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Chimeric antigen receptor (CAR) T cells have induced remarkable antitumor responses in B cell malignancies. Some patients do not respond because of T cell deficiencies that hamper the expansion, persistence, and effector function of these cells. We used longitudinal immune profiling to identify phenotypic and pharmacodynamic changes in CD19-directed CAR T cells in patients with chronic lymphocytic leukemia (CLL). CAR expression maintenance was also investigated because this can affect response durability. CAR T cell failure was accompanied by preexisting T cell-intrinsic defects or dysfunction acquired after infusion. In a small subset of patients, CAR silencing was observed coincident with leukemia relapse. Using a small molecule inhibitor, we demonstrated that the bromodomain and extra-terminal (BET) family of chromatin adapters plays a role in downregulating CAR expression. BET protein blockade also ameliorated CAR T cell exhaustion as manifested by inhibitory receptor reduction, enhanced metabolic fitness, increased proliferative capacity, and enriched transcriptomic signatures of T cell reinvigoration. BET inhibition decreased levels of the TET2 methylcytosine dioxygenase, and forced expression of the TET2 catalytic domain eliminated the potency-enhancing effects of BET protein targeting in CAR T cells, providing a mechanism linking BET proteins and T cell dysfunction. Thus, modulating BET epigenetic readers may improve the efficacy of cell-based immunotherapies., Introduction The adoptive transfer of autologous CD19-targeted chimeric antigen receptor (CAR) T cells has shown remarkable activity in patients with B cell malignancies (1-3). Upon treatment with a CAR signaling [...]

Mesothelin is a cell-surface molecule over-expressed on a large fraction of carcinomas, and thus is an attractive target of immunotherapy. A molecularly targeted therapy for these cancers was created by engineering T cells to express a chimeric receptor with high affinity for human mesothelin. Lentiviral vectors were used to express a single-chain variable fragment that binds mesothelin and that is fused to signaling domains derived from T-cell receptor zeta, CD28, and CD137 (4-1BB). When stimulated by mesothelin, lentivirally transduced T cells were induced to proliferate, express the antiapoptotic gene Bcl-[X.sub.L], and secrete multiple cytokines, all features characteristic of central memory T cells. When transferred intratumorally or intravenously into NOD/scid/IL2r[[gamma].sup.-/-] mice engrafted with large pre-established tumors, the engineered T cells reduced the tumor burden, and in some cases resulted in complete eradication of the tumors at low effector-to-target ratios. Incorporation of the CD137 signaling domain specifically reprogrammed cells for multifunctional cytokine secretion and enhanced persistence of T cells. These findings have important implications for adoptive immunotherapy of cancer, especially in the context of poorly immunogenic tumors. Genetically redirected T cells have promise of targeting T lymphocytes to tumor antigens, confer resistance to the tumor microenvironment, and providing immunosurveillance. adoptive immunotherapy | chimeric receptor | mesothelin

A role for PKC-[delta] and PI 3-kinase in TNF-[alpha]-mediated antiapoptotic signaling in the human neutrophil. Am J Physiol Cell Physiol 283: C48-C57, 2002. First published February 6, 2002; 10.1152/ajpcell.00385.2001.--The proinflommatory cytokine tumor necrosis factor (TNF)-[alpha] has been implicated in the attenuation of neutrophil spontaneous apoptosis during sepsis. Antiapoptotic signaling is principally mediated through the p60TNF receptor (p60TNFR). In neutrophils, TNF-[alpha] is an incomplete secretagogue and requires input from a ligated integrin(s) for neutrophil activation. In adherent neutrophils, TNF-[alpha] triggers association of both protein kinase C (PKC)-[delta] and phosphatidylinositol (PI) 3-kinase with the p60TNFR. In this study, a role for PKC-[delta] and PI 3-kinase in TNF-[alpha]-mediated antiapoptotic signaling was examined. TNF-[alpha] inhibited spontaneous apoptosis in fibronectin-adherent neutrophils, and this antiapoptotic signaling was blocked by the PKC-[delta] inhibitor rottlerin, but not by an inhibitor of [Ca.sup.2+]-dependent PKC isotypes, Go-6976. Inhibition of PI 3-kinase by LY-294002 also inhibited TNF-[alpha]-mediated antiapoptotic signaling. Cycloheximide blocked TNF-[alpha]-mediated antiapoptotic signaling, suggesting protein synthesis is required. Inhibition of either PKC-[delta] or PI 3-kinase attenuated TNF-[alpha]-mediated activation of the antiapoptotic transcription factor NF[kappa]B. Thus both PKC-[delta] and PI 3-kinase have essential roles in TNF-[alpha]-mediated antiapoptotic signaling in adherent neutrophils. sepsis; inflammation; signal transduction; nuclear factor [kappa]B; protein kinase C-[delta]; tumor necrosis factor-[alpha]