Safety and real-world effectiveness of eptacog beta with emicizumab prophylaxis: an interim analysis of the ATHN 16 study.

Eptacog beta, a recombinant factor VIIa bypassing agent, has demonstrated safety and efficacy in the management of bleeding events (BEs) in people with hemophilia and inhibitors. Data describing eptacog beta use in patients receiving emicizumab prophylaxis remains limited. This interim analysis of the American Thrombosis and Hemostasis Network 16 study, a phase 4, multicenter, US based, open-label study, evaluates the safety and real-world effectiveness of eptacog beta for the treatment of BEs experienced on emicizumab prophylaxis. Nineteen participants with hemophilia A and inhibitors who agreed to treat BEs with eptacog beta were included. Eptacog beta dosing was determined by the treating physician and participant. During the interim observational period, 9 of 19 participants (47%) experienced breakthrough BEs. Thirty-three BEs were treated using eptacog beta, with 1 participant contributing 18 BEs. Initial eptacog beta doses ranged from 56.8 to 245.1 μg/kg. A single eptacog beta dose was used to manage 66.7% of BEs. All events resolved without concomitant hemostatic medications. Bleeds treated with an initial eptacog beta dose ≥76 μg/kg had higher single-dose effectiveness and required fewer total doses than bleeds treated with an initial dose <76 μg/kg; differences were not statistically significant. Two participants were treated with eptacog beta perioperatively for 3 minor surgical procedures, and 1 participant was also treated with concomitant tranexamic acid. These observations demonstrate that eptacog beta was effectively used across a range of initial doses for bleed management and perioperative hemostasis by participants receiving emicizumab prophylaxis. No treatment-related adverse events, such as thrombosis, thrombotic microangiopathy, or immune responses, were observed. This trial was registered at www.clinicaltrials.gov as #NCT04647227.