199 Efficacy and Safety With Andexanet Alfa in Traumatic Intracranial Hemorrhage: An ANNEXA-4 Substudy

Abstract

Acute major bleeding secondary to trauma is a significant complication of anticoagulated patients. In patients taking Factor Xa (FXa) inhibitors, major bleeding events can be life-threatening in the absence of a specific reversal agent. ANNEXA-4 was a prospective, single-arm, open-label study evaluating the efficacy and safety of andexanet alfa in patients with acute major bleeding while taking FXa inhibitors. Eligible patients presented within 18 hours of their last FXa inhibitor dose. Co-primary efficacy endpoints were the percent change from baseline in anti-FXa activity, and the proportion of patients achieving excellent or good hemostatic efficacy over the first 12 hours after treatment, as determined by an independent adjudication committee. The criteria for hemostatic efficacy in patients with intracranial hemorrhage (ICH) were largely volume based; a 20 percent or lower increase in hematoma volume and/or thickness was considered excellent, a 20-35% increase was good, and a >35% increase was poor/none. Safety outcomes (including thrombotic events and death) were evaluated over 30 days. Among 352 patients enrolled in the study, 99 (28.1%) had an ICH associated with trauma. Mean age was 81.5 years. A total of 72 patients took apixaban, 22 rivaroxaban, 3 enoxaparin, and 1 edoxaban. Of the 99 ICH patients, 34 (34.3%) had bleeding in multiple compartments. The mean baseline hematoma volume in the 11 trauma patients with single-compartment intraparenchymal bleeding was 13.3 cc. Among 71 efficacy-evaluable ICH patients, 60 (84.5%) had excellent or good hemostatic efficacy. The median percent reduction in anti-FXa activity was 94.3% and 91.8% in ICH patients taking apixaban and rivaroxaban, respectively. The 30-day rates of thrombotic events and mortality were 7 of 99 (7.1%) and 10 of 99 (10.1%), respectively. In patients taking FXa inhibitors with ICH due to trauma, andexanet alfa resulted in a high rate of excellent or good hemostatic efficacy, with a relatively low occurrence of thrombotic events. These results are comparable to what was observed for ANNEXA-4 patients with spontaneous bleeding events and suggest that andexanet alfa could be a safe and effective treatment option in the traumatic ICH population.