Patient-derived pancreatic tumour organoids identify therapeutic responses to oncolytic adenoviruses

Oncolytic virus V937 in combination with PD-1 blockade therapy to target immunologically quiescent liver and colorectal cancer

V937 is an investigational, genetically unmodified Kuykendall strain of coxsackievirus A21, which has been evaluated in the clinic for advanced solid tumor malignancies. V937 specifically infects and lyses tumor cells that overexpress intercellular adhesion molecule-1 (ICAM-1). Intratumoral V937 as a monotherapy and in combination with anti-PD-1 antibody pembrolizumab has shown clinical response in patients with metastatic melanoma, which overexpresses ICAM-1. Here, we investigate in preclinical studies the potential bidirectional cross-talk between hepatocellular carcinomas (HCC) or colorectal carcinomas (CRC) and immune cells when treated with V937 alone or in combination with pembrolizumab. We show that while V937 treatment of tumor cell lines or organoids or peripheral blood mononuclear cells (PBMCs) alone induced a minimal immunological response, V937 treatment of non-contact co-cultures of tumor cell lines or CRC organoids with PBMCs led to robust production of proinflammatory cytokines and immune cell activation. In addition, both recombinant interferon-gamma and pembrolizumab increased ICAM-1 on tumor cell lines or organoids and, in turn, amplified V937-mediated oncolysis and immunogenicity. These findings provide critical mechanistic insights on the cross-talk between V937-mediated oncolysis and immune responses, demonstrating the therapeutic potential of V937 in combination with PD-1 blockade to treat immunologically quiescent cancers.

A prospects tool in virus research: Analyzing the applications of organoids in virus studies

Organoids have emerged as a powerful tool for understanding the biology of the respiratory, digestive, nervous as well as urinary system, investigating infections, and developing new therapies. This article reviews recent progress in the development of organoid and advancements in virus research. The potential applications of these models in studying virul infections, pathogenesis, and antiviral drug discovery are discussed.

Tutorial: design, production and testing of oncolytic viruses for cancer immunotherapy

Oncolytic viruses (OVs) represent a novel class of cancer immunotherapy agents that preferentially infect and kill cancer cells and promote protective antitumor immunity. Furthermore, OVs can be used in combination with established or upcoming immunotherapeutic agents, especially immune checkpoint inhibitors, to efficiently target a wide range of malignancies. The development of OV-based therapy involves three major steps before clinical evaluation: design, production and preclinical testing. OVs can be designed as natural or engineered strains and subsequently selected for their ability to kill a broad spectrum of cancer cells rather than normal, healthy cells. OV selection is further influenced by multiple factors, such as the availability of a specific viral platform, cancer cell permissivity, the need for genetic engineering to render the virus non-pathogenic and/or more effective and logistical considerations around the use of OVs within the laboratory or clinical setting. Selected OVs are then produced and tested for their anticancer potential by using syngeneic, xenograft or humanized preclinical models wherein immunocompromised and immunocompetent setups are used to elucidate their direct oncolytic ability as well as indirect immunotherapeutic potential in vivo. Finally, OVs demonstrating the desired anticancer potential progress toward translation in patients with cancer. This tutorial provides guidelines for the design, production and preclinical testing of OVs, emphasizing considerations specific to OV technology that determine their clinical utility as cancer immunotherapy agents.

Octyl itaconate enhances VSVΔ51 oncolytic virotherapy by multitarget inhibition of antiviral and inflammatory pathways

The presence of heterogeneity in responses to oncolytic virotherapy poses a barrier to clinical effectiveness, as resistance to this treatment can occur through the inhibition of viral spread within the tumor, potentially leading to treatment failures. Here we show that 4-octyl itaconate (4-OI), a chemical derivative of the Krebs cycle-derived metabolite itaconate, enhances oncolytic virotherapy with VSVΔ51 in various models including human and murine resistant cancer cell lines, three-dimensional (3D) patient-derived colon tumoroids and organotypic brain tumor slices. Furthermore, 4-OI in combination with VSVΔ51 improves therapeutic outcomes in a resistant murine colon tumor model. Mechanistically, we find that 4-OI suppresses antiviral immunity in cancer cells through the modification of cysteine residues in MAVS and IKKβ independently of the NRF2/KEAP1 axis. We propose that the combination of a metabolite-derived drug with an oncolytic virus agent can greatly improve anticancer therapeutic outcomes by direct interference with the type I IFN and NF-κB-mediated antiviral responses.

