Ustekinumab Level and Anti-Ustekinumab Antibody
Label Mnemonic: USTE
Epic Lab Code: LAB8601
Downtime Form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Commercial Mail-out Laboratory
5231 RCP
Specimen Instructions:
Note: Dose and Interval are required.
Collection Medium:
BD Gold SST 5 mL Vacutainer BD Gold SST 5 mL Vacutainer
Preferred Minimum: 7 mL serum in TWO Full Gold Top SST tubes.
Absolute Minimum: 5 mL serum in ONE Full Gold Top SST tube.

This test needs its own dedicated tubes and cannot be shared with any other tests. Please submit full draw.
Rejection Criteria:
Grossly hemolyzed samples not accepted. Red top tube is NOT acceptable.
Testing Schedule:
Monday through Friday
Turn Around Time:
5-7 days upon receipt at reference laboratory.
Reference Range:
Ustekinumab 0.1 - 10 ug/mL
Anti-Ustekinumab antibody 3 - 100 AU/mL
Interpretive Data:
Ustekinumab (UST)
-In both the induction and the maintenance phase of the UST phase III trials in patients with CD, serum UST levels were positively associated with the proportion of patients achieving clinical remission and inversely related to CRP levels.1

-In the induction phase of the UST phase II trial (week 6), patients with UST levels > 1.5 ug/mL showed higher rates of clinical response.

-More than 78% of patients in the 3rd UST concentration quartile (>/= 1.05 ug/mL) and more than 84% of patients in the 4th UST concentration quartile (> 2.5 ug/mL) achieved clinical remission at Week 24 in the combined analysis.3

-The maintenance study showed that both UST 90 mg IM q8w and q12w maintained clinical response and remission through Week 44. However, the q8w regimen more consistently demonstrated efficacy across the range of endpoints.4

-A second study of patients with CD treated with UST showed 78% of patients were receiving UST 90 mg IM every 4 weeks after > 6 months.5

-In a sub study of patients (n=102) with endoscopy at baseline and Week 44, the proportions of patients achieving endoscopic response, endoscopic remission, and mucosal healing were higher in the 2nd (> 0.5 ug/mL - 1.39 ug/mL), 3rd (>1.39 ug/mL - 2.67 ug/mL), and 4th (>2.67 ug/mL) concentration quartiles.6

Antibodies to Ustekinumab
-In the phase II clinical trial, the incidence of antibodies to UST was 0.7% at week 36.2 In the pooled results of the phase III clinical trial, the incidence of antibodies to UST was 2.3% through one year.1

-Some patients on biologic therapy may develop antibodies that resolve over time.7,8,9
These findings are not diagnostic. They should be independently evaluated by the treating physician and used to supplement clinical findings in accordance with the treating physician's independent medical judgment.
Automated ELISA assay for simultaneous analysis of both drug and anti- drug antibody.
CPT Code:
80299, 83520