Philochem AG, Otelfingen, Switzerland.
Swiss Federal Institute of Technology (ETH Zürich), Zurich, Switzerland.
Mol Cancer Ther. 2024 Jul 2;23(7):1010-1020. doi: 10.1158/1535-7163.MCT-23-0766.
Metastatic colorectal cancer remains a leading cause of cancer-related deaths, with a 5-year survival rate of only 15%. T cell-engaging bispecific antibodies (TCBs) represent a class of biopharmaceuticals that redirect cytotoxic T cells toward tumor cells, thereby turning immunologically "cold" tumors into "hot" ones. The carcinoembryonic antigen (CEA) is an attractive tumor-associated antigen that is overexpressed in more than 98% of patients with colorectal cancer. In this study, we report the comparison of four different TCB formats employing the antibodies F4 (targeting human CEA) and 2C11 (targeting mouse CD3ε). These formats include both antibody fragment-based and IgG-based constructs, with either one or two binding specificities of the respective antibodies. The 2 + 1 arrangement, using an anti-CEA single-chain diabody fused to an anti-CD3 single-chain variable fragment, emerged as the most potent design, showing tumor killing at subnanomolar concentrations across three different CEA+ cell lines. The in vitro activity was three times greater in C57BL/6 mouse colon adenocarcinoma cells (MC38) expressing high levels of CEA compared with those expressing low levels, highlighting the impact of CEA density in this assay. The optimal TCB candidate was tested in two different immunocompetent mouse models of colorectal cancer and showed tumor growth retardation. Ex vivo analysis of tumor infiltrates showed an increase in CD4+ and CD8+ T cells upon TCB treatment. This study suggests that bivalent tumor targeting, monovalent T-cell targeting, and a short spatial separation are promising characteristics for CEA-targeting TCBs.
转移性结直肠癌仍然是癌症相关死亡的主要原因，其 5 年生存率仅为 15%。T 细胞结合双特异性抗体（TCBs）是一类生物制药，可将细胞毒性 T 细胞重新导向肿瘤细胞，从而将免疫“冷”肿瘤转化为“热”肿瘤。癌胚抗原（CEA）是一种有吸引力的肿瘤相关抗原，在超过 98%的结直肠癌患者中过度表达。在这项研究中，我们报告了使用针对人 CEA 的抗体 F4 和针对鼠 CD3ε 的抗体 2C11 的四种不同 TCB 格式的比较。这些格式包括基于抗体片段和 IgG 的构建体，具有各自抗体的一个或两个结合特异性。使用与抗 CD3 单链可变片段融合的抗 CEA 单链二价体的 2 + 1 排列，表现出最有效的设计，在三种不同的 CEA+细胞系中，以亚纳摩尔浓度显示出肿瘤杀伤作用。在表达高水平 CEA 的 C57BL/6 小鼠结肠腺癌细胞（MC38）中，体外活性比表达低水平 CEA 的细胞高 3 倍，突出了 CEA 密度在该测定中的影响。最佳 TCB 候选物在两种不同的结直肠癌免疫功能正常的小鼠模型中进行了测试，显示出肿瘤生长延迟。肿瘤浸润物的离体分析显示，TCB 治疗后 CD4+和 CD8+T 细胞增加。这项研究表明，双价肿瘤靶向、单价 T 细胞靶向和短空间分离是 CEA 靶向 TCB 的有前途的特征。
