Introduction: The Quest for the Hemostatic Holy Grail
For decades, the primary challenge in clinical anticoagulation has been the inseparable link between antithrombotic efficacy and bleeding risk. Traditional therapies, including low-molecular-weight heparins (LMWH) and direct oral anticoagulants (DOACs), target the common or final pathways of coagulation—specifically Factor Xa or thrombin. While effective, these agents inevitably impair the hemostatic process, leading to a narrow therapeutic window. The emergence of Factor XI (FXI) as a therapeutic target represents a paradigm shift in vascular medicine, promising to uncouple pathological thrombosis from physiological hemostasis.
The ROXI-VTE-I and ROXI-VTE-II trials, recently published in The Lancet, provide critical insights into this transition. By evaluating two distinct monoclonal antibodies—REGN9933A2 and REGN7508Cat—these trials not only test clinical efficacy in high-risk orthopedic patients but also offer a profound look into the mechanistic drivers of postoperative venous thromboembolism (VTE).
