Low-dose rituximab as an adjuvant therapy in pemphigus.

Background: Pemphigus is a chronic autoimmune blistering disease where systemic steroids and immunosuppressants are the mainstay of therapy, but long-term treatment with these agents is associated with many side effects. Rituximab, a chimeric monoclonal anti-CD20 antibody, in low doses has shown efficacy as an adjuvant to reduce the dose of steroids.

Aim: To study the clinical efficacy and safety of low-dose rituximab as an adjuvant therapy in pemphigus.

Methods: Fifty patients with extensive pemphigus were selected, who either had recalcitrant pemphigus, were steroid dependent, had relapsed after pulse therapy, had anti-desmoglein levels >20, had contraindications to conventional treatment or wanted to avoid conventional treatment and its side effects. Two doses of rituximab (500 mg) were given 2 weeks apart and patients were regularly followed up every 2 weeks for 3 months and then monthly upto 2 years. Complete blood counts, liver function tests, renal function tests, skin biopsy, direct immunofluorescence and desmoglein levels were checked before and after rituximab administration. Pre-rituximab chest X-ray and electrocardiograph were also obtained.

Results: At 3 months, 41 (82%) patients showed complete remission. Nine (18%) patients had partial remission. After 6-12 months, 20 (40% of enrolled patients) continued to be in remission and were off all systemic therapy and the remaining 19 (38%) were continuing to take low doses of steroids with or without other adjuvant immunosuppressants and 2 (4%) had to be given another 2 doses of rituximab and subsequently could be managed with low-dose steroids. Of the 9 patients in partial remission at 3 months, after 6-12 months 5 (10% of the total) were completely off treatment and went into complete remission and 4 (8%) were on additional treatment out of which 2 (4%) had to be given 2 additional doses of rituximab and were in partial remission with low-dose therapy at the end of 12 months. One patient developed urticaria as a side effect. Another developed herpes zoster.

Conclusion: Our results show that low-dose rituximab is a well-tolerated and beneficial adjuvant therapy in recalcitrant pemphigus which helps reduce both the severity of disease as well as the dose of steroids and immunosuppressants.