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P453 Efficacy of therapeutic drug monitoring of anti-TNF therapy in the control of patients with inflammatory bowel disease

Bernardo S., Fernandes S., Gonçalves A.R., Baldaia C., Valente A., Moura Santos P., Correia L., Velosa J.

Hospital Santa Maria, CHLN, Department of Gastroenterology and Hepatology, Lisbon, Portugal

Background

Infliximab (IFX) and Adalimumab (ADA) are effective drugs in the treatment of inflammatory bowel disease (IBD). Studies suggest that therapeutic drug monitoring (TDM) may allow optimization of drug treatment, but it remains unclear if this strategy is associated with greater therapeutic efficacy and better outcomes.

Methods

We compared clinical-based adjustment (CB) with drug-monitoring adjustment (DM) in patients with IBD under IFX and ADA on several outcomes including hospitalization, surgery, clinical remissio and therapeutic failure at 48 weeks of treatment. We also determined the number of therapeutic adjustments, C-reactive protein (CRP) and faecal calprotectin (FC) values (negative <0.5 mg/dl and <50 ug/ml) at 48 weeks of treatment. Clinical remission was defined as absence of hospitalization, surgery and failure or switch of anti-TNF at 48 weeks of treatment.

Results

117 patients were included: 98 with Crohn's disease (CD) and 19 with Ulcerative Colitis (UC). 54.7% were male with a mean age of 29.1 years (range 7–65). 117 were allocated to the DM group and 101 to the CB group.

Therapeutic escalation was more frequent in the DM group (47.0% vs 10.9%, p<0.001). DM was associated with longer time to relapse (8.74±42 vs 6.00±3.1 months, p=0.045) and, in patients with positive baseline CRP, with higher probability of clinical remission (p=0.05). The number of patients with negative FC was higher in DM group (77.3% vs 54.2%, p=0.029).

There was a trend for higher therapeutic failure in the CB group (5.9% vs 1.7%, p=0.097). There were no differences in the rates of surgery (5.0% vs 6.8%, p=0.385), Hospitalization (6.9% vs 6.8%, p=0.593) or clinical remission (73.5% vs 78.2%, p=0.258).

The prevalence of infratherapeutic IFX serum levels (IFX <3.5) and positive antibodies (>10) was 33.6% and 17.7%. In the DM group, escalation occurred mainly due to Infratherapeutic serum levels and not due to positive antibodies (p<0.001 and p=0.175). Clinical remission (78.7% vs 60.5%, p=0.036) was more common in patients with higher drug serum levels (7.12±7.34 vs 4.56±3.81, p=0.018).

Conclusion

Our results suggest some benefit from DM-based management. The high rates of clinical remission found in both cohorts (73.5% vs 78.2%) may have partly been responsible for the absence of a significant difference between both cohorts. However, the rates of escalation were 4 times higher in the DM group. We hypothesize that longer follow-ups would allow us to reach a difference between both cohorts.