A trial of humanized anti-TFPI monoclonal antibody (mAb 2021, concizumab) administered intravenously or subcutaneously to patients with hemophilia A and B showed a dose-dependent procoagulant effect.8An RNAi therapeutic drug that targets AT (fitusiran) was evaluated in patients with hemophilia A and B; weekly and monthly doses of fitusiran administered subcutaneously decreased AT levels and increased thrombin generation.7Evidence from these clinical trials indicates that AT and TFPI play important roles in regulating coagulation in hemophilia patients. The gene discussed is TFPI; the disease is hemophilia.