treatment (post-induction), analysed as continuous variables or categorised into high or low groups based on the median. Correlations were assessed using the Pearson’s correlation coefficients with false discovery rate (FDR) adjustment. Predictive capacity of clinical and protein data was evaluated with regularised linear regression models. Analyses were stratified by treatment (infliximab, adalimumab, vedolizumab) and diagnosis (Crohn’s disease (CD), ulcerative colitis (UC)).

Results: Patient demographics and clinical characteristics are provided in Table 1. Median (interquartile range, IQR) post-induction infliximab levels were 5.3 (2.2-9.5) μg/ml in patients with CD (n=34) and 3.8 (1.7-5.6) μg/ml in UC (n=33). The corresponding levels were 12.5 (7.0-16.1) μg/ml (n=36) and 8.8 (5.7-12.7) μg/ml (n=13) for adalimumab, 13.9 (6.4-24.4) μg/ml (n=19) and 17.7 (9.8-22.6) μg/ml (n=9) for vedolizumab. Principal component analyses revealed potential baseline protein profile differences between patients with high vs low post-induction levels for infliximab (p=0.09) and adalimumab (p=0.07) in CD, but no differences for vedolizumab (p=0.78) or UC. Individual protein analyses indicated that patients with higher drug levels post-induction seemed to display lower baseline estimates of inflammatory proteins compared to those with lower drug levels. However, statistical significance after correction for multiple comparisons was only observed for CDCP1 in adalimumab-treated CD patients (PFDR=0.04) (Figure 1). Additionally, baseline Flt31 (r=-0.57, PFDR=0.03) and Wisp1 (r=-0.61, PFDR=0.02) correlated with post-induction s-adali-mumab levels in CD, while Mcp3 (r=-0.89, PFDR=0.04) and Frgamma (r=-0.87, PFDR=0.05) correlated in UC. Integrating baseline protein data in prediction models for post-induction drug levels did not improve their accuracy compared to models based on only clinical and biochemical variables.

Conclusion: Inflammatory protein levels may influence post-induction drug levels in IBD, particularly in adalimumab treated CD patients. This insight could aid in optimising personalised treatment.