A Phase III Study of Enoxaparin vs Aspirin vs Low-Dose Warfarin as Thromboprophylaxis for Newly Diagnosed Myeloma Patients Treated with Thalidomide Based-Regimens.

The risk of venous thromboembolism (VTE) is high in newly diagnosed myeloma (MM) patients who receive thalidomide-based regimens. Anticoagulant prophylaxis is recommended. Controversies exist on the best thromboprophylactic regimen to adopt. Aims. In this prospective, multicenter phase III trial we evaluated the safety and the efficacy of low-molecular weight heparin (LMWH) or low-dose aspirin (ASA) or low-fixed dose warfarin (WAR) as anticoagulant prophylaxis. End-points were incidence of VTE, acute cardiovascular events, sudden death, major and minor bleeding.

In a GIMEMA study, 991 newly diagnosed MM patients were randomized to VTD (Velcade 1.3 mg/m2 d 1,4,8,11; Thalidomide 200 mg/d; Dexamethasone 320 mg/21 d) or TD (Thalidomide 200 mg/d; Dexamethasone 320 mg/21 d) or VMPT (Velcade 1.3 mg/m2 d 1,8,15,22; Melphalan 9 mg/m2 d 1-4; Prednisone 60 mg/m2 d 1-4; Talidomide 50 mg/d) or VMP (Velcade 1.3 mg/m2 d 1,8,15,22; Melphalan 9 mg/m2 d 1-4; Prednisone 60 mg/m2 d 1-4). In a sub-study, patients treated with VTD or TD or VMPT were randomly assigned to receive LMWH (Enoxaparin 40 mg/d, N=223) or ASA (Aspirin 100 mg/d, N=227) or WAR (Warfarin 1.25 mg/d, N=223) for the duration of the induction therapy; 61 patients were excluded from sub-study because of indication for anticoagulant/antiplatelet therapy or high-risk of bleeding. Patients treated with VMP (N=257) did not receive any prophylaxis and were used as controls.

Patient characteristics and distribution of major risk factors were similar in all groups. The incidence of VTE was 5% in the LMWH group, 6% in the ASA group and 8% in the WAR group (p not significant). VTEs were 2% in the VMP group. Median time to onset of VTE for patients who received LMWH or ASA or WAR were 4.7, 2.4 and 2.4 months, respectively. Patients who received higher doses of both steroids and thalidomide (VTD and TD) had a higher VTE incidence (7%) in comparison with those who received lower doses (VMPT, 3%, p=0.06). Patients treated with bortezomib (VTD and VMPT) had a lower VTE incidence (5%) in comparison with patients on TD (8%, p=0.08). The rates of cardiovascular events were 2% in the LMWH group, 1% in the ASA group and 0.5% in the WAR group. The incidence of major and minor bleeding was 2% in the LMWH group, 3% in the ASA group and 1% in the WAR group (p not significant). The incidence of combined thrombosis, bleeding and cardiovascular events was 9% in the LMWH group, 10% in the ASA group and 9% in the WAR group (p not significant).

The overall incidence of VTE was less than 10% in all groups and was not superior to that expected during the natural course of MM. The LMWH patients had lower risk of VTE, although no statistical difference was observed. LMWH, WAR and ASA are likely to be effective thromboprophylactic regimens. The final analysis on 991 patients will be presented at the meeting.

No relevant conflicts of interest to declare.