IL17A and psoriasis: Advances in treatment with biological agents represented by monoclonal antibodies, such as TNF-α inhibitors (TNFI), IL-17A and IL-12/23 antagonists have not only benefited from outstanding clinical efficacy with lower side effects compared to conventional systemic therapy, but also raised the standards towards therapeutic success, fact reflected in the greater Psoriasis Area and Severity Index (PASI) response rates.