Rituximab Associated With Glucocorticoid-Free Remission in Polymyalgia Rheumatica

In patients with polymyalgia rheumatica (PMR), glucocorticoid-free remission was found to be maintained with a single dose of rituximab, according to study findings published in The Lancet Rheumatology.

The BRIDGE-PMR trial is a proof-of-concept, randomized, controlled trial in which the administration of a single rituximab 1000-mg infusion was associated with a high glucocorticoid-free remission rate at 21 weeks among patients with PMR. Participants in in the trial randomly assigned 1:1 to receive rituximab or placebo.

In the 1-year extension of BRIDGE-PMR, the researchers sought to evaluate whether glucocorticoid-free remission was maintained at 1 year after rituximab therapy, thus implying the existence of a disease-modifying effect that continues beyond the anticipated pharmacodynamic effects of rituximab in other inflammatory disorders, including rheumatoid arthritis (RA).

The extension analysis, which was initiated after the 21-week follow-up period, was completed at 1 year after baseline infusion.

The primary study outcome was glucocorticoid-free remission at 1 year after rituximab therapy. Glucocorticoid-free remission was defined as a PMR-activity score (PMR-AS) of less than 10 without the use of systemic glucocorticoids.

Secondary outcomes included the following:

• PMR-AS at 1 year following rituximab infusion
• Percentage of participants with a relapse during the extension study
• Proportion of participants with elevated C-reactive protein (CRP) levels during the extension period
• Percentage of patients receiving low-dose glucocorticoids (≤5 mg/d) 1 year after rituximab infusion
• Cumulative glucocorticoid dose at 1 year after rituximab infusion
• Disease-modifying antirheumatic drug (DMARD) utilization 1 year after rituximab infusion
• Quality of life according to EuroQoL-5 Dimensions-5 Level (EQ-5D-5L) 1 year after rituximab infusion
• Number/percentage of participants with an adverse event (AE)

Patients with PMR who were evaluated in the original BRIDGE-PMR trial were included in the extension study. A total of 47 patients with PMR were included, with 23 (11 women; mean age, 64 years) in the rituximab group and 24 (13 women; mean age, 66 years) in the placebo group. Among these, 38 had recently been diagnosed with PMR and 9 had relapsing PMR.

Results of the complete case analysis revealed that 47% (n=9/19) of those in the rituximab group were in glucocorticoid-free remission at 1 year following the infusion, compared with 23% (n=5/22) of those in the placebo group (absolute difference, 25% [95% CI, -4% to 53%]; relative risk [RR], 2.1 [95% CI, 0.8-5.2]; P =.12).

Following imputation, the percentages of individuals in glucocorticoid-free remission were 52% in the rituximab group vs 21% in the placebo group (absolute difference, 31% [95% CI, 5%-57%]; RR, 2.5 [95% CI, 1.0-6.0]; P =.04).

At week 52, the median PMR-AS was lower in the rituximab group compared with the placebo group (4.2 vs 7.2, respectively). In addition, the percentage of patients with CRP levels of greater than 5 mg/L at any time in the extension study did not differ significantly between the treatment groups (30% with rituximab vs 58% with placebo; RR, 0.52; 95% CI, 0.3-1.1; P =.08).

Overall, 8 AEs were reported in 7 patients who received rituximab, compared with 10 AEs in 8 participants who received placebo.

Study limitations included the lack of a consensus-based criteria for remission or relapse for PMR, thus, the classification and treatment of relapses were at the discretion of physicians; and that the study may not have been large enough or of sufficient length to reveal any secondary effects, including differences in EQ-5D-5L or AEs between the treatment groups.

“[It] remains unknown whether a subgroup of patients might benefit from rituximab retreatment, comparable to patients with [RA],” the researchers emphasized. “A larger trial, with optional rituximab retreatment, is needed to confirm these results and better study treatment effect modification,” they concluded.

Disclosure: This study was supported by Sint Maartenskliniek. The study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.