Feasibility of Intratumoral Administration With EPHB4-CAR-T Cells for the Treatment of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) represents the most common type of oral cancer, and its prognosis remains poor. In this study, we found that almost OSCC cases showed high Ephrin type-B receptor 4 (EPHB4) expression that was mainly localized on the membrane of tumor cells. Therefore, EPHB4 represents a potential target of chimeric antigen receptor (CAR) T cell therapy for OSCC treatment. Because the oral cavity can be directly accessed, local administration of CAR-T cells is feasible for treating OSCC. In this study, we investigated the efficacy of intratumoral injection of EPHB4-specific CAR-T cells in OSCC using xenograft models. To evaluate the anti-tumor effect, the SAS OSCC cell line or an OSCC patient-derived xenograft (PDX) tumor was subcutaneously implanted into NOD SCID gamma mice, and EPHB4-CAR-T cells were intratumorally injected twice. As expected, administration of CAR-T cells suppressed tumor growth of both SAS cells and PDX tumor. EPHB4 expression in tumor tissues was attenuated by CAR-T cell treatment, which was accompanied by a reduction in tumor area and accumulation of CAR-T cells. Our findings suggest that intratumoral injection of EPHB4-CAR-T cells represents a potential therapeutic strategy for OSCC.