Loss of cancer drug activity in colon cancer HCT-116 cells during spheroid formation in a new 3-D spheroid cell culture system

► We report on a new 3-D spheroid cell culture system aimed to mimic solid tumors. ► The cells reproducibly formed spheroids in the NanoCulture® plates. ► Cells in spheroids showed properties reminiscent of hypoxic stem cells. ► Measurement of cytotoxicity was simplified, using fluorescence from GFP marked cells. ► This new 3-D system shows features of potential utility in cancer drug development.