Can efficacy and safety data from clinical trials of rituximab in RA be extrapolated? Insights from 1984 patients from the AIR-PR Registry

Objectives: To investigate whether the efficacy and safety data from drug-registration trials can be extrapolated to real-life RA patients receiving RTX.

Methods: The 'AutoImmunity and Rituximab' (AIR-PR) registry is a French multicentre, prospective cohort of RA patients treated with RTX in a real-life setting. We compared treatment responses at 12 months and serious adverse events (AEs) between eligible and non-eligible patients, by retrieving the eligibility criteria of the three rituximab-registration trials. We determined critical eligibility criteria and modelled the benefit-risk ratio according to the number of fulfilled critical eligibility criteria.

Results: Among 1984 RA patients, only 9-12% fulfilled all eligibility criteria. Non-eligible patients had fewer EULAR responses at 12 months (40.3% vs 46.9%, P = 0.044). Critical inclusion criteria included swollen joints count ≥4, tender joints count ≥4, CRP ≥15 mg/l and RF positivity. Critical exclusion criteria were age >80 years, RA-associated systemic diseases, ACR functional class IV, DMARD other than MTX and prednisone >10 mg/day. Only 20.8% fulfilled those critical eligibility criteria. During the first year, serious AEs occurred for 182 (9.2%) patients (70.3% serious infections) and patients with ≥1 critical exclusion criterion were at higher risk (hazard ratio 3.03; 95% CI 2.25-4.06; for ≥3 criteria vs 0). The incremental risk-benefit ratio decreased with the number of unmet critical inclusion criteria and of fulfilled exclusion criteria.

Conclusion: Few real-life RA patients were eligible for the drug-registration trials. Non-eligible patients had lower chance of response, and higher risk of serious AEs. Efficacy and safety data obtained from those trials may not be generalizable to RA patients receiving RTX in real-world clinical practice.