Promising results for subcutaneous belimumab in subset of SLE patients
medwireNews: Treatment with subcutaneous belimumab may be beneficial for patients with SLE who are hypocomplementemic and positive for antibodies against double-stranded (ds)DNA, subgroup analyses of a phase III trial suggest.
Prior studies have demonstrated that SLE patients with these characteristics derive greater benefits from treatment with the intravenous form of belimumab than other patients, say Andrea Doria (University of Padova, Italy) and fellow researchers.
They add that “[t]he development of a novel liquid formulation of belimumab, along with a prefilled syringe and autoinjector device, enables patients to self-administer subcutaneous belimumab,” and note the efficacy of this formulation has previously been demonstrated in a placebo-controlled phase III trial of 836 patients with active, autoantibody-positive SLE.
In a prespecified subgroup analysis of this trial, reported in Arthritis & Rheumatology, Doria and team evaluated the efficacy of weekly subcutaneous belimumab 200 mg versus placebo, given alongside standard care for 1 year, in the 356 patients who were hypocomplementemic (complement C3 <90 mg/dL and/or C4 <10 mg/dL) and anti-dsDNA positive at baseline.
At the 1-year follow-up, 64.6% of the 248 patients in this subgroup who were given belimumab achieved an SLE Responder Index (SRI) response, compared with 47.2% of the 108 patients given placebo, translating into an absolute difference of 17.4% between groups and a significant odds ratio (OR) of 2.23 in favor of belimumab.
Although there was no significant interaction between the subgroup studied and SRI response rate, the researchers note that “a trend towards greater benefit compared with the overall intent-to-treat population was observed.”
SRI response rates in the overall trial population were 61.4% for belimumab-treated patients versus 48.4% for those given placebo (treatment difference=13.0%; OR=1.68).
Among the hypocomplementemic and anti-dsDNA positive patients, those given belimumab also had a significantly lower incidence of severe flares than placebo-treated patients (14.1 vs 31.5%), and a numerically greater proportion of patients in the belimumab group who were taking corticosteroids at baseline were able to reduce their corticosteroid dose by at least 25% to 7.5 mg/day or lower (20.7 vs 11.4%).
In the safety analysis, the researchers observed that the adverse event profile in the subgroup studied was “similar” to that in the overall trial population, and was “consistent with the known safety profile of belimumab.”
Taken together with analyses of the BLISS IV studies, these results suggest that “irrespective of the formulation used, belimumab is effective in patients with SLE who are hypocomplementemic and anti-dsDNA positive,” conclude Doria and team.
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