Add-on belimumab efficacy maintained for up to 13 years in SLE patients
medwireNews: Individuals with systemic lupus erythematosus (SLE) who respond to belimumab plus standard of care (SOC) therapy can hope to experience long-term disease control, suggests a trial in which participants received treatment for up to 13 years.
Moreover, “the long-term safety profile of belimumab was acceptable,” say the investigators in Arthritis & Rheumatology.
They report on a continuation study that included the participants of a double-blind phase II trial who achieved a satisfactory response to intravenous belimumab given alongside SOC. In all, 62.6% of the 476 participants entered the continuation study, with 32.2% remaining in the study until it closed and 29.7% participating for at least 11 years.
The proportion of patients attaining an SRI response to treatment with belimumab 10 mg/kg every 4 weeks plus SOC rose from 32.8% of 268 patients at the 1-year mark to 75.6% of 90 patients at year 12, and similar increases were seen for other outcome measures as well, including in the SELENA-SLEDAI and BILAG scores.
The study authors note that although such increases were inevitable given patient withdrawals over time and the consequent decreases in sample size, the long-term effects of the study regimen on disease control were also evident in the low risk for flare over the course of the study.
Specifically, SELENA–SLEDAI Flare index (SFI) flares occurred at a rate of 2.3 per patient–year in the first year, falling to 1.6 per patient–year in year 2, and ranging from 0.6 to 1.1 per patient–year from the third to beyond the 11th year. The incidence of severe SFI flares was also highest in year 1, at 0.3 per patient–year, after which the incidence ranged from 0.0 to 0.1 per patient–year.
The annual incidence of adverse events (AEs) either decreased or remained stable through the course of the study, and there were no new safety signals, report Daniel Wallace (Cedars-Sinai Medical Center, Los Angeles, California, USA) and colleagues. Specifically, the rate of all AEs gradually decreased from 1203.1 cases per 100 patient–years in year 1 to 603.4 per 100 patient–years in year 11, with the occasional rise at the 7- and 8-year marks.
The researchers add that the rate of serious infections and infestations “remained steady,” and “[t]he rate of self-injury/suicide remained low throughout this study.”
Wallace and team also demonstrated a reduction in corticosteroid use over the course of the study. In the subgroup of patients who were using a higher dose of corticosteroids than 7.5 mg/day prednisone equivalent, the proportion achieving a dose equal to or below this cutoff increased as the study progressed, reaching a maximum of 53.8% at 12 years.
Wallace et al caution that “[p]atients who remained in the study were likely to be those who responded better or tolerated belimumab better than patients who withdrew; hence, the findings may not be representative of all patients with SLE.”
Looking to the future, they believe that “[i]t will be important to investigate the effects of stopping belimumab in patients who have achieved stable, long-term low-level disease activity; and a study (NCT02119156) is under way to investigate this question.”
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