02 Combined anti-angiogenic treatment to increase intratumoral persistence of CAR T-cells in lung cancer brain metastases

Background Brain metastasis in lung cancer carries a devastating prognosis, emphasizing the urgent clinical demand for innovative therapeutic strategies. While immunotherapeutic approaches such as the treatment with chimeric antigen receptor T-cells (CAR T-cells) have demonstrated efficacy in hematologic malignancies, their success in treating solid tumors remains elusive. This challenge arises from immunosuppressive factors within the tumor microenvironment but also from physical barriers, such as elevated interstitial pressure caused by dysfunctional tumor vessels—significant obstacles, particularly in solid tumors. We therefore aimed to assess the potential synergy between anti-angiogenic drugs and CAR T-treatment to overcome these barriers and enhance therapeutic outcomes using an innovative mouse model. Materials and Methods We set up an immunocompetent syngeneic orthotopic cerebral metastasis model in mice by combining a chronic cranial window with repetitive intracerebral two-photon laser scanning microscopy (TPLSM). This model allows in-vivo characterization of fluorescent tumor cells and CAR T-cells on a single cell level over time. Intraparenchymal injection of red fluorescent EpCAM-transduced Lewis Lung carcinoma cells (EpCAM/tdtLL/2 cells) followed by injection of EpCAM-directed or untransduced T-cells into the adjacent brain tissue was performed. Additionally, antibodies directed against VEGF-A and VEGF-R2 and the respective isotype control were injected intraperitoneally. Results Compared to untransduced T-cells, mice receiving EpCAM-directed CAR T-cells showed higher intratumoral CAR T-cell densities after intraparenchymal injection. This finding was accompanied with reduced tumor growth and ultimately translated into a survival benefit. However, intratumoral CAR T-cell numbers diminished over time indicating insufficient persistence inside of the tumor microenvironment. Additional anti-VEGF-A/VEGF-R2 treatment resulted in reduced tumor growth after EpCAM/GFPCAR T-cell and GFPT-cell treatment, respectively. Most interestingly, in vivo imaging reveals higher intratumoral CAR T-cell numbers after anti-angiogenic treatment compared to isotype controls pointing towards enhanced CAR T-cell persistence resulting in a survival benefit. Conclusions Collectively, our findings indicate that locally injected CAR T-cells may safely induce relevant anti-tumor effects in brain metastases from lung cancer. Additional anti-angiogenic treatment provides a mechanism to enhance intratumoral CAR T-cell persistence and reduce tumor growth. C. Eberle: None. J. Blobner: None. L. Dengler: None. J.J. Herold: None. A. Mühlbauer: None. T. Xu: None. K.J. Müller: None. N. Teske: None. P. Karschnia: None. S. Langer: None. H. Ishikawa-Ankerhold: None. M. Subklewe: None. N. Thon: None. J. Tonn: None. V.R. Buchholz: None. L. von Baumgarten: None.