TheraVision: Engineering platform technology for the development of oncolytic viruses based on herpes simplex virus type 1

Viruses are able to efficiently penetrate cells, multiply, and eventually kill infected cells, release tumor antigens, and activate the immune system. Therefore, viruses are highly attractive novel agents for cancer therapy. Clinical trials with first generations of oncolytic viruses (OVs) are very promising but show significant need for optimization. The aim of TheraVision was to establish a broadly applicable engineering platform technology for combinatorial oncolytic virus and immunotherapy. Through genetic engineering, an attenuated herpes simplex virus type 1 (HSV1) was generated that showed increased safety compared to the wild-type strain. To demonstrate the modularity and the facilitated generation of new OVs, two transgenes encoding retargeting as well as immunomodulating single-chain variable fragments (scFvs) were integrated into the platform vector. The resulting virus selectively infected epidermal growth factor receptor (EGFR)-expressing cells and produced a functional immune checkpoint inhibitor against programmed cell death protein 1 (PD-1). Thus, both viral-mediated oncolysis and immune-cell-mediated therapy were combined into a single viral vector. Safety and functionality of the armed OVs have been shown in novel preclinical models ranging from patient-derived organoids and tissue-engineered human in vitro 3D tumor models to complex humanized mouse models. Consequently, a novel and proprietary engineering platform vector based on HSV1 is available for the facilitated preclinical development of oncolytic virotherapy.

Cancer organoids: A platform in basic and translational research

An accumulation of previous work has established organoids as good preclinical models of human tumors, facilitating translation from basic research to clinical practice. They are changing the paradigm of preclinical cancer research because they can recapitulate the heterogeneity and pathophysiology of human cancers and more closely approximate the complex tissue environment and structure found in clinical tumors than in vitro cell lines and animal models. However, the potential applications of cancer organoids remain to be comprehensively summarized. In the review, we firstly describe what is currently known about cancer organoid culture and then discuss in depth the basic mechanisms, including tumorigenesis and tumor metastasis, and describe recent advances in patient-derived tumor organoids (PDOs) for drug screening and immunological studies. Finally, the present challenges faced by organoid technology in clinical practice and its prospects are discussed. This review highlights that organoids may offer a novel therapeutic strategy for cancer research.

Oncolytic virotherapy in cancer treatment: challenges and optimization prospects

Oncolytic viruses (OVs) are emerging cancer therapeutics that offer a multifaceted therapeutic platform for the benefits of replicating and lysing tumor cells, being engineered to express transgenes, modulating the tumor microenvironment (TME), and having a tolerable safety profile that does not overlap with other cancer therapeutics. The mechanism of OVs combined with other antitumor agents is based on immune-mediated attack resistance and might benefit patients who fail to achieve durable responses after immune checkpoint inhibitor (ICI) treatment. In this Review, we summarize data on the OV mechanism and limitations of monotherapy, which are currently in the process of combination partner development, especially with ICIs. We discuss some of the hurdles that have limited the preclinical and clinical development of OVs. We also describe the available data and provide guidance for optimizing OVs in clinical practice, as well as a summary of approved and promising novel OVs with clinical indications.

Application of organoids in precision immunotherapy of lung cancer (Review)

In immunotherapy, the immune system is modulated in order to treat cancer. Traditional two dimensional in vitro models and in vivo animal models are insufficient to simulate the complex tumor microenvironment (TME) in the original tumor. As tumor immunotherapy involves the immune system, additional tumor mimic models, such as patient-derived organoids, are required for the evaluation of the efficacy of immunotherapy. Furthermore, non-tumor components and host tumor cells in the TME may interact to promote cancer incidence, progression, drug resistance and metastasis. It is possible to produce organoid models for lung cancer by retaining endogenous stromal components (e.g., multiple immune cell types), supplying cancer-associated fibroblasts and exogenous immune cells, constructing tumor vasculature and adding other biological or chemical components that emulate the TME. Therefore, the lung cancer organoid culture platform may facilitate preclinical testing of immunotherapy drugs for lung cancer by mimicking immunotherapy responses. The present review summarizes current lung cancer organoid culture methods for TME modeling and discusses the use of lung cancer-derived organoids for the detection of lung cancer immunotherapy and individualized cancer immunotherapy.

Cancer Spheroids and Organoids as Novel Tools for Research and Therapy: State of the Art and Challenges to Guide Precision Medicine

Spheroids and organoids are important novel players in medical and life science research. They are gradually replacing two-dimensional (2D) cell cultures. Indeed, three-dimensional (3D) cultures are closer to the in vivo reality and open promising perspectives for academic research, drug screening, and personalized medicine. A large variety of cells and tissues, including tumor cells, can be the starting material for the generation of 3D cultures, including primary tissues, stem cells, or cell lines. A panoply of methods has been developed to generate 3D structures, including spontaneous or forced cell aggregation, air-liquid interface conditions, low cell attachment supports, magnetic levitation, and scaffold-based technologies. The choice of the most appropriate method depends on (i) the origin of the tissue, (ii) the presence or absence of a disease, and (iii) the intended application. This review summarizes methods and approaches for the generation of cancer spheroids and organoids, including their advantages and limitations. We also highlight some of the challenges and unresolved issues in the field of cancer spheroids and organoids, and discuss possible therapeutic applications.

