Assessment of Efficacy of Adjuvant Topical Rituximab Encapsulated in Nanoparticle Gel in Oral Pemphigus Vulgaris: A Randomized, Double-Blind, Placebo-Controlled, Pilot Study.

BACKGROUND: Oral pemphigus vulgaris (PV) presents with persistent, painful, nonhealing oral erosions, with a slower treatment response compared to cutaneous lesions. PATIENTS AND METHODS: To assess the efficacy of adjuvant topical rituximab encapsulated in nanoparticle gel in oral PV. Of 31 oral PV patients recruited, 16 were randomized to rituximab incorporated in calcium alginate nanoparticles (study group) and 15 to calcium alginate nanoparticle gel only (placebo group), applied twice daily on oral erosions for 12 weeks. Both groups, in addition, received oral prednisolone (tapering doses) and azathioprine. RESULTS: In the topical rituximab group, 75% of patients and in the placebo group, 86.7% of patients achieved remission (P = 0.65) over 12 weeks of therapy. The median time to remission in the topical rituximab group was 4 weeks, and in the placebo group, it was 8 weeks (P = 0.53). Median oral pemphigus scores showed an earlier reduction in the rituximab group (P = 0.52). The median circulating CD20 count was reduced in the topical rituximab group from 100 to 74/mm(3) at week 8. In the placebo group, the value increased from 89 to 118/mm(3) (intergroup P = 0.29). A significantly greater number of cases in the topical rituximab group had a negative mucosal CD20 count (P = 0.001). There was a comparable fall in desmoglein 3 titers in both groups (P = 0.58). The mean cumulative prednisolone dose was 3567 mg in the topical rituximab group and 3869 mg in the placebo group (P = 0.125). No side effects of rituximab were observed. LIMITATIONS: A small sample size, and need of pharmacokinetic studies in animal models to assess absorption of rituximab in nanogel formulation. CONCLUSION: With topical rituximab incorporated in nanogel, there was a trend toward earlier remission, lower total cumulative oral prednisolone dose, earlier improvement in oral pemphigus score, and greater reduction in CD20 count.