The predictive utility of a biomarker classifier has tremendous clinical appeal. It is envisioned that there will be a growing number of examples in which use of a companion diagnostic will need to be considered and may become an integral part for practicing medicines. The credible mechanism to test the clinical utility of a genomic classifier is crucial for choices of trial designs in late phase registration trials. In this talk, we present some current FDA thinking on biomarker classifier. The study design issues and analyses approaches on the use of genomic biomarker classifier throughout a drug development program will also be discussed in light of the regulatory guidance.