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Test Code RAVU Ravulizumab, Serum


Ordering Guidance


To measure only serum concentration of ravulizumab, order RAVU / Ravulizumab, Serum.

 

To measure the impact of ravulizumab on complement activity and its effect on complement blockage, order RAVMP / Ravulizumab Monitoring Panel, Serum which measures the alternative pathway function.



Specimen Required


Patient Preparation: Suggest discontinuing natalizumab at least 4 weeks prior to testing for ravulizumab 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 a 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 ravulizumab therapy

 

Assessing the need for dose escalation

 

Evaluating the potential for dose deescalation or discontinuation of therapy in remission states

 

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

 

This test is not useful as the sole basis for a diagnosis or treatment decisions

Method Name

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

Reporting Name

Ravulizumab, S

Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Reference Values

Lower limit of quantitation=5.0 mcg/mL

 

>175 mcg/mL-Therapeutic concentration for paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome

Interpretation

Target trough therapeutic concentrations (immediately before next infusion) of ravulizumab are expected to be above 175 mcg/mL for paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome.

 

Pharmacodynamic studies of complement blockage may also be recommended for patients undergoing therapy.

Clinical Reference

1. Willrich MA, Murray DL, Barnidge DR, Ladwig PM, Snyder MR. Quantitation of infliximab using clonotypic peptides and selective reaction monitoring by LC-MS/MS. Int Immunopharmacol. 2015;28(1):513-520. doi:10.1016/j.intimp.2015.07.007

2. 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. doi:10.1007/s13361-016-1566-y

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). doi:10.1128/CVI.00545-16

4. Sridharan M, Willrich MA, Go R. Personalized dosing of eculizumab using C5 functional activity and eculizumab level in complement-mediated thrombotic microangiopathy: A safe and cost-saving approach. Presented at XXVIII Congress of the International Society on Thrombosis and Haemostasis; July 12-14, 2020; Virtual ISTH 2020

5. Kulasekararaj AG, Hill A, Rottinghaus ST, et al. Ravulizumab (ALXN1210) vs eculizumab in C5-inhibitor-experienced adult patients with PNH: the 302 study. Blood. 2019;133(6):540-549. doi:10.1182/blood-2018-09-876805

6. Stern RM, Connell NT. Ravulizumab: a novel C5 inhibitor for the treatment of paroxysmal nocturnal hemoglobinuria. Ther Adv Hematol. 2019;10:2040620719874728. doi:10.1177/2040620719874728

7. Alexion Pharmaceuticals. BLA 761108-S1 Multi-disciplinary review and evaluation: Ultomiris (ravulizumab-cwvz). FDA; April 2, 2019. Accessed August 31, 2023. Available at www.fda.gov/media/135113/download

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
RAVU Ravulizumab, S 97184-6

 

Result ID Test Result Name Result LOINC Value
609420 Ravulizumab, S 97184-6

Day(s) Performed

Wednesday

Report Available

3 to 9 days