Optimizing serum adalimumab levels in maintenance therapy via proactive therapeutic drug monitoring improves markers of disease activity in Crohn's disease.

OBJECTS: The benefit of a proactive therapeutic drug monitoring (TDM) strategy in patients with inflammatory bowel disease receiving biological therapy remains disputed. We aimed to evaluate whether optimizing serum adalimumab levels (s-ADL), guided by proactive TDM, is associated with improved markers of disease activity in patients with Crohn's disease.

MATERIALS AND

METHODS

In this longitudinal cross-sectional study, 72 patients receiving adalimumab maintenance therapy from our outpatient clinic, were included. Patients underwent five study visits at 3-month intervals over one year. Disease activity was assesed using the Harvey-Bradshaw Index, plasma C-reactive protein (CRP), and fecal calprotectin. s-ADL levels were measured at each visit, and dosing was adjusted to maintain a therapeutic target range of 5.0-12.0 mg/L.

RESULTS

At baseline, subtherapeutic s-ADL levels were associated with higher CRP levels (p = 0.03), and in these patients' drug levels increased significantly over the study (p = 0.001), whereas CRP levels decreased (p = 0.03). Longitudinal analysis demonstrated that higher s-ADL levels (≥5.0 mg/L) were associated with lower CRP levels (p = 0.008) and lower HBI scores (p = 0.03). Additionally, lower CRP- and fecal calprotectin levels at any visit were associated with higher s-ADL levels at the preceding visit (p = 0.04 for both). Lower CRP levels were also associated with higher s-ADL levels using 7.0 mg/L as the therapeutic threshold in longitudinal analyses (p = 0.003).

CONCLUSION

Proactive TDM-guided optimization of s-ADL levels in Crohn's disease patients on adalimumab maintenance therapy was associated with the modest but significant improvements in markers of disease activity over one year of follow-up.