OC-11 - Anticoagulation therapy in selected cancer patients at risk of recurrence of venous thromboembolism

Introduction: Venous thromboembolism (VTE) in cancer patients is an increasingly frequent clinical problem. The overall impact of VTE on cancer patients can be considerable. Targeted patient selection by identifying patients with clinically significant recurrent VTE may have wider health economic benefits whilst reducing patient risk through over-treatment. In the UK, dalteparin is one licensed anticoagulant for the extended treatment and prevention of recurrence of VTE in cancer patients. Rivaroxaban is a highly selective direct Factor Xa inhibitor with oral bioavailability.

Aim: To assess VTE recurrence in selected cancer patients at risk of recurrence of VTE treated with rivaroxaban or dalteparin. The secondary objectives include safety, acceptability, biomarker identification and health economics.

Materials and methods: Select-d is a prospective, randomised, open label, multicentre pilot trial comparing dalteparin (200 IU/kg daily subcutaneously for 1 month and 150 IU/kg months 2-6); and rivaroxaban (15mg orally twice daily for 3 weeks and 20mg once daily for 6 months in total) for cancer patients with VTE - symptomatic and incidental pulmonary embolism (P)E or symptomatic lower limb proximal deep vein thrombosis (DVT) - with a second placebo-controlled randomisation (rivaroxaban vs placebo) comparing the duration of therapy (6 vs 12 months) in all patients with PE and those with a DVT who are residual vein thrombosis (RVT) positive. 70% of DVT patients are estimated to be RVT positive after initial treatment. 530 patients are being recruited toprovide reliable estimates of the primary outcome (VTE recurrence rates) to within the 95% confidence interval of 8% assuming VTE rates are 10% at six months.

Results: As of 1st December 2015, 264 patients have been recruited from 61 open sites across the UK. Preliminary data indicate that the majority of patients presented with solid tumours (98%), ranging from early or locally advanced (41%) to metastatic disease (57%), and primarily comprising colorectal, lung, and breast malignancies. Only a small number of select-d patients presented with haematological malignancies (2%), which included; leukaemia, myeloma and lymphoma. Over half of the select-d patients had an incidental PE (54%); the remainder had symptomatic PE or DVT (46%). The median number of hours on anticoagulation prior to starting select-d randomised treatment was 48 hours.

Conclusions: select-d is the first randomised trial for treatment of VTE, investigating the direct oral anticoagulants vs a low molecular weight heparin in patients with cancer. The results will support optimal treatment for this key patient group and are eagerly awaited.