Randomized, Double blind, Phase II Trial of Vortosiran to Evaluate Safety, Tolerability, and Pharmacodynamic Efficacy in Participants with Prior Venous Thromboembolism After Completion of Initial Anticoagulant Therapy (Cohort A) and in Cancer Patients at High Risk of Venous Thromboembolism (Cohort B)

A blood clot in a vein can be a serious medical problem. These clots most often happen in the deep veins of the legs (known as deep vein thrombosis) or can travel to the lungs (pulmonary embolism). Doctors usually treat them with medicines called blood thinners. While these medicines work well, they carry a risk of causing heavy or dangerous bleeding. Because of this, scientists are searching for newer treatments that prevent dangerous clots while still allowing the blood to clot normally when you get an ordinary cut.

This trial is looking at an experimental medicine called vortosiran. Vortosiran targets a body protein called Factor XI. Factor XI plays an important role in forming harmful blood clots inside veins, but it is less important for stopping normal bleeding from everyday injuries. By reducing the activity of Factor XI, researchers hope vortosiran can protect against clots with a lower risk of bleeding than current treatments.

Researchers are running this study to test the medicine in two specific groups of people. The first group includes people who have had a blood clot before and have finished their normal course of blood thinners. The second group includes people with cancer who face a higher risk of developing a clot. Testing both groups helps doctors learn if the drug behaves safely across different patient needs.

During the study, doctors will look closely at blood samples, heart health tests, and general wellbeing. By measuring how much Factor XI activity decreases, especially after eight weeks, researchers can decide the best and safest dose to test in larger future studies.