Comparison of the efficacy and cost-effectiveness of an immunologically targeted low-dose rituximab protocol with the conventional rheumatoid arthritis protocol in severe pemphigus.

Background: Various dosing protocols of rituximab have been used in pemphigus. B-cell repopulation following rituximab treatment can be considered a forerunner of clinical relapse. Immunologically guided dosing may remove the need for fixed timepoint maintenance dosing, hence being more cost-effective and perhaps safer.

Aim: To compare the overall efficacy and cost-effectiveness of a low-dose rituximab regimen (500 mg, 2 weeks apart) with immunologically guided, ultralow-dose (200 mg) top-up infusions on immunological relapse vs. the use of a rheumatoid arthritis (RA) protocol with rituximab 500 mg repeat infusion to treat clinical relapse in severe pemphigus, over a 1-year period, METHODS: In total, 23 patients with severe pemphigus were randomized into Group A (RA protocol: 1000 mg given as two doses, 2 weeks apart) and Group B (low-dose rituximab 500 mg given as two doses, 2 weeks apart). Both groups also received short-term oral corticosteroids, and underwent clinical and immunological (3-monthly flow cytometry assessments of B-cell subtypes) monitoring. Group A received a top-up dose of rituximab 500 mg upon clinical relapse, while Group B received an ultralow top-up dose (200 mg) following detection of B-cell repopulation, which was intended to prevent clinical relapse. Outcome parameters [complete remission off treatment (CROT), relapse (clinical and immunological), total corticosteroid dose and direct cost of therapy] were compared.

Results: The mean ± SD time to CROT (Group A, 27.1 ± 1.6 weeks; Group B, 26 ± 1.2 weeks, P = 0.09) and the cumulative prednisolone dose (P = 0.28) were comparable between the two groups. In Group A, 3 of 9 (33.3%) patients had clinical relapse (mean ± SD time of 9.3 ± 0.4 months). In Group B, B-cell repopulation was seen in 10 of 11 (90.9%) patients within a mean time of 8.4 ± 2.4 months, and a single top-up dose of 200 mg successfully prevented clinical relapse. The overall cost of therapy was 37.4% cheaper in Group B.

Conclusion: An immunologically guided low-dose rituximab regimen can be an equally effective but more affordable alternative to conventional rituximab regimens in pemphigus.