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 (
SUMMARY
Genetically modified T cells expressing chimeric antigen receptors (CARs) demonstrate robust responses against lineage restricted, non-essential targets in hematologic cancers. However, in solid tumors, the full potential of CAR T cell therapy is limited by the availability of cell surface antigens with sufficient cancer-specific expression. The majority of CAR targets have been normal self-antigens on dispensable hematopoietic tissues or overexpressed shared antigens. Here, we established that abnormal self-antigens can serve as targets for tumor rejection. We developed a CAR that recognized cancer-associated Tn glycoform of MUC1, a neoantigen expressed in a variety of cancers. Anti-Tn-MUC1 CAR T cells demonstrated target-specific cytotoxicity and successfully controlled tumor growth in xenograft models of T cell leukemia and pancreatic cancer. These findings demonstrate the therapeutic efficacy of CAR T cells directed against Tn-MUC1 and present aberrantly glycosylated antigens as a novel class of targets for tumor therapy with engineered T cells.
The proinflammatory cytokine tumor necrosis factor (TNF)-α 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-α is an incomplete secretagogue and requires input from a ligated integrin(s) for neutrophil activation. In adherent neutrophils, TNF-α triggers association of both protein kinase C (PKC)-δ and phosphatidylinositol (PI) 3-kinase with the p60TNFR. In this study, a role for PKC-δ and PI 3-kinase in TNF-α-mediated antiapoptotic signaling was examined. TNF-α inhibited spontaneous apoptosis in fibronectin-adherent neutrophils, and this antiapoptotic signaling was blocked by the PKC-δ inhibitor rottlerin, but not by an inhibitor of Ca2+-dependent PKC isotypes, Go-6976. Inhibition of PI 3-kinase by LY-294002 also inhibited TNF-α-mediated antiapoptotic signaling. Cycloheximide blocked TNF-α-mediated antiapoptotic signaling, suggesting protein synthesis is required. Inhibition of either PKC-δ or PI 3-kinase attenuated TNF-α-mediated activation of the antiapoptotic transcription factor NFκB. Thus both PKC-δ and PI 3-kinase have essential roles in TNF-α-mediated antiapoptotic signaling in adherent neutrophils.
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