medwireNews: Phase 3 trial findings presented at the ACR Convergence 2021 virtual meeting suggest that adding a single cycle of rituximab to belimumab therapy does not improve disease control rates among patients with systemic lupus erythematosus (SLE).
Speaking in a poster presentation, Cynthia Aranow (Northwell Health, Great Neck, New York, USA) explained that belimumab and rituximab have “potentially synergistic mechanisms of action,” leading the BLISS-BELIEVE investigators to hypothesize that “combination therapy may enhance clinical benefits in SLE.”
Aranow reported that the rate of disease control at week 52 – defined as a SLEDAI-2K score of 2 points or lower with a prednisone-equivalent dose of 5 mg/day or less and no other immunosuppressants – was 19.4% for the 144 participants who were randomly assigned to receive 52 weeks of treatment with belimumab 200 mg/week alongside rituximab 1000 mg at weeks 4 and 6.
This was similar to the disease control rate of 16.7% for the 72 patients given belimumab plus placebo, with no significant difference between the groups. The average SLEDAI-2K score at baseline was approximately 10 points.
There were also no significant differences in rates of disease control at the 104-week follow-up and clinical remission (SLEDAI-2K=0 with no immunosuppressants) at week 64 with rituximab versus placebo, with rates of 11.1% versus 6.9% and 6.3% versus 5.6%, respectively.
However, Aranow noted that the average duration of disease control was significantly greater in the rituximab versus the placebo arm (105.4 vs 60.1 days), as was the average decrease in SLEDAI-2K score from baseline to week 104 (7.2 vs 5.1 points).
Among participants with anti–double-stranded (ds)DNA antibodies at baseline, there was a significantly greater decrease in median levels at 52 weeks among those in the rituximab group than those in the placebo arm, with reductions of 69.2% versus 46.1%.
Similar findings suggesting possible beneficial effects of combination therapy on anti-dsDNA antibody levels were observed in the BEAT-LUPUS trial, reported previously by medwireNews, which compared rituximab plus belimumab with rituximab monotherapy.
Aranow reported that the overall safety findings for belimumab and rituximab in the BLISS-BELIEVE trial were consistent with the known safety profiles of both drugs. There were more serious infections in the rituximab than the placebo group, with respective rates of 5.6% versus 2.8% at the 52-week timepoint, and 9.0% versus 2.8% at the 104-week follow-up.
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