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

To compare antibody-based HIV-1 vaccine candidates in Phase I and II trials, both the magnitude and breadth of neutralization against multiple strains of virus are main endpoints. These also are key markers to be evaluated in vaccine efficacy trials as immune correlates of protection against HIV-1 infection. More generally, magnitude and breadth are considered when there is interest in comparing quantitative multivariate response data between groups. In this article, 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. We discuss applications to data from a phase III clinical trial (Vax004). We also present simulation-based sample size calculations and power analyses of the described methods.