Mesothelin CAR‐engineered NK cells derived from human embryonic stem cells suppress the progression of human ovarian cancer in animals

CAR-NK cell therapy does not require HLA matching and has minimal side effects. However, traditional methods of engineering CARs into human tissue-derived NK cells exhibit heterogeneity, low transduction efficiency, and high manufacturing costs. Here, we provide a reliable approach for generating large-scale and cryopreserved mesothelin (MSLN) CAR-NK cells from human embryonic stem cells (hESCs) as an alternative cell source. We first constructed MSLN CAR-expressing hESCs to reduce CAR engineering costs and subsequently differentiated these stem cells into MSLN CAR-NK cells via an efficient organoid induction system. The MSLN CAR-NK cells exhibit the typical expression patterns of activating receptors, inhibitory receptors, and effector molecules of NK cells. In the presence of tumour cells, the MSLN CAR-NK cells show increased secretion of IFN-γ and TNF-α, as well as elevated CD107a expression level compared with induced NK cells. We cryopreserved the MSLN CAR-NK cells in liquid nitrogen using a clinical-grade freezing medium (CS10) for more than 6 months to mimic an off-the-shelf CAR-NK cell product. The thawed MSLN CAR-NK cells immediately recovered after 48-72-h culture and effectively eliminated ovarian tumour cells, including human primary ovarian tumour cells from patients. The thawed MSLN CAR-NK cells efficiently suppressed ovarian tumour development in vivo and prolonged the survival of tumour-bearing mice. Our study provides insights into the clinical translation of hESC-derived MSLN CAR-NK cells as a promising off-the-shelf cell product.