Combining TAG ‐ 72CAR with anti‐ MUC16CAR improves the potency of ovarian cancer treatment

Ovarian cancer (OC) is typically associated with poor prognosis and high mortality. Chimeric antigen receptor (CAR) T‐cell therapy offers a promising strategy, yet its application in solid tumours remains constrained by limited efficacy and on‐target/off‐tumour toxicities. We previously developed K101CAR T cells targeting CA125, the cleaved extracellular domain of MUC16, and demonstrated potent antitumour activity against OC. However, because MUC16 exhibits low‐level expression in certain normal tissues, safety concerns remain regarding potential off‐tumour effects. We designed a combinatorial CAR composed of two single‐chain variable fragments (scFvs): (i) TAG‐72 targeting the Sialyl‐Tn antigen highly expressed on malignant cells, and (ii) the K101 scFv. The first unit is linked to a CD3ζ signalling domain, whereas the second is linked to a 4‐1BB costimulatory domain, leading to a combinatorial CAR fully reactive against double‐positive targets, Tz‐KBBCAR. We demonstrate that Tz‐KBBCAR T cells efficiently eliminate MUC16 + /TAG‐72 + ‐, while sparing MUC16 + /TAG‐72 − ‐ cells in vitro and markedly suppress tumour progression in vivo . We also observed that compared to K101CAR T cells, Tz‐KBBCAR T cells exhibit enhanced expansion, sustained viability, and a reduced exhaustion phenotype. Overall, our study presents an efficient combinatorial CAR T‐cell strategy predicted to be safer than single CAR T‐cell therapy for OC.