The high attrition rate of drug candidates in clinical trials has led to a critical need for alternatives to currently used in vitro assays and animal models that better predict clinical outcome, especially in cancer therapeutics. Three dimentional in vitro tumor models that incorporate specific tissue properties and physico-chemical stimuli have been shown to more closely mimic in vivo conditions. Nortis has developed a novel technology for generating vascularized tissue-microenvironments in disposable fluidic devices including model of the neurovascular unit of the human brain. During the proposed project, Nortis will develop this model into assays that quantify rate-limiting steps in breast cancer metastases to the brain: tumor cell extravasation, micrometastases growth, and tumor angiogenesis. The ultimate goal of the entire project is a platform for the validation of anticancer drug candidates that is scalable to currently existing analysis systems.