A randomized phase II trial of apixaban for the prevention of thromboembolism in patients with metastatic cancer

BACKGROUND: Cancer patients receiving chemotherapy are at increased risk for thrombosis. Apixaban, a factor Xa inhibitor, is oral and does not require laboratory monitoring. OBJECTIVES: A pilot study was conducted to evaluate whether apixaban would be well tolerated and acceptable in cancer patients receiving chemotherapy. PATIENTS/METHODS: Subjects receiving either first-line or second-line chemotherapy for advanced or metastatic lung, breast, gastrointestinal, bladder, ovarian or prostate cancers, cancer of unknown origin, myeloma or selected lymphomas were randomized to 5 mg, 10 mg or 20 mg once daily of apixaban or placebo in a double-blind manner for 12 weeks. Use of the study drug began within 4 weeks of the start of chemotherapy. The primary outcome was either major bleeding or clinically relevant non-major (CRNM) bleeding. Secondary outcomes included venous thromboembolism (VTE) and grade III or higher adverse events related to the study drug. Thirty-two patients received 5 mg, 30 patients 10 mg, 33 patients 20 mg, and 30 patients placebo. In these groups, there were 0, 0, 2 and 1 major bleeds, respectively. The corresponding data for CRNM bleeds were 1, 1, 2, and 0. The rate of major bleeding in the 93 apixaban patients was 2.2% (95% confidence interval 0.26-7.5%). There were no fatal bleeds. Three placebo patients had symptomatic VTE. CONCLUSIONS: Apixaban was well tolerated in our study population. These results support further study of apixaban in phase III trials to prevent VTE in cancer patients receiving chemotherapy.