In vivo models of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with high mortality rate. Within the next decade, PDAC is projected to become the second leading cause of cancer-associated death in the United States. Understanding the pathophysiology of PDAC tumorigenesis and metastases is crucial toward developing new therapeutics. One of the challenges in cancer research is generating in vivo models that closely recapitulate the genomic, histological, and clinical characteristics of human tumors. An ideal model for PDAC not only captures the tumor and stromal environment of human disease, but also allows for mutational control and is easy to reproduce in terms of time and cost. In this review, we highlight evolution of in vivo models for PDAC including spontaneous tumors models (i.e., chemical induction, genetic modification, viral delivery), implantation models including patient derived xenografts (PDX), and humanized PDX. We discuss the implementation of each system and evaluate the benefits and shortcomings of these models. Overall, this review provides a broad overview of prior and current techniques of in vivo PDAC modeling and their associated challenges.

Patient-derived three-dimensional culture techniques model tumor heterogeneity in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) outcomes remain stagnant, in part due to a poor understanding of HNSCC biology. The importance of tumor heterogeneity as an independent predictor of outcomes and treatment failure in HNSCC has recently come to light. With this understanding, 3D culture systems, including patient derived organoids (PDO) and organotypic culture (OTC), that capture this heterogeneity may allow for modeling and manipulation of critical subpopulations, such as p-EMT, as well as interactions between cancer cells and immune and stromal cells in the microenvironment. Here, we review work that has been done using PDO and OTC models of HNSCC, which demonstrates that these 3D culture models capture in vivo tumor heterogeneity and can be used to model tumor biology and treatment response in a way that faithfully recapitulates in vivo characteristics. As such, in vitro 3D culture models represent an important bridge between 2D monolayer culture and in vivo models such as patient derived xenografts.

Andrographis Reverses Gemcitabine Resistance through Regulation of ERBB3 and Calcium Signaling Pathway in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, primarily due to intrinsic or acquired resistance to chemotherapy, such as Gemcitabine (Gem). Naturally occurring botanicals, including Andrographis (Andro), can help enhance the anti-tumorigenic therapeutic efficacy of conventional chemotherapy through time-tested safety and cost-effectiveness. Accordingly, we hypothesized that Andro might reverse Gem resistance in PDAC. The critical regulatory pathways associated with Gem resistance in PDAC were identified by analyzing publicly available transcriptomic profiling and PDAC tissue specimens. A series of systematic in vitro experiments were performed using Gem-resistant (Gem-R) PDAC cells and patient-derived 3D-organoids to evaluate the Andro-mediated reversal of Gem resistance in PDAC. Transcriptomic profiling identified the calcium signaling pathway as a critical regulator of Gem-resistance (Fold enrichment: 2.8, p = 0.002). Within this pathway, high ERBB3 expression was significantly associated with poor prognosis in PDAC patients. The combination of Andro and Gem exhibited superior anti-cancer potential in Gem-R PDAC cells through potentiating cellular apoptosis. The combined treatment down-regulated ERBB3 and decreased intracellular calcium concentration in Gem-R PDAC cells. Finally, these findings were successfully interrogated in patient-derived 3D-organoids. In conclusion, we demonstrate novel evidence for Andro-mediated reversal of chemoresistance to Gem in PDAC cells through the regulation of ERBB3 and calcium signaling.

Patient-derived xenografts or organoids in the discovery of traditional and self-assembled drug for tumor immunotherapy

In addition to the rapid development of immune checkpoint inhibitors, there has also been a surge in the development of self-assembly immunotherapy drugs. Based on the immune target, traditional tumor immunotherapy drugs are classified into five categories, namely immune checkpoint inhibitors, direct immune modulators, adoptive cell therapy, oncolytic viruses, and cancer vaccines. Additionally, the emergence of self-assembled drugs with improved precision and environmental sensitivity offers a promising innovation approach to tumor immunotherapy. Despite rapid advances in tumor immunotherapy drug development, all candidate drugs require preclinical evaluation for safety and efficacy, and conventional evaluations are primarily conducted using two-dimensional cell lines and animal models, an approach that may be unsuitable for immunotherapy drugs. The patient-derived xenograft and organoids models, however, maintain the heterogeneity and immunity of the pathological tumor heterogeneity.

