Rheumatoid arthritis

Ultra-low rituximab dose effective in patients with RA

Long-term use of an ultra-low dose of rituximab in patients with rheumatoid arthritis (RA) was effective at maintaining low disease activity for up to four years, according to research presented at ACR Convergence 2021.

Furthermore, patients were rarely switched to other disease-modifying anti-rheumatic drugs (DMARDs) or needed to use glucocorticoids to aid disease control, according to the extension study of the REDO trial designed to clarify the optimal dose of rituximab in RA.

As previously reported by the limbic, REDO initially showed comparable six-month efficacy of continued treatment with 500mg and 200mg rituximab compared to 1,000mg, but was unable to establish formal non-inferiority.

For the extension trial, researchers analysed 118 patients’ disease activity (using DAS028 and C-reactive protein levels) and their use of RA medications, including biologic or targeted DMARDs, conventional synthetic DMARDs and glucocorticoids, for up to four years (median follow-up 3.2 years).

Seven patients switched to another biologic or targeted synthetic DMARD, at which point they were removed from the analyses of disease activity.

The extension trial showed that disease activity in both ultra-low dose groups was non-inferior to the 1,000mg group, with a mean DAS28-CRP during follow-up of 2.2 in the 1000mg group, 2.2 in the 500mg group and 2.3 in the 200mg group. The researchers also noted that lower rituximab dose was “significantly associated” with a higher DAS28-CRP: 0.15 points higher per 1,000mg more rituximab.

“The majority of patients treated with ultra-low dose rituximab remained on ultra-low doses for up to 4 years, while disease activity remained low and did not relevantly differ between rituximab doses,” they concluded.

According to co-author Nathan den Broeder, a PhD student at Sint Maartenskliniek in the Netherlands, the benefits of ultra-low dose rituximab in this setting are significant. “We showed in the original trial that ultra-low dose rituximab results in fewer infections compared to the standard 1,000 mg dose, something that is especially relevant in the current pandemic.”

“Another benefit is that the duration of the infusion, which can normally take several hours, can be shortened with administering these lower doses. Finally, there are important cost-savings with using ultra-low dose rituximab, a relatively expensive drug. In short, by using ultra-low dose rituximab, patients can expect fewer infections as side effects, shorter infusion times, and lower treatment costs.”

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