Brunn, S. | bioRxiv Science

bioRxiv2024

Cancer-cell-derived cGAMP limits the activity of tumor-associated CD8+ T cells

Using a mouse tumor model with inducible cancer-cell-intrinsic cGAS expression, we show that cancer-cell-derived cGAMP is essential and sufficient to trigger a sustained type I interferon response within the tumor microenvironment. This led to improved CD8+ T cell-dependent tumor restriction. However, cGAMP limits the proliferation, survival, and function of STING-expressing but not of STING-deficient CD8+ T cells. In vivo, STING deficiency in CD8+ T cells enhanced tumor restriction. Consequently, cancer-cell-derived cGAMP both drives and limits the anti-tumor potential of CD8+ T cells. Mechanistically, T cell-intrinsic STING is associated with pro-apoptotic and antiproliferative gene signatures. Our findings suggest that STING signaling acts as a checkpoint in CD8+ T cells that balances tumor immunity. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/620471v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@13b075borg.highwire.dtl.DTLVardef@601b49org.highwire.dtl.DTLVardef@19f58e4org.highwire.dtl.DTLVardef@84e8bf_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

Anti-CD117 CAR T cells incorporating a safety switch eradicate human acute myeloid leukemia and hematopoietic stem cells

Acute Myeloid Leukemia originates from the accumulation of mutations in hematopoietic stem and progenitor cells, leading to the emergence of leukemia-initiating cells, which sustain blast formation. CAR T cells specific for the CD117 antigen can deplete malignant and healthy hematopoietic stem cells. Here we exploit non-viral technology to achieve early termination of CAR T cell activity to prevent incoming graft rejection. Transient expression of an anti-CD117 CAR by mRNA conferred T cells the ability to eliminate CD117+ targets in vitro and in vivo. As an alternative approach, we used a Sleeping Beauty transposon vector for the generation of CAR T cells incorporating an inducible Caspase 9 safety switch. Stable CAR expression was associated with high proportion of T memory stem cells, low levels of exhaustion markers, and potent cellular cytotoxicity. Anti-CD117 CAR T cells mediated depletion of leukemic cells and healthy hematopoietic stem cells in NSG mice reconstituted with human leukemia or CD34+ cord blood cells, respectively, and could be chemically terminated in vivo. The use of a non-viral technology to control CAR T cell pharmacokinetic properties is attractive for a first-in-human study in patients with acute myeloid leukemia prior to hematopoietic stem cell transplantation.

cancer biology↗