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Test ID: USTEK Ustekinumab Quantitation with Antibodies, Serum


Specimen Required


Patient Preparation: Collect immediately before the next dose of drug administration (trough level)

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL


Useful For

Evaluation of loss of response to therapy

 

Quantification of ustekinumab in human serum

 

Trough level quantitation for evaluation of patients treated with ustekinumab

 

Detection of antibodies to ustekinumab in human serum

Profile Information

Test ID Reporting Name Available Separately Always Performed
USQN Ustekinumab QN, S No Yes
USTAB Ustekinumab Ab, S No Yes

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

Ustekinumab QN with Antibodies, S

Specimen Type

Serum

Specimen Minimum Volume

0.35 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Clinical Information

Ustekinumab (UTK) is a fully human IgG1 kappa monoclonal antibody (1) that binds with high affinity to the p40 subunit of human interleukin (IL)12 and IL23 and has been approved for the treatment of patients with moderate to severe Crohn disease (CD), moderate to severe ulcerative colitis (UC), psoriatic arthritis, and plaque psoriasis. The drug prevents IL12 and IL23 bioactivity by binding and neutralizing the shared p40 subunit, preventing interaction with the cell surface receptor protein IL12Rbeta1. Through this mechanism of action, UTK effectively neutralizes IL12 and IL23, proteins that are thought to be associated with gastrointestinal inflammation in CD and UC. In the setting of the inflammatory bowel diseases (IBD), CD and UC, the treatment regimen is started with a single weight-based loading dose of the t-mab administered intravenously (IV), and a maintenance regimen with standard (non-weight based) subcutaneous administration of ustekinumab 8 weeks after induction dose, and every 8 weeks thereafter. There is very little data supporting proactive therapeutic drug monitoring for ustekinumab.

 

The test is most useful in the evaluation of loss of response to therapy. A gradual decrease in efficacy over time following an initial response to biologics is common. In many cases, antibodies generated to the biologic are responsible for treatment failure, as they bind to the drug creating an immunocomplex and clearing the drug faster from circulation.

 

For IBD, measurements in nonresponders are indicated at post-induction (week 8) and concentrations of ustekinumab associated with favorable outcomes are greater than 3.5 mcg/mL. In addition, for measurements during maintenance stages of therapy, ustekinumab concentrations ≥1 mcg/mL are associated with clinical response and clinical remission. At maintenance stages, ustekinumab concentrations ≥4.5 mcg/mL are associated with mucosal healing.

 

In clinical trials, 6% to 12.4% of patients using ustekinumab for psoriasis or psoriatic arthritis developed antibodies-to-ustekinumab (ATU) over time. For IBD, between 2.9% and 4.6% of patients developed ATU when treated with ustekinumab for one year.(1) Therefore, it is important to monitor trough concentrations of serum UTK to correlate drug levels with loss of response to therapy. ATU may increase drug clearance in treated patients or neutralize the drug effect, thereby potentially contributing to the loss of response. ATU could also cause adverse events such as serum sickness and hypersensitivity reactions.

 

Currently, ustekinumab quantitation is performed in conjunction with immunogenicity assessment for ATU.

Reference Values

USTEKINUMAB QN, S:

Limit of quantitation is 0.3 mcg/mL

 

In inflammatory bowel disease, at post-induction measurement (week 8), concentrations above 3.5 mcg/mL are associated with good outcomes

 

For maintenance stages:

Concentrations ≥1.0 mcg/mL are associated with clinical response and clinical remission

Concentrations ≥4.5 mcg/mL are associated with mucosal healing

 

USTEKINUMAB AB, S:

Limit of quantitation is 10 AU/mL

Absent: <10 AU/mL

Present: ≥10 AU/mL

Interpretation

Antibodies to ustekinumab (ATU) absent

ATU present

Ustekinumab quantification

<1.0 mcg/mL

 For nonresponders: Insufficient ustekinumab is present.

In the absence of ATU, consider optimizing therapy by increasing the dose or shortening the administration intervals, or by adding an immunomodulator to the therapeutic regimen.

For nonresponders:

Insufficient ustekinumab is present. Antibodies-to-ustekinumab detected can contribute to faster clearance of ustekinumab and treatment failure. Clinical evaluation is recommended.

Ustekinumab quantification

≥1.0 mcg/mL

For nonresponders:

If the sample was collected at trough ie, immediately before the next infusion, the results could suggest a mechanistic failure of ustekinumab. The provider may consider switching therapeutic regimen outside of the drug class.

 For nonresponders:

If the sample was collected at trough ie, immediately before the next infusion, the results could suggest a mechanistic failure of ustekinumab. The provider may consider switching therapeutic regimen outside of the drug class.

Clinical Reference

1. Stelara (ustekinumab). Package insert: Prescribing information. Janssen Pharmaceuticals; revised 03/2020

2. Papamichael K, Cheifetz AS, Melmed GY, et al. Appropriate therapeutic drug monitoring of biologic agents for patients with inflammatory bowel diseases. Clin Gastroenterol Hepatol 2019;17:1655-68 e3

Day(s) and Time(s) Performed

Tuesday, Friday; 11:00 a.m.

Analytic Time

1 day

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

80299

83520

LOINC Code Information

Test ID Test Order Name Order LOINC Value
USTEK Ustekinumab QN with Antibodies, S In Process

 

Result ID Test Result Name Result LOINC Value
USQN Ustekinumab QN, S 87408-1
USTAB Ustekinumab Ab, S 87409-9
Mayo Clinic Laboratories | Gastroenterology Catalog Additional Information:

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