Interpretation

Adalimumab quantitation is generally performed in conjunction with immunogenicity assessment for antibodies to adalimumab (ATAs). Most often, this testing is ordered for patients with inflammatory bowel disease (IBD) who are on adalimumab therapy and who are experiencing loss of response (reactive monitoring)(6), but the testing may be ordered for anyone on adalimumab-even when treatment is going well (proactive monitoring).(7-9)

Results from adalimumab and ATAs testing play an important role in patient management. In the setting of loss of response to adalimumab therapy for adults with active IBD, a clinical decision tool from the American Gastroenterology Association(6,10,11) suggests the following scenarios for a blood draw that occurred at trough, ie, immediately before the next injected dose:

-For patients who have undetectable or low concentrations of adalimumab (<8 mcg/mL) but no detectable ATAs, the patient care team may choose to increase the dose of adalimumab in an attempt to increase the amount of the drug in circulation.

-If the patient has subtherapeutic adalimumab concentrations (<8 mcg/mL) in the presence of an ATA, the patient care team may switch the patient to another tumor necrosis factor inhibitor.

-For patients with increased trough concentrations of adalimumab (therapeutic or greater), whether an ATA is present or not, it may be necessary to switch the patient to a therapy with a different mechanism of action such as the anti-alpha4-beta-7-integrin antibody vedolizumab or the IL12/IL23 antibody ustekinumab.

-Low trough concentrations may be correlated with loss of response to adalimumab.

Adalimumab concentration results above 35 mcg/mL are suggestive of a blood draw at a timepoint in treatment other than trough.

Test interpretation relies on clinical presentation and may differ from the statements above, which were designed for adults with IBD experiencing loss of response. For individuals on adalimumab therapy for other conditions such as rheumatoid arthritis, or pediatric patient populations or proactive monitoring, drug concentration therapeutic targets and patient management decision may be individualized.