Abstract Number: PB0666
Meeting: ISTH 2021 Congress
Background: The development of anti-drug antibody in patients with Hemophilia A treated with emicizumab is a rare event. Nevertheless, as already described, patients may develop neutralizing anti-emicizumab antibody which could be associated with unexpected bleeding.
Aims: To describe a new case of partially neutralizing anti-emicizumab antibody, developed in a Hemophilia A patient with no FVIII inhibitor treated with emicizumab which disappeared with continuous use of drug.
Methods: Case: The patient is a 33-years-old male with severe HA without FVIII inhibitor, previously in prophylaxis with 2000U of recombinant FVIII every other day. His replacement therapy was switched to emicizumab receiving the initial four standard loading doses with 3 mg/kg/week followed by the 1.5 mg/kg/week regimen. After receiving the 5thdose, the patient developed an acute bleeding episode at his right elbow confirmed with ultrasound. This acute bleeding required additional treatment of FVIII. Emicizumab plasma level and development of anti-drug antibody has been controlled.
Results: The bleeding episode in our patient at 5th dose of emicizumab was associated with a modest reduction of emicizumab concentration from 49 to 31.7 ug/mL and presence of anti-emicizumab antibody tested with western blot analysis on total IgG fraction. Since the neutralization was not complete the patient has continued his regular administration using emicizumab and a reduced dose of FVIII (4 total infusions) with a close clinical (ultrasound) and laboratory (emicizumab level and anti-emicizumab antibody) monitoring. The intensity of anti-drug antibody was reduced at 7th dose and completely disappeared at 8th dose with a gradual recovery of emicizumab concentration up to 41 ug/mL in patient’s plasma.
Conclusions: During the initial phase of emicizumab treatment (<20 exposure days) patients need particular attention with an accurate clinical and laboratory monitoring. Some transitory anti-drug antibody could have a functional effect creating bleeding episodes, and this need to be properly treated.
To cite this abstract in AMA style:Peyvandi F, Braham S, Gualtierotti R, Arcudi S, Schiavone L, Novembrino C, Valsecchi C. Functional Transitory Anti-emicizumab Antibody Creating Bleeding Episodes [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/functional-transitory-anti-emicizumab-antibody-creating-bleeding-episodes/. Accessed October 2, 2023.
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