Abstract 3175: Exploring the potential of CEA-CAR-NK cells in colorectal cancer

Chimeric Antigen Receptor (CAR) therapy targeting carcinoembryonic antigen (CEA/CEACAM5) is a promising strategy for colorectal cancer (CRC). CAR-T cells, however, carry significant side effects, and the fact that CEA is also expressed at low levels in normal tissues makes CAR-NK cells a safer alternative, offering reduced toxicity while maintaining effective anti-tumor activity. Despite this potential, CAR-NK systems targeting CEA remain underexplored. In this study, we generated and evaluated clones of the NK-92 cell line expressing two CAR constructs with distinct affinity for CEA: BW431/26 (moderate affinity) and hMN-14 (high affinity). The BW431/26-based CAR, with its lower affinity, may offer a safer profile by reducing potential on-target, off-tumor effects. On the other hand, the hMN-14-based CAR demonstrated superior cytotoxicity in in vitro studies due to its higher affinity. Sorted populations and clones of CAR-NK cells transduced with these constructs were evaluated for killing activity both in vitro and in vivo. In vitro, the high affinity hMN-14 CAR exhibited enhanced killing capacity compared to the BW431/26 CAR. However, in vivo experiments on CRC xenografts in NOD/Scid mice showed comparable tumor growth inhibition between the two constructs. These findings suggest that higher scFv affinity does not necessarily translate to improved in vivo efficacy of CEA-CAR-NK cells, emphasizing the multiplicity of factors influencing their activity—such as persistence and activation—and highlighting the need for further modifications to optimize their functionality. Citation Format: Alice D'Andrea, Marco Cortese, Enzo Medico. Exploring the potential of CEA-CAR-NK cells in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3175.