Table 3.

Therapeutic drug monitoring-based algorithm for handling patients with treatment failure on biologic therapy[59-61]

	Detectable anti-drug antibodies	Undetectable anti-drug sntibodies
Sub-therapeutic anti-TNF drug levels	Change to different TNF-inhibitor.	Intensify the treatment regimen of the currently used TNF-inhibitor.
Therapeutic anti-TNF drug levels	(Repeat assessments of anti-TNF drug and anti-drug antibodies over time) Switch to another biological agent with a different mechanism of action.	Switch to another biological agent with a different mechanism of action.

TNF: Tumor necrosis factor.