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2133 Efficacy and Safety of Apixaban for Primary Prevention of Thromboembolism in Cancer Patients with a Newly Inserted Central Venous Catheter: A Post-Hoc Analysis of the Avert Trial

Program: Oral and Poster Abstracts
Session: 332. Anticoagulation and Antithrombotic Therapies: Poster II
Hematology Disease Topics & Pathways:
Clinical Trials, Clinical Research
Sunday, December 12, 2021, 6:00 PM-8:00 PM

Willem Brandt1*, Cameron Brown1,2*, Amin Zahrai, MSc3,4*, Ranjeeta Mallick, PhD, MSc, BSc5*, Philip S. Wells, MD, MSc, FRCP5,6,7 and Marc Carrier8

1Department of Medicine, University of Ottawa/The Ottawa Hospital, Ottawa, ON, Canada
2Faculty of Arts and Science, Queen's University, Kingston, ON, Canada
3University of Ottawa, Ottawa, ON, Canada
4Ottawa Hospital Research Institute, Ottawa, ON, ON, Canada
5Ottawa Hospital Research Institute, Ottawa, ON, Canada
6Department of Medicine, University of Ottawa, Ottawa, ON, Canada
7The Ottawa Hospital, Ottawa, ON, Canada
8Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, ON, Canada

Background

Venous thromboembolism (VTE) is a common complication in ambulatory patients with cancer initiating systemic chemotherapy. Central venous catheters (CVCs) used for chemotherapy administration are associated with a heightened risk of VTE in this patient population. Primary thromboprophylaxis using a direct oral anticoagulant decreases the risk of VTE without significantly increasing the risk of major bleeding complications in ambulatory cancer patients at intermediate-to-high risk of VTE with a Khorana risk score of ≥ 2. We sought to determine the efficacy and safety of apixaban in intermediate-to-high risk patients with cancer and a CVC.

Methods

This post-hoc analysis was done using the AVERT trial data, which was a randomized, placebo-controlled, double-blind clinical trial assessing the efficacy and safety of apixaban for primary thromboprophylaxis in intermediate-to-high risk patients with cancer initiating chemotherapy. The primary efficacy outcome was major VTE within 180 days of randomization and the primary safety outcome was major bleeding. The hazard ratios (HRs) for the primary efficacy and safety outcomes in patients with and without CVC were calculated using a Cox regression model controlling for age, gender, and study center.

Results

A total of 217 patients were included in the subgroup analyses with 126 and 91 patients receiving apixaban or placebo, respectively. The baseline characteristics are depicted in Table 1. Major VTE occurred in 6 (4.8%) patients in the apixaban group and 17 (18.7%) patients in the placebo group (HR 0.26; 95% CI, 0.14-0.47; p<0.0001). Major bleeding occurred in 2 (1.6%) patients in the apixaban group and 2 (2.2%) patients in the placebo group (HR 0.69; 95% CI, 0.20-2.35; p=0.556).

Conclusions

Primary thromboprophylaxis with apixaban in patients with cancer and a CVC seems to reduce the risk of VTE without increasing the risk of major bleeding. Future studies are needed to confirm these findings.

Disclosures: Wells: BMS/Pfizer: Research Funding; Bayer: Honoraria; Pfizer: Honoraria; Bristol-Myers Squibb: Honoraria; Servier: Honoraria. Carrier: Bristol Myers Squibb: Honoraria; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Aspen: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Honoraria; Servier: Honoraria; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees; LEO Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi Aventis: Honoraria, Membership on an entity's Board of Directors or advisory committees.

*signifies non-member of ASH