NEW YORK (Reuters Health) – Among patients with myeloma treated with thalidomide, antithrombotic prophylactic therapies with aspirin, warfarin or enoxaparin reduce thromboembolic events to a similar degree, according to an Italian study.

The researchers note in their report in the Journal of Clinical Oncology online January 31 that treatment with melphalan, prednisone, and thalidomide is now standard in elderly patients with myeloma, but thalidomide increases the risk of thromboembolism substantially.

“Without thromboprophylaxis,” the authors point out, “the incidence of thromboembolic events has been reported to be 14% to 26% in patients with myeloma receiving thalidomide plus dexamethasone and 10% to 20% in patients receiving thalidomide plus melphalan.” The advantage of different single-agent antithrombotic strategies is unclear.

Dr. Michele Cavo, with Azienda Ospedaliero-Universitaria S. Orsola-Malpighi, in Bologna, and colleagues conducted a multicenter, open-label study to compare aspirin, fixed low-dose warfarin or low molecular weight heparin for preventing thromboembolism in this setting.

They randomly assigned 667 myeloma patients receiving thalidomide-containing regimens to thromboprophylaxis with aspirin 100 mg/d, warfarin 1.25 mg/d, or enoxaparin 40 mg/d. Results for 659 patients were analyzed.

The median duration of prophylaxis was about 2.5 months. The overall 6-month rate of serious thromboembolic events, cardiovascular events or sudden deaths was 6.5%, according to the report.

Broken down by prophylactic regimen, the 6-month rates were 6.4% with aspirin, 8.2% with warfarin, and 5.0% with enoxaparin. After a median follow-up of nearly 25 months, corresponding rates were 8.6%, 10.0% and 7.8%.

The absolute between-group differences were not statistically significant at either time point.

“Major bleeding occurred during the first 6 months in three patients (1.4%) who received aspirin but in no patients who received either warfarin or low molecular weight heparin,” Dr. Cavo and colleagues found.

They conclude, “Both aspirin and warfarin showed similar safety and efficacy in reducing thromboembolic complications when compared with low molecular weight heparin in patients with myeloma treated with thalidomide-based regimens.”

Reference:

Aspirin, Warfarin, or Enoxaparin Thromboprophylaxis in Patients With Multiple Myeloma Treated With Thalidomide:A Phase III, Open-Label, Randomized Trial

J Clin Oncol 2011;28.