a Scatter plot showing the results of the 1770 compound high-throughput phenotypic screen for enhancers of anti-tumor T-cell function. The majority of compounds did not elicit any change in tumor spheroid phenotype and clustered with the DMSO vehicle control samples. Hit compounds that yielded desirable anti-tumor phenotypes were broadly classified by their ability to reduce tumor size (Hit Class I) or size and structure (Hit Class II). Solid lines indicate the mean for either the spheroid area (y axis) or the spheroid shape factor (x axis); dotted lines indicate three standard deviations from the mean. b Example of a hit compound from the screen. Tumor spheroids treated with the CDK4/6 inhibitor are shown in three different channels alongside the DMSO negative control. Scale bars indicate 100 µm.