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Test Code LABECUMP Eculizumab Monitoring Panel, Serum

Important Note

Fasting preferred.

Recommended timeframe for the blood collection is a trough, or immediately prior to next intravenous infusion.

Additional Codes

Test Name in EPIC  EPIC Test Code Mnemonic Mayo Test ID
Eculizumab Monitoring Panel LABECUMP ECUMP ECUMP

 

Useful For

Therapeutic drug monitoring of eculizumab

Profile Information

Test ID Reporting Name Available Separately Always Performed
C5FX C5 Complement, Functional, S Yes Yes
C5AG2 C5 Complement, Antigen, S Yes, (Order C5AG) Yes
INT86 ECUMP Interpretation No Yes

Method Name

C5AG2: Nephelometry

C5FX: Automated Liposome Lysis Assay

Reporting Name

Eculizumab Monitoring Panel, S

Specimen Type

Serum Red


Specimen Required


Patient Preparation: Fasting preferred

Supplies: Aliquot Tube, 5 mL (T465)

Specimen Type: Serum

Collection Container/Tube: Red top

Submission Container/Tube: Plastic, 5 mL tube

Specimen Volume: 1.5 mL

Collection Instructions:

1. Recommended timeframe for the blood collection is a trough, or immediately prior to next intravenous infusion.

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

3. Centrifuge and separate serum from clot.

4. Freeze specimen within 30 minutes.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Frozen 14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject

Clinical Information

Eculizumab (Soliris, Alexion Pharmaceuticals) is a humanized hybrid monoclonal antibody (IgG2/IgG4) that blocks complement C5 cleavage, thereby preventing the activation of the proinflammatory effects of C5a and the cytolytic effects of the membrane attack complex (MAC) formed by C5b-C9. It is FDA-approved for atypical hemolytic uremic syndrome,(1) and paroxysmal nocturnal hemoglobinuria,(2) and also prescribed for other conditions such as C3 glomerulopathies.(3) The dosing regimen for an average adult may vary from 300 to 1,200 mg intravenously every 2 weeks during the maintenance stages, according to the condition for which the drug is prescribed. Therapy efficacy may be monitored by measuring efficiency of complement blockade.(4) Eculizumab will affect complement function assays that rely on the formation of the MAC to generate cell lysis. Although CH50 and sMAC have been recommended for eculizumab monitoring, the measurement of C5 function and C5 antigen will more specifically indicate the impact of eculizumab on the complement system blockage and may help guide the next dose of the drug.

 

This panel measures the pharmacodynamics effects of eculizumab on the complement system.

Reference Values

C5 COMPLEMENT ANTIGEN

10.6-26.3 mg/dL

 

C5 COMPLEMENT FUNCTIONAL

29-53 U/mL

Interpretation

The panel will measure the pharmacodynamic effects of eculizumab on the complement system. Total complement function (CH50), alternative pathway function (AH50), and C5 function assays will be decreased to a similar extent in the presence of eculizumab. The function of C5 may be completely absent when eculizumab is present at therapeutic concentrations. C5 antigen, on the other hand, will be normal or elevated. C5 complement function drops on average 30% with 25 mcg/mL of eculizumab, and 70% with 50 mcg/mL. In the presence of 100 mcg/mL of eculizumab in serum, there is on average 20% residual C5 function.

 

Decreased C5 function in the presence of normal or elevated C5 antigen concentrations suggests eculizumab is partially blocking C5 activity.

 

Absent C5 function in the presence of normal or elevated C5 antigen concentrations suggests eculizumab is completely blocking C5 activity.

 

Normal C5 function in the presence of normal or elevated C5 antigen concentrations suggests eculizumab concentration is not sufficient to block C5 activity.

 

If C5 function and C5 antigen concentrations are all decreased, it may be due to a secondary consumption process, poor hepatic synthesis of complement proteins or C5 deficiency. Clinical correlation recommended. If indicated, resubmit samples to confirm results.

Cautions

As with all complement assays, proper sample handling is of utmost importance to ensure that the complement system is not activated before clinical testing

 

This panel of assays will not quantitate eculizumab concentrations.

 

This panel will not measure the soluble membrane attack complex (sMAC).

Supportive Data

In a Mayo Clinic study with samples from individual subjects with normal complement activity defined by the total complement (CH50) assay and spiked with varying concentrations of eculizumab,(5) there was a significant decrease in CH50, alternative pathway function (AH50), and C5 functional results with eculizumab. Considering that the therapeutic target concentrations are expected to be above 50 mcg/mL, the results showed that eculizumab is partially blocking the complement cascade at 25 mcg/mL, with a complete blockage for C5 functional at 100 mcg/mL.

Day(s) and Time(s) Performed

Varies

Analytic Time

2 days

Specimen Retention Time

14 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. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

86160

86161

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ECUMP Eculizumab Monitoring Panel, S In Process

 

Result ID Test Result Name Result LOINC Value
C5FX C5 Complement, Functional, S 60472-8
C5AG2 C5 Complement, Antigen, S 4505-4
INT86 ECUMP Interpretation 69048-7

Forms

If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.