Introduction The Royal Alexandra and Vale of Leven Hospitals have a comprehensive and structured yearly biologicals meeting to carry out case reviews on all patients receiving anti-TNF treatment. This report aims to describe outcomes following the introduction of drug level and antibody testing (TDM) to our assessment criteria.
Method In July 2015, drug level and antibody testing was introduced as part of the case review process for all patients actively treated with either Infliximab (IFx) or Adalimumab (ADA). Bloods obtained were processed at the Exeter Clinical Laboratory using ELISA assay kits. Drug levels were sub-categorised; greater than or equal to 3 µg/mL [Group 1-therapeutic] greater than 0.8 µg/mL but less than 3 µg/mL [Group 2- subtherapeutic] or less than 0.8 µg/mL [Group 3- undetectable]. This information was used in addition to clinical assessment which included colonoscopy, faecal calprotectin, serum biomarkers and radiological imaging where applicable. Treatment decisions were then made based on the available information and an algorithm was adapted to guide treatment changes
Results 44 patients had TDM levels obtained (32 ADA and 12 IFx).
In group 1; 31/44 (70%) had therapeutic drug levels. Despite therapeutic drug levels, 6/31 patients (19%) had ongoing disease activity and switched biological agent.
In group 2; 3/44 (7%) had subtherapeutic levels with ongoing disease activity and had switch of biologic agent.
In group 3; 10/44 (23%) had undetectable levels and 9/10 (90%) had developed antibodies. 5/10 (50%) had endoscopic remission and were withdrawn from treatment and maintained on thiopurines. All 5 maintain remission to date at 18 months post withdrawal. 5/10 (50%) had ongoing disease activity and had a switch of biologic agent.
In total 13/44 (30%) had treatment changes based on TDM.
Conclusion The addition of TDM contributed to clinical decision making in 30% of this cohort. TDM facilitated early identification of 11% of this cohort suitable for treatment withdrawal who sustained remission at 18 months. These data may support other units establishing a business plan for introduction of TDM.
Disclosure of Interest None Declared
- Biologic therapy
- Inflammatory Bowel Disease
- therapeutic drug monitoring
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