TARGETING TUMOR-ASSOCIATED MACROPHAGES WITH CHIMERIC ANTIGEN RECEPTOR T CELLS: A NOVEL APPROACH FOR SOLID TUMORS

Tumor-associated macrophages (TAMs) are abundant cells in the tumor microenvironment and have the ability to suppress T lymphocytes. Among distinct subsets, the CD163+ TAMs are classically associated with poor prognosis in distinct tumor types including breast, ovarian and pancreatic cancers. Chimeric Antigen Receptor T cells (CAR-T cells) have revolutionized the treatment of hematological cancers, however, their success in solid tumors is limited by intratumoral immunosuppression. Therefore, strategies aimed at eliminating TAMs may show promising therapeutic potential. Using a lentiviral vector our study proposes the use of a second-generation CAR-T cell against CD163 (αCD163) aiming to eliminate CD163+ TAMs. We compared, αCD19 CAR-T and αCD163 CAR-T cells transduction, proliferation and functional status using either a lentiviral or a piggyBac transposase system. CAR transduction was performed in T lymphocytes 24 hours after activation, showing an efficiency of about 39% (± 1,34%, n = 2) for αCD19 CAR and about 10,3% (n = 1) of αCD163 CAR expression. CAR-T cells showed up-regulation of memory and activation markers (CCR7, CD45RO and HLA-DR) 10 days post-transduction. Furthermore, the expression levels of memory markers CCR7⁺CD45RO⁺ and activation marker HLA-DR were similar when comparing non-transduced T cells with all transduced lymphocytes. Cytotoxic activity of αCD19 CAR-T was tested against THP-1 cells and CD19+ cell lines. Results show a dose-dependent cytotoxic response across the 3 tested donors using the THP-1 cell line. Also, a higher CD19+ NALM6 cell killing was promoted by αCD19 CAR-T when compared to non-transduced counterparts. These findings support the antitumor potential of expanded CAR-T cells, marked by an enhanced cytotoxic function. Future steps involve producing αCD163 CAR-T cells and evaluating cytotoxicity against CD163+ myeloid cells in vitro .