Direct-acting oral anticoagulants (DOACs) do not appear to interact with prostate cancer drugs to increase bleeding or clotting risks in patients, researchers report.

It follows the largest study of its kind to date which found that in patients taking androgen-receptor pathway inhibitors (ARPIs) there was no increased risk with DOACs compared to non-DOACs.

“These results can help clinicians and patients feel more confident when managing anticoagulation alongside modern prostate cancer treatments,” the Canadian authors reported in Cancer [link here].  

The retrospective, population-based analysis involved 2,997 patients with advanced prostate cancer who were prescribed a DOAC or a non-DOAC and a potentially interacting ARPI (including enzalutamide, apalutamide, or abiraterone) between 2012 and 2023.

Among those who received enzalutamide or apalutamide, there was no increased risk of thrombosis in the DOAC versus non-DOAC groups (pooled hazard ratio, 0.83).

Similarly, there were no significant differences in any bleeding events between the DOAC and non-DOAC arms in patients taking abiraterone (pooled hazard ratio, 1.16).

Anticoagulants are the standard therapy for treating or preventing thromboembolism, the second leading cause of death in people with cancer after disease progression.

But there have been concerns about the risk of thromboembolism in patients with advanced prostate cancer because some previous in vitro pharmacokinetic studies suggested that ARPIs can interact with DOACs.

Notably the in vitro studies found that both enzalutamide and apalutamide could lower DOAC drug levels, leading to an increased risk of thrombosis. By contrast, abiraterone could lead to an increase in DOAC drug levels, raising the risk of bleeding. 

“Our findings suggest that pharmacokinetic drug-drug interaction concerns may not translate into adverse clinical outcomes in the real world,” the authors noted.

“As clinicians, we are faced with the question of choosing the best anticoagulant option for patients on a daily basis, and the complexity further increases in patients with cancer taking many other medications including anticancer therapies that could cause concerning drug-drug interactions,” said lead author Tzu-Fei Wang, MD, of the University of Ottawa at The Ottawa Hospital and the Ottawa Hospital Research Institute.

“Our results provide reassuring data indicating that the concurrent use of DOACs with enzalutamide, apalutamide, or abiraterone could be safe and anticoagulant switches, discontinuation, or dose adjustment could be avoided if patients were to start one of these ARPIs.”