Paclitaxel was identified as an agent potentiating CD47 blockade–mediated phagocytosis through macrophages. (A) A schematic showing the high-throughput screening strategy for identifying agents to enhance CD47 blockade-induced phagocytosis. (B) LB-LTMK high-throughput screens of 147 FDA-approved anticancer small molecule compounds; Raji cells were treated with antibodies blocking CD47-Sirpα interaction (anti-CD47 or anti-Sirpα) and subjected to the LB-LTMK assay; phagocytosis was normalized to dimethyl sulfoxide control; spots represent individual compounds. (C) Representative bioluminescence images of the LB-LTMK assay evaluating the effect of imiquimod, cabazitaxel, and paclitaxel on aSirpα-mediated phagocytosis with Raji cells equipped with luciferase-eGFP as the target cells; BMDMs were used for the assay. (D) Paclitaxel potentiated the effect of CD47 blocking antibody-mediated phagocytosis in a dose-dependent manner. **P < .01; ***P < .001 (1-way ANOVA test). (E) Paclitaxel dose-dependently enhanced phagocytosis of CD47-deficient Raji cells. **P < .01; ***P < .001 (1-way ANOVA test). (F) Paclitaxel enhanced aCD47-mediated phagocytosis of Raji cells by human peripheral blood monocyte-derived macrophages with a luminescence-based phagocytosis assay. **P < .01; ***P < .001 (1-way ANOVA test). (G) A schematic showing the experimental design to evaluate the effect of paclitaxel on BMDMs or Raji cells in enhancing phagocytosis; phagocytosis assays were performed using paclitaxel-treated BMDMs and untreated Raji cells or paclitaxel-treated Raji cells and untreated BMDMs. (H) Pretreatment of BMDMs with paclitaxel significantly enhanced aCD47-mediated phagocytosis of Raji cells. *P < .05; **P < .01; ***P < .001 (1-way ANOVA test). (I) Paclitaxel enhanced the potency of aCD47-mediated phagocytosis of Raji cells by shifting EC50 from 76.48 ng/mL to 21.26 ng/mL and the maximal capacity of aCD47 from clearing 75% of cancer cells within 24 hours to nearly 100% clearance.