P38

Interference of Monoclonal Antibody Therapies with Serum Protein Electrophoresis Analysis

Claus Brasen1,*, Jakub Krejcik2, Torben Plesner2

1Clinical Immunology and Biochemistry, 2Department of Hematology, Hospital of Lillebaelt, Vejle, Denmark

Introduction: During routine serum protein electrophoresis of patients treated for multiple myeloma we have identified a drop in the concentration of free light chains while a serum M-component appears. This M-component appears a short time after therapeutic monoclonal antibody treatment has commenced.

Objectives: To investigate the possible association between therapeutic monoclonal antibody treatment and a false-positive M-component.

Methods: In order to investigate this, we have performed protein electrophoresis analysis on normal serum samples spiked with varying levels of six different monoclonal antibody compounds used at Vejle Hospital Denmark. Blood was drawn using gel-serum tubes (vacutainer, Becton Dickinson) and protein electrophoresis analysis was performed using Capillarys (Sebia Inc, Georgia, USA )

Results: All therapeutic monoclonal antibodies resulted in M-components although at different retention times. In the case of the monoclonal antibody Elotuzumab, we performed protein electrophoresis analysis prior and immediately following intravenous administration of a therapeutic infusion of Elotuzumab to a patient resulting in a significant increase of the level of M-component. 

Conclusion: Since a resulting M-component seems to be largely determined by the concentration of the compound, all therapeutic monoclonal antibodies should be tested for interference resulting in false-positive M-components which could hide complete remission in multiple myeloma patients. 

Keywords: Biomarker