EVIR: chimeric receptors that enhance dendritic cell cross-dressing with tumor antigens.

We describe a lentivirus-encoded chimeric receptor, termed extracellular vesicle (EV)-internalizing receptor (EVIR), which enables the selective uptake of cancer-cell-derived EVs by dendritic cells (DCs). The EVIR enhances DC presentation of EV-associated tumor antigens to CD8+ T cells primarily through MHCI recycling and cross-dressing. EVIRs should facilitate exploring the mechanisms and implications of horizontal transfer of tumor antigens to antigen-presenting cells.

Polymeric nanoparticle-based delivery of TRAIL DNA for cancer-specific killing.

Lack of specificity in cancer therapeutics severely limits the efficacy of many existing treatment modalities. The use of Tumor Necrosis Factor-related Apoptosis-Inducing Ligand (TRAIL) is of interest to the field due to this protein's ability to cause cell death specifically in cancer cells without harming the surrounding healthy tissue. Here, we report that polymeric nanoparticles, based on synthetic poly(beta-amino ester)s (PBAEs) and containing DNA, are able to selectively transfect cancer cells in vitro over healthy cells of the same tissue type. Moreover, PBAE-based nanoparticles containing TRAIL DNA are able to transfect several human cancer cell cultures in vitro and cause cell death. While certain cell types, including human glioblastoma (GBM), showed resistance to TRAIL, we found that the expression of TRAIL-binding surface proteins was predictive of each cell type's resistance to TRAIL therapy. We demonstrate a non-viral nanomedicine approach to cancer gene therapy that can improve cancer specificity via both biomaterial selection and through the use of cancer-targeting genetic cargo.

Suppression of microRNA activity amplifies IFN-γ-induced macrophage activation and promotes anti-tumour immunity.

Tumour-associated macrophages (TAMs) largely express an alternatively activated (or M2) phenotype, which entails immunosuppressive and tumour-promoting capabilities. Reprogramming TAMs towards a classically activated (M1) phenotype may thwart tumour-associated immunosuppression and unleash anti-tumour immunity. Here we show that conditional deletion of the microRNA (miRNA)-processing enzyme DICER in macrophages prompts M1-like TAM programming, characterized by hyperactive IFN-γ/STAT1 signalling. This rewiring abated the immunosuppressive capacity of TAMs and fostered the recruitment of activated cytotoxic T lymphocytes (CTLs) to the tumours. CTL-derived IFN-γ exacerbated M1 polarization of Dicer1-deficient TAMs and inhibited tumour growth. Remarkably, DICER deficiency in TAMs negated the anti-tumoral effects of macrophage depletion by anti-CSF1R antibodies, and enabled complete tumour eradication by PD1 checkpoint blockade or CD40 agonistic antibodies. Finally, genetic rescue of Let-7 miRNA activity in Dicer1-deficient TAMs partly restored their M2-like phenotype and decreased tumour-infiltrating CTLs. These findings suggest that DICER/Let-7 activity opposes IFN-γ-induced, immunostimulatory M1-like TAM activation, with potential therapeutic implications.

Polymeric nanoparticles for nonviral gene therapy extend brain tumor survival in vivo.

Biodegradable polymeric nanoparticles have the potential to be safer alternatives to viruses for gene delivery; however, their use has been limited by poor efficacy in vivo. In this work, we synthesize and characterize polymeric gene delivery nanoparticles and evaluate their efficacy for DNA delivery of herpes simplex virus type I thymidine kinase (HSVtk) combined with the prodrug ganciclovir (GCV) in a malignant glioma model. We investigated polymer structure for gene delivery in two rat glioma cell lines, 9L and F98, to discover nanoparticle formulations more effective than the leading commercial reagent Lipofectamine 2000. The lead polymer structure, poly(1,4-butanediol diacrylate-co-4-amino-1-butanol) end-modified with 1-(3-aminopropyl)-4-methylpiperazine, is a poly(ß-amino ester) (PBAE) and formed nanoparticles with HSVtk DNA that were 138 ± 4 nm in size and 13 ± 1 mV in zeta potential. These nanoparticles containing HSVtk DNA showed 100% cancer cell killing in vitro in the two glioma cell lines when combined with GCV exposure, while control nanoparticles encoding GFP maintained robust cell viability. For in vivo evaluation, tumor-bearing rats were treated with PBAE/HSVtk infusion via convection-enhanced delivery (CED) in combination with systemic administration of GCV. These treated animals showed a significant benefit in survival (p = 0.0012 vs control). Moreover, following a single CED infusion, labeled PBAE nanoparticles spread completely throughout the tumor. This study highlights a nanomedicine approach that is highly promising for the treatment of malignant glioma.