For example, ustekinumab is a monoclonal antibody against p40, the common subunit of IL-12 and IL-23, and is effective against psoriasis and Crohn's disease [14, 15] but has not succeeded in MS [16], possibly because it is directed against the p40 domain and therefore not only inhibits IL-23, but also IL-12. Here, IL23A is linked to psoriasis.