Background/Purpose: To analyze the effectiveness and safety of rituximab (RTX) for the treatment of refractory systemic sclerosis (SSc)–associated calcinosis.

Methods: We undertook an observational study of patients with this complication treated with 1 or more cycles of RTX (1 g x 2 weeks) and evaluated for at least 12 months after RTX treatment in a single center. The end point of patient follow-up was the date of the last clinic visit. All patients had baseline pre-rituximab (RTX) and follow-up X-rays every 12 months. The primary outcome measures of the study were the improvement of calcinosis symptoms (pain, signs of local inflammation, and new episodes of skin ulceration) and the radiologic evolution of the calcification(s).Clinical response was defined as a sustained improvement in the VAS of ≥50% and no new episodes of local inflammation or skin ulceration. Radiologic response was defined as the complete resolution of the calcification(s) on the X-ray or as a significant reduction in calcification size (≥20% using the measurement functionality of the DICOM viewer), without appearance of new lesions.

Results: Thus far, we have treated 8 SSc patients with calcinosis with RTX (off-label use).

The mean number of previous treatments tested for calcinosis was 3. Of the 8 patients, 4 (50%) presented limited cutaneous scleroderma, and 4 (50%) had diffuse cutaneous involvement. The main indications for RTX were complicated calcinosis unresponsive to previous therapies with concomitant arthritis in 2 patients and refractory arthritis or interstitial lung fibrosing disease in the remaining 6 patients.

The mean number of RTX cycles administered was 3.12 ± 2.1 (range, 1-7), the median duration of RTX treatment was 9 months (interquartile range [IQR], 7.5-36 months), and the median follow-up after the first infusion of RTX dose was 19 months (IQR, 15-45 months).

Four patients (50%) had a significant improvement in clinical symptoms (sustained improvement in the visual analog scale for pain of at least 50% and no new episodes of local inflammation or skin ulceration). Two of these patients (25%) also had a complete resolution or significant reduction in the size of the calcification(s) on X-ray. None of them had drainage or surgical removal of these deposits that could explain the improvement of symptoms.

In the remaining 4 patients (50%), RTX did not provide any significant clinical or radiological benefit for calcinosis. In one of these patients, RTX was discontinued due to inefficacy; in the other three, treatment was maintained due to its beneficial effect in arthritis and interstitial lung disease.

No clinical predictor of response could be identified.

The frequency of adverse effects was low, occurring in only 1 patient (12.5%), who developed upper-respiratory tract infections not requiring hospitalization.

Conclusion: There is no definitely effective treatment for SSc-associated calcinosis to date. Our results and those previously reported suggest that RTX may be helpful in some patients with SSc-related calcinosis. These positive data remain preliminary and need to be viewed with caution, restricting for the moment its off-label use as a rescue therapy in selected cases of severe and refractory SSc-related calcinosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effectiveness-and-safety-of-rituximab-for-the-treatment-of-refractory-systemic-sclerosis-associated-calcinosis-a-case-series/