Subcutaneous Engineered Factor Viia Marzeptacog Alfa (Activated) In Hemophilia With Inhibitors: Phase 2 Trial Of Pharmacokinetics, Pharmacodynamics, Efficacy, And Safety

Background: Marzeptacog alfa (activated) (MarzAA), a novel recombinant activated human factor VII (FVIIa) variant, was developed to provide increased procoagulant activity, subcutaneous (SC) administration, and longer duration of action in people with hemophilia.Objectives: To investigate if daily SC administration of MarzAA in subjects with inhibitors can provide effective prophylaxis.Methods: This multicenter, open-label phase 2 trial (NCT03407651) enrolled men with severe congenital hemophilia with an inhibitor. All subjects had a baseline annualized bleeding rate (ABR) of >= 12 events/year. Subjects received a single 18 mu g/kg intravenous dose of MarzAA to measure 24-hour pharmacokinetics (PK) and pharmacodynamics (PD), single 30 mu g/kg SC dose to measure 48-hour PK/PD, then daily SC 30 mu g/kg MarzAA for 50 days. If spontaneous bleeding occurred, the dose was sequentially escalated to 60, 90, or 120 mu g/kg, with 50 days at the final effective dose without spontaneous bleeding to proceed to a 30-day follow-up. The primary end point was reduction in ABR. Secondary end points were safety, tolerability, and antidrug antibody (ADA) formation.Results: In the 11 subjects, the mean ABR significantly reduced from 19.8 to 1.6, and the mean proportion of days with bleeding significantly reduced from 12.3% to 0.8%. Of a total of 517 SC doses, six injection site reactions in two subjects were reported. No ADAs were detected. One fatal unrelated serious adverse event occurred: intracerebral hemorrhage due to untreated hypertension.Conclusions: The data demonstrated that MarzAA was highly efficacious for prophylactic treatment in patients with inhibitors by significantly decreasing bleed frequency and duration of bleeding episodes.