Rituximab retention rate in systemic sclerosis: a long term real-life multicentre study

Objectives: to report real-life data on rituximab retention-rate as indicator of safety and efficacy in a multicentric national cohort of systemic sclerosis patients. Methods: SSc patients treated with rituximab and followed for at least 36 months were included, clinically characterized, and longitudinally monitored. A competing risk analysis with sub-Hazard Ratio(sHR) definition was performed to explore the clinical variables linked to specific cause of rituximab discontinuation. Results: One-hundred-fifty-two SSc-patients (mean age 47.3 ± 12.3 years; females 79.6%; diffuse disease 77.6%; anti-topoisomerase-I positivity 63.2%) were evaluated over a median(IQR) time of 3.3(1.7-5.0) years. The primary indication for rituximab were interstitial lung disease (ILD)(38.8%), worsening skin fibrosis(36.8%), and arthritis(13.8%); 138 patients(90.8%) received more than one rituximab course. The 5-years rituximab retention rate was 59.9%(44.6-64.7%). Clinical response was the most common reason for rituximab discontinuation[5.7(3.7-8.4) per 100 patient-year] and was associated with a shorter disease duration[sHR 0.8(0.7-0.9)], anti-topoisomerase-I negativity[sHR 0.4(0.2-0.9)], previous digital ulcers[sHR 2.6(1.1-6.2] and no history of arthritis[sHR 0.3 (0.1-0.8)]. Treatment failure was the second cause of rituximab discontinuation[3.7(2.2-6.0) per 100 patient-year] and was associated with anti-centromere antibody positivity[sHR 2.8(1.1-7.4)] and anti-topoisomerase-I negativity[sHR 0.2(0.1-0.6)]. Adverse events(AEs) were the less common cause of discontinuation[3.1(1.7-5.2) per 100 patient-year], associated with limited cutaneous subset[sHR 3.4(1.2-9.7)] and previous mycophenolate mofetil treatment[sHR 4.5(1.2-16.3)]. Conclusion: rituximab is a safe and effective treatment in SSc: clinical response emerged as the primary reason for rituximab discontinuation, and AEs had a limited impact on treatment persistence. The identification of specific disease features associated with a response to rituximab will be useful in the management of SSc-patients.