IL17A and psoriasis 14, pustular: Several biologics are approved in Japan for the treatment of GPP; including, anti-tumor necrosis factor (TNF)-α agents (adalimumab, infliximab, and certolizumab pegol), anti-interleukin (IL)-17 agents (IL-17A: secukinumab and ixekizumab; IL-17 receptor: brodalumab), and anti-IL-23 agents (risankizumab and guselkumab); the supporting efficacy data mainly arise from small, uncontrolled clinical trials (6, 7, 56).