Simultaneous Evaluation of the Magnitude and Breadth of a Left and Right Censored Multivariate Response, with Application to HIV Vaccine Development.

Both the magnitude and breadth of neutralization against multiple strains of virus are main endpoints for comparing antibody-based HIV-1 vaccine candidates in Phase I and II trials, and are key markers to be evaluated in vaccine efficacy trials as immune correlates of protection against HIV-1 infection. More generally, consideration of both magnitude and breadth is encountered when there is interest in comparing quantitative multivariate response data between groups. In this paper, we discuss two approaches to simultaneously evaluating the magnitude and breadth of a multivariate response. We suggest methods for the summarization and group comparison of multivariate response data that are subject to left and/or right censoring. Applications to data from a phase III clinical trial (Vax004) are discussed. Simulation-based sample size calculations and power analyses of the described methods also are presented.