MADRID – Retreatment of rheumatoid arthritis (RA) with an ultra low-dose of rituximab failed to meet the predefined noninferiority endpoint relative to a higher dose in a double-blind randomized trial, but the investigators still think this strategy may be viable in selected patients.
Lise M. Verhoef, MSc, a researcher in rheumatology at the Sint Maartenskliniek in Nijmegen, the Netherlands, who presented the data as a late-breaker at the European Congress of Rheumatology, explains in a video interview why the negative trial still might support an ultra low-dose strategy.
This trial, called REDO, was conceived after it was observed that most patients with RA are well controlled on a single injection of 1,000 mg of rituximab even though this is half the standard dose of two 1,000 mg doses given 15 days apart. The study was designed to determine whether even lower doses could be used.
The study enrolled 142 patients with RA who were being retreated with rituximab after responding previously to this therapy. In a 1:2:2 ratio, patients were randomized to single rituximab injections of 1,000 mg, 500 mg, or 200 mg. Outcome then were compared at the end of 6 months.
Noninferiority was defined as 0.5 difference in DAS28-CRP score (disease activity score using C-reactive protein instead of erythrocyte sedimentation rate) score adjusted for baseline disease status and use of conventional disease-modifying antirheumatic drugs (DMARDs).
Although noninferior at 3 months, the 500 mg dose did not meet the noninferiority criteria at 6 months. Due to a hierarchical design, evaluation of the 200 mg dose was precluded by the negative result with the 500 mg dose.
However, the majority of patients did respond to both the 500 mg and 200 mg dose. The failure to meet noninferiority was due to a limited number of patients who required rescue therapy for a flare. As a result, the investigators believe a trial of ultra low-dose therapy still might be reasonable.
In this interview, Ms. Verhoef explains that at her center patients who are well controlled on a 1,000 mg dose of rituximab now are being offered a 500 mg dose for retreatment. If they continue to respond, further retreatment with a 200 mg dose is considered.
Ms. Verhoef had no relevant financial disclosures.