Development of chimeric antigen receptor-modified T cells for the treatment of esophageal cancer

Abstract

Background: Human epidermal growth factor receptor 2 (HER2) is an overexpressed antigen in esophageal squamous cell carcinomas (ESCCs) but with limited expression levels in normal esophageal tissues. Therefore, employing the adoptive transfer of T cells genetically modified to express chimeric antigen receptor (CAR) targeting HER2 could be a promising therapeutic strategy against ESCC. Methods: Two different second-generation CAR-T cells expressing antibodies for HER2 and CD19 antigens were developed using retroviral vector transduction. The expression of HER2 antigen in ESCC tissue and cell lines was examined by immunohistochemistry and flow cytometry, respectively. The tumor killing efficacy of the CAR-T cells in mice model and ESCC cell lines and its potential for the treatment of ESCC was evaluated by determining tumor size in mice xenograft, and by crystal violet staining, MTS assay, and cytokine release. Results: In vitro, HER2.CAR-T cells efficiently recognized and killed HER2-positive tumor cells as evidenced by the secretion of proinflammatory cytokines, interferon-γ, and interleukin 2 and by cytotoxicity assays. In vivo, intratumor injection of HER2.CAR-T cells resulted in a significant suppression of established ESCCs in a subcutaneous xenograft BALB/c nude mouse model. In contrast, the injection of CD19.CAR-T cells did not affect the tumor growth pattern. Conclusions: An effective HER2 CAR targeting ESCC was developed successfully. The HER2.CAR-T cell showed promising immunotherapeutic potential for the treatment of HER2-positive esophageal cancer.