Pemphigus is a chronic autoimmune blistering disease affecting both the skin and mucous membranes. Rituximab, a biological drug targeting B cells, has recently proved to be effective in pemphigus treatment. As rituximab’s patent is expired, biosimilars have been increasingly used. At present, the rituximab biosimilar CT-P10 is one of the most widely used for pemphigus treatment in Italy. EMA and AIFA approval is based on studies on rheumatic and oncological patients. No data on the use of CT-P10 in pemphigus are available. 
In this study we report preliminary data on pemphigus patients treated with rituximab biosimilar obtained from 4 Italian specialized dermatological hospitals. Clinical score, anti-desmoglein (Dsg) 1 and 3 levels, clinical outcome and adverse events during follow-up were assessed. 
A total of 24 patients (18 pemphigus vulgaris,1 vegetans and 5 foliaceus) were enrolled. The mean age was 52.5 years (range 35-73) and the mean follow-up time was 5.3 months (range 1-12). A notable decrease in clinical score that paralleled anti-Dsg 1 and 3 titers was observed. Mean delay to achieve disease activity control was 6.8 wks (range 1-32). At 6 months after rituximab infusion only 1 of 16 patients (6%) relapsed and 12 of 16 patients (75%) obtained remission (2 partial remission on therapy, 3 partial remission off therapy, 2 complete remission on therapy and 5 complete remission off therapy). No serious adverse events or infections have been observed. Infusion related reactions led to drop out in 2 of 24 patients (8%). 
Although only preliminary conclusions can be drawn, the present findings suggest that administration of rituximab biosimilar in pemphigus patients is associated with desirable outcomes in terms of efficacy and safety.

A prospective observational study to assess efficacy and safety of rituximab biosimilar in Italian pemphigus patients