title: Bayesian sample size calculations in phase II clinical trials using a mixture of informative priors.
abstract: A number of researchers have discussed phase II clinical trials from a Bayesian perspective. A recent article by Mayo and Gajewski focuses on sample size calculations, which they determine by specifying an informative prior distribution and then calculating a posterior probability that the true response will exceed a prespecified target. In this article, we extend these sample size calculations to include a mixture of informative prior distributions. The mixture comes from several sources of information. For example consider information from two (or more) clinicians. The first clinician is pessimistic about the drug and the second clinician is optimistic. We tabulate the results for sample size design using the fact that the simple mixture of Betas is a conjugate family for the Beta- Binomial model. We discuss the theoretical framework for these types of Bayesian designs and show that the Bayesian designs in this paper approximate this theoretical framework.
authors.affiliation: Schools of Allied Health and Nursing, Center for Biostatistics and Advanced Informatics, The University of Kansas Medical Center, Kansas City, 66160, USA. bgajewski@kumc.edu
authors.forename: Byron J
authors.initials: BJ
authors.lastname: Gajewski
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Mayo
mesh_terms: D000465:Algorithms; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001499:Bayes Theorem; D017322:Clinical Trials, Phase II as Topic / Q000379:methods*; D003198:Computer Simulation; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D000077143:Docetaxel; D006258:Head and Neck Neoplasms / Q000188:drug therapy; D006801:Humans; D007890:Leiomyosarcoma / Q000188:drug therapy; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D000077150:Oxaliplatin; D018401:Sample Size; D043823:Taxoids / Q000627:therapeutic use; D000093542:Gemcitabine
chemical_list: D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D043823:Taxoids; D000077150:Oxaliplatin; D003841:Deoxycytidine; D000077143:Docetaxel; D000093542:Gemcitabine