The study is being conducted in order to obtain safety and efficacy data for an injectable biologic and U0279 as combination therapy compared to that of an injectable biologic alone for severe plaque-type psoriasis. The subjects will be randomized to either U0279 or placebo after having been on an injectable biologic for 12 weeks previously. The subject will be on study medication for 12 weeks. The subjects must have moderate to severe Psoriasis