Abstract LB-186: Sustained efficacy of immunotherapy for solid tumors with novel dual CD4/CD8 T cell receptor engineered synergistic combination of hematopoietic stem cells and T cells (2017)

Abstract The goal of our studies is to generate durable anti-cancer T cell responses to improve the outcome of patients with solid tumors. Re-engineering patient’s mature immune cells and administering billions of these cells have shown to be promising but unfortunately, the anti-tumor effect is largely short-lived. In an effort to generate tumor-associated antigen (TAA) specific T cells we have identified NYESO-1 as the prototypic TAA for cancer immunotherapy. We have recently discovered a novel and distinct subset of human CD4+ Th1 cells that directly recognize NYESO-1 naturally presented by MHC II on cancer cells. In contrast to conventional CD4 T cells, these tumor-recognizing (TR) CD4 T cells also potently provide help to CD8 T cells in an antigen-presenting cell (APC) independent fashion. Our central hypothesis is that CD4TCR engineered human hematopoietic stem/progenitor cells (hHSC) will lead to durable in vivo supply of fully active TR-CD4 cells with anti-tumor activity, and provide sustained help to co-injected CD8TCR transduced effector T cells (which will serve to immediately "debulk" the tumor), leading to long-lasting tumor rejection. Results: We successfully accomplished molecular cloning, construction and generation of lentiviral viral vectors with two unique NYESO-1 (TR)CD4TCRs (MHC II restricted HLA DR1 and DP4), as well as, another novel CD8 (MHC I HLA A2.1) TCR for NYESO-1. Transduction efficiency of hHSC was high with transgene expression levels of 40-51% (0.5-1 vector copies/cell); and 65-92% tetramer+ for mature T cells. We confirmed specific functional activity of all TCRs by co-incubating transduced T cells with various tumor targets (SKMEL-37, MZ19, or aAPC: K562/DR1/DP4/A2.1 +/- cognate peptides) by ELISA and intracellular staining for IFNg. For this project we generated new transgenic mouse models based on a highly immunodeficient NSG background with expression of human MHC II DP4 and DR1 in order to study hHSC differentiation/function in vivo and to test anti-human cancer activity with our adoptive cell transfer (ACT) platform. Utilizing these transgenic mice, we injected CD34+ hHSC transduced with (TR)CD4 TCR and after 2 to 3 months we confirmed generation of engineered TCR expressing human T cells by FACS-based immunophenotyping through blood sampling. We then moved forward to test anti-tumor efficacy in vivo with s.q. injection of human melanoma (MZ19) or human ovarian carcinoma (A2780/A2/NY) cells in mice injected with (TR)CD4 TCR transduced or non-transduced-control hHSC. We injected a low dose (5x10^5 cells) of NYESO-1 HLA A2.1 CD8TCR-transduced hPBMC and followed tumor growth. Remarkable tumor control was obtained (p&lt;0.05) in the mouse group that received (TR)CD4 TCR transduced hHSC (tumor size=28mm^2; SE+/-11) versus mice that received untransduced hHSC (152.7mm^2; SE+/-24) or control untreated (no hHSC, no CD8 T cell ACT) (196mm^2; SE+/-40) assessed at day 32 after tumor (A2780/A2/NY) injection. Conclusion: Here we demonstrate for the first time that a combined ACT approach of (TR)CD4 TCR transduced hHSC with CD8 TCR transduced PBMC leads to a synergistic and efficient in vivo control of tumor burden. These results provide basis to pursue a Phase I/IIa clinical trial based on our novel adoptive cell immunotherapy platform to benefit patients with advanced solid tumors. Citation Format: Richard C. Koya, Thinle Chodon, Junko Matsuzaki, Takemasa Tsuji, Satoko Matsueda, Kunle Odunsi. Sustained efficacy of immunotherapy for solid tumors with novel dual CD4/CD8 T cell receptor engineered synergistic combination of hematopoietic stem cells and T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-186. doi:10.1158/1538-7445.AM2017-LB-186