Catalyst Biosciences, Inc. announced the initiation and open enrollment of the Phase 2 part of the Phase 2/3 program of marzeptacog alfa (activated) (MarzAA), a potent, subcutaneously administered, Factor VIIa therapy being developed for prophylaxis in hemophilia A or B with inhibitors. For individuals with hemophilia B with inhibitors there are no approved subcutaneous therapies, and a recently approved subcutaneous treatment for hemophilia A with inhibitors has safety concerns. With the initiation of this Phase 2 MarzAA trial, Catalyst is now conducting two clinical studies with subcutaneous candidates for individuals with hemophilia. This Phase 2 open-label, subcutaneous efficacy trial in individuals with hemophilia A or B with inhibitors will evaluate the ability of MarzAA to eliminate, or minimize, spontaneous bleeding episodes. The primary endpoint is a reduction in annualized bleed rate that will be compared with each individual's historical annualized bleed rate as the control. Safety and tolerability of daily subcutaneous dosing and potential inhibitor formation will also be monitored. The trial will enroll up to 12 individuals with hemophilia and an inhibitor across approximately ten clinical trial sites globally.