Inducing expression of ICOS-L by oncolytic adenovirus to enhance tumor-specific bi-specific antibody efficacy.

BACKGROUND: Intratumoral injection of oncolytic viruses (OVs) shows promise in immunotherapy: ONCOS-102, a genetically engineered OV that encodes Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) demonstrated efficacy in early clinical trials, enhancing T cell infiltration in tumors. This suggests OVs may boost various forms of immunotherapy, including tumor-specific bi-specific antibodies (BsAbs). METHODS: Our study investigated in vitro, how ONCOS-204, a variant of ONCOS-virus expressing the ligand of inducible T-cell co-stimulator (ICOSL), modulates the process of T cell activation induced by a BsAb. ONCOS-102 was used for comparison. Phenotypic and functional changes induced by combination of different OVs, and BsAb in T cell subsets were assessed by flow cytometry, viability, and proliferation assays. RESULTS: Degranulation and IFNγ and TNF production of T cells, especially CD4 + T cells was the most increased upon target cell exposure to ONCOS-204. Unexpectedly, ONCOS-204 profoundly affected CD8 + T cell proliferation and function through ICOS-L/ICOS interaction. The effect solely depended on cell surface expression of ICOS-L as soluble ICOSL did not induce notable T cell activity. CONCLUSIONS: Together, our data suggests that oncolytic adenoviruses encoding ICOSL may enhance functional activity of tumor-specific BsAbs thereby opening a novel avenue for clinical development in immunotherapeutics.

Characterization of ascites- and tumor-infiltrating γδ T cells reveals distinct repertoires and a beneficial role in ovarian cancer.

The role of γδ T cells in antitumor immunity has been under investigation for the past two decades, but little is known about their contribution to clinical outcomes in patients. Here, we set out to define the clonotypic, phenotypic, and functional features of γδ T cells in peripheral blood, ascites, and metastatic tumor tissue from patients with advanced epithelial ovarian cancer. T cell receptor (TCR) sequencing of the γ chain revealed that tumor-infiltrating γδ T cells have a unique and skewed repertoire with high TCR diversity and low clonality. In contrast, ascites-derived γδ T cells presented a lower TCR diversity and higher clonality, suggesting a TCR-dependent clonal focusing at this site. Further investigation showed that tumor samples had abundant γδ T cells with a tissue-resident, activation-associated phenotype, less usage of Vγ9 and an impaired response to adaptive-associated stimuli, implying an innate-like activation pathway, rather than an adaptive TCR-engaging pathway, at these tumor sites. Furthermore, high γδ T cell cytokine responsiveness upon stimulation was associated with a favorable outcome for patients in terms of both overall survival and reduced residual tumor burden after primary surgery. Last, the functionality of γδ T cells and patient survival were negatively affected by the proportions of CD39-expressing T cells, highlighting the potential of CD39 as a target to improve γδ T cell responses and unleash their antitumor capabilities.

Profound Functional Suppression of Tumor-Infiltrating T-Cells in Ovarian Cancer Patients Can Be Reversed Using PD-1-Blocking Antibodies or DARPin® Proteins.

PD-1/PD-L1 blockade has revolutionized the field of immunooncology. Despite the relative success, the response rate to anti-PD-1 therapy requires further improvements. Our aim was to explore the enhancement of T-cell function by using novel PD-1-blocking proteins and compare with clinically approved monoclonal antibodies (mAbs). We isolated T-cells from the ascites and tumor of 17 patients with advanced epithelial ovarian cancer (EOC) and analyzed the effects using the mAbs nivolumab and pembrolizumab and two novel engineered ankyrin repeat proteins (DARPin® proteins). PD-1 blockade with either mAb or DARPin® molecule significantly increased the release of IFN-γ, granzyme B, IL-2, and TNF-α, demonstrating successful reinvigoration. The monovalent DARPin® protein was less effective compared to its bivalent equivalent, demonstrating that bivalency brings an additional benefit to PD-1 blockade. Overall, we found a higher fold increase of lymphokine secretion in response to the PD-1 blockade by tumor-derived T-cells; however, the absolute amounts were significantly lower compared to the release from ascites-derived T-cells. Our results demonstrate that PD-1 blockade can only partially reinvigorate functionally suppressed T-cells from EOC patients. This warrants further investigation preferably in combination with other therapeutics. The study provides an early pilot proof-of-concept for the potential use of DARPin® proteins as eligible alternative scaffold proteins to block PD-1.