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Test Code (รหัสการทดสอบ):
090-81-2022

Order Name (ชื่อการทดสอบ):
Ustekinumab Quantitation with Antibodies, Serum **

 
Specimen / Container (สิ่งส่งตรวจ/ภาชนะ):
Blood/ Plain blood (Red top) 6 mL, 2 tubes

Collection Instructions:
Draw blood immediately before next scheduled dose (trough specimen).

 
 
Turnaround Time (ระยะเวลารอผล):
Received specimen to reported within 14 days
 
 
Useful For (ประโยชน์การทดสอบ):

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 

 
Methodology (วิธีการทดสอบ):

Enzyme-Linked Immunosorbent Assay (ELISA)

 
Test List In Profile (การทดสอบใน Profile):
Ustekinumab QN
Ustekinumab Ab
 
AliasesName (ชื่อเรียกอื่นๆ) :
Stelara (Ustekinumab) Level
ID: USTEK
 
 
 
Test Code (รหัสการทดสอบ):
090-81-2022

Order Name (ชื่อการทดสอบ):
Ustekinumab Quantitation with Antibodies, Serum **

 
Collection Specimen Or Container (สิ่งส่งตรวจ/ภาชนะ):
Blood/ Plain blood (Red top) 6 mL, 2 tubes

Collection Instructions:
Draw blood immediately before next scheduled dose (trough specimen).

 
 
Specimen Testing Type (สิ่งส่งตรวจที่ใช้ในการทดสอบ):
Serum, minimum volume 1 mL x 2 tubes
 
Sub Mission Container (ภาชนะส่งตรวจ):
Plastic tube
 
Rejection Criteria (เกณฑ์ปฏิเสธสิ่งส่งตรวจ):
Gross hemolysis Reject
Gross lipemia Reject
Heat-inactivated specimen Reject
 
Specimen Stabillity (ความคงตัวของสิ่งส่งตรวจ):
Specimen Type Temperature Time
Serum Refrigerated, 2oC to 8oC  (preferred) 21 days
Frozen 21 days
 
 
 
Test Code (รหัสการทดสอบ):
090-81-2022

Order Name (ชื่อการทดสอบ):
Ustekinumab Quantitation with Antibodies, Serum **

 
Method detail (วิธีการทดสอบ):

Enzyme-Linked Immunosorbent Assay (ELISA)

 
Schedule (ตารางการทดสอบ):
N/A **Sent out to MAYO, USA
 
Turnaround Time (ระยะเวลารอผล):
Received specimen to reported within 14 days
 
 
Performing Location (หน่วยงานที่ทำการทดสอบ):
MAYO Laboratory
Referral Lab Services, Laboratory Department 14160-2
 
 
 
Test Code (รหัสการทดสอบ):
090-81-2022

Order Name (ชื่อการทดสอบ):
Ustekinumab Quantitation with Antibodies, Serum **

 
 
Clinical Information (ข้อมูลทางคลินิก):

Ustekinumab (UTK) is a fully human IgG1 kappa monoclonal antibody 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 > or =1 mcg/mL are associated with clinical response and clinical remission. At maintenance stages, ustekinumab concentrations > or =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. 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 Value (ค่าอ้างอิง):

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 > or =1.0 mcg/mL are associated with clinical response and clinical remission
Concentrations > or =4.5 mcg/mL are associated with mucosal healing

USTEKINUMAB AB, S:
Limit of quantitation is 10 AU/mL
Absent: <10 AU/mL
Present: > or =10 AU/mL

 
Interpretation (การแปลผล):
  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

> or =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.


Cautions: 
This assay measures free ustekinumab. This assay does not measure ustekinumab bound to anti-ustekinumab antibodies (immunocomplexes).

Presence of ustekinumab at concentrations greater than 1 mcg/mL may impair detection of antibodies to ustekinumab (ATU), as the ATU assay is not drug tolerant. This assay measures free ATU. This assay does not measure ATU bound to UTK (immunocomplexes).

Elevated rheumatoid factor (RF) may falsely increase results of ATU. During validation studies, negative ATU samples remained negative and positive ATU samples remained positive; however the quantitative result differed by more than 20% when compared to the non-RF spiked original samples. If patients are positive for RF, clinical correlation is recommended for ATU test interpretation.

 
Clinical Reference (เอกสารอ้างอิง):
www.mayocliniclabs.com (Retrieved: 7 May 2021)