If the patient has to discontinue the study drug within the 6 month study period or during the subsequent follow-up period (up to month 12) because of a lack of response (or failure), flare or side effect, he/she will be randomized again to receive one of the remaining two study drugs (stage 2, with a 1:1 randomization ratio) for 6 months. Endpoint in this second stage will again be the response to treatment at 6 months.