Minimal dose of edoxaban is effective for treatment of deep vein thrombosis in cancer patients

Background In cancer patients, anticoagulation is recommended for distal deep vein thrombosis (DVT) because of high risk of worsening without treatment. Edoxaban is frequently selected for treating DVT during cancer therapy due to its lower risk of drug interactions compared to other direct oral anticoagulants. On the other hand, edoxaban has been reported to increase bleeding in a dose-dependent manner. Therefore, a minimal dose of edoxaban should be the preferred choice for treating DVT in cancer patients. However, the efficacy of a minimal dose of edoxaban has not yet been reported. Purpose The aim of this study is to investigate whether a minimal dose of edoxaban has an effect on reducing thrombus size. Methods This is a retrospective cohort study at a single institution. A total of 224 consecutive patients with distal DVT of the lower extremities (excluding proximal DVT and pulmonary thromboembolism) were included from April 2019 to March 2020. Of these, 172 could be followed by repeated ultrasound examinations, for up to 33 months. The following patients were excluded: those who used anticoagulants other than edoxaban 15 mg/day or 30 mg/day (n=34), those who discontinued edoxaban due to bleeding within days after starting it (n=8), those with a history of anticoagulant therapy for DVT within the past year (n=5), and those who had a dose change (n=2). Finally, we divided the included study subjects (n=123) into 3 groups: Group 0: 33 patients with no anticoagulation therapy; Group 1: 35 patients using edoxaban 15 mg/day; Group 2: 55 patients using edoxaban 30 mg/day. The primary endpoint was worsening of DVT defined as an increase in total length of DVT by ultrasound. Results As shown in Figure 1, in group 0 with no anticoagulant therapy, 21 patients experienced an increase in thrombus length. In Group 1 with edoxaban 15 mg/day, 4 patients worsened. In group 2 with edoxaban 30 mg/day, we found that 5 patients worsened. There was significant worsening of DVT in group 0 with no anticoagulation therapy compared to group 1 with edoxaban 15 mg/day (p<0.0001), but no significant difference between group 1 with edoxaban 15 mg/day and group 2 with edoxaban 30 mg/day (p=0.73). As shown in Figure 2, pairwise log-rank analysis showed significantly higher event incidence in the no anticoagulation group compared to both edoxaban groups (p < 0.001), whereas no significant difference was observed between edoxaban 15 mg/day and 30 mg/day. Conclusion A minimal dose of edoxaban (15 mg/day) is an effective treatment option for distal deep vein thrombosis in cancer patients.