INVESTIGATING A SEQUENCE OF RANDOMIZED PHASE-II TRIALS TO DISCOVER PROMISING TREATMENTS

We consider clinical trial strategies to study diseases in which there is rapidly developing technology. We assume the availability of a lim ited number of patients for screening treatments over a time horizon, and that availability of new tratements for test is staggered over tim e. We assume further that patient response is binary and rapidly obser vable. We consider the strategy of conducting a sequence of two-armed randomized clinical trials. We carry over the treatment with the large r number of observed successes on the current trial to the next trial for comparison with a new treatment, with this process repeated at eac h step. For a fixed total number of patients (N), the number of trials one may conduct in sequence (k) is inversely related to the sample si ze per trial (2n), N = 2nk. We investigate how k and n influence (a) t he expected success probability for the treatment selected at the end, and (b) the expected number of total successes for the N patients. Th e ultimate objective is to select one treatment, the winner at stage k , to test against a standard regimen in a randomized comparative phase III trial.