Factor XI Antisense Oligonucleotide for Prevention of Venous Thrombosis

This RCT compared daily 200mg or 300mg of FXI-ASO (an antisense oligonucleotide that reduces levels of factor XI) to daily 40mg of enoxaparin in pts undergoing knee replacement surgery.  The end point was thromboembolism.  FXI-ASO significantly reduced factor XI levels in a dose-response manner.  FXI-ASO 200 mg was equivalent to enoxaparin in frequency of the end point  (27% vs 30%) and FXI-ASO was superior (4%).  Bleeding was evident in 8% after enoxaparin and in 4% after either dose of FXI-ASO.