Estimation of multiple response rates in phase II clinical trials with missing observations.

Responses are often correlated in clinical trials. A patient who is not evaluable for a response may still provide some information to the response through his or her status on other responses. Under the assumption of missing at random, we propose the utilization of a self-consistent estimator. We show that the proposed estimators are more efficient than the conventional estimators by asymptotic relative efficiency and simulation study. An example from a Phase II clinical trial on children with chronic myelogenous leukemia is provided.