Glioblastoma (GBM) is the most common and aggressive brain tumor with poor outcome. Immune checkpoint inhibitors (ICIs) have been tested in GBM and, despite disappointing results, the identification of a small subgroup of responders underlies the need to improve our understanding of the tumor microenvironment (TME) immunity. The aim of this study was to determine whether the expression of selected immune checkpoints on tissue-resident memory T cells (Trm) may predict patient outcome. We conducted a single cohort observational study. Tumor samples were collected from 45 patients with histologically confirmed, IDH wild type, GBM (WHO grade IV) and processed to obtain single cell suspensions. Using multiparametric flow cytometry and uni/multivariate analyses, patients were assessed for the correlation of Trm with overall survival (OS) and progression-free survival (PFS). High and low frequency of Trm expressing PD1 and TIM3 was found to be linked to clinical outcome. In fact, low frequency of Trm expressing PD1 or TIM3 or both markers defined subgroups as independent positive prognostic factors for patient survival. On multivariate analysis, low CD8+CD103+PD1+TIM3+ Trm and KPS ≥70 were confirmed to be the most predictive independent factors associated with longer OS (HR [95%CI]: 0.14 [0.04 - 0.52] p˂0.001, 0.39 [0.16 - 0.96] p=0.04, respectively). The CD8+CD103+ Trm subgroups also resulted age-linked predictors for survival in GBM.

We investigated an innovative anti-SARS-CoV-2 immune strategy finalized to oral administration of extracellular vesicles (EVs) inducing an anti-SARS-CoV-2 N CD8+ T cytotoxic lymphocyte (CTL) immune response. We previously reported that the SARS-CoV-2 N protein can be uploaded at high levels in EVs upon fusion with Nefmut, i.e., a biologically inactive HIV-1 Nef mutant incorporating into EVs at quite high levels. Here, we analyze the immunogenic properties in human cells of EVs engineered with SARS-CoV-2 N fused at the C-terminus of either Nefmut or a deletion mutant of Nefmut referred to as NefmutPL. Analysis of in vitro produced EVs proven the uploading of N protein also when fused with truncated Nefmut. Mice injected with DNA vectors expressing each fusion protein developed robust SARS-CoV-2 N-specific CD8+ T cell immune responses. When ex vivo human dendritic cells were challenged with EVs engineered with either fusion products, the induction of a robust N-specific CTL activity, as evaluated by both CD107a and trogocytosis assays, was observed. Through these data we achieved the proof-of-principle that engineered EVs can be instrumental to elicit anti-SARS-CoV-2 CTL immune response in human cells. This achievement represents a mandatory step towards the upcoming experimentations in pre-clinical models.