Abstract: The present invention discloses crosslinked poly(alkylene glycol) (PAG)-based hydrogel compositions, systems containing a plurality of cancer cells in contact with a cell culture media and encapsulated in the crosslinked PAG-based hydrogel composition and methods of making such crosslinked hydrogel compositions and systems. Also disclosed herein are methods of using such compositions and systems, such as, for example for screening an agent for effectiveness of the agent against cancer cells. Also disclosed herein are kits containing one or more components including one or more systems of the present disclosure and one or more instructions.