In 2021, she suffered an episode of epistaxis and she needed hospital admission. Treatment was started correcting the coagulopathy during this period. Given the frequent association between this deficit and AL, abdominal fat pad biopsy was performed, which was negative for Congo red staining. Thrombin Time (TT) did not show alterations. She presented with prolonged PT and aPTT measurements, which corrected after incubation with normal plasma. Initial laboratory studies revealed an alteration in the hemostasis tests, not previously present, evidencing an acquired origin. Results: A 77-year-old patient was diagnosed with MM IgG Lambda. Methods: Description of a clinical case diagnosed in our haematology service about the acquired FX deficiency at diagnosis of a patient with MM without AL Introduction: Acquired factor X (FX) deficiency is usually associated with the presence of amyloidosis (AL) and very rarely appears in Multiple Myeloma (MM) patients without AL Jorge 1ġHematology, Hospital Virgen de la Salud, Toledo, Toledo, Spain Weber Employee of: Baxalta Innovations GmbH, a Takeda company PO002 ACQUIRED FACTOR X DEFICIENCY IN A PATIENT WITH MULTIPLE MYELOMA WITHOUT ASSOCIATED AMYLOIDOSIS Zlabinger Employee of: Baxalta Innovations GmbH, a Takeda company, A. Engelmaier Employee of: Baxalta Innovations GmbH, a Takeda company, C. Billwein Employee of: Baxalta Innovations GmbH, a Takeda company, A. Schrenk Employee of: Baxalta Innovations GmbH, a Takeda company, M. Due to the assay principle, this approach is expected to work also for novel FVIII activity-mimicking compounds, probably demonstrating no specific binding to human coagulation factors.ĭisclosure of Interest: G. Emicizumab, measured in test buffer, essentially provided no signal.ĭiscussion/Conclusion: Combining the antibody-mediated specific capture of human FVIII and a chromogenic FVIII activity assay enables for the measurement of FVIII activities in the presence of therapeutically relevant Emicizumab levels. The dose-response curves obtained were parallel to that of human plasma. FVIII recoveries of 101.2%, 106.2% and 103.7% rather reflect assay variability than an influence of Emicizumab. The addition of increasing concentrations (60, 200 and 600 nM, representing 9 to 90 μg/mL) of Emicizumab to human normal plasma did not influence the measured FVIII activity. Intermediate precision, determined by 108 measurement of a control plasma sample over six-months period, was 10.8%, expressed as the relative standard deviation. Results: The six-point calibration curve ranged from 3.03 to 97.0 mIU/mL. A human plasma pool was spiked with therapeutically relevant Emicizumab concentrations (60, 200, and 600 nM) to determine any influence on the FVIII measurement. A human reference plasma preparation was used to construct the calibration curve. Bound human FVIII was measured with a chromogenic activity assay. Methods: Murine IgG1 (GMA-8024, Green Mountain Antibodies) was used for the specific capture of human FVIII. This method is based on the selective adsorption of FVIII by a monoclonal antibody so that accompanying sample matrix compounds including Emicizumab can be removed. Here, we report on a novel chromogenic assay for measuring FVIII activity in the presence of Emicizumab. However, novel FVIII activity-mimicking agents could lack this specificity and thus not allow to successfully follow this approach. Because of Emicizumab's specificity for human coagulation factors, FVIII levels in the presence of Emicizumab can be measured by using a chromogenic FVIII activity assay based on using bovine reagents. Introduction: During the treatment of Hemophilia A patients without inhibitors using the factor VIII (FVIII) activity-mimicking bispecific antibody Emicizumab (Hemlibra) bleeding episodes can occur, which require the administration of FVIII concentrates to restore hemostasis. Weber 2,*ġPharm Sci Analytical Development 2Pharm Sci PDT R&D, Baxalta Innovations GmbH, a Takeda company, Vienna, Austria PO001 A NOVEL CHROMOGENIC METHOD FOR MEASURING FACTOR VIII ACTIVITY IN THE PRESENCE OF THE BISPECIFIC ANTIBODY EMICIZUMAB
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