TNF and psoriasis: Biologic agents approved for the treatment of psoriasis belong to four main pharmacologic classes: TNF-α inhibitors (i.e., adalimumab, etanercept, infliximab, certolizumab pegol), IL-17 inhibitors (i.e., secukinumab, brodalumab, and ixekizumab), IL-23 inhibitors (i.e., guselkumab, tildrakizumab, and risankizumab), and the IL-12/23 inhibitor ustekinumab [10].