The pivotal application of patient-derived organoid biobanks for personalized treatment of gastrointestinal cancers

Gastrointestinal cancers (GICs) occupy more than 30% of the cancer-related incidence and mortality around the world. Despite advances in the treatment strategies, the long-term overall survival has not been improved for patients with GICs. Recently, the novel patient-derived organoid (PDO) culture technology has become a powerful tool for GICs in a manner that recapitulates the morphology, pathology, genetic, phenotypic, and behavior traits of the original tumors. Excitingly, a number of evidences suggest that the versatile technology has great potential for personalized treatment, suppling the clinical application of molecularly guided personalized treatment. In the paper, we summarize the literature on the topics of establishing organoid biobanks of PDOs, and their application in the personalized treatment allowing for radiotherapy, chemotherapy, targeted therapy, and immunotherapy selection for GICs. Despite the limitations of current organoid models, high-throughput drug screening of GIC PDO combined with next-generation sequencing technology represents a novel and pivotal preclinical model for precision medicine of tumors and has a great value in promoting the transformation from basic cancer research to clinical application.

Berberine Overcomes Gemcitabine-Associated Chemoresistance through Regulation of Rap1/PI3K-Akt Signaling in Pancreatic Ductal Adenocarcinoma

Gemcitabine (Gem)-based chemotherapy is one of the first-line treatments for pancreatic ductal adenocarcinoma (PDAC). However, its clinical effect is limited due to development of chemoresistance. Various naturally occurring compounds, including Berberine (BBR), provide an anti-cancer efficacy with time-tested safety, individually and in combination with chemotherapeutic drugs. Accordingly, we hypothesized that BBR might enhance the chemosensitivity to Gem in PDAC. In this study, cell culture studies using MIA PaCa-2 and BxPC-3 cells, followed by analysis in patient-derived organoids were performed to evaluate the anti-cancer effects of BBR in PDAC. Considering that cancer is a significant manifestation of increased chronic inflammatory stress, systems biology approaches are prudent for the identification of molecular pathways and networks responsible for phytochemical-induced anti-cancer activity, we used these approaches for BBR-mediated chemosensitization to Gem. Firstly, Gem-resistant (Gem-R) PDAC cells were established, and the combination of BBR and Gem revealed superior anti-cancer efficacy in Gem-R cells. Furthermore, the combination treatment induced cell cycle arrest and apoptosis in Gem-R PDAC cells. Transcriptomic profiling investigated the Rap1 and PI3K-Akt signaling pathway as a key regulator of Gem-resistance and was a key mediator for BBR-mediated chemosensitization in PDAC cells. All cell culture-based findings were successfully validated in patient-derived organoids. In conclusion, we demonstrate that BBR-mediated reversal of chemoresistance to Gem manifests through Rap1/PI3K-Akt signaling in PDAC.

Oncolytic viruses: challenges and considerations in an evolving clinical landscape

Despite advances in treatment, cancer remains a leading cause of death worldwide. Although treatment strategies are continually progressing, cancers have evolved many mechanisms for evading therapies and the host immune system. Oncolytic viruses (OVs) could provide a much-needed option for cancers that are resistant to existing treatments. OVs can be engineered to specifically target and kill cancer cells, while simultaneously triggering an immune response at the site of infection. This review will focus on the challenges of developing a successful OV and translation to clinical practice, discussing the innovative strategies that are being used to optimize the potential of OVs. Here, we will also explore the current clinical landscape and the prospects of OVs in early clinical development.

Organoid Models for Precision Cancer Immunotherapy

Cancer immunotherapy is exploited for the treatment of disease by modulating the immune system. Since the conventional in vivo animal and 2D in vitro models insufficiently recapitulate the complex tumor immune microenvironment (TIME) of the original tumor. In addition, due to the involvement of the immune system in cancer immunotherapy, more physiomimetic cancer models, such as patient-derived organoids (PDOs), are required to evaluate the efficacy of immunotherapy agents. On the other hand, the dynamic interactions between the neoplastic cells and non-neoplastic host components in the TIME can promote carcinogenesis, tumor metastasis, cancer progression, and drug resistance of cancer cells. Indeed, tumor organoid models can properly recapitulate the TIME by preserving endogenous stromal components including various immune cells, or by adding exogenous immune cells, cancer-associated fibroblasts (CAFs), vasculature, and other components. Therefore, organoid culture platforms could model immunotherapy responses and facilitate the immunotherapy preclinical testing. Here, we discuss the various organoid culture approaches for the modeling of TIME and the applications of complex tumor organoids in testing cancer immunotherapeutics and personalized cancer immunotherapy.

