Two Studies Report on Biosimilar Rituximab's Utility in Treating Pemphigus

Pemphigus is a rare autoimmune disease of the skin that can cause blisters and sores, leaving the skin vulnerable to infection. In June 2018, the FDA approved the brand-name rituximab, Rituxan, for the treatment of pemphigus vulgaris (PV), one type of pemphigus, making rituximab the first newly approved treatment for the disease in more than 60 years.

Given the cost of the brand-name drug, there is interest among providers, particularly in contexts with limited resources, in using a biosimilar rituximab to treat pemphigus, and recently, 2 studies reported on the use of biosimilar rituximab in treating this disease.

First, a research team, writing in the Journal of Dermatological Treatment, reported the results of a study in 110 patients who were treated with biosimilar rituximab for PV and who were followed up for a mean (SD) of 16.22 (3.45) months.¹

According to the authors, the median time to complete remission was 3 months, the median duration of remission was 9 months, and the median time to relapse was 12 months after treatment with the biosimilar rituximab. Newly diagnosed patients had a higher rate of complete response and a longer period of remission and risk of relapse versus patients who had received previous PV treatment.

In total, 47 adverse events (AEs) were observed in 33 patients, with mild infusion-related reactions being the most commonly reported.

The second study reported on a retrospective review of 146 patients with pemphigus who received biosimilar rituximab according to a rheumatoid arthritis protocol of 2 doses infused 14 days apart.

In total, 73.3% of patients attained complete remission. The mean (SD) interval between rituximab and complete remission was 6.6 (3.4) months. The mean (SD) duration of complete remission was 9.1 (8.5) months.

Patients who had the pemphigus foliaceus disease subtype required longer to achieve remission than patients with PV, and they needed significantly higher doses of steroid therapy over a longer duration after rituximab treatment.

No deaths and no long-term complications were reported, the authors say.

While the study was limited by the fact that immunological parameters, such as B-cell count, were not assessed, it reinforces, write the authors, the beneficial role of biosimilar rituximab in treating this dermatological condition.

References

1. Toosi R, Mahmoudi H, Balighi K, et al. Efficacy and safety of biosimilar rituximab in patients with pemphigus vulgaris: a prospective observational study [published online May 28, 2019]. J Dermatol Treat. doi: 10.1080/09546634.2019.1617831.

2. De D, Bishoni A, Handa S, Mahapatra T, Mahajan R. Effectiveness and safety analysis of rituximab in 146 Indian pemphigus patients: a retrospective single-center review of up to 68 months follow-up [published online May 9, 2019]. Indian J Dermatol Venerol Leprol. doi: 10.4103/ijdvl.IJDVL_848_17.