6ER-010 Therapeutic drug monitoring of tumour necrosis factor α inhibitors in inflammatory bowel disease: evidence from a real world setting

Background and importance Biologics have become the mainstay for treatment of inflammatory bowel disease (IBD) but these drugs often require dose escalation to maintain effectiveness. Currently, therapeutic drug monitoring (TDM) can be used to measure drug concentrations in blood and antibodies against tumour necrosis factor α (TNFα) inhibitors and therefore individualise recommended doses in IBD. TDM is associated with greater effectiveness compared with empirical dose adjustment. Aim and objectives The study aimed to characterise TDM of the TNFα inhibitor adalimumab in patients diagnosed with IBD. Material and methods This was a retrospective observational study based on medical and pharmaceutical records. Inclusion criteria comprised patients with a diagnosis of IBD, on maintenance therapy with adalimumab in a general hospital, between 2014 and 2019. The main outcomes included dose escalations, therapy discontinuation and TDM. Results A total of 40 patients met the inclusion criteria, with a mean age of 39.6 (SD 15.7) years, 50.0% were women, average weight was 66.2 (SD 15.7) kg, and 90.0% had Crohn’s disease and the remaining had ulcerative colitis. Adalimumab was more frequently administrated as a fourthline therapy for IBD (32.5%), considering also conventional therapy. Prior to adalimumab, 80% of patients were treated with immunosuppressants, 57.5% with salicylates, 52.5% with infliximab, 45.0% with corticosteroids and 12.5% had been previously treated with adalimumab. The majority of patients (60%) were being treated with adalimumab as monotherapy, 30% concomitantly with immunosuppressants and the remaining with salicylates or corticosteroids. Median time on therapy with adalimumab was 25.1 months. For all patients, although in a small proportion of patients TDM was performed (15.0%), 83.3% maintained therapy with adalimumab, while only 67.6% of patients without TDM remained on therapy with adalimumab. Dose escalation occurred in 32.5% of patients, 15.4% following TDM and 84.6% occurred empirically. All patients with TDM continued therapy whereas 45.5% of patients with empirical dose escalation either discontinued therapy or showed a low response. Conclusion and relevance The study showed that TDM of adalimumab led to a lower proportion of discontinuations or low response in IBD treatment. Although TDM is still performed in a minority of patients, its use should be encouraged in a real world context. References and/or acknowledgements No conflict of interest.