Combination of Dara and Hu5F9-IgG2σ in r/r T-ALL PDX samples. (A) Antibody-dependent cellular phagocytosis in eleven r/r T-ALL PDX samples treated with datatumumab (Dara), a CD47-blocking antibody (Hu5F9-IgG2σ), the combination (Dara + Hu5F9-IgG2σ [combi]), or no treatment (control) using live cell imaging. Error bars indicate standard error of the mean of technical triplicates. One representative experiment of 3 experiments with different donor macrophages is depicted. The remaining experiments with the other donor macrophages are depicted in supplemental Figure 7. (B) Summary of all ADCP in r/r T-ALL PDX samples with human macrophages from 3 different healthy donors. (C) In vivo phase 2–like preclinical study in overt leukemia with eleven r/r T-ALL PDX samples injected into NSG mice subjected to Dara, Hu5F9-IgG2σ alone, or the combination (Dara + Hu5F9-IgG2σ [combi]), or left untreated (control). Survival was analyzed by using the Kaplan-Meier method and log-rank statistics. **P < .01, ***P < .001, ****P < .0001. ns, not significant; ROI, red object counts per image.