Application of Bayesian Probability of Success (POS) in Design of Vaccine Clinical Trials

• Activity Number: 390
• Type: Topic Contributed
• Date/Time: Tuesday, July 31, 2012 : 2:00 PM to 3:50 PM
• Sponsor: Biopharmaceutical Section
• Author(s): Guanghan Liu*+
• Companies: Merck Research Laboratories
• Keywords: Bayesian ; Probability of Success ; Vaccine Clinical Trials

Abstract

In conventional power and sample size calculations for clinical trials, the treatment effect and its variability are typically taken as the point estimates obtained from previous studies or similar trials in the literature. However, the uncertainty of those parameter may not be incorporated in the calculations. Recently, the probability of success (POS) has been used as an additional measure, which combines a Bayesian concept for parameter uncertainty with the traditional frequentist hypothesis testing in clinical trials. In this talk, we will consider some unique features on using this POS evaluation in vaccine clinical trials, specifically on testing acceptability and non-inferiority hypotheses that are commonly used in vaccine studies. Discussions will be given on the definition of POS, construction of prior distribution based on previous studies, and the impact of prior on the POS evaluation. Some challenges of evaluating POS for immunogenicity and safety endpoints in vaccine clinical trials will be shared with examples.