<prompt> Ustekinumab is used inLichen planusPsoriasisDarier diseasePemphigus  <response>: Ustekinumab acts by blocking interleukin IL-12 and IL-23 which help to activate T-cells. Used to treat psoriasis, was also approved to treat Crohns disease. Other biologics approved in psoriasis are anti-TNF alpha agents Etanercept, Adalimumab, Infliximab, Golimumab Ref: Harrison 19e pg: 348 