Combined targeting of soluble latent TGF-ß and a solid tumor-associated antigen with adapter CAR T cells.

Solid tumors consist of malignant and nonmalignant cells that together create the local tumor microenvironment (TME). Additionally, the TME is characterized by the expression of numerous soluble factors such as TGF-ß. TGF-ß plays an important role in the TME by suppressing T cell effector function and promoting tumor invasiveness. Up to now CAR T cells exclusively target tumor-associated antigens (TAA) located on the cell membrane. Thus, strategies to exploit soluble antigens as CAR targets within the TME are needed. This study demonstrates a novel approach using Adapter CAR (AdCAR) T cells for the detection of soluble latent TGF-ß within the TME of a pancreatic tumor model. We show that AdCARs in combination with the respective adapter can be used to sense soluble tumor-derived latent TGF-ß, both in vitro and in vivo. Sensing of the soluble antigen induced cellular activation and effector cytokine production in AdCAR T cells. Moreover, we evaluated AdCAR T cells for the combined targeting of soluble latent TGF-ß and tumor cell killing by targeting CD66c as TAA in vivo. In sum, our study broadens the spectrum of targetable moieties for AdCAR T cells by soluble latent TGF-ß.

TH1 cytokines induce senescence in AML.

Cancer testis antigen PRAME is over-expressed in a variety of malignant cells but is not or minimally expressed in normal non-germ line cells. Adoptive transfer of PRAME-specific T cells is thus under investigation in clinical trials as an innovative therapeutic option for acute myeloid leukemia (AML). However, their senescence-inducing activity has not been studied. This study therefore examines senescence induction in AML cells by PRAME-specific TH1 cells. Analysis of cell cycle and marker expression demonstrate that the supernatants of antigen-stimulated PRAME-specific TH1 cells induce senescence in AML cell lines Kasumi and Nomo-1 through combinative IFN-γ and TNF-α. Additionally IFN-γ and TNF-α secreted by TCR-activated Vδ2+ or CMV-specific T cells can also drive these AML cell lines into terminal growth arrest. G1/0 arrest is also suggested in patient-derived AML by TH1 cytokines or supernatants from Zoledronate-stimulated or aCD3/aCD28-stimulated PBMCs. Thus, we show for the first time that senescence is induced in AML cells by combined IFN-γ and TNF-α, and that these cytokines can be derived either from TCR-engineered CD4+ T cells, or intriguingly from Virus-specific as well as innate Vδ2+ T cells responding to their cognate antigens, namely T-cell responses targeting an antigen that is NOT expressed by the leukemic cells.