1. Isatuximab-Specific Immunofixation Electrophoresis Assay to Remove Interference in Serum M-Protein Measurement in Patients with Multiple Myeloma.
- Author
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Thoren K, Menad S, Nouadje G, and Macé S
- Subjects
- Humans, Antibodies, Monoclonal therapeutic use, Multiple Myeloma blood, Multiple Myeloma drug therapy, Multiple Myeloma immunology, Multiple Myeloma diagnosis, Immunoelectrophoresis methods, Myeloma Proteins analysis, Antibodies, Monoclonal, Humanized therapeutic use
- Abstract
Background: Isatuximab, an IgG-kappa (IgGκ) anti-cluster of differentiation 38 (CD38) monoclonal antibody approved for use in patients with relapsed or refractory multiple myeloma (MM), can potentially interfere with the visualization of endogenous monoclonal protein (M-protein) on standard immunofixation electrophoresis (IFE) and lead to inaccurate classification of a patient's response to therapy. The Hydrashift 2/4 isatuximab IFE assay (Hydrashift isatuximab assay) removes isatuximab interference from IFE. Using samples from patients enrolled in clinical trials of isatuximab-based therapy for MM, we demonstrate how the Hydrashift isatuximab assay improves the ability to detect residual M-protein and offer recommendations for when the assay is most useful., Methods: Samples from 141 patients with a variety of known M-protein isotypes were selected and analyzed by standard IFE and the Hydrashift isatuximab assay. A positive control containing isatuximab was run on every standard IFE and Hydrashift gel., Results: The Hydrashift isatuximab assay reliably shifted the migration of isatuximab in patient samples. Standard IFE was adequate for determining 104 patients' M-protein status, and the Hydrashift isatuximab assay confirmed these results. In samples from 37 patients with a history of IgGκ MM and a single IgGκ band visible on standard IFE near the isatuximab migration site, the Hydrashift isatuximab assay was able to separate isatuximab from endogenous M-protein, identifying residual M-protein in 17 samples and preventing false-positive interpretations of standard IFE in 20 samples., Conclusions: The Hydrashift isatuximab assay is most useful in patients with known IgGκ MM when a single IgGκ band appears near the isatuximab migration site on standard IFE during isatuximab-based therapy., Clinicaltrials.gov Registration Numbers: NCT03275285 and NCT03319667., (© Association for Diagnostics & Laboratory Medicine 2024.)
- Published
- 2024
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