Pemphigus relapse: Mechanisms, risk factors, and agents associated with disease recurrence.

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Pemphigus represents a spectrum of potentially life-threatening autoimmune-mediated skin blistering conditions caused by antibody production against desmoglein 1 and 3 (anti-DSG 1 and 3) in keratinocytes. Greater than 50% of pemphigus patients experience relapse, which complicates long-term medical management, including risks associated with re-treatment and complications such as infection and dehydration. This review aims to elucidate mechanisms, risk factors, and medications associated with pemphigus relapse. Mechanisms of relapse include the persistence of auto-reactive B-cell populations post-treatment and CD20- B-cell populations that reactivate after B-cell depletion therapy. Risk factors for relapse include high body surface area (BSA) of pemphigus involvement, high body mass index, high severity according to the Pemphigus Disease Area Index (PDAI) at onset, treatment delay, and high anti-DSG1 and DSG3 titers post-treatment. Targeted B-cell localization is associated with better clinical outcomes, including less frequent relapses. Rituximab is currently the gold standard of treatment for moderate-severe pemphigus and has relapse rates of 11%-44% in selected studies, with a mean time to relapse of 5.8 months to 36 months following treatment. Relapse rates across lymphoma dosing (375 mg/m2) versus rheumatoid arthritis dosing (1 g dosing weekly) was inconsistent; however, more frequent dosing, earlier treatment, and higher cumulative dosing were associated with lower relapse rates. Alternative agents that have clinical efficacy include corticosteroid monotherapy, mycophenolate mofetil, azathioprine, and intravenous immunoglobulin. Future studies should include head-to-head comparators over long follow-up periods to identify the best treatment agents associated with the least relapse risk.