Consensus recommendations on appropriate coagulation tests during emicizumab administration in Saudi Arabia.

Introduction: Emicizumab is a bispecific monoclonal antibody with the ability to bridge FIXa and FX, mimic FVIII, and restore normal hemostasis in patients with hemophilia A. Moreover, substantial evidence has shown that emicizumab-treated patients do not require monitoring, except before surgery or invasive procedures. However, introducing this novel drug to the market poses some challenges to physicians and clinical laboratories due to its interaction with conventional coagulation tests.

Methods: Given the challenges and laboratory interactions posed by this novel drug, there is an unmet clinical need to develop clear recommendations for emicizumab laboratory monitoring to highlight which laboratory tests should be used, which tests should be avoided, and when these tests should be performed. These expert recommendations are essential to prevent inappropriate testing or misleading interpretations and reduce the extra costs of unnecessary monitoring.

Results: A consensus meeting was conducted in December 2019, including top experts on hemophilia from Saudi Arabia, to discuss this issue.

Conclusion: The experts agreed that, aPTT (activated Partial Thromboplastin Time)-based tests are not suitable for laboratory monitoring patients treated with emicizumab. Only FVIII chromogenic assays based on bovine FIX and FX proteins can be used to measure FVIII levels. They reviewed and recommended the type and time of testing for anti-factor VIII antibodies. Drug levels should be measured using the recommended test only when the anti-drug antibody (ADA) is clinically suspected and after excluding other causes (such as patient non-compliance).