STATISTICAL DESIGN The study follows a two-stage design, according to the Simon model. We assume that with a response rate of 5% (H0) or less the drug is likely to be ineffective, and also, that, for the drug to be effective, a target response rate of 15% (H1) is required. With a probability errors alfa of 5% and beta 20%, the calculated sample size is as reported in "PLANNED NUMBER OF PTS."