Because vorapaxar increased bleeding complications in the clinical setting, the alternative PAR1 antagonist atopaxar (E5555) [267] was tested in a phase II clinical trial called (Lessons From Antagonizing the Cellular Effects of Thrombin-Acute Coronary Syndromes (LANCELOT-ACS; details at www.ClinicalTrials.gov; NCT00548587) study [273]. Here, F2R is linked to acute coronary syndrome.