Pulmonary vascular disease & thromboembolismRandomised controlled trial
Efficacy and safety of REGN9933A2 and REGN7508Cat for preventing postoperative venous thromboembolism (ROXI-VTE-I and ROXI-VTE-II): two randomised, open-label, phase 2 trials
- Two randomised controlled trials (ROXI-VTE-I and ROXI-VTE-II)
- open-label
- phase 2
- Bayesian primary analysis
- multicentre
Authors' conclusion
REGN7508Cat was superior to enoxaparin for venous thromboembolism prevention; REGN9933A2 was not superior to enoxaparin.
Study context
- Population
- Patients aged ≥50 years undergoing knee arthroplastyROXI-VTE-I n=373
- Comparison
- REGN9933A2 or REGN7508Cat (factor XI (FXI) antibodies) vs enoxaparin, with apixaban as exploratory comparator
- Primary endpoint
- Objectively confirmed VTE (asymptomatic DVT of operated leg, symptomatic DVT of either leg, or non-fatal or fatal PE)
- Follow-up
- Through day 12 after the first dose
Primary result
As reported in the abstract
VTE · through day 12
Each group vs enoxaparinMean aOR
REGN9933A2CrI; posterior probability 78.5%; not superior
0.78(90% CrI 0.47–1.32)
REGN7508Catvs combined enoxaparin groups; posterior probability 99.8%; superior
0.37(CrI 0.20–0.68)
Safety
Postoperative anaemia (most common TEAE)
Serious adverse events · first three ROXI-VTE-I; last two ROXI-VTE-II
- Postoperative anaemia (most common TEAE): ROXI-VTE-I: 9/123, 11/125, 16/125; ROXI-VTE-II: REGN7508Cat 6/120
- Serious adverse events: Enoxaparin 0 events
Major or clinically relevant non-major bleeding
- No major or clinically relevant non-major bleeds in any group
Serious adverse events
- No treatment-related deaths
Original publication
Efficacy and safety of REGN9933A2 and REGN7508Cat for preventing postoperative venous thromboembolism (ROXI-VTE-I and ROXI-VTE-II): two randomised, open-label, phase 2 trials. Lancet. Published 8 November 2025. doi:10.1016/s0140-6736(25)02097-5
Summarised from the published abstract; every number is checked against it