A Safety and Efficacy Study of Ustekinumab in Patients With Plaque Psoriasis Who Have Had an Inadequate Response to Methotrexate

This purpose of this study is to assess the safety of ustekinumab in psoriasis patients who receive ustekinumab following an inadequate response to methotrexate therapy. The study will provide information for doctors on how to manage the transfer from methotrexate to the biologic agent ustekinumab. The study is designed to compare two methods of transferring patients from methotrexate to ustekinumab. The two methods being compared are discontinuation of methotrexate with immediate initiation of ustekinumab versus initiation of ustekinumab with overlap and gradual dose reduction of methotrexate over 4 weeks.