Long-term effectiveness and safety of annual biosimilar Rituximab retreatment in seropositive Rheumatoid Arthritis: A 4-year real-world study.

BACKGROUND

Rituximab is an established biologic disease-modifying antirheumatic drug (bDMARD) for rheumatoid arthritis (RA) patients with inadequate response to conventional synthetic DMARDs, particularly in seropositive disease. In resource-limited settings such as India, biosimilar rituximab (bRTX) is widely used because of its cost advantage; however, real-world data on long-term retreatment strategies with biosimilar rituximab remain limited.

OBJECTIVE

To evaluate the long-term effectiveness, tolerability, and safety of multiple dosing of biosimilar rituximab in seropositive, biologic-naïve patients with RA.

METHODS

This retrospective, single-centre observational cohort study included seropositive RA patients with inadequate response to conventional DMARDs who received at least four annual cycles of bRTX. Each treatment cycle comprised two intravenous infusions of 1000 mg administered 14 days apart. Clinical data were collected from routine outpatient follow-up visits over a four-year period. Disease activity was assessed using Disease Activity Score (DAS28-ESR/CRP), Simplified Disease Activity Index (SDAI), and American College of Rheumatology (ACR) response criteria. Adverse events were recorded. Statistical comparisons of longitudinal outcomes were measured with repeated-measures ANOVA.

RESULTS

Thirty-five patients initiated biosimilar rituximab therapy, of whom 27 continued annual retreatment for four years. The cohort was predominantly female (71.4%), with a mean age of 46 years and a Baseline disease activity was high (mean DAS28-ESR 7.66). Significant and sustained reductions in DAS28-ESR, DAS28-CRP, and SDAI were observed at all 6 monthly follow-up visits compared with baseline (p < 0.05). An ACR20 response was achieved in ≥ 80% of patients after each treatment course. No serious adverse events, serious infections, or treatment discontinuations were observed.

CONCLUSION

In this retrospective cohort of 27 patients, annual retreatment with bRTX was associated with sustained disease control and a favourable safety profile over four years, supporting its feasibility as a pragmatic long-term maintenance strategy for seropositive RA patients in routine clinical practice, particularly in emerging economies. Key Points Annual retreatment with biosimilar rituximab provided sustained disease control over four years in seropositive, biologic-naïve rheumatoid arthritis patients with inadequate response to conventional DMARDs. • Significant improvements in DAS28-ESR, DAS28-CRP, SDAI, and ACR20 responses were maintained throughout repeated annual treatment cycles. • Long-term biosimilar rituximab therapy demonstrated a favourable safety profile, with no serious adverse events,serious infections, malignancies, or treatment discontinuations. • This real-world study supports annual biosimilar rituximab retreatment as a pragmatic and cost-conscious maintenance strategy for rheumatoid arthritis in resource-limited settings.