Background and importance Adalimumab is an anti-TNFα monoclonal antibody used in inflammatory bowel disease (IBD). Its efficacy can benefit from therapeutic drug monitoring (TDM). Certain biomarkers can be useful in future pharmacokinetics adjustment model designs.

Aim and objectives To study the correlation between plasmatic concentrations of adalimumab and the plasmatic concentrations (Cp) of prealbumin and albumin in patients with IBD.

Material and methods An observational, retrospective study was carried out from September 2020 to September 2021.

Inclusion criteria: (1) patients older than 18 years with diagnosis of IBD (Crohn’s disease or ulcerative colitis); (2) patients receiving treatment with adalimumab maintenance therapy; and (3) having a trough Cp of adalimumab, albumin and prealbumin obtained the same day.

Exclusion criterion: (1) the presence of anti-adalimumab antibodies.

The following variables were collected: gender, age, diagnosis, adalimumab trough concentration, albumin and prealbumin. The analytical determinations of adalimumab were made by ELISA technique (Theradiag) with a test range 0.3–16 μg/mL. The statistical analysis was made using R 4.1.1 statistical software.

Results In this study, 39 patients were included, of which 34 (87.2%) were diagnosed with Crohn’s disease and 5 (13%) suffered from ulcerative colitis; 53.8% were women. The mean age and weight were: 35.9 years (95% CI 31.3 to 40.5) and 68.5 kg (95% CI 61.9 to 75.1), respectively.

A positive and statistically significant correlation was found between the adalimumab trough Cp and the Cp of prealbumin (R² 0.113; p: 0.019). In those patients with prealbumin levels higher or equal to 22 mg/dL, the mean adalimumab trough Cp in maintenance therapy was significantly higher than those obtained in patients that had prealbumin levels lower than 22 mg/dL (adalimumab trough concentration: 8.73 mg/L (95% CI 6.03 to 11.43) vs 5.16 mg/L (95% CI 3.74 to 6.58), respectively (p=0.043)) (figure 1). There was no correlation between the Cp of adalimumab and those of albumin.

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Abstract 4CPS-170 Figure 1

Conclusion and relevance In the studied population sample of patients with IBD, a positive correlation between the concentration of adalimumab and prealbumin was observed. To our knowledge this is the first study to find this association, and as prealbumin is a protein with a smaller half-life than albumin, it could be used as a predictive biomarker of adalimumab clearance modification.

Conflict of interest No conflict of interest