Establishment and immune phenotyping of patient-derived glioblastoma models in humanized mice

Glioblastoma (GBM) is the most aggressive and common type of malignant brain tumor diagnosed in adults. Preclinical immunocompetent mouse tumor models generated using mouse tumor cells play a pivotal role in testing the therapeutic efficacy of emerging immune-based therapies for GBMs. However, the clinical translatability of such studies is limited as mouse tumor lines do not fully recapitulate GBMs seen in inpatient settings. In this study, we generated three distinct, imageable human-GBM (hGBM) models in humanized mice using patient-derived GBM cells that cover phenotypic and genetic GBM heterogeneity in primary (invasive and nodular) and recurrent tumors. We developed a pipeline to first enrich the tumor-initiating stem-like cells and then successfully established robust patient-derived GBM tumor engraftment and growth in bone marrow-liver-thymus (BLT) humanized mice. Multiplex immunofluorescence of GBM tumor sections revealed distinct phenotypic features of the patient GBM tumors, with myeloid cells dominating the immune landscape. Utilizing flow cytometry and correlative immunofluorescence, we profiled the immune microenvironment within the established human GBM tumors in the BLT mouse models and showed tumor infiltration of variable human immune cells, creating a unique immune landscape compared with lymphoid organs. These findings contribute substantially to our understanding of GBM biology within the context of the human immune system in humanized mice and lay the groundwork for further translational studies aimed at advancing therapeutic strategies for GBM.

Developing and characterizing a two-layered safety switch for cell therapies

Gene edited and engineered cell-based therapies are a promising approach for treating a variety of disorders, including cancer. However, the ability of engineered cells to persist for prolonged periods along with possible toxicity raises concerns over the safety of these approaches. Although a number of different one-dimensional suicide systems have been incorporated into therapeutic cell types, the incorporation of a two-layered suicide system that allows controlled killing of therapeutic cells at different time points is needed. In this study, we engineered a variety of therapeutic cells to express two different kill switches, RapaCasp9 and HSV-TK and utilized Rapamycin and Ganciclovir respectively to activate these kill switches. We show that the function of both RapaCasp9 and HSV-TK molecules is preserved and can be activated to induce apoptosis detected early (24 h) and late (48 h) post-activation respectively, with no toxicity. In vivo, we show the eradication of a majority of cells after treatment in subcutaneous and orthotopic models. Furthermore, we demonstrate how both suicide switches work independently and can be activated sequentially for an improved killing, thus ensuring a failsafe mechanism in case the activation of a single one of them is not sufficient to eliminate the cells. Our findings highlight the reliability of the double suicide system, effective on a variety of cells with different biological characteristics, independent of their anatomic presence.

Bifunctional cancer cell-based vaccine concomitantly drives direct tumor killing and antitumor immunity

The administration of inactivated tumor cells is known to induce a potent antitumor immune response; however, the efficacy of such an approach is limited by its inability to kill tumor cells before inducing the immune responses. Unlike inactivated tumor cells, living tumor cells have the ability to track and target tumors. Here, we developed a bifunctional whole cancer cell-based therapeutic with direct tumor killing and immunostimulatory roles. We repurposed the tumor cells from interferon-β (IFN-β) sensitive to resistant using CRISPR-Cas9 by knocking out the IFN-β-specific receptor and subsequently engineered them to release immunomodulatory agents IFN-β and granulocyte-macrophage colony-stimulating factor. These engineered therapeutic tumor cells (ThTCs) eliminated established glioblastoma tumors in mice by inducing caspase-mediated cancer cell apoptosis, down-regulating cancer-associated fibroblast-expressed platelet-derived growth factor receptor β, and activating antitumor immune cell trafficking and antigen-specific T cell activation signaling. This mechanism-based efficacy of ThTCs translated into a survival benefit and long-term immunity in primary, recurrent, and metastatic cancer models in immunocompetent and humanized mice. The incorporation of a double kill-switch comprising herpes simplex virus-1 thymidine kinase and rapamycin-activated caspase 9 in ThTCs ensured the safety of our approach. Arming naturally neoantigen-rich tumor cells with bifunctional therapeutics represents a promising cell-based immunotherapy for solid tumors and establishes a road map toward clinical translation.

