Results of Phase III APEX study of betrixaban for venous thromboembolism.-Portola Pharma

Portola Pharmaceuticals announced topline data from the Phase III APEX (Acute Medically Ill VTE Prevention with Extended Duration Betrixaban) Study, which evaluated the superiority of extended-duration anticoagulation with oral betrixaban compared with standard of care anticoagulation with injectable enoxaparin for the prevention of venous thromboembolism (VTE), or blood clots, in acute medically ill patients. These are patients who are hospitalized for serious common medical conditions, such as heart failure, stroke, infection and pulmonary disease. APEX was designed to assess the relative risk (RR) in the composite endpoint of ultrasound-detected (asymptomatic) proximal deep venous thrombosis (DVT), symptomatic DVT, non-fatal pulmonary embolism (PE) or VTE-related death in high-risk acute medically ill patients treated with oral betrixaban for 35-47 days versus standard of care preventive anticoagulation with injectable enoxaparin dosed for 10±4 days.

APEX enrolled 7,513 patients at more than 450 clinical sites worldwide. The primary efficacy and safety analysis consisted of three pre-specified patient groups of increasing sample size: Cohort 1 - patients with elevated D-dimer levels (62 percent of the overall study population), Cohort 2 - patients with elevated D-dimer levels or age 75 years or over (91 percent of the overall study population), and the overall study population. By protocol definition, primary efficacy analysis testing of Cohort 1 was done first and required a p value of 0.05 or less in order to test Cohort 2, which in turn required a p value of 0.05 or less in order to test the overall study population.

Cohort 1 achieved a p value of 0.054, which did not meet the threshold. Cohort 2 and the overall study population achieved p values of 0.029 and 0.006, respectively. There was no statistical difference in major bleeding between the betrixaban and enoxaparin arms in any of these three patient groups. The number of fatal bleeds was balanced between the two arms, and the number of intracranial hemorrhages was numerically lower in the betrixaban arm. Positive net clinical benefit with betrixaban was observed.