Glioblastoma (GBM) is the deadliest form of brain cancer, characterized as a highly angiogenetic and immunosuppressive malignancy. Although immune checkpoint blockades have revolutionized cancer therapy, their therapeutic efficacy in GBM has been far less than expected or even ineffective. Here, we reveal that the genomic signature of glioma-derived endothelial cells (GdECs) correlates with an immunosuppressive state and poor prognosis of glioma patients. In vitro model of GdECs differentiation is established for drug screening, and we identify that cAMP activators could effectively block the GdECs formation by inducing oxidative stress. cAMP activator impairs the GdECs differentiation in vivo, normalizes the tumor vessels, and alters the immune profile, especially increasing the influx and function of CD8+ effector T cells. The dual blockade of GdECs and PD-1 induces tumor regression and establishes anti-tumor immune memory. Our study reveals that endothelial transdifferentiation of GBM shapes an endothelial immune cell barrier and supports the clinical development of combining GdECs blockade and immunotherapy for GBM.

The predictive abilities of m6A regulators for the prognosis and immunotherapy response in gastric cancer (GC) remain indistinct. FTO was overexpressed and predicted poor prognosis in GC. Based on consensus clustering analysis, two independent subgroups (G1/G2) were identified. Notably, FTO was upregulated in the G1 subgroup. Meanwhile, the infiltration level of CD8+ T cells was strikingly decreased while the stemness features were enhanced in the G1 subgroup. More importantly, FTO was negatively correlated with MSI and TMB. Furthermore, ICB response prediction indicated that patients with upregulated FTO showed high TIDE scores. Subsequently, FTO was confirmed to be related to multiple immune checkpoints, particularly PD-L1. Specifically, FTO was dramatically upregulated in GC cell lines and clinical cancer samples. Functional experiments illustrated that FTO acted as an oncogene to facilitate malignant phenotypes. Notably, PD-L1 was remarkably downregulated after RNA interference-mediated knockdown of FTO.FTO can aggravate GC malignant phenotypes. More importantly, it could be utilized to predict the long-term prognosis and the immunotherapy response in GC individuals. However, larger trials should be performed to verify the prediction accuracy.

BackgroundPancreatic ductal adenocarcinoma (PDAC) does not respond to immune checkpoint inhibitors (ICI) therapy as single agent treatments including anti-PD-1 antibody. One of the mechanisms for the resistance of PDAC to ICI is now attributed to the immunosuppressive microenvironment (TME) in PDAC. Myeloid cells are thought to be the predominant immunosuppressive cells in the TME. Human interleukin-8 (IL-8) is a pro-inflammatory chemokine in the CXC family and has the capability of recruiting myeloid cells into the TME to promote tumor progression and immune escape. Therefore, several anti-IL-8 blockade antibodies were developed including HuMax-IL8 and B108-IL8, which both are fully human IgG1 kappa monoclonal antibodies. We therefore tested whether anti-IL-8 antibodies can potentiate anti-tumor activity of anti-PD-1 antibody in a humanized model of PDAC.Materials and MethodsWe reconstituted the immune system of the NGS mice with ex vivo activated human T cells and a combination of CD14+ and CD16+ myeloid cells after the mice were orthotopically implanted with human PDAC cells. 10x single nuclei RNA-Seq data processing was further performed to analyze differentially expressed genes among certain cell clusters.ResultsOur results showed that anti-PD-1 antibody alone had a minimal anti-tumor activity when mice was reconstituted with ex vivo activated T cells. Interestingly, the infusion of the combination of CD14+ and CD16+ myeloid cells together with anti-PD-1 antibody resulted in a modest anti-tumor activity. Adding either HuMAX-IL8 or B108-IL8 led to a significantly enhanced anti-tumor activity. Both CD14+ and CD16+ myeloid cells appeared to be needed for the full anti-tumor activity of IL-8 blockade because mice infused with only CD14+ myeloid cells did not respond to IL-8 blockade and mice infused with only CD16+ myeloid cells responded partially to IL-8 blockade. This result suggested that the target of IL-8 is mainly present in CD16+ myeloid cells and is likely to be granulocytes. Tumor infiltrating immune cells were isolated and demonstrated that IL-8 blockade increases CD45+CD11b+CD15+CD14- myeloid cells, which is known to comprise neutrophils and granulocytic myeloid derived suppressive cells (G-MDSC), in the tumors. Reconstitution of the mice with myeloid cells led to a decrease of CD8+ T cells in the tumors; however, IL-8 blockade brought the CD8+ T cell number back to the baseline. Consistent with an effect of IL-8 blockade on the increase of CD15+CD14- myeloid cells, single nuclear RNA sequencing analysis of the tumor tissues showed that the innate immune response and cytokine response pathways in the myeloid cell cluster were activated by IL-8 blockade.ConclusionsThis result suggested that IL-8 blockade did not simply inhibit myeloid cells as previously anticipated, but potentiated myeloid cells for the innate immune response and concomitant production of type I cytokines. Such immune responses may subsequently activate the effector T cells as the single nuclear RNA sequencing analysis demonstrated enhanced activation signals in the T cell cluster from the tumors treated by anti-IL-8 antibodies. Taken together, this study supports further testing of anti-IL-8 antibodies including B108-IL8 and HuMax-IL8 in combination with anti-PD-1 antibodies for PDAC treatment.Disclosure InformationP. Li: None. N. Rozich: None. J. Wang: None. J. Gai: None. J. Wang: None. Y. Xu: None. B. Herbst: None. R. Yu: A. Employment (full or part-time); Significant; NovaRock. S. Muth: None. N. Niu: None. K. Li: None. V. Fune: None. A. Osipov: None. C. Wolfgang: None. M. Lei: A. Employment (full or part-time); Significant; NovaRock. T. Liang: None. L. Zheng: B. Research Grant (principal investigator, collaborator or consultant and pending grants as well as grants already received); Significant; Bristol-Meyer Squibb, Merck, iTeos, Amgen, NovaRock, Inxmed, Halozyme. E. Ownership Interest (stock, stock options, patent or other intellectual property); Significant; Alphamab, Mingruzhiyao. F. Consultant/Advisory Board; Significant; Biosion, Alphamab, NovaRock, Akrevia/Xilio, Ambrx, Novagenesis, Datarevive, Snow Lake Capitals, Mingruzhiyao. Other; Significant; Aduro Biotech.