In this phase @ , randomised , multicentre , double-dummy , placebo-controlled , @-week , non-inferiority trial , adult patients with chronic stable plaque psoriasis ( for @ months ) who were candidates for systemic or phototherapy and had a Psoriasis Area and Severity Index ( PASI ) score of @ or higher and a Physician 's Global Assessment ( PGA ) of moderate or severe , and had failed to respond to , had a contraindication to , or were intolerant to at least one conventional systemic therapy , were enrolled from @ investigational dermatology centres worldwide .