Rituximab falls short in Sjögren's syndrome trial
medwireNews: Treatment with two courses of rituximab does not reduce fatigue or oral dryness among patients with primary Sjögren's syndrome (PSS), results of the TRACTISS trial suggest.
“[T]he lack of effect of 2 courses of rituximab seems in line with the lack of benefit of one course in randomised trials,” say the study authors.
Simon Bowman (University Hospitals Birmingham NHS Foundation Trust, UK) and colleagues found that 39.8% of 61 patients receiving two courses of the anti-CD20 antibody – each comprising two doses of 1000 mg – achieved the primary endpoint of a 30% reduction in fatigue or oral dryness at 48 weeks, as measured on the Visual Analog Scale. By comparison, 37.5% of 56 patients receiving placebo met the primary endpoint.
After multiple imputation of missing outcomes and adjustment for factors including age, disease duration, and study center, patients receiving rituximab were not significantly more likely to achieve the primary endpoint than those receiving placebo, reports the team in Arthritis & Rheumatology.
There was also no improvement in composite patient-reported outcomes or disease activity indices at 48 weeks among patients receiving rituximab versus placebo.
Although log-transformed measurements of unstimulated salivary flow were significantly different between the rituximab and placebo groups at weeks 36 and 48 (1.0 vs 0.6 mL/15 min at both timepoints), the authors note that “given the many statistical tests performed in these secondary outcome analyses, this may well be a Type I error and should not be over-interpreted.”
Furthermore, the cost of treatment per patient was significantly higher with rituximab than placebo, at £ 10,752 (US$ 13,434; € 12,430) versus £ 2,672 (US$ 3338; € 3090), indicating that “[r]ituximab is neither clinically or cost-effective in this patient population.”
Patients receiving rituximab experienced “slightly more” adverse events (AEs) than those receiving placebo, but there was no increase in the incidence of serious AEs with rituximab treatment, with 10 patients in each group experiencing a serious AE.
“Although there did not appear to be any excess risk due to rituximab, the results of the TRACTISS trial do not support the general use of rituximab in treating PSS,” say Bowman and colleagues.
The authors of an accompanying editorial, Hendrika Bootsma (University Medical Center Groningen, the Netherlands) and colleagues, believe that the results raise the question of “whether rituximab is indeed a failing drug or whether rituximab is only effective in a selected category of pSS patients.”
PSS “is a heterogeneous disease,” they add, noting that “rituximab might be of value in a particular, yet to be selected, subgroup of pSS patients.”
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