Patient-Derived Tumor Organoids: New Progress and Opportunities to Facilitate Precision Cancer Immunotherapy

Cancer immunotherapy has revolutionized the field of cancer treatment in recent years. However, not all patients receiving cancer immunotherapy exhibit durable responses, and reliable, high-throughput testing platforms are urgently needed to guide personalized cancer immunotherapy. The ability of patient-derived tumor organoids to recapitulate pivotal features of original cancer tissues makes them useful as a preclinical model for cancer research and precision medicine. Nevertheless, many challenges exist in the translation of tumor organoid research to clinical decision making. Herein we discuss the applications of patient-derived tumor organoid models and the advances and potential of using complex immune-organoid systems as testing platforms to facilitate precision cancer immunotherapy. In addition, we highlight intriguing applications of tumor organoids with novel multi-omics in preclinical cancer research, highlighting genetic editing, proteomics, and liquid biopsy.

A Three-Dimensional Organoid Model of Primary Breast Cancer to Investigate the Effects of Oncolytic Virotherapy

Background: Although several oncolytic viruses have already been tested in early-stage clinical studies of breast cancer, there is still an urgent need to develop patient-derived experimental systems that mimic the response of breast cancer to oncolytic agents in preparation of testing different oncolytic viruses in clinical trials. We addressed this need by developing a protocol to study the effects of oncolytic viruses in stable organoid cell cultures derived from breast cancer tissue.

Methods: We used an established three-dimensional organoid model derived from tissue of 10 patients with primary breast cancer. We developed an experimental protocol for infecting organoid cultures with oncolytic viruses and compared the oncolytic effects of a measles vaccine virus (MeV) and a vaccinia virus (GLV) genetically engineered to express either green fluorescent protein (MeV-GFP) and red fluorescent protein (GLV-0b347), respectively, or a suicide gene encoding a fusion of cytosine deaminase with uracil phosphoribosyltransferase (MeV-SCD and GLV-1h94, respectively), thereby enabling enzymatic conversion of the prodrug 5-fluorocytosine (5-FC) into cytotoxic compounds 5-fluorouracil (5-FU) and 5-fluorouridine monophosphate (5-FUMP).

Results: The method demonstrated that all oncolytic viruses significantly inhibited cell viability in organoid cultures derived from breast cancer tissue. The oncolytic effects of the oncolytic viruses expressing suicide genes (MeV-SCD and GLV-1h94) were further enhanced by virus-triggered conversion of the prodrug 5-FC to toxic 5-FU and toxic 5-FUMP.

Conclusions: We were able to develop a protocol to assess the effects of two different types of oncolytic viruses in stable organoid cell cultures derived from breast cancer tissue. The greatest oncolytic effects were observed when the oncolytic viruses were engineered to express a suicide gene (MeV-SCD and GLV-1h94) in the presence of the prodrug 5-FC. The model therefore provides a promising in vitro method to help further testing and engineering of new generations of virotherapeutic vectors for in vivo use.

Pancreatic Cancer Organoids in the Field of Precision Medicine: A Review of Literature and Experience on Drug Sensitivity Testing with Multiple Readouts and Synergy Scoring

Simple Summary

New treatments are urgently needed for pancreatic ductal adenocarcinoma because it is one of the most aggressive and lethal cancers, detected too late and resistant to conventional chemotherapy. Tumors in most patients feature a similar set of core mutations but so far it has not been possible to design a one-fits-all treatment strategy. Instead, efforts are underway to personalize the therapies. To find the treatments that might work the best for each patient, entirely new experimental platforms based on living miniature tumors, organoids, have been developed. We review here the latest international findings in designing personalized treatments pancreatic cancer patients using organoids as testing beds. Our own work adds important clues about how such testing could, and perhaps should, be conducted.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a silent killer, often diagnosed late. However, it is also dishearteningly resistant to nearly all forms of treatment. New therapies are urgently needed, and with the advent of organoid culture for pancreatic cancer, an increasing number of innovative approaches are being tested. Organoids can be derived within a short enough time window to allow testing of several anticancer agents, which opens up the possibility for functional precision medicine for pancreatic cancer. At the same time, organoid model systems are being refined to better mimic the cancer, for example, by incorporation of components of the tumor microenvironment. We review some of the latest developments in pancreatic cancer organoid research and in novel treatment design. We also summarize our own current experiences with pancreatic cancer organoid drug sensitivity and resistance testing (DSRT) in 14 organoids from 11 PDAC patients. Our data show that it may be necessary to include a cell death read-out in ex vivo DSRT assays, as metabolic viability quantitation does not capture actual organoid killing. We also successfully adapted the organoid platform for drug combination synergy discovery. Lastly, live organoid culture 3D confocal microscopy can help identify individual surviving tumor cells escaping cell death even during harsh combination treatments. Taken together, the organoid technology allows the development of novel precision medicine approaches for PDAC, which paves the way for clinical trials and much needed new treatment options for pancreatic cancer patients.

