OTTAWA, ON, March 13, 2026 – The global thrombosis community has reached a significant milestone with the publication of the COBRRA trial results in the New England Journal of Medicine (NEJM). The study, a flagship project of the CanVECTOR network led by Dr. Lana Castellucci, addresses a critical question in the treatment of acute venous thromboembolism (VTE).
For years, clinicians have utilized both apixaban and rivaroxaban as equivalent standard treatments for VTE. However, the COBRRA trial—an international, randomized study—provides the first definitive head-to-head evidence regarding their safety profiles. The results demonstrate that the risk of clinically relevant bleeding was significantly lower with apixaban than with rivaroxaban during the initial three-month treatment period after acute VTE.
Path to Publication
This landmark result was years in the making. The COBRRA Pilot Trial was the first pilot trial to be supported by CanVECTOR, marking a full-circle achievement for the network’s mission to foster high-impact thrombosis research in Canada.
A Message from Dr. Deborah Siegal, CanVECTOR Co-Director
“The completion of the COBRRA trial, published this week in the New England Journal of Medicine, is a tremendous achievement. CanVECTOR is proud to have supported both the pilot and full-scale trials. This milestone highlights the strength of our pilot funding model, the impact of empowering early‑career investigators, and the importance of collaborating with our national and international community to conduct practice-changing research in VTE.”
By identifying the treatment option with the lowest bleeding risk, the COBRRA trial empowers physicians to make more informed decisions, ultimately improving the safety and quality of care for patients suffering from blood clots. The success of the trial highlights the power of collaborative research through the CanVECTOR network and its partners.
Read the full study: NEJM.
Learn more on the study: CIHR EN | CIHR FR
Learn more about the impact: https://ohri.ca/en/newsroom/safer-blood-clot-treatment-apixaban-rivaroxaban-according-large-venous-thrombosis-trial