High anti-TNF alfa drugs trough levels are not associated with the occurrence of adverse events in patients with inflammatory bowel disease

Objectives: Up to 40% of inflammatory bowel disease (IBD) patients treated with anti-TNF drugs lose response within 1 year of treatment, therefore requiring drug optimization. Although higher drug trough levels (TLs) are associated with sustained clinical outcomes, there are concerns that they may be associated with a higher risk of adverse events (AEs). The aim was to evaluate the presence of a possible association between drug TLs and the occurrence of AEs in IBD patients treated with anti-TNF drugs. Methods: We retrospectively studied a cohort of 113 IBD patients treated with adalimumab or infliximab, of whom 27 were in combination therapy with immunosuppressants. TLs were measured using a homogeneous mobility shift assay. Results: During a median follow-up of 16 months (range 1-144), we observed 103 AEs occurring in 58 patients. We found no statistically significant difference (p = .21) in median TLs between patients who did 6.7 mcg/mL; range 0.0-36.2) or did not (7.7 mcg/mL; range 0.0-20.7) experience an AE. No difference was observed in the rate of AEs between patients in mono- or combination therapy (p = .38), as well as between elderly (i.e., >65 years) and younger patients (p = .32). Considering a TL cutoff of 7 mcg/mL for infliximab and 12 mcg/mL for adalimumab, or even double these TL values, we observed no statistically significant difference in the rate of AEs occurrence. Conclusion: Our study suggests that, when clinically required, anti-TNF drug dosage may be increased without particular concerns regarding the risk of AEs occurrence in IBD patients, even in patients on combination therapy and elderly ones.