Safety and efficacy of rituximab biosimilar (CT-P10) in systemic sclerosis: an Italian multicentre study

Objectives. Recent data have shown a significant efficacy of rituximab (RTX) in SSc. An RTX biosimilar (RTX-B) is a more affordable option. We assessed the safety and efficacy of an RTX-B (CT-P10) in SSc.Methods. SSc patients treated with RTX-B with at least 6 months of follow-up were retrospectively identified from six Italian referral centres. SSc patients naive to RTX-B (RTX-Bn) or already treated with RTX originator and switched to an RTX-B (RTX-Bs) were evaluated. A comprehensive assessment of disease characteristics and organ involvement at baseline and after 6 months was obtained.Results. Thirty-three SSc patients were selected: 29 (87.9%) females, mean age 51.6years (s.D. 14.2), mean disease duration 9.8years (s.D. 8.1); 21 (64.5%) with dcSSc, 20 (60.1%) anti-topoisomerase I, 7 (21.2%) anti-RNA polymerase III and 6 (18.2%) anti-centromere positive. Seventeen (51.5%) were RTX-Bn and 16 were on RTX-Bs (48.5%). RTX was introduced because of skin progression in 18 patients (54.5%), interstitial lung disease (ILD) worsening in 11 (33.3%) and arthritis in 12 (36.4%). All patients were previously treated with immunosuppressants. At RTX-B introduction, 21 (63.6%) patients were on concomitant immunosuppressants: 15 (71.4%) on MMF and 6 (28.6%) on MTX. Twenty-three (69.7%) were on low-dose steroids. After 6 months, a significant reduction of the modified Rodnan skin score (mRSS), 28-joint DAS and CRP was observed (P=0.002, 0.005 and 0.008, respectively); the mRSS significantly improved both in RTX-Bn (P<0.024) and RTX-Bs patients (P<0.031). No significant changes were observed for lung function tests, either in the entire cohort or in the subgroup of ILD patients. Only one RTX-Bs patient experienced transient neutropenia.Conclusion. Our data suggest that RTX-B can represent a cheaper option in SSc patients, as it is effective in improving skin and joint involvement and in stabilizing lung function.