Treatment outcomes in a cohort of patients with mucosal-predominant pemphigus vulgaris

Background: Pemphigus vulgaris (PV) is a rare autoimmune blistering condition. Treatment typically combines corticosteroids with another immunosuppressive agent, such as azathioprine, mycophenolate mofetil (MMF) or rituximab. Aim: This study aims to compare these second agents for their clinical efficacy and steroid-sparing effect. Methods: This was a single-centre, retrospective observational cohort study of 21 patients with oral PV over a 6-year period, 18 of whom were newly diagnosed. Of the latter, the first 13 were initially given azathioprine, progressing to MMF and then rituximab on treatment failure, while the next five patients started directly on MMF. Results: Of the 13 newly diagnosed patients, 2/13 were intolerant of azathioprine, and only 1/11 was controlled, with a median time to treatment failure (MTTF) of 254 days. MMF was given to 17 patients, either de novo (5) or after azathioprine (12), and was significantly more effective, controlling activity in 4/17 patients, and for a significantly longer time (MTTF 395 days, P = 0.019). All 13 patients failing MMF received rituximab, seven required a second dose, and three, a third dose. All patients responded, with 11/13 able to cease steroids. Control was maintained for a similar time to MMF (MTTF 364 days, P = NS). Rituximab also had the best steroid-sparing effect followed by MMF, then azathioprine. Side-effects were common with azathioprine, while the other two agents were well tolerated. Conclusion: Rituximab was the most effective of the three immunosuppressives for PV, although repeat dosing was frequently required. These observations have significant implications for the choice of drugs for this condition.