Combination of STING agonism and CD33-directed T-cell–engaging molecules efficiently eliminates pAML cells and shows superior in vivo efficacy. (A) Flow cytometric analysis of cGAMP-mediated cytotoxicity after 48 hours against pAML cells (n = 4). (B) Flow cytometric analysis of AMG 330–mediated (0.5 ng/mL) cytotoxicity after 48 hours against pAML cells in cocultures with human T cells (E:T, 1:10; n = 10). Specific lysis was calculated relative to the c-BiTE condition. The concentration of added cGAMP in cocultures was 10 μg/mL. (C) Flow cytometric analysis of AMG 330–mediated (0.5 ng/mL) cytotoxicity after 48 hours against pAML cells in cocultures with human T cells (E:T, 1:10; n = 11). The concentration of added diABZI in cocultures was 1 nM. Corresponding levels of secreted IFN-γ as determined by CBA analysis are shown. (D) Timeline and overview of the AML xenograft model. Injections are indicated with arrows (n = 3 mice per group). (E-F) Tumor burden was analyzed by bioluminescence imaging, and probability of survival is depicted after Kaplan-Meier analysis. (G) MOLM-13 tumor burden in the bone marrow of mice was analyzed by flow cytometric analysis at the time of euthanasia. Means ± SEM are presented. Statistical analysis was performed using the ordinary 1-way ANOVA with the Tukey comparison or the Kaplan-Meier analysis with the Mantel-Cox test (panel F). ns, P > .05; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001. E:T, effector-to-target ratio; i.p., intraperitoneal; ns, not significant.