Hemostatic effects of the ticagrelor antidote MEDI2452 in pigs treated with ticagrelor on a background of aspirin

Background: Ticagrelor, a P2Y12 antagonist, is approved for the prevention of thromboembolic events. However, antiplatelet therapies carry a risk of bleeding. Objective: To explore the hemostatic effects of MEDI2452, an antidote for ticagrelor. Methods: Pigs, pretreated with aspirin, were given an intravenous infusion of ticagrelor or vehicle. At the end of the infusion, a piece of a liver lobe was cut off and a bolus of MEDI2452 or vehicle was administered intravenously. Blood was collected to monitor blood loss, mean arterial blood pressure (MAP) was recorded and survival time was observed over 4 h. Blood samples for drug plasma exposures and platelet aggregation were collected. Results: MEDI2452 eliminated the free concentrations of ticagrelor and its active metabolite AR-C124910XX within 5 min. ADP-induced platelet aggregation was close to normal at 60 min, which was not significantly different from aspirin alone. MEDI2452 numerically reduced ticagrelor-mediated effects: bodyweight- adjusted blood loss in the 15-to 90-min interval, 12 (confidence interval [ CI] 95% 7-28] vs. 17 (CI 95% 5-31) (ticagrelor and aspirin) vs. 5 (CI 95% 3-9) mL kg(-1) (aspirin alone), survival 70% (CI 95% 47-100) vs. 45% (CI 95% 21-92) (ticagrelor and aspirin) vs. 100% (CI 95% 100-100) (aspirin alone), and median survival time, 240 (CI 95% 180-240) vs. 169 (CI 95% 64-240) (ticagrelor and aspirin) vs. 240 (CI 95% 240-240) min (aspirin alone). Finally, MEDI2452 significantly attenuated the decline in MAP, 0.08 (CI 95% 0.07-0.09) vs. 0.141 (CI 95% 0.1350.148) (ticagrelor and aspirin) vs. 0.04 (CI 95% 0.030.05) mmHg per min (aspirin alone) and maintained MAP at a significantly higher level, 73 (CI 95% 51-95) vs. 48 (CI 95% 25-70) (ticagrelor and aspirin) vs. 115 (CI 95% 94136) mmHg (aspirin alone). Conclusion: MEDI2452 eliminated free ticagrelor and AR-C124910XX within 5 min. This translated into a gradual normalization of ADPinduced platelet aggregation and significant improvement in blood pressure and numerical but non-significant improvements in blood-loss and survival.