In vivo dynamics and anti-tumor effects of EpCAM-directed CAR T-cells against brain metastases from lung cancer

Abstract

Lung cancer patients are at risk for brain metastases and often succumb to their intracranial disease. Chimeric Antigen Receptor (CAR) T-cells emerged as a powerful cell-based immunotherapy for hematological malignancies; however, it remains unclear whether CAR T-cells represent a viable therapy for brain metastases. Here, we established a syngeneic orthotopic cerebral metastasis model in mice by combining a chronic cranial window with repetitive intracerebral two-photon laser scanning-microscopy. This approach enabled in vivo -characterization of fluorescent CAR T-cells and tumor cells on a single-cell level over weeks. Intraparenchymal injection of Lewis lung carcinoma cells (expressing the tumor cell-antigen EpCAM) was performed, and EpCAM-directed CAR T-cells were injected either intravenously or into the adjacent brain parenchyma. In mice receiving EpCAM-directed CAR T-cells intravenously, we neither observed substantial CAR T-cell accumulation within the tumor nor relevant anti-tumor effects. Local CAR T-cell injection, however, resulted in intratumoral CAR T-cell accumulation compared to controls treated with T-cells lacking a CAR. This finding was accompanied by reduced tumorous growth as determined per in vivo -microscopy and immunofluorescence of excised brains and also translated into prolonged survival. However, the intratumoral number of EpCAM-directed CAR T-cells decreased during the observation period, pointing toward insufficient persistence. No CNS-specific or systemic toxicities of EpCAM-directed CAR T-cells were observed in our fully immunocompetent model. Collectively, our findings indicate that locally (but not intravenously) injected CAR T-cells may safely induce relevant anti-tumor effects in brain metastases from lung cancer. Strategies improving the intratumoral CAR T-cell persistence may further boost the therapeutic success.

Chimeric Antigen Receptor (CAR) T-Cell Therapy for Patients with Lung Cancer: Current Perspectives

“…EpCAM is expressed in about 50% of NSCLC tumors. 50 Similar to CEA, expression by normal cells is polarized to the luminal surface, whereas such polarity is not evident in transformed cells. Once again, however, pulmonary immunopathology has been noted in some pre-clinical models when EpCAM has been targeted using CAR T-cells.…”

“…51 Using an orthotopic Lewis lung carcinoma tumor model, Xu et al demonstrated that a 2G (CD28) CAR T-cells targeted against EpCAM could delay intracranial disease progression following local but not systemic delivery, although persistence of cells was insufficient to achieve disease eradication. 50 One strategy that may be used to dial down risk of toxicity associated with the targeting of self-antigens such as EpCAM entails the use of low affinity targeting moieties that can discriminate between healthy (EpCAM low) and malignant cells (EpCAM) high. 52 Nonetheless, risk of antigen downregulation leading to therapeutic failure needs to be considered with this approach.…”

Informed by Cancer Stem Cells of Solid Tumors: Advances in Treatments Targeting Tumor-Promoting Factors and Pathways

“…Adoptive transfer of peripheral blood lymphocytes (PBL) transduced with an EpCAM-specific CAR prevented metastasis of prostate cancer PC3 cells and significantly reduced tumor growth of PC3M cells in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice [104]. A recent publication examined the ability of anti-EpCAM CAR-T cells to prevent lung cancer brain metastasis [105]. While intraparenchymal injection of anti-EpCAM CAR-T cells reduced LL/2 tumor growth in the brain in vivo, intravenous administration of the CAR-T cells failed to accumulate within the tumor and, in both cases, failed to persist within the tumor, suggesting that the success of CAR-T cells may be cancer-and location-specific [105].…”

Harnessing immunotherapy for brain metastases: insights into tumor–brain microenvironment interactions and emerging treatment modalities

“…Xu et al [ 203 ] explored the effect of application methods on the performance of CAR-T cells in treating lung cancer BM and concluded that, compared to intravenous injection, local application of EpCAM-CAR-T cells achieved a more significant accumulation in the target tumor and significantly stimulated antitumor effects without causing central nervous system or systemic off-target toxicity. Nevertheless, the researchers found that CAR-T cells lacked sufficient persistence in tumor aggregation and failed to consistently exert tumor cell killing effects.…”