Generation Of Exhaustion Resistant Memory Cd8 T-Cells By Simultaneous Downmodulation Of Mtorc1 And Pd-1 In Activated Cd8 T-Cells

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PACD8 memory T cells play a crucial role in controlling chronic infections and certain malignancies. It is possible to expand the population redirecting early-activated T-cells toward memory differentiation by altering intracellular signaling of mTORC1 pathway. Indeed, treatment with mTORC1 inhibitor rapamycin increased formation of memory cells as published previously; however, animals treated with the drug exhibited signs of immune suppression and rapamycin-generated CD8 memory T-cells failed to protect animals against melanoma challenge. We introduced highly efficient RNAi-based method to downmodulate mTORC1 signaling specifically in target cells. siRNA against raptor, a critical component of the signaling complex, was delivered in vivo into activated T-cells by conjugating to the 4-1BB-binding RNA aptamer resulting in expansion of CD8+ memory T-cells formation.Memory T-cells are generally resistant to immune suppression, yet in vivo, the population suffers from the gradual attrition mediated by PD-1 signalling. We developed the conjugate with two highly effective siRNAs against raptor and PD-1 linked to the same 4-1BB aptamer molecule. In vitro, both siRNAs efficiently dissociated from the conjugate inside target cells and simultaneously downregulated its respective mRNAs. In vivo, using OT-I adoptive transfer model, we demonstrated that treatment with 4-1BB-raptor-PD1 conjugates increased formation of memory CD8+ T-cells (as measured by absolute number of OT-1 cells 30 days after the treatment) in a rate similar to the 4-1BB-raptor conjugate. There was, however, qualitative difference between two populations, as CD8+ memory T-cells expanded with 4-1BB-raptor-PD1 conjugates expressed significantly less PD-1 on cell surface, and were, therefore, resistant to PD-1-mediated immune suppression. Thus, we introduced a new method to generate memory cells with enhanced functional potential and currently exploring its therapeutic usefulness in various models.Citation Format: Alexey Berezhnoy, Agata Levay, Anugraha Rajagopalan, Yvonne Puplampu-Dove, Eli Gilboa. Generation of exhaustion-resistant memory CD8 T-cells by simultaneous downmodulation of mTORC1 and PD-1 in activated CD8 T-cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3147. doi:10.1158/1538-7445.AM2015-3147