Modulation of the Btla-HVEM Axis to Enhance CAR T Cell Immunotherapy Against Cancer

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.768-768
• Main Authors: Guruprasad, Puneeth, Carturan, Alberto, Zhang, Yunlin, Kumashie, Kingsley Gideon, Cohen, Ivan J, Ghilardi, Guido, Kim, Ki-Hyun, Lee, Jong-Seo, Lee, Yoon, Kim, Jong-Hoon, Chung, Junho, Shestov, Maksim, Pajarillo, Raymone, Harris, Jaryse, Lee, Yong Gu, Wang, Michael, Ballard, Hatcher, Gupta, Aasha, Ugwuanyi, Ositadimma, Hong, Seok Jae, Chen, Linhui, Paruzzo, Luca, Kammerman, Shane, Patel, Ruchi P., Shestova, Olga, Vella, Laura, Schuster, Stephen J., Svoboda, Jakub, Porazzi, Patrizia, Ruella, Marco
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-189633

Introduction: The efficacy of adoptive T cell immunotherapies against cancer, such as chimeric antigen receptor (CAR) T cells, is severely blunted by the immunosuppressive tumor microenvironment (TME). We sought to investigate the role of the TME in cancer resistance to effector T cells in order to define actionable targets to enhance CAR T cell immunotherapies. We initially used Hodgkin lymphoma (HL) as an ideal tumor model since it is characterized by a TME that is profoundly infiltrated by immunosuppressive cells, and then we expanded our findings to multiple cancer models. We first sought to identify the dominant interactions of immunosuppressive cellular compartments and effector T cells by analyzing single-cell RNA sequencing data on a total of 26 (4 exploratory + 22 validation) HL patient tumor biopsies. Using the CellPhoneDB algorithm, we inferred that the ligand B- and T-lymphocyte attenuator (BTLA) on effector T cells and the receptor Herpesvirus entry mediator (HVEM, TNFRSF14) on immunosuppressive cells (e.g., regulatory T cells, monocytes) strongly interact in the TME and promote T cell dysfunction ( Fig 1a). Akin to the canonical checkpoint PD1, BTLA recruits two potent tyrosine phosphatases, SHP-1 and SHP-2, to disable early T cell activation. Thus, we rationalized that BTLA expression on T cells might reduce their anti-tumor function. We hypothesized that deleting BTLA in CAR T cells would abolish BTLA-HVEM trans interactions at the immunological synapse and unleash the cytotoxic potential of CAR T cells. Methods and Results: We first generated BTLA KO anti-CD30 CAR T (CART30) cells against HL. To test their function in vivo, 15x10 6 HDLM-2 (CD30+HVEM+ HL) cells were subcutaneously implanted into NSG mice on day 0, and on day 62, 3x10 5 CAR30+ T cells were infused intravenously. Our results demonstrated that BTLA KO significantly enhances the function of anti-CD30 CAR T cells in HVEM+ HL ( Fig 1b), as assessed via tumor size (caliper) and CART30 expansion in the peripheral blood (flow cytometry). Additionally, we generated BTLA KO 4-1BBζ CART19 cells, which showed greater in vivo anti-tumor function in a subcutaneous tumor model of DLBCL (CD19+ HVEM+ OCI-Ly18). Serum collected from OCI-Ly18-bearing NSG mice infused with BTLA KO CART19 was enriched in effector cytokines (e.g., TNF, IFNγ, IL-2) as measured by Luminex. We then extended these findings into HVEM+ solid tumor models. BTLA KO improved tumor control in vitro in short-term killing ex