Regional Responses To Sifalimumab Differ Among SLE Patients

Results from a Phase 2a clinical trial  recently presented during the European League Against Rheumatism Annual European Congress of Rheumatology revealed regional differences in the response to sifalimumab treatment in systemic lupus erythematosus (SLE) patients.

Sifalimumab (formerly MEDI-545) is an investigational human monoclonal antibody that targets IFN-α, a type of inflammatory cytokine in the body known to play a role in the development of SLE. Previous studies have shown that high levels of type I IFN-α are correlated with a more severe disease activity in SLE patients, and early studies of sifalimumab have demonstrated that this agent blocks signalling of all interferon alpha subtypes.

In the study a team of researchers led by Dr. Kamashta M. randomized 431 patients with systemic lupus erythematosus (SLE) to receive either sifalimumab intravenously at 200 mg, 600 mg or 1,200 mg every month or placebo for a period of 52 weeks. Based on the parameters of high or low standard of care responses, the researchers grouped patients into two geographical regions. Region 1 included Central America, South America, Asia and Eastern Europe, and was considered as the high-expected response to standard of care group (n=296 patients). Region 2 included Western Europe, North America and South Africa (n=135 patients) and was considered the low expected standard of care response group.

In comparison to placebo, patients treated with sifalimumab in both regions had greater response rates. However patients in Region 1 had better improvements than those in Region 2, even though these differences were not correlated with disease activity scores. Furthermore, the results showed differences between the two groups in clinical and demographic characteristics.

In Region 2, the results revealed higher mean Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology Damage Index scores, mean age, mean weight, standard of care and median time to diagnosis until randomization (researchers defined standard of care as including the use of mycophenolate, azathioprine, methotrexate, antimalarials, and corticosteroids and dose).