A 12 Week Double-blind, Randomised, Placebo-controlled, Modified Dose-escalation Trial to Investigate Safety, Efficacy, and Pharmacokinetics of BIRT 2584XX Tablets at Doses of 100, 300 and 500 mg Administered Once Daily in Patients With Moderate to Severe Psoriasis With a 12 Week Treatment Extension

The proposed study is a phase 2a/b international multicentre clinical trial. The general aim of this study is to investigate the safety and efficacy (clinical proof of concept) of three different doses (100 mg, 300 mg, or 500 mg) of BIRT 2584 XX tablets administered orally once daily compared to placebo tablets for the treatment of patients with moderate to severe plaque-type psoriasis patients who are candidates for systemic treatment or phototherapy. This study may also provide dose-finding information for future pivotal studies.

The response to treatment will be measured for all patients in the study after 12 weeks of treatment using the PASI as the primary endpoint, and also the sPGA. Both instruments evaluate the clinical severity of plaque-type psoriatic lesions. Training on PASI and sPGA assessment will be provided in order to decrease inter-observer variability. The sPGA is thus to be validated for future phase 3 trials.

After 12 weeks of treatment, only those patients with a response equivalent or better than PASI50 and with a satisfactory safety experience will enter a 12 week extension of the treatment period. The total time of exposure to study drug in this subgroup of patients will be 24 weeks. All other study patients will terminate treatment with study drug after 12 weeks.

In addition, the durability of remission/response, and the occurrence of any relapse or rebound during the treatment with study drug and after the end of treatment will be assessed in an 8 weeks follow-up period. The follow-up period is applicable to all study participants who have taken at least one dose of study drug. It initiates after the last dose of study medication has been taken, irrespective of the duration of the patients actual treatment period.

The trial will use a modified dose-escalation scheme. The randomisation to the 500 mg treatment arm will initiate only after a Data Safety Monitoring Board (DSMB) decision on the safety of the other treatment arms. An IVRS will be used for randomisation in this trial.