Histone deacetylase inhibitors enhance oncolytic herpes simplex virus therapy for malignant meningioma.

Approximately 20% of meningiomas are not benign (higher grade) and tend to relapse after surgery and radiation therapy. Malignant (anaplastic) meningioma (MM) is a minor subset of high-grade meningioma that is lethal with no effective treatment options currently. Oncolytic herpes simplex virus (oHSV) is a powerful anti-cancer modality that induces both direct cell death and anti-tumor immunity, and has shown activity in preclinical models of MM. However, clinically meaningful efficacy will likely entail rational mechanistic combination approaches. We here show that epigenome modulator histone deacetylase inhibitors (HDACi) increase anti-cancer effects of oHSV in human MM models, IOMM-Lee (NF2 wild-type) and CH157 (NF2 mutant). Minimally toxic, sub-micromolar concentrations of pan-HDACi, Trichostatin A and Panobinostat, substantively increased the infectability and spread of oHSV G47Δ within MM cells in vitro, resulting in enhanced oHSV-mediated killing of target cells when infected at low multiplicity of infection (MOI). Transcriptomics analysis identified selective alteration of mRNA processing and splicing modules that might underlie the potent anti-MM effects of combining HDACi and oHSV. In vivo, HDACi treatment increased intratumoral oHSV replication and boosted the capacity of oHSV to control the growth of human MM xenografts. Thus, our work supports further translational development of the combination approach employing HDACi and oHSV for the treatment of MM.

The GM-CSF-IRF5 signaling axis in eosinophils promotes antitumor immunity through activation of type 1 T cell responses.

The depletion of eosinophils represents an efficient strategy to alleviate allergic asthma, but the consequences of prolonged eosinophil deficiency for human health remain poorly understood. We show here that the ablation of eosinophils severely compromises antitumor immunity in syngeneic and genetic models of colorectal cancer (CRC), which can be attributed to defective Th1 and CD8+ T cell responses. The specific loss of GM-CSF signaling or IRF5 expression in the eosinophil compartment phenocopies the loss of the entire lineage. GM-CSF activates IRF5 in vitro and in vivo and can be administered recombinantly to improve tumor immunity. IL-10 counterregulates IRF5 activation by GM-CSF. CRC patients whose tumors are infiltrated by large numbers of eosinophils also exhibit robust CD8 T cell infiltrates and have a better prognosis than patients with eosinophillow tumors. The combined results demonstrate a critical role of eosinophils in tumor control in CRC and introduce the GM-CSF-IRF5 axis as a critical driver of the antitumor activities of this versatile cell type.

A Monoclonal Antibody Against ß1 Integrin Inhibits Proliferation and Increases Survival in an Orthotopic Model of High-Grade Meningioma.

BACKGROUND: High-grade meningiomas (HGMs; World Health Organization [WHO] classification grade II and III) have high relapse rates and poor clinical outcomes despite surgery and radiation treatments. No effective medical therapy currently exists for HGMs, and developing novel therapeutic strategies depends on the identification of molecular drivers. In cancer, ß1 integrin enhances malignant characteristics, including proliferation, invasion, and drug resistance. OBJECTIVE: We conducted this study to investigate whether ß1 integrin could be a therapeutic target in HGMs. PATIENTS AND METHODS: Expression of ß1 integrin was examined in gene array datasets, with proteomics of clinical meningioma specimens, and in patient-derived HGM xenografts. Anti-tumor activity of OS2966, a first-in-class humanized antagonizing monoclonal antibody against ß1 integrin, was tested in vitro and in vivo using an orthotopic mouse model of patient-derived malignant meningioma. RESULTS: ß1 integrin was expressed in meningiomas of all WHO grades and two xenografts tested. In vitro, OS2966 suppressed the viability of NF2-deficient MN3 sphere cells and NF2-wild-type IOMM-Lee malignant meningioma cells only when plated on laminin-coated plastic. While OS2966 decreased phosphorylation of ERK1/2 in both MN3 cells and laminin-grown IOMM-Lee cells, OS2966 only affected the phosphorylation of FAK (Tyr397) in MN3, and of Akt (Ser473) in IOMM-Lee cells, respectively, indicating differential pathway inhibition. Systemic administration of OS2966 in mice bearing orthotopic MN3 HGMs inhibited HGM cell proliferation and significantly extended overall survival of the treated mice. CONCLUSIONS: ß1 Integrin may be a therapeutic target in HGMs, and further preclinical and clinical development of OS2966 for HGM therapy is warranted.

Extracellular RNAs: A New Awareness of Old Perspectives.

Extracellular RNA (exRNA) has recently expanded as a highly important area of study in biomarker discovery and cancer therapeutics. exRNA consists of diverse RNA subpopulations that are normally protected from degradation by incorporation into membranous vesicles or by lipid/protein association. They are found circulating in biofluids, and have proven highly promising for minimally invasive diagnostic and prognostic purposes, particularly in oncology. Recent work has made progress in our understanding of exRNAs-from their biogenesis, compartmentalization, and vesicle packaging to their various applications as biomarkers and therapeutics, as well as the new challenges that arise in isolation and purification for accurate and reproducible analysis. Here we review the most recent advancements in exRNA research.