I found that the phase 3 clinical trial[1] that supports Ustekinumab to get marketed with placebo. To me knowledge, in clinical trials the patients are usually allowed to take some background drugs, so the placebo control arms are actually background drugs plus placebo and the experimental arms plus drugs to be studied. However, in this Ustekinumab trial the participants were prohibited to take any other drug. I understand that because psoriasis is not a life threatened disease, even if the studied drug has no effect a short period of time without treatment is OK. Is it necessary to compare the new drugs with a standard treatment? How does the drug administration make the decision if the new drug is allowed on the market?