medwireNews: Findings from the proof-of-concept BRIDGE-PMR study suggest that rituximab, a chimeric monoclonal antibody against CD20 that causes B cell depletion, may be beneficial for the treatment of polymyalgia rheumatica (PMR).
For the study, 47 patients with recently diagnosed PMR (n=38) or relapsing disease on at least 7.5 mg/day of prednisolone (n=9) were randomly assigned to receive either a single infusion of rituximab 1000 mg or placebo, together with a 17-week glucocorticoid treatment with taper to 0 mg. All participants (mean age approximately 65 years) had received standard premedication according to local treatment protocol in rheumatoid arthritis.
The authors observed that at 21 weeks, 48% of the 23 patients in the rituximab group and 21% of 24 individuals included in the placebo group achieved glucocorticoid-free remission, defined as a PMR activity score of less than 10. These findings translated into an absolute risk difference of 27 percentage points and a significant 2.3-fold higher odds of glucocorticoid-free remission favoring rituximab.
Moreover, a significantly higher proportion of patients in the rituximab-treated group versus the placebo group reached a glucocorticoid dose of 5 mg/day or less (100 vs 54%).
“No differences [between rituximab and placebo] were seen in other secondary outcomes, including measures of patient functioning and quality of life, with the exception of change from baseline in median morning stiffness, which favoured rituximab,” write Diane Marsman (Sint Maartenskliniek, Nijmegen, the Netherlands) and fellow investigators in The Lancet Rheumatology.
When assessing the safety of rituximab, the team notes that there was only one serious adverse event, a pulmonary embolism, observed in one patient in the rituximab group and no deaths were reported during the study. There were 10 infusion-related adverse events in the rituximab group versus three in the placebo arm.
Writing in an accompanying comment, Elisabeth Brouwer and colleagues, from the University Medical Center Groningen in the Netherlands, say that “[t]he results of the BRIDGE-PMR study are encouraging.” However, they add that “a longer-term, phase 3, randomised controlled trial is needed to further substantiate the results of the present study and to inform on the long-term efficacy and safety of rituximab in patients with polymyalgia rheumatica.”
And Marsman et al conclude: “If these results are confirmed in larger trials, rituximab could be a valuable treatment for patients with polymyalgia rheumatica, particularly if they have (relative) contraindications for treatment with glucocorticoids or a poor prognosis.”
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