ver the past 10 years, our ability to realistically model the critical biological steps in disease have dramatically improved, due in part to the advances in microfluidic technologies.  In particular, the capabilities to create realistic 3D microenvironments, including microvascular perfusion, have led to in vitro models for disease that offer, in many respects, considerable advantages over in vivo experiments.  In this talk, I will present some recent advances in creating microvascular networks in vitro and using these to model the successive stages of metastatic cancer, especially in the context of immunotherapies and organ-specific models of metastasis.