Potential Treatment for Thrombotic APS in Lupus Patients Shows Promise in Clinical Trial

The results of a Phase 2/3 trial at two hospitals in the U.K. comparing the effectiveness of Xarelto (rivaroxaban) and Coumadin (warfarin) in the treatment of patients with thrombotic antiphospholipid syndrome (APS), with or without systemic lupus erythematosus, showed that Xarelto can be a safe and effective option for patients with APS.

Results from the RAPS study were published in The Lancet Haematology journal, titled “Rivaroxaban Versus Warfarin To Treat Patients With Thrombotic Antiphospholipid Syndrome, With Or Without Systemic Lupus Erythematosus (RAPS): A Randomised, Controlled, Open-Label, Phase 2/3, Non-Inferiority Trial,” by Dr. Hannah Cohen, MD, and her colleagues.

Thrombosis (blockage of a blood vessel) is one of the clinical hallmarks of APS, a heterogeneous autoimmune disorder associated with the presence of antiphospholipid antibodies (antibodies against the main component of cell membranes, the phospholipids) in the blood. Approximately 15 percent of patients with systemic lupus erythematosus (SLE) have thrombotic APS, which greatly worsens the disease.

Anticoagulants such as Coumadin and other vitamin K antagonists, are usually administered to prevent venous thromboembolism. However, there are reports of APS patients who suffered thrombosis while taking these drugs, so it’s necessary that other treatment options are found.

“We did the Rivaroxaban in Antiphospholipid Syndrome (RAPS) trial to investigate whether [Xarelto] would provide anticoagulation non-inferior to that achieved with standard-intensity [Coumadin] in patients with antiphospholipid syndrome and previous venous thromboembolism, with or without systemic lupus erythematosus,” the authors wrote in their report.

The trial included 116 APS patients who were taking Coumadin for previous venous thromboembolism, 54 of whom switched to Xarelto (an oral daily dose of 20 mg), and 56 of whom stayed on Coumadin. In both groups, 11 patients had SLE.

The endogenous thrombin potential (the parameter that describes coaguability) indicated that Xarelto was less effective than Coumadin. However, when researchers analyzed the peak thrombin concentrations, which they consider to be a parameter that better reflects thrombotic risk than endogenous thrombin potential, they observed that Xarelto was no less effective than Coumadin. The results obtained for markers of coagulation in the blood support that both drugs have a similar anticoagulant effect.

Moreover, no new thrombotic events or major bleeds were reported in the six-month study follow-up, and the quality of life of patients treated with Xarelto was improved, supporting the theory that this drug can be a safe and effective option to Coumadin.

But given the small sample of patients and the limited duration of the study (42 days), future trials with larger population samples and longer follow-up periods are required before considering Xarelto as a treatment for APS in patients with or without SLE.