Patient-derived organoids as a model for tumor research

Cancer represents a leading cause of death, despite the rapid progress of cancer research, leading to urgent need for accurate preclinical model to further study of tumor mechanism and accelerate translational applications. Cancer cell lines cannot fully recapitulate tumors of different patients due to the lack of tumor complexity and specification, while the high technical difficulty, long time, and substantial cost of patient-derived xenograft model makes it unable to be used extensively for all types of tumors and large-scale drug screening. Patient-derived organoids can be established rapidly with a high success rate from many tumors, and precisely replicate the key histopathological, genetic, and phenotypic features, as well as therapeutic response of patient tumor. Therefore, they are extensively used in cancer basic research, biobanking, disease modeling and precision medicine. The combinations of cancer organoids with other advanced technologies, such as 3D bio-printing, organ-on-a-chip, and CRISPR-Cas9, contributes to the more complete replication of complex tumor microenvironment and tumorigenesis. In this review, we discuss the various methods of the establishment and the application of patient-derived organoids in diverse tumors as well as the limitations and future prospects of these models. Further advances of tumor organoids are expected to bridge the huge gap between bench and bedside and provide the unprecedented opportunities to advance cancer research.

Pancreatic Cancer Patient-Derived Organoid Platforms: A Clinical Tool to Study Cell- and Non-Cell-Autonomous Mechanisms of Treatment Response

For many years, cell lines and animal models have been essential to improve our understanding of the basis of cell metabolism, signaling, and genetics. They also provided an essential boost to cancer drug discovery. Nevertheless, these model systems failed to reproduce the tumor heterogeneity and the complex biological interactions between cancer cells and human hosts, making a high priority search for alternative methods that are able to export results from model systems to humans, which has become a major bottleneck in the drug development. The emergent human in vitro 3D cell culture technologies have attracted widespread attention because they seem to have the potential to overcome these limitations. Organoids are unique 3D culture models with the ability to self-organize in contained structures. Their versatility has offered an exceptional window of opportunity to approach human cancers. Pancreatic cancers (PCs) patient-derived-organoids (PDOs) preserve histological, genomic, and molecular features of neoplasms they originate from and therefore retain their heterogeneity. Patient-derived organoids can be established with a high success rate from minimal tissue core specimens acquired with endoscopic-ultrasound-guided techniques and assembled into platforms, representing tens to hundreds of cancers each conserving specific features, expanding the types of patient samples that can be propagated and analyzed in the laboratory. Because of their nature, PDO platforms are multipurpose systems that can be easily adapted in co-culture settings to perform a wide spectrum of studies, ranging from drug discovery to immune response evaluation to tumor-stroma interaction. This possibility to increase the complexity of organoids creating a hybrid culture with non-epithelial cells increases the interest in organoid-based platforms giving a pragmatic way to deeply study biological interactions in vitro. In this view, implementing organoid models in co-clinical trials to compare drug responses may represent the next step toward even more personalized medicine. In the present review, we discuss how PDO platforms are shaping modern-day oncology aiding to unravel the most complex aspects of PC.

Preclinical testing of oncolytic adenovirus sensitivity in patient-derived tumor organoids

Patient-derived organoids (PDOs) have shown the potential to reflect patient sensitivity to chemotherapeutic or targeted drugs. Recently, we showed that organoid models can also serve as a platform to screen for selectivity and potency of oncolytic adenoviruses (OAds). In this protocol, we describe the steps for tumor organoid adenoviral infection and functional assessment of patient-specific responses to OAds. We provide methods to determine OAd relative efficacy by evaluation of PDO viability after infection and adenoviral replication within cancer cells.

For complete details on the use and execution of this protocol, please refer to Raimondi et al. (2020).

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Protocol for infection of organoids with oncolytic adenoviruses

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Steps to quantify adenoviral replication within organoids

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Evaluation of viability after infection to determine relative oncolytic efficacy

Tumor organoids: synergistic applications, current challenges, and future prospects in cancer therapy

Patient-derived cancer cells (PDCs) and patient-derived xenografts (PDXs) are often used as tumor models, but have many shortcomings. PDCs not only lack diversity in terms of cell type, spatial organization, and microenvironment but also have adverse effects in stem cell cultures, whereas PDX are expensive with a low transplantation success rate and require a long culture time. In recent years, advances in three-dimensional (3D) organoid culture technology have led to the development of novel physiological systems that model the tissues of origin more precisely than traditional culture methods. Patient-derived cancer organoids bridge the conventional gaps in PDC and PDX models and closely reflect the pathophysiological features of natural tumorigenesis and metastasis, and have led to new patient-specific drug screening techniques, development of individualized treatment regimens, and discovery of prognostic biomarkers and mechanisms of resistance. Synergistic combinations of cancer organoids with other technologies, for example, organ-on-a-chip, 3D bio-printing, and CRISPR-Cas9-mediated homology-independent organoid transgenesis, and with treatments, such as immunotherapy, have been useful in overcoming their limitations and led to the development of more suitable model systems that recapitulate the complex stroma of cancer, inter-organ and intra-organ communications, and potentially multiorgan metastasis. In this review, we discuss various methods for the creation of organ-specific cancer organoids and summarize organ-specific advances and applications, synergistic technologies, and treatments as well as current limitations and future prospects for cancer organoids. Further advances will bring this novel 3D organoid culture technique closer to clinical practice in the future.

