Cancer-associated
thrombosis (CT) is associated with a high risk of recurrent venous thromboembolic (VTE) events that require extended anticoagulation in patients with active
cancer, putting them at risk of
bleeding. The aim of the API-CAT study (NCT03692065) is to assess whether a reduced-dose regimen of
apixaban (2.5 mg twice daily [bid]) is noninferior to a full-dose regimen of
apixaban (5 mg bid) for the prevention of recurrent VTE in patients with active
cancer who have completed ≥6 months of
anticoagulant therapy for a documented index event of proximal
deep-vein thrombosis and/or
pulmonary embolism. API-CAT is an international, randomized, parallel-group, double-blind, noninferiority trial with blinded adjudication of outcome events. Consecutive patients are randomized to receive
apixaban 2.5 or 5 mg bid for 12 months. The primary efficacy outcome is a composite of recurrent symptomatic or incidental VTE during the treatment period. The principal safety endpoint is clinically relevant
bleeding, defined as a composite of major
bleeding or nonmajor clinically relevant
bleeding. Assuming a 12-month incidence of the primary outcome of 4% with
apixaban and an upper limit of the two-sided 95% confidence interval of the hazard ratio <2.0, 1,722 patients will be randomized, assuming an up to 10% loss in total patient-years (β = 80%; α one-sided = 0.025). This trial has the potential to demonstrate that a regimen of extended treatment for patients with CT beyond an initial 6 months, with a reduced
apixaban dose, has an acceptable risk of recurrent VTE recurrence and decreases the risk of
bleeding.