(A) Design of an unbiased functional screen to identify drugs that synergize with anti-CD47 therapy using primary human macrophages and GFP⁺ PC9 cancer cells. (B) Representative whole-well microscopy images showing GFP⁺ area (purple) from wells treated with drugs that enhanced (erlotinib, gefitinib) or inhibited (dexamethasone) macrophage-dependent cytotoxicity of PC9 cells. Scale bar: 800 μm. (C) Volcano plot summarizing drug screen results. Each point represents the mean from n = 5 experimental trials. The phenotypic effect size (x axis) is depicted as log₂ fold change of GFP⁺ area in the macrophage+anti-CD47 condition relative to PC9 cells alone. Values were normalized to account for variation due to well position. Dashed lines represent 2-fold change in effect size (x axis) and P < 0.05 by t test (y axis). Gefitinib and erlotinib (blue) were identified as the top enhancers of macrophage-dependent cytotoxicity, whereas drugs depicted with red dots inhibited macrophage-dependent cytotoxicity or were drugs that macrophages protected against. (D) Curves from 1 representative plate showing macrophage-dependent cytotoxicity over time, as measured by decreases in GFP⁺ area of macrophage+anti-CD47 condition relative to the control condition. Gefitinib and erlotinib enhanced macrophage-dependent cytotoxicity within approximately 48 hours. Dashed lines indicate empirical 95% tolerance interval. (E) Box-and-whisker plot of drug classes ranked by normalized log₂ fold change of GFP⁺ area in macrophage versus PC9 control condition. Boxes indicate the median and interquartile range, and whiskers indicate maxima and minima (excluding outliers) for the indicated drug class. Drug classes that significantly increased relative GFP⁺ area are depicted in red, whereas EGFR TKIs (blue) were identified as the only drug class that significantly decreased relative GFP⁺ area. Each class of drugs was compared with controls (DMSO and empty wells) using a t test (**FDR < 0.01, ***FDR < 0.001).