Biologics for pityriasis rubra pilaris treatment: A review of the literature

Pityriasis rubra pilaris (PRP) is a rare inflammatory papulosquamous skin disease that is often refractory to conventional therapies. The off-label use of biologics, such as anti-tumor necrosis factor, anti-interleukin (IL) 12/IL-23, and anti-IL-17 agents, has been proven successful in the past 2 decades for PRP treatment. Our aim was to analyse the literature for the use of biologics in PRP treatment. We conducted a review by performing PubMed and ClinicalTrials.gov searches. Sixty-eight articles met our selection criteria and are herein discussed. Out of 86 PRP patients, the vast majority were treated with anti-tumor necrosis factor, anti-IL-12/IL-23, or anti-IL-17 biologics, either alone or in combination therapy. A marked-to-complete response was observed in 50%-78%, a partial response in 11%-25%, and no or poor response in 11%-25%. This review has several limitations, including small sample sizes and the lack of shared study design criteria. In some instances, PRP might have resolved spontaneously. Further, the presence of concomitant therapy or the lack of detailed data on previous treatments, makes it difficult to strictly define a therapeutic role per se of specific biologics in PRP. This review shows that biologics may be regarded as a tool for PRP treatment alone or in combination therapy although clinical trials are needed to better assess their efficacy and safety.