Generation and Functional Characterization of PLAP CAR-T Cells against Cervical Cancer Cells

Abstract

Chimeric antigen receptor (CAR) T cell therapy is one of the cancer treatment modalities that has recently shown promising results in treating hematopoietic malignancies. However, one of the obstacles that need to be addressed in solid tumors is the on-target/off-tumor cytotoxicity due to the lack of specific tumor antigens with low expression in healthy cells. Placental alkaline phosphatase (PLAP) is a shared placenta/tumor-associated antigen (TAA) that is expressed in ovarian, cervical, colorectal, and prostate cancers and is negligible in normal cells. In this study, we constructed second-generation CAR T cells with a humanized scFv against PLAP antigen, then evaluated the characteristics of PLAP CAR T cells in terms of tonic signaling and differentiation in comparison with {Delta}PLAP CAR T cells and CD19 CAR T cells. In addition, by coculturing PLAP CAR T cells with HeLa cells, we analyzed the tumor-killing function and secretion of anti-tumor molecules. Results showed that PLAP CAR T cells not only could eliminate the cancer cells but also increase their proliferation in vitro. We also observed increased secretion of IL-2, granzyme A, and IFN-{gamma} by PLAP CAR T cells upon exposure to the target cells. In conclusion, PLAP CAR T cells are potential candidates for further investigation in cervical cancer and potentially other solid tumors.