Psoriasis and psoriasiform reactions secondary to Immune Checkpoint Inhibitors

Background: The advent of Immune Checkpoint Inhibitors (ICIs) as a standard of care for several cancers, including melanoma and head/neck squamous cell carcinoma has changed the therapeutic approach to these conditions, drawing at the same time the attention on some safety issues related to their use. Aims: to assess the incidence of psoriasis as a specific immune-related cutaneous adverse event attributing to ICIs using the Eudravigilance reporting system. Methods: all reports of adverse drug reactions (ADRs) concerning either exacerbation of psoriasis or de novo onset of psoriasis/psoriasiform reactions associated to the use of Cytotoxic T-Lymphocyte Antigen-4 (CTLA-4) inhibitors ipilimumab and tremelimumab, and the Programmed cell Death protein 1/Programmed Death-Ligand 1 (PD-1/PD-L1) inhibitors nivolumab, pembrolizumab, atezolizumab, durvalumab, avelumab and cemiplimab were identified and extracted from the Eudravigilance reporting system, during the period between the date of market licensing (for each study drug) and 30th October 2020. Results: 8,213 reports of cutaneous ADRs associated with at least one of study drug have been recorded, of which 315 (3.8%) reporting psoriasis and/or psoriasiform reactions as ADR. In 70.8% of reports patients had pre-existing disease. Conclusion: ICIs-related skin toxicity is a well-established phenomenon, presenting with several conditions, sustained by an immune background based on the activity of some cells (CD4+/CD8+ T-cells, neutrophils, eosinophils, plasmocytes), inflammatory mediators, chemokines and tumor-specific antibodies. In this setting, psoriasis represents probably the most paradigmatic model of these reactions, thus requiring adequate recognition as no guidelines on management are now available.