Two-dimensional entrapment of tumor cells to study dormancy has been studied before using ECM-induced, cell signaling-induced, biochemical-induced, etc. modes for cancers such as prostate, lung, colorectal, pancreatic, etc. in vitro, but not in vivo. Due to the lack of three-dimensional (3D) in vivo models for such studies, this project hypothesizes that a 3D tumor dormancy model can be formed using polymer-based encapsulation of melanoma and breast tumor cells. This model consists of tumor cells cultured on a novel hydrogel platform to form spheroids to induce dormancy and their physical confinement by encapsulation in amikabeads, followed by injection and treatment in vivo.