CD70 has emerged as a promising target in acute myeloid leukemia (AML), and we have previously demonstrated the potency of an optimized CD70-targeted ligand-based chimeric antigen receptor (CAR). However, here, we identify in vivo CD70 antigen escape as a limitation of single-antigen targeting. Combination targeting of CD70 and CD33 may overcome AML antigen heterogeneity. We hypothesized that modifying our CD70 CAR platform to secrete a bispecific T-cell engaging antibody molecule (TEAM) targeting CD33 (7033) would create a therapeutic window whereby AML heterogeneity could be addressed without increasing tissue toxicity. We found that CD33 TEAMs mediated specific cytotoxicity across AML cell lines, including CD33 or CD70 single-antigen knockout tumors. 7033 CAR T cells eradicated tumor in an in vivo mixed tumor model of CD70 antigen escape and outperformed the previously optimized CD70 CAR in a patient-derived xenograft. In vivo gene expression profiling of CAR T cells revealed enhanced 7033 CAR T-cell pathway scoring for persistence, activation, and T-cell receptor signaling. Additionally, CD33 TEAMs successfully redirected T cells isolated from patients with AML to activate, secrete cytokines, and kill tumor targets despite exposure to substantial prior cytotoxic therapies. In summary, our findings demonstrate the feasibility of our 7033 CAR to overcome AML heterogeneity and leverage the bystander T cells of patients; this approach warrants further study in patients with this dire clinical need.

中文翻译：

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分泌抗 CD33/抗 CD3 双靶点抗体的 CD70 CAR T 细胞克服了 AML 中的抗原异质性


CD70 已成为急性髓性白血病 （AML） 的一个有前途的靶点，我们之前已经证明了优化的 CD70 靶向配体的嵌合抗原受体 （CAR） 的效力。然而，在这里，我们将体内 CD70 抗原逃逸确定为单抗原靶向的限制。CD70 和 CD33 的联合靶向可以克服 AML 抗原异质性。我们假设修改我们的 CD70 CAR 平台以分泌靶向 CD33 （7033） 的双特异性 T 细胞结合抗体分子 （TEAM） 将创建一个治疗窗口，从而可以在不增加组织毒性的情况下解决 AML 异质性。我们发现 CD33 TEAM 介导了 AML 细胞系的特异性细胞毒性，包括 CD33 或 CD70 单抗原敲除肿瘤。7033 CAR T 细胞在 CD70 抗原逃逸的体内混合肿瘤模型中根除肿瘤，并在患者来源的异种移植物中优于先前优化的 CD70 CAR。CAR T 细胞的体内基因表达谱显示，7033 CAR T 细胞通路的持久性、激活和 T 细胞受体信号传导评分增强。此外，CD33 TEAM 成功地重定向从 AML 患者身上分离的 T 细胞，以激活、分泌细胞因子并杀死肿瘤靶标，尽管之前暴露于大量的细胞毒性治疗。总之，我们的研究结果证明了我们的 7033 CAR 克服 AML 异质性并利用患者旁观者 T 细胞的可行性;这种方法值得在具有这种迫切临床需求的患者中进一步研究。