Interference of Therapeutic Monoclonal Antibodies With Routine Serum Protein Electrophoresis and Immunofixation in Patients With Myeloma: Frequency and Duration of Detection of Daratumumab and Elotuzumab

• Published in: American journal of clinical pathology Vol. 150; no. 2; pp. 121 - 129
• Main Authors: Tang, Felicia, Malek, Ehsan, Math, Susan, Schmotzer, Christine L, Beck, Rose C
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 03.07.2018
• Subjects: Antibodies, Monoclonal - blood; Antibodies, Monoclonal - therapeutic use; Antibodies, Monoclonal, Humanized - blood; Antibodies, Monoclonal, Humanized - therapeutic use; Antineoplastic Agents, Immunological - blood; Antineoplastic Agents, Immunological - therapeutic use; Blood Protein Electrophoresis; False Positive Reactions; Humans; Induction therapy; Monoclonal antibodies; Multiple myeloma; Multiple Myeloma - drug therapy; Myeloma; Myeloma Proteins - analysis; Proteins
• ISSN: 0002-9173; 1943-7722
• DOI: 10.1093/AJCP/AQY037

We investigated the frequency and pattern of detection of therapeutic monoclonal antibodies (t-mAbs) daratumumab and elotuzumab by routine serum protein electrophoresis (SPE) and immunofixation (IF) in treated patients with myeloma. Detection of t-mAb was assessed in 22 patients by retrospective review of SPE/IF ordered prior to, during, and after 26 individual courses of therapy. t-mAb was distinguishable from M-protein in 16 of 26 courses, with daratumumab detected in nine of nine and elotuzumab in six of seven patients. t-mAb was detected on first follow-up SPE/IF in 12 patients, with earliest detection 7 days after therapy initiation and latest detection 70 days after therapy. t-mAb persisted throughout induction therapy in most patients, with loss of detection during maintenance daratumumab. When distinguishable from M-protein, t-mAbs are detectable in 93% of treated patients as soon as 7 days after the initial dose and are consistently observed throughout induction therapy, warranting increased monitoring and careful interpretation of SPE/IF.