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Test Code ECULI Eculizumab, Serum


Ordering Guidance


Therapeutic drug monitoring of eculizumab may be useful when providers are considering personalized treatment decisions, such as therapy discontinuation of extended dose intervals when patients are in remission states.



Specimen Required


Patient Preparation: Suggest discontinuing natalizumab at least 4 weeks prior to testing for eculizumab quantitation in serum. Patient should consult the healthcare provider who prescribed this drug to determine if discontinuation is an option. If not, ok to proceed with testing while taking natalizumab.

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Draw blood immediately before next scheduled dose.

2. Immediately after specimen collection, place the tube on wet ice.

3. After specimen has clotted on wet ice, centrifuge at 4° C and aliquot serum into plastic vial.

4. Freeze specimen within 30 minutes of centrifugation. Specimen must be placed on dry ice if not frozen immediately.


Useful For

Assessing the response to eculizumab therapy

 

Assessing the need for dose escalation

 

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

 

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

Method Name

Liquid Chromatography Tandem Mass Spectrometry, High-Resolution Accurate Mass (LC-MS/MS HRAM)

Reporting Name

Eculizumab, S

Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Frozen (preferred) 30 days
  Refrigerated  28 days
  Ambient  4 days

Reference Values

Lower limit of quantitation =5.0 mcg/mL

>35 Therapeutic concentration for paroxysmal nocturnal hemoglobinuria (PNH)

>50 Therapeutic concentration for atypical hemolytic uremic syndrome (aHUS)

Interpretation

Minimum trough therapeutic concentrations (immediately before next infusion) of eculizumab are expected to be above 35 mcg/mL for paroxysmal nocturnal hemoglobinuria and above 50 mcg/mL for atypical hemolytic uremic syndrome.

Clinical Reference

1. Ladwig PM, Barnidge DR, Willrich MA. Quantification of the IgG2/4 kappa monoclonal therapeutic eculizumab from serum using isotype specific affinity purification and microflow LC-ESI-Q-TOF mass spectrometry. J Am Soc Mass Spectrom. 2017;28(5):811-817

2. Willrich MA, Murray DL, Barnidge DR, et al. Quantitation of infliximab using clonotypic peptides and selective reaction monitoring by LC-MS/MS. Int Immunopharmacol. 2015;28(1):513-520

3. Ladwig PM, Barnidge DR, Willrich MA. Mass spectrometry approaches for identification and quantitation of therapeutic monoclonal antibodies in the clinical laboratory. Clin Vaccine Immunol. 2017;24(5):e00545-16

Day(s) Performed

Wednesday

Report Available

3 to 9 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

CPT Code Information

80299

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ECULI Eculizumab, S 90240-3

 

Result ID Test Result Name Result LOINC Value
65676 Eculizumab, S 90240-3

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Renal Diagnostics Test Request (T830)

-Coagulation Test Request (T753)

-Therapeutics Test Request (T831)