Activation of Tumor-Cell STING Primes NK-Cell Therapy

Abstract

Activation of the stimulator of interferon genes (STING) pathway promotes antitumor immunity but STING agonists have yet to achieve clinical success. Increased understanding of the mechanism of action of STING agonists in human tumors is key to developing therapeutic combinations that activate effective innate antitumor immunity. Here, we report that malignant pleural mesothelioma cells robustly express STING and are responsive to STING agonist treatment ex vivo. Using dynamic single-cell RNA sequencing of explants treated with a STING agonist, we observed CXCR3 chemokine activation primarily in tumor cells and cancer-associated fibroblasts, as well as T-cell cytotoxicity. In contrast, primary natural killer (NK) cells resisted STING agonist–induced cytotoxicity. STING agonists enhanced migration and killing of NK cells and mesothelin-targeted chimeric antigen receptor (CAR)-NK cells, improving therapeutic activity in patient-derived organotypic tumor spheroids. These studies reveal the fundamental importance of using human tumor samples to assess innate and cellular immune therapies. By functionally profiling mesothelioma tumor explants with elevated STING expression in tumor cells, we uncovered distinct consequences of STING agonist treatment in humans that support testing combining STING agonists with NK and CAR-NK cell therapies.

NK cells and solid tumors: therapeutic potential and persisting obstacles

“…Of note, the ability of autophagy inhibitors to promote NK cell chemotaxis downstream of CXCL10 and CCL5 hypersecretion has been linked (at least some settings) with superior CGAS signaling [ 57 ]. In line with this notion, pharmacological agonism of the CGAS signal transducer stimulator of interferon response cGAMP interactor 1 (STING1) has recently been shown to drive an abundant recruitment of CAR-expressing NK cells to mesothelioma organoids, culminating with potent tumor killing [ 58 ]. A similar improvement in tumor infiltration by natural or adoptively transferred NK cells has been documented in preclinical melanoma models secreting CCL5 downstream of viral infection [ 59 ], as well as in models of HCC receiving a CCL5-coding adenoviral vector [ 60 ].…”

Organoids as an Enabler of Precision Immuno-Oncology

“…Strikingly, a recent study with ovarian cancer organoids shows that bi-specific PD-1/PD-L1 antibody activates NK cells in addition to CTLs [ 170 ], while another study with CRC organoids demonstrates the anti-tumour effect of ICIs from γδ-T cells (rather than αβ-T) when there is MHC-I defect on tumour cells [ 171 ], underlining their importance in I/O effectiveness. Organoid testing has also shown tumoricidal activity of γδ-T cells [ 172 ] and (CAR-)NK cells [ 173 ] for melanoma and mesothelioma, respectively. Importantly, while 3D killing assays have been performed and published extensively for NK and γδ-T cells, most “tumours” are only spheroid aggregates of cancer cell lines, which do not recapitulate the TME.…”

Engineered Microphysiological Systems for Testing Effectiveness of Cell-Based Cancer Immunotherapies

“…However, the tumor spheroids most commonly used for MPS oncology studies are aggregates of cancer cell lines, either in monoculture or in combination with other cell types such as cancer-associated fibroblasts (CAFs) or endothelial cells (ECs), and in many instances lacking extracellular matrix. Immune components are typically incorporated with the addition of lymphocytes from peripheral blood mononuclear cells (PBMC), tumor infiltrating lymphocytes, CAR T, or CAR NK cells [ 28 , 29 , 30 , 31 , 32 ]. A unique approach to replicating the TIME in MPS is to collect organotypic spheroids directly from tumor tissues.…”

“…One of the main advantages of these platforms is the ability to control the specific cell and tissue architecture to emulate chemical gradients and biomechanical forces [ 16 ]. This allows for precise control over the biochemical and cellular milieu to model in vivo-like environments and responses [ 31 , 32 , 33 ]. Compared to other advanced 3D models, microfluidic culture allows the precise formation of microvascular networks and large blood vessels to mimic multicellular vascular interactions.…”

“…MPS systems offer the alternative of generating fully human 3D systems that can be used to culture either established cell lines or patient-derived tissues. Patient-derived organotypic tumor spheroids (PDOTS) have been embedded in microfluidic devices to enable research groups to track immune cell migration towards spheroids, monitor cell death with live/dead stains, and to perform immunostaining to identify different cellular populations within the samples, which can come from biopsies or surgical resections [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Furthermore, ex vivo patient-derived tumor spheroids retain drug sensitivities of the primary tumor, similar to what is seen in PDX models as well [ 34 , 35 , 36 ].…”