Significance of measurement of serum trough level and anti‐drug antibody of adalimumab as personalised pharmacokinetics in patients with Crohn's disease: a subanalysis of the DIAMOND trial

BACKGROUND: Significance of monitoring adalimumab trough levels and anti-adalimumab antibodies (AAA) for disease outcome in Crohn's disease (CD) patients remained unclear. AIM: To evaluate the association of adalimumab trough levels and AAA at week 26 with clinical remission at week 52, the effect of azathiopurine on AAA and factors influencing trough levels in CD patients in the DIAMOND trial. METHODS: We performed this study using adalimumab trough levels, AAA at week 26 and 6-thioguanine nucleotide (TGN) in red blood cells at week 12. A multiple regression model and receiver operating analysis was performed to identify factors influencing adalimumab trough levels and AAA, and adalimumab thresholds for predicting disease activity. RESULTS: RBCs yielded sensitivity (100%) and specificity (60.6%) for AAA negativity. CONCLUSION: Adalimumab trough levels and AAA occurrence were significantly associated with clinical remission. Higher 6TGN affected AAA negativity. The combination therapy is beneficial in some relevant aspects for CD patients. (UMIN Registration No. 000005146).