Background/Purpose: Rituximab (RTX) was approved in Japan as a new treatment strategy for systemic sclerosis (SSc). Intravenous rituximab (375mg/m2) is administered once a week for 4 weeks, every 6 months. This RTX regimen is unique compared to those used in other countries. However, there are few studies on the long-term efficacy and safety of this RTX treatment strategy.This study aimed to evaluate the real-world efficacy of RTX for skin involvement and its safety up to 2 years in SSc patients treated at our institution.

Methods: We retrospectively analyzed the efficacy of RTX treatment for skin involvement at 0, 6, 12 and 24 months in SSc patients at our hospital from August 2021 to April 2025. Efficacy for skin lesions was evaluated using the modified Rodnan’s total skin thickness score (mRSS). Safety was evaluated based on adverse events after RTX administration, with particular attention to infections.

Results: Twenty-five SSc patients who could be evaluated at 6 months after administered RTX were included in our analysis. There were 10 cases with diffuse cutaneous systemic sclerosis and 15 cases with limited cutaneous systemic sclerosis (Table 1). The mean disease duration prior to the initiation of RTX was 10.26 ± 9.63 years. Figure 1 showed mRSS trend after RTX administration. The mean mRSS at the initiation of RTX was 9.36 ± 9.41, and at 6 months average score of 8.68 ± 11.01 was not significantly reduced (p=0.185). However, the average mRSS at 12 months was 7.65 ± 9.64, which was significantly lower compared to 0 and 6 months respectively (p=0.045 and 0.026)(n=20). On the other hand, the mean mRSS at 24 months were 6.17 ± 6.21, which was not significantly different from 0, 6, 12 months respectively (P=0.125, 0.375, and 0.750)(n=6).Table 2 showed the adverse events after RTX therapy. Infections were the most common adverse events during the 24-month period. Notably, the frequency of infections tended to increase in the latter 12 months. The most frequently observed infections were COVID-19 in the first 12 months and bacterial pneumonia in the second 12 months.

Conclusion: RTX therapy for SSc improved skin stiffness up to 12 months after initiation of treatment. However, there was a trend toward increased adverse events such as infection after 12 months. Further study is needed to determine the long-term efficacy and safety of RTX therapy for SSc.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-and-safety-of-rituximab-for-skin-involvement-in-systemic-sclerosis-a-single-center-study/