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Test Code MIRI Mirikizumab, Serum


Ordering Guidance


Therapeutic drug monitoring of mirikizumab may be useful when assessing response to therapy is difficult or when patients need to be above a certain therapeutic concentration to improve the odds of a clinical response for therapy optimization, dose increases, or de-escalation or discontinuation of therapy.



Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL Serum

Collection Instructions:

1. Draw blood immediately before next scheduled dose (trough specimen).

2. Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.


Secondary ID

623669

Useful For

Assessing the response to mirikizumab therapy

 

Assessing the need for dose escalation

 

Evaluating the potential for dose de-escalation or discontinuation of therapy

 

Monitoring patients who need to be above a certain mirikizumab concentration to improve the odds of a clinical response for therapy optimization

Method Name

Liquid Chromatography Mass Spectrometry (LC-MS)

Reporting Name

Mirikizumab, S

Specimen Type

Serum

Specimen Minimum Volume

Serum: 0.25 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Reject Due To

Gross hemolysis OK
Lipemia Reject
Gross icterus OK

Clinical Information

Drug and target:

Mirikizumab (Omvoh, Lilly) is a humanized IgG4 monoclonal antibody that selectively binds the p19 subunit of interleukin 23 (IL23), inhibiting IL23 signaling.

 

Indications:

Mirikizumab is US Food and Drug Administration-approved for inflammatory bowel disease (IBD). It is used in moderately to severely active ulcerative colitis (UC) and Crohn disease (CD).

 

Pharmacokinetic highlights:

Mirikizumab has linear pharmacokinetics with dose-proportional exposure. Higher body weight is associated with lower mean concentrations of the drug. Dosing for UC is 300 mg IV at weeks 0, 4 and 8, followed by 200 mg subcutaneous injections at week 12 and every 4 weeks thereafter. Dosing for CD is 900 mg IV at weeks 0, 4 and 8, and 300 mg subcutaneous injections at week 12 and every 4 weeks thereafter. Steady state is achieved after approximately 16 weeks in therapy, and laboratory testing is recommended at trough, after steady state.(1)

 

Immunogenicity:

During clinical trials, 23% of UC and 13% of CD patients developed anti-drug-antibodies (ADA), with no clinically significant effect of ADA on safety of mirikizumab. In UC subjects only, some of the ADA identified had an association with reduced trough concentrations.

 

Evidence for therapeutic drug monitoring:

The prescribing information for mirikizumab notes an exposure-response relationship in UC, and in CD, this is not yet fully characterized. Validated therapeutic ranges and trough targets have not been established. Model-based steady state mirikizumab exposures during subcutaneous maintenance doses every 4 weeks in patients with IBD suggest trough concentrations ranging from 1.5 to 3.0 mcg/mL and Cmax (peak) around 10 to 11 mcg/mL.

Reference Values

Lower limit of quantitation = 0.5 mcg/mL

Interpretation

The optimal therapeutic concentration of mirikizumab associated with favorable outcomes in inflammatory bowel disease (IBD) is not known at this time. The recommendation is to use the lowest concentration that maintains response. Model-based analyses suggest steady-state trough concentrations of 1.5 to 3.0 mcg/mL, with peak concentrations of approximately 10 to 11 mcg/mL during subcutaneous maintenance dosing every-4 weeks in patients with IBD.

 

Therapeutic thresholds vary according to the disease, treatment regimen, and response or lack of response to therapy.

CPT Code Information

80299

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MIRI Mirikizumab, S In Process

 

Result ID Test Result Name Result LOINC Value
623669 Mirikizumab, S In Process