Anti-GD2 CAR MSCs against metastatic Ewing's sarcoma

BACKGROUND

Ewing's sarcoma (ES) is an aggressive cancer affecting children and young adults. We pre-clinically demonstrated that mesenchymal stromal/stem cells (MSCs) can deliver tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) against primary ES after local injection. However, ES is often metastatic calling for approaches able to support MSC targeting to the ES multiple remote sites. Considering that the disialoganglioside GD2 is expressed by ES and to optimise MSC tumour affinity, bi-functional (BF) MSCs expressing both TRAIL and a truncated anti-GD2 chimeric antigen receptor (GD2 tCAR) were generated and challenged against ES.

METHODS

The anti-GD2 BF MSCs delivering a soluble variant of TRAIL (sTRAIL) were tested in several in vitro ES models. Tumour targeting and killing by BF MSCs was further investigated by a novel immunodeficient ES metastatic model characterized by different metastatic sites, including lungs, liver and bone, mimicking the deadly clinical scenario.

FINDINGS

In vitro data revealed both tumour affinity and killing of BF MSCs. In vivo, GD2 tCAR molecule ameliorated the tumour targeting and persistence of BF MSCs counteracting ES in lungs but not in liver.

INTERPRETATION

We here generated data on the potential effects of BF MSCs within a complex ES metastatic in vivo model, exploring also the biodistribution of MSCs. Our BF MSC-based strategy promises to pave the way for potential improvements in the therapeutic delivery of TRAIL for the treatment of metastatic ES and other deadly GD2-positive malignancies.

Mesenchymal stem cell immunomodulation: In pursuit of controlling COVID-19 related cytokine storm

The coronavirus disease 2019 (COVID-19) pandemic has grown to be a global public health crisis with no safe and effective treatments available yet. Recent findings suggest that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the coronavirus pathogen that causes COVID-19, could elicit a cytokine storm that drives edema, dysfunction of the airway exchange, and acute respiratory distress syndrome in the lung, followed by acute cardiac injury and thromboembolic events leading to multiorgan failure and death. Mesenchymal stem cells (MSCs), owing to their powerful immunomodulatory abilities, have the potential to attenuate the cytokine storm and have therefore been proposed as a potential therapeutic approach for which several clinical trials are underway. Given that intravenous infusion of MSCs results in a significant trapping in the lung, MSC therapy could directly mitigate inflammation, protect alveolar epithelial cells, and reverse lung dysfunction by normalizing the pulmonary microenvironment and preventing pulmonary fibrosis. In this review, we present an overview and perspectives of the SARS-CoV-2 induced inflammatory dysfunction and the potential of MSC immunomodulation for the prevention and treatment of COVID-19 related pulmonary disease.

Abstract A17: Challenging pancreatic ductal adenocarcinoma and its stroma by a combination of chemo and gene therapy: A preclinical study

