Hemlibra

Hemlibra is a bispecific factor IXa- and factor X-directed antibody indicated for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adult and pediatric patients ages newborn and older with hemophilia A (congenital factor VIII deficiency) with or without factor VIII inhibitors.

Recommended loading dose is 3 mg/kg by subcutaneous injection once weekly for the first 4 weeks, followed by a maintenance dose of:
1.5 mg/kg once every week, or
3 mg/kg once every two weeks, or
6 mg/kg once every four weeks.

The following serious adverse reactions are described:
Thrombotic Microangiopathy Associated with HEMLIBRA and aPCC
Thromboembolism Associated with HEMLIBRA and aPCC
Immunogenicity

Immunogenicity
: Anti-Hemlibra antibodies (including neutralizing antibodies) have developed in Hemlibra-treated patients. In case of clinical signs of loss of efficacy, promptly assess the etiology and consider a change in treatment if neutralizing antibodies are suspected.
Laboratory Coagulation Test Interference
: Hemlibra interferes with activated clotting time (ACT), activated partial thromboplastin time (aPTT), and coagulation laboratory tests based on aPTT, including one-stage aPTT-based single-factor assays, aPTT-based Activated Protein C Resistance (APC-R), and Bethesda assays (clotting-based) for factor VIII (FVIII) inhibitor titers. Intrinsic pathway clotting-based laboratory tests should not be used.

Emicizumab mimics the function of coagulation factor VIII, therefore it binds to the activated form of Factor IX (Factor IXa). This binding forms a complex that will later bind to the X factor of the coagulation factor. The ability of Emicizumab to interact with both factors (Factor IXa and Factor X) activates the coagulation cascade that will subsequently lead to the segmentation of fibrinogen into fibrin and the formation of blood clots. The effect of Emicizumab is translated into the restoration of the blood coagulation process and, therefore, in the reduction of hemorrhagic episodes. The activity of emicizumab can also produce changes in activated clotting time (ACT), activated partial thromboplastin time (aPTT) and one-step Factor VIII activity. In addition, the unique bispecific structure of Emicizumab prevents the formation of Factor VIII inhibitors or their effect.
Emicizumab exerts its action by performing the function of the coagulation Factor VIII without presenting a structural homology. It presents a dual specificity which allows it to bind to both the Factor IXa and Factor X, performing the required bridging activity for the launch of the coagulation cascade.