Belimumab Has Favorable Safety, Efficacy in Patients With SLE

A new report suggests long-term use of Benlysta (belimumab) is safe in patients with systemic lupus erythematosus (SLE) and can lead to durable responses similar to those in other populations.

The study, published in RMD Open, offers some of the first long-term safety and efficacy data among patients in East Asia and shows that the therapy can reduce reliance on corticosteroids.

The authors noted that SLE is more common, and generally more severe, in non-White populations than in White populations.

“​​In Japan, SLE is estimated to affect 4.3 to 37.7 people per 100,000, and in South Korea, the estimated prevalence is 20.6 to 26.5 people per 100,000,” they wrote.

The treatment landscape for SLE has gaps. Although patients are generally prescribed immunosuppressants and corticosteroids, many patients still experience a significant disease burden and can suffer adverse effects (AEs) from long-term use of those drugs.

Belimumab is a recombinant humanized immunoglobulin G1 lambda monoclonal antibody that binds to and antagonizes the biology of B-lymphocyte stimulator protein. Patients with SLE have elevated levels of this protein, the investigators wrote.

Intravenous belimumab is approved in the United States, Europe, Japan, and South Korea, yet the authors said there is little in the way of long-term safety and efficacy evidence in Japanese and South Korean populations, despite higher prevalence of the disease in those populations.

They constructed a phase 3 open-label continuation study that built upon 2 previous studies of belimumab. Patients who completed the earlier studies were given 10 mg/kg of belimumab once every 4 weeks for up to 7 years. The study’s primary end point was safety, and the secondary end points were response rate, SLE flares, and prednisone use.

A total of 142 patients were enrolled, all of whom had moderate SLE; 73.2% of patients completed the study. The patients in the study sought care from one of 27 study centers in Japan and South Korea.

In terms of safety, most of the patients (97.4%) experienced AEs, although only about one-third (33.8%) were considered serious AEs. Cellulitis, contusion, and herpes zoster were the most commonly reported serious AEs. Only 4.9% of patients experienced an AE that led to withdrawal from the study.

“No trends of clinical concern were observed over time with regard to incidence of grade 3 or 4 values in hematology parameters, clinical chemistry, and urinary values,” the authors wrote. “There were no grade 3 or 4 serum IgG values reported post first dose of belimumab.”

Turning to the secondary end points, disease activity index scores suggested a significant reduction in disease activity in many patients over the life of the study. For instance, the number of patients achieving the benchmark of SLE Responder Index 4 (SRI4) increased over time.

“Overall, the proportion of SRI4 responders during belimumab treatment increased from 47.8% (65 of 136 patients) at Year 1, Week 24, to 68.2% (15 of 22 patients) at Year 6, Week 48,” the investigators said.

Severe flares occurred in 14.8% of patients, at a median of 585 days following the first dose of belimumab. However, the data also showed that patients’ use of prednisone decreased over the long term, a positive sign for belimumab’s efficacy.

“In conclusion, the safety results of this 7-year study of patients with SLE from Japan and South Korea are consistent with those observed in previous 7- [to] 13-year open-label continuation studies of belimumab added to standard therapy,” the authors wrote.

Reference

Tanaka Y, Bae S-C, Bass D, et al. Long-term open-label continuation study of the safety and efficacy of belimumab for up to 7 years in patients with systemic lupus erythematosus from Japan and South Korea. RMD Open. Published online July 7, 2021. doi:10.1136/rmdopen-2021-001629