Treatment of refractory pityriasis rubra pilaris with biologic therapy: a case series

Pityriasis rubra pilaris (PRP) is a rare inflammatory dermatosis. There are limited data on its treatment with biologic therapies. We present a case series to evaluate the efficacy, time to primary response (TTPR) and tolerability of biologics in PRP management. A retrospective analysis of 11 patients with PRP treated with biologics at a tertiary Australian dermatology department was conducted. Patient demographics, prior therapies and treatment outcomes were reviewed. Biologics demonstrated variable efficacy: significant responses were seen with secukinumab (three of four, 75%), tildrakizumab (two of seven, 29%), ixekizumab (one of two, 50%) and risankizumab (one of one, 100%). Adalimumab yielded a partial response for two of three patients (67%). Combination therapy with systemic agents appeared to improve outcomes. Tildrakizumab had the shortest mean TTPR (6.8 weeks). Adverse effects were rare but led to treatment discontinuation in three patients. Sequential biologic therapy demonstrated some benefit to those who did not initially respond. These findings highlight the need for standardized treatment outcome measures and further research in PRP treatment.