Project description:CD38, an ecto-enzyme involved in NAD+ catabolism, is highly expressed in exhausted CD8+ T cells and has emerged as an attractive target to improve response to immune checkpoint blockade (ICB) by blunting T cell exhaustion. However, the precise role(s) and regulation of CD38 in exhausted T cells and the efficacy of CD38-directed therapeutic strategies in human cancer remain incompletely defined. Here, we show that CD38+CD8+ T cells are induced by chronic TCR activation and type I interferon stimulation and confirm their association with ICB resistance in human melanoma. Disrupting CD38 restores cellular NAD+ pools and improves T cell bioenergetics and effector functions. Targeting CD38 restores ICB sensitivity in a cohort of patient-derived organotypic tumor spheroids from explanted melanoma specimens. These results support further preclinical and clinical evaluation of CD38-directed therapies in melanoma and underscore the importance of NAD+ as a vital metabolite to enhance those therapies.
Project description:CD38, an ecto-enzyme involved in NAD+ catabolism, is highly expressed in exhausted CD8+ T cells and has emerged as an attractive target to improve response to immune checkpoint blockade (ICB) by blunting T cell exhaustion. However, the precise role(s) and regulation of CD38 in exhausted T cells and the efficacy of CD38-directed therapeutic strategies in human cancer remain incompletely defined. Here, we show that CD38+CD8+ T cells are induced by chronic TCR activation and type I interferon stimulation and confirm their association with ICB resistance in human melanoma. Disrupting CD38 restores cellular NAD+ pools and improves T cell bioenergetics and effector functions. Targeting CD38 restores ICB sensitivity in a cohort of patient-derived organotypic tumor spheroids from explanted melanoma specimens. These results support further preclinical and clinical evaluation of CD38-directed therapies in melanoma and underscore the importance of NAD+ as a vital metabolite to enhance those therapies.
Project description:Immunotherapeutics represent highly promising agents with the potential to improve patient outcomes in a variety of cancer types. Unfortunately, single-agent immunotherapy has achieved limited clinical benefit to date in patients suffering from pancreatic ductal adenocarcinoma (PDAC). This may be due to the presence of a uniquely immunosuppressive tumor microenvironment (TME) present in PDACs, which creates a barrier to effective immune surveillance. Critical obstacles to immunotherapy in PDAC tumors include the dense desmoplastic stroma that acts as a barrier to T-cell infiltration and the high numbers of tumor-associated immunosuppressive cells. We have identified hyperactivated focal adhesion kinase (FAK) activity in neoplastic PDAC cells as a significant regulator of the fibrotic and immunosuppressive TME. We found that FAK activity was elevated in human PDAC tissues and correlates with high levels of fibrosis and poor CD8+ cytotoxic T-cell infiltration. Single-agent FAK inhibition (VS-4718) dramatically limited tumor progression, resulting in a doubling of survival in the p48-Cre/LSL-KrasG12D/p53Flox/+ (KPC) mouse model of human PDAC. This alteration in tumor progression was associated with dramatically reduced tumor fibrosis, decreased numbers of tumor-infiltrating immature myeloid cells and immunosuppressive macrophages. We postulated that these desirable effects of FAK inhibition on the TME might render PDAC tumors more sensitive to immunotherapy. Accordingly, we found that VS-4718 rendered the previously unresponsive KPC mouse model responsive to anti-PD1 and anti-CTLA4 antagonists leading to a nearly tripling of survival times. These data suggest that FAK inhibition increases immune surveillance by overcoming the fibrotic and immunosuppressive PDAC TME thus rendering tumors more responsive to immunotherapy. We treated KP orthotopic tumor-bearing mice with vehicle and FAK inhibitor (FAKi) for 14 days, then extracted total RNA from tumor tissues.