I-SPY 2 will compare the efficacy of novel drugs in combination with standard chemotherapy with the efficacy of standard therapy alone. The goal is identify improved treatment regimens for subsets on the basis of molecular characteristics (biomarker signatures) of their disease. As described for previous adaptive trials, regimens that show a high Bayesian predictive probability of being more effective than standard therapy will graduate from the trial with their corresponding biomarker signature(s). Regimens will be dropped if they show a low probability of improved efficacy with any biomarker signature. New drugs will enter as those that have undergone testing complete their evaluation.