Pre-clinical Models of Metastasis in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a hostile solid malignancy coupled with an extremely high mortality rate. Metastatic disease is already found in most patients at the time of diagnosis, resulting in a 5-year survival rate below 5%. Improved comprehension of the mechanisms leading to metastasis is pivotal for the development of new targeted therapies. A key field to be improved are modeling strategies applied in assessing cancer progression, since traditional platforms fail in recapitulating the complexity of PDAC. Consequently, there is a compelling demand for new preclinical models that mirror tumor progression incorporating the pressure of the immune system, tumor microenvironment, as well as molecular aspects of PDAC. We suggest the incorporation of 3D organoids derived from genetically engineered mouse models or patients as promising new tools capable to transform PDAC pre-clinical modeling and access new frontiers in personalized medicine.

Pouring petrol on the flames: Using oncolytic virotherapies to enhance tumour immunogenicity

Oncolytic viruses possess the ability to infect, replicate and lyse malignantly transformed tumour cells. This oncolytic activity amplifies the therapeutic advantage and induces a form of immunogenic cell death, characterized by increased CD8 + T-cell infiltration into the tumour microenvironment. This important feature of oncolytic viruses can result in the warming up of immunologically 'cold' tumour types, presenting the enticing possibility that oncolytic virus treatment combined with immunotherapies may enhance efficacy. In this review, we assess some of the most promising candidates that might be used for oncolytic virotherapy: immunotherapy combinations. We assess their potential as separate agents or as agents combined into a single therapy, where the immunotherapy is encoded within the genome of the oncolytic virus. The development of such advanced agents will require increasingly sophisticated model systems for their preclinical assessment and evaluation. In vivo rodent model systems are fraught with limitations in this regard. Oncolytic viruses replicate selectively within human cells and therefore require human xenografts in immune-deficient mice for their evaluation. However, the use of immune-deficient rodent models hinders the ability to study immune responses against any immunomodulatory transgenes engineered within the viral genome and expressed within the tumour microenvironment. There has therefore been a shift towards the use of more sophisticated ex vivo patient-derived model systems based on organoids and explant co-cultures with immune cells, which may be more predictive of efficacy than contrived and artificial animal models. We review the best of those model systems here.

Progress and Challenges in the Use of a Liver-on-a-Chip for Hepatotropic Infectious Diseases

The liver is a target organ of life-threatening pathogens and prominently contributes to the variation in drug responses and drug-induced liver injury among patients. Currently available drugs significantly decrease the morbidity and mortality of liver-dwelling pathogens worldwide; however, emerging clinical evidence reveals the importance of host factors in the design of safe and effective therapies for individuals, known as personalized medicine. Given the primary adherence of cells in conventional two-dimensional culture, the use of these one-size-fit-to-all models in preclinical drug development can lead to substantial failures in assessing therapeutic safety and efficacy. Advances in stem cell biology, bioengineering and material sciences allow us to develop a more physiologically relevant model that is capable of recapitulating the human liver. This report reviews the current use of liver-on-a-chip models of hepatotropic infectious diseases in the context of precision medicine including hepatitis virus and malaria parasites, assesses patient-specific responses to antiviral drugs, and designs personalized therapeutic treatments to address the need for a personalized liver-like model. Second, most organs-on-chips lack a monitoring system for cell functions in real time; thus, the review discusses recent advances and challenges in combining liver-on-a-chip technology with biosensors for assessing hepatocyte viability and functions. Prospectively, the biosensor-integrated liver-on-a-chip device would provide novel biological insights that could accelerate the development of novel therapeutic compounds.

