Emerging genetic and pharmacologic therapies for controlling hemostasis: beyond recombinant clotting factors

For more than 3 decades, the scientific community has pursued gene correction of hemophilia, with the goal that an individual with congenitally deficient factor VIII or factor IX might synthesize adequate endogenous clotting factor to be relieved of burdensome repeated clotting factor infusions, as well as the emotional weight of continuous hemorrhage risk. Recent reports of successful factor IX gene therapy and partial correction of the bleeding phenotype have raised the bar for success for a robust crop of new clinical gene therapy efforts for both hemophilia A and B. At the same time that gene therapy is gaining momentum, suggesting the possibility of relief from regular intravenous coagulation protein replacement, a number of innovative technologies that enhance hemostatic potential independently of replacement factor administration are demonstrating success in human clinical application. Human clinical trial progress is reviewed regarding a recombinant bispecific IgG antibody to factors IXa and X that mimics factor VIII cofactor activity, as well as monoclonal antibody and short interfering RNA strategies that demonstrate hemostatic efficacy via opposing inhibitors of coagulation. These strategies, associated with prolonged hemostatic potential following subcutaneous (ACE910, ALN-AT3, Concizumab) or single administration (eg, gene therapy) make it possible to imagine a day when recombinant clotting factor administration, rather than being a daily preoccupation, is relegated to an adjunctive role in supporting more novel standard of care therapies.