Apixaban Use in Patients with Protein C and S Deficiency: A Case Series and Review of Literature.

Background: Historically, warfarin was the mainstay anticoagulant agent to manage patients presenting with thrombotic disorders caused by Protein C or S deficiency. Several direct oral anticoagulants (DOACs) were introduced over the past decade. They showed superiority over warfarin in patients with venous thromboembolism in many landmark trials. Insufficient data are available that examine the outcome of utilizing apixaban in patients with protein S deficiency induce thrombosis. Cases Presentation: We reported the clinical outcomes of utilizing apixaban in four patients with systemic thrombosis caused by protein C or S deficiency who presented to a tertiary hospital in Riyadh, Saudi Arabia. Four patients exhibited typical features of thrombotic events. After confirming the diagnosis, one patient was initially started on apixaban, and the other three patients were converted from warfarin to apixaban. Three of the four patients tolerated the apixaban during the follow-up period. Additionally, they did not have any bleeding or thrombotic complications. However, one patient developed recurrent thrombotic events despite switching to different type of DOAC and was ultimately transitioned back to warfarin. Conclusion: Based on the available emerging evidence and our case series, the use of apixaban could be effective in preventing recurrent thrombotic events in patients with inherited thrombophilia without safety concerns. Further, large studies are warranted to investigate the safety and efficacy of apixaban in these population.