Background The clinical benefit of extending prophylaxis for venous thromboembolism (VTE) beyond hospital discharge after laparoscopic surgery for cancer is unclear. The efficacy and safety of thromboprophylaxis with direct oral anticoagulants in cancer surgery is unexplored.

Methods PROLAPS II is an investigator-initiated, prospective, randomized, double-blind study aimed at assessing the efficacy and safety of extended prophylaxis with rivaroxaban compared with placebo after laparoscopic surgery for colorectal cancer (NCT03055026). All patients received antithrombotic prophylaxis with low molecular-weight heparin for 7±2 days and were then randomized to receive rivaroxaban (10 mg once daily) or placebo for the following 3 weeks (up to day 28±2 from surgery).

The primary study outcome was the composite of symptomatic objectively confirmed VTE, asymptomatic ultrasonography-detected deep vein thrombosis (DVT) or VTE-related death within 28±2 days from laparoscopic surgery. The primary safety outcome was ISTH-defined major bleeding. By assuming an 8% incidence of primary study outcome in patients randomized to placebo and a 60% reduction with rivaroxaban, 323 patients per group were necessary to show the superiority of rivaroxaban.

Results. Patient recruitment in PROLAPS II study was preliminary closed in June 7 th, 2021 due to study drug expiry, after the inclusion of 577 patients. The main patients features are reported in the Table. Study results will be available after the last study patient will complete the 90-day follow-up (scheduled on September 7th, 2021) and will be ready to be presented at the ASH 2021 Congress.

Conclusion PROLAPS II is the first study with an oral anti-Xa agent in cancer surgery. The study has the potential to improve clinical practice by assessing the clinical benefit of extending prophylaxis after laparoscopic surgery for colorectal cancer.

Figure 1
Figure 1.
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Disclosures

Becattini: Bayer HealthCare: Honoraria; Daiichi Sankyo: Honoraria; Bristol Myers Squibb: Honoraria. Dentali: Pfizer: Honoraria; Bristol-Myers Squibb: Honoraria; Daiichi Sankyo: Honoraria; Bayer: Honoraria; Sanofi: Honoraria; Novartis: Honoraria; Boehringer: Honoraria; Alfa Sigma: Honoraria. Agnelli: Bayer HealthCare: Honoraria; Daiichi Sankyo: Honoraria; Pfizer: Honoraria; Bristol Myers Squibb: Honoraria.

© 2021 by The American Society of Hematology
2021
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