Myeloma Therapy for Monoclonal Gammopathy of Thrombotic Significance
Giselle Salmasi, David Murray, Anand Padmanabhan
Abstract
Monoclonal gammopathy of thrombotic significance (MGTS) is a recently described highly prothrombotic neoplastic condition characterized by monoclonal anti-platelet factor 4 (PF4) antibodies 1 .Here, we describe the first report on eradicating an MGTS antibody using plasma cell-directed therapy.A 67-year-old male on aspirin treatment for coronary artery disease presented with thrombocytopenia (38 x 10 3 /uL) and mesenteric ischemia secondary to extensive splanchnic vein thrombosis.Emergent small bowel resection was performed.Heparin treatment worsened splanchnic vein thrombosis, requiring additional resection.Heparin-induced thrombocytopenia (HIT) testing was positive (Figure 1A & B), and he was switched to argatroban.He developed bilateral deep vein thrombosis and pulmonary embolism, leading to cardiac arrest, requiring resuscitation.Testing also showed a monoclonal gammopathy of undetermined significance (MGUS, an IgG lambda at 0.2g/dL).He was switched to therapeutic daily fondaparinux before discharge.Positive HIT testing, MGUS, and thrombocytopenia were persistent (Figure 1A & B), and bone marrow biopsy showed 5% lambda-restricted plasma cells.Despite compliance with aspirin and fondaparinux, he presented with a cerebrovascular accident due to acute right middle cerebral and internal carotid artery occlusion, requiring thrombectomy and stent placement at which point clopidogrel was added to his regimen.Study of antibody light chains 1,2 from the MGUS (Figure 1C) and immuno-enriched anti-PF4 antibody (Figure 1D) demonstrated monoclonality in both cases, and the identical molecular masses of the MGUS and anti-PF4 antibody suggested they were synonymous.