Organoids in Tissue Transplantation

Improvements in stem cell-based research and genetic modification tools enable stem cell-based tissue regeneration applications in clinical therapies. Although inadequate cell numbers in culture, invasive isolation procedures, and poor survival rates after transplantation remain as major challenges, cell-based therapies are useful tools for tissue regeneration.Organoids hold a great promise for tissue regeneration, organ and disease modeling, drug testing, development, and genetic profiling studies. Establishment of 3D cell culture systems eliminates the disadvantages of 2D models in terms of cell adaptation and tissue structure and function. Organoids possess the capacity to mimic the specific features of tissue architecture, cell-type composition, and the functionality of real organs while preserving the advantages of simplified and easily accessible cell culture models. Thus, organoid technology might emerge as an alternative to cell and tissue transplantation. Although transplantation of various organoids in animal models has been demonstrated, liöitations related to vascularized structure formation, cell viability and functionality remain as obstacles in organoid-based transplantation therapies. Clinical applications of organoid-based transplantations might be possible in the near future, when limitations related to cell viability and tissue integration are solved. In this review, the literature was analyzed and discussed to explore the current status of organoid-based transplantation studies.

Modeling pancreatic cancer in mice for experimental therapeutics

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy that is characterized by early metastasis, low resectability, high recurrence, and therapy resistance. The experimental mouse models have played a central role in understanding the pathobiology of PDAC and in the preclinical evaluation of various therapeutic modalities. Different mouse models with targetable pathological hallmarks have been developed and employed to address the unique challenges associated with PDAC progression, metastasis, and stromal heterogeneity. Over the years, mouse models have evolved from simple cell line-based heterotopic and orthotopic xenografts in immunocompromised mice to more complex and realistic genetically engineered mouse models (GEMMs) involving multi-gene manipulations. The GEMMs, mostly driven by KRAS mutation(s), have been widely accepted for therapeutic optimization due to their high penetrance and ability to recapitulate the histological, molecular, and pathological hallmarks of human PDAC, including comparable precursor lesions, extensive metastasis, desmoplasia, perineural invasion, and immunosuppressive tumor microenvironment. Advanced GEMMs modified to express fluorescent proteins have allowed cell lineage tracing to provide novel insights and a new understanding about the origin and contribution of various cell types in PDAC pathobiology. The syngeneic mouse models, GEMMs, and target-specific transgenic mice have been extensively used to evaluate immunotherapies and study therapy-induced immune modulation in PDAC yielding meaningful results to guide various clinical trials. The emerging mouse models for parabiosis, hepatic metastasis, cachexia, and image-guided implantation, are increasingly appreciated for their high translational significance. In this article, we describe the contribution of various experimental mouse models to the current understanding of PDAC pathobiology and their utility in evaluating and optimizing therapeutic modalities for this lethal malignancy.

Patient-derived xenograft models of BRCA-associated pancreatic cancers

Pancreatic ductal adenocarcinoma (PDAC) is a dismal disease. The majority of patients diagnosed at an advanced, metastatic stage, and poor overall survival rates. The most clinically meaningful subtype obtained from PDAC genomic classification is represented by unstable genomes, and co-segregated with inactivation of DNA damage repair genes, e.g., Breast cancer 1/2 (BRCA1/2). The FDA and EMA has recently approved olaparib, a Poly (ADP-ribose) polymerase (PARP) inhibitor, as a maintenance strategy for platinum-sensitive advanced PDAC patients with BRCA mutations. However, susceptibility to treatment varies, and resistance may develop. Resistance can be defined as innate or acquired resistance to platinum/PARP-inhibition. Patient-derived xenograft (PDX) models have been utilized in cancer research for many years. We generated a unique PDX model, obtained from BRCA-associated PDAC patients at distinct time points of the disease recapitulating the different clinical scenario. In this review we discuss the relevant PDX-derived models for investigating BRCA-associated PDAC and drug development.

Expanding the Spectrum of Pancreatic Cancers Responsive to Vesicular Stomatitis Virus-Based Oncolytic Virotherapy: Challenges and Solutions

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a devastating malignancy with a poor prognosis and a dismal survival rate. Oncolytic virus (OV) is an anticancer approach that utilizes replication-competent viruses to preferentially infect and kill tumor cells. Vesicular stomatitis virus (VSV), one such OV, is already in several phase I clinical trials against different malignancies. VSV-based recombinant viruses are effective OVs against a majority of tested PDAC cell lines. However, some PDAC cell lines are resistant to VSV. This review discusses multiple mechanisms responsible for the resistance of some PDACs to VSV-based OV therapy, as well multiple rational approaches to enhance permissiveness of PDACs to VSV and expand the spectrum of PDACs responsive to VSV-based oncolytic virotherapy.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a devastating malignancy with poor prognosis and a dismal survival rate, expected to become the second leading cause of cancer-related deaths in the United States. Oncolytic virus (OV) is an anticancer approach that utilizes replication-competent viruses to preferentially infect and kill tumor cells. Vesicular stomatitis virus (VSV), one such OV, is already in several phase I clinical trials against different malignancies. VSV-based recombinant viruses are effective OVs against a majority of tested PