AGA releases recommendations on therapeutic drug monitoring in IBD

The American Gastroenterological Association (AGA) released recommendations this month on monitoring pharmacologic therapy in inflammatory bowel disease (IBD).

The AGA developed the recommendations to guide appropriate use of therapeutic drug monitoring in adult patients with IBD taking anti-tumor necrosis factor (TNF)-alpha agents and thiopurines, as well as the use of genetic or enzymatic testing before starting thiopurine therapy. The AGA Clinical Guidelines Committee considered quality of the evidence along with the balance of benefits and harms, patients' values and preferences, and resource utilization, although cost-effectiveness was not considered because it could not be accurately assessed.

The AGA recommendations are as follows:

• In patients with active IBD who are taking anti-TNF agents, reactive therapeutic drug monitoring is suggested to guide treatment changes. Suggested optimal trough concentrations are 5 μg/mL or greater for infliximab, 7.5 μg/mL or greater for adalimumab, and 20 μg/mL or greater for certolizumab pegol. No suggested trough concentration was given for golimumab.
• The AGA suggests routine thiopurine methyltransferase testing for enzymatic activity or genotype to guide thiopurine dosing in patients in whom this therapy is being started. The committee noted that routine laboratory monitoring should always be done, including complete blood count, regardless of the test results.
• In patients with active IBD who are treated with thiopurines or who are experiencing adverse events believed to be related to thiopurine toxicity, reactive thiopurine metabolite monitoring is suggested to guide treatment changes.
• The AGA suggests against routine thiopurine metabolite monitoring in patients with quiescent IBD who are treated with thiopurines.

All of these recommendations are conditional and based on very low-quality evidence, the committee noted. The AGA made no recommendation for use of routine proactive therapeutic drug monitoring in patients with quiescent IBD who are taking thiopurine therapy.

The committee called for additional research to better determine whether therapeutic drug monitoring should be done during induction therapy in patients whose response is suboptimal, as well as whether target trough concentrations should vary by disease phenotype, disease state, or treatment. Further studies are also needed to better define when antidrug antibodies should be considered clinically meaningful for dose escalation or change of therapy, based on titers and/or persistence with repeated testing. Randomized controlled trials are also needed to compare routine proactive monitoring and reactive monitoring, among other areas, the committee wrote. The recommendations were published online Aug. 2 by Gastroenterology.