Pancreatic ductal adenocarcinoma (PDAC) is a gastrointestinal malignancy still characterized by unacceptable prognosis (Malvezzi et al., 2014). Treatments include surgery, chemotherapy, radiation therapy, and palliative care and the most appropriate option is selected depending on the stage of PDAC (Kamisawa et al., 2016; Vincent et al., 2011). Among the most important factors contributing to the failure of treatments, a pivotal role is played by a pronounced desmoplastic stromal reaction composed by extracellular matrix (ECM), blood vessels, endothelial cells, connective tissue elements such as tumor-associated fibroblasts (TAF), immune cells and soluble proteins such as cytokines and growth factors (Erkan et al., 2012; Horimoto et al., 2012; Kalluri and Zeisberg, 2006). Therefore, next to selective PDAC-targeting agents, approaches able to modify PDAC microenvironment may impact tumor/stroma interactions allowing a better therapeutic profile (Bijlsma et al., 2015). For years, we have been developing a gene-therapy strategy based on adipose-derived mesenchymal stromal cells (AD-MSC) to deliver the novel variant of the potent anticancer agent TRAIL (sTRAIL) (Spano et al., 2019; Rossignoli et al. 2019). Gene-modified AD-MSC delivering sTRAIL can reshape the PDAC microenvironment inducing tumor cell apoptosis (Schug et al. 2018; Spano et al. 2019). Starting from this concept, we here challenged the gene therapy approach in combination with standard anti-PDAC agents, such as gemcitabine and nab-paclitaxel as prerequisite for a phase I/II clinical trial. Next to 2D cytotoxicity assays, complex 3D in vitro models, mimicking the structure of PDAC, demonstrated a relevant cytotoxic effect exerted by AD-MSC sTRAIL when given alone or in combination with gemcitabine and nab-paclitaxel against BxPC-3; MiaPaca-2 and PATU8988T cell lines. In particular, the pretreatment with nab-paclitaxel reverted the molecular mechanisms related to TRAIL-resistant PDAC cell line. The synergistic effect between gemcitabine and AD-MSC sTRAIL has been further demonstrated in two orthotopic mouse models, in which mice bearing pancreatic cancer received 2 weekly doses of gemcitabine (50 or 100 mg/kg) followed by AD-MSC sTRAIL intratumoral eco-guided injections. Animals treated by this combinatory approach showed a massive destruction of pancreatic malignant tissue and its stroma, visible as hypoechoic regions by ultrasound imaging system. Collectively, these results indicate the powerful potential of combining a gene therapy approach with chemotherapy, suggesting the transferability of an anticancer MSC-based approach in patients affected by PDAC.

Citation Format: Giulia Grisendi, Massimiliano Dall'Ora, Angela D'Esposito, Giulia Casaria, Carlotta Spano, Filippo Rossignoli, Giulia Golinelli, Olivia Candini, Massimo Dominici. Challenging pancreatic ductal adenocarcinoma and its stroma by a combination of chemo and gene therapy: A preclinical study [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr A17.

Soluble TRAIL Armed Human MSC As Gene Therapy For Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is still one of the most aggressive adult cancers with an unacceptable prognosis. For this reason novel therapies accounting for PDAC peculiarities, such as the relevant stromal reaction, are urgently needed. Here adipose mesenchymal stromal/stem cells (AD-MSC) have been armed to constantly release a soluble trimeric and multimeric variant of the known anti-cancer TNF-related apoptosis-inducing ligand (sTRAIL). This cancer gene therapy strategy was in vitro challenged demonstrating that sTRAIL was thermally stable and able to induce apoptosis in the PDAC lines BxPC-3, MIA PaCa-2 and against primary PDAC cells. sTRAIL released by AD-MSC relocated into the tumor stroma was able to significantly counteract tumor growth in vivo with a significant reduction in tumor size, in cytokeratin-7+ cells and by an anti-angiogenic effect. In parallel, histology on PDAC specimens form patients (n = 19) was performed to investigate the levels of TRAIL DR4, DR5 and OPG receptors generating promising insights on the possible clinical translation of our approach. These results indicate that adipose MSC can very efficiently vehicle a novel TRAIL variant opening unexplored opportunities for PDAC treatment.

MSC-Delivered Soluble TRAIL and Paclitaxel as Novel Combinatory Treatment for Pancreatic Adenocarcinoma

Pancreatic cancer is the fourth leading cause of cancer death in western countries with more than 100,000 new cases per year in Europe and a mortality rate higher than 90%. In this scenario, advanced therapies based on gene therapies are emerging, thanks to a better understanding of tumour architecture and cancer cell alterations. We have demonstrated the efficacy of an innovative approach for pancreatic cancer based on mesenchymal stromal cells (MSC) genetically engineered to produce TNF-related Apoptosis Inducing Ligand (TRAIL). Here we investigated the combination of this MSC-based approach with the administration of a paclitaxel (PTX)-based chemotherapy to improve the potential of the treatment, also accounting for a possible resistance onset.

Methods: Starting from the BXPC3 cell line, we generated and profiled a TRAIL-resistant model of pancreatic cancer, testing the impact of the combined treatment in vitro with specific cytotoxicity and metabolic assays. We then challenged the rationale in a subcutaneous mouse model of pancreatic cancer, assessing its effect on tumour size accounting stromal and parenchymal organization.

Results: PTX was able to restore pancreatic cancer sensitivity to MSC-delivered TRAIL by reverting its pro-survival gene expression profile. The two compounds cooperate both in vitro and in vivo and the combined treatment resulted in an improved cytotoxicity on tumour cells.

Conclusion: In summary, this study uncovers the potential of a combinatory approach between MSC-delivered TRAIL and PTX, supporting the combination of cell-based products and conventional chemotherapeutics as a tool to improve the efficacy of the treatments, also addressing possible mechanisms of resistance.

Human Herpes simplex 1 virus infection of endometrial decidual tissue-derived MSC alters HLA-G expression and immunosuppressive functions

OBJECTIVES

Mesenchymal stromal/stem cells have immunosuppressive functions. Our previous results demonstrated that one of the players of this immunomodulation can be ascribed to the Human Leukocyte Antigen-G. HLA-G, a non classical HLA class I antigen, is involved in immune tolerance during pregnancy, organ transplantation, autoimmune and inflammatory diseases. In this study we wanted to verify whether human endometrial decidual tissue derived (EDT)-MSC could express HLA-G. Additionally we assessed the permissivity to Human Herpesvirus infections, using HSV-1 as a model, and the possible effect on EDT-MSC immunosuppressive functions towards peripheral blood mononuclear cell (PBMC) proliferation.

METHODS

We analyzed immune-inhibitory functions and HLA-G expression in human EDT-MSC before and after HSV-1 infection.

RESULTS

We observed that EDT-MSC express HLA-G molecules, that partly are responsible for the immune-inhibitory functions of EDT-MSC towards PBMC proliferation. EDT-MSC are permissive for a productive infection by HSV-1, that decreases HLA-G expression and affects EDT-MSC immune-inhibitory functions.

CONCLUSIONS

We demonstrate that EDT-MSC are susceptible to HSV-1 infection, that reduces HLA-G expression and their immune-inhibitory function. These data could have a clinical implication in the use of EDT-MSC as an immunosuppressant, in particular in steroid-refractory GvHD after allogeneic hematopoietic stem cell transplantation and in autoimmune diseases.

Mesenchymal stem/stromal cells as a delivery platform in cell and gene therapies

Regenerative medicine relying on cell and gene therapies is one of the most promising approaches to repair tissues. Multipotent mesenchymal stem/stromal cells (MSC), a population of progenitors committing into mesoderm lineages, are progressively demonstrating therapeutic capabilities far beyond their differentiation capacities. The mechanisms by which MSC exert these actions include the release of biomolecules with anti-inflammatory, immunomodulating, anti-fibrogenic, and trophic functions. While we expect the spectra of these molecules with a therapeutic profile to progressively expand, several human pathological conditions have begun to benefit from these biomolecule-delivering properties. In addition, MSC have also been proposed to vehicle genes capable of further empowering these functions. This review deals with the therapeutic properties of MSC, focusing on their ability to secrete naturally produced or gene-induced factors that can be used in the treatment of kidney, lung, heart, liver, pancreas, nervous system, and skeletal diseases. We specifically focus on the different modalities by which MSC can exert these functions. We aim to provide an updated understanding of these paracrine mechanisms as a prerequisite to broadening the therapeutic potential and clinical impact of MSC.

[The health of the foreign immigrants in Turin in the current informative systems]

The rising phenomenon of immigration to Italy makes necessary to be equipped with basic tools allowing to work out a health pattern of the immigrated foreigners useful to develop programs for their health protection. We describe the image of the health pattern of foreigners immigrated to Turin obtained using the current socio-sanitary informative systems and the record of some outpatient's department. The resulting health condition is similar to that of the general population, with a few epidemiological peculiarities of the origin countries (a larger diffusion of tubercolosys and intestinal parasitosis) and with acute problems typical of populations with high mobility (traumatology, respiratory diseases). Besides, these sources suggest to examine carefully health problems pregnancy and work related. Completeness and quality limits of the informative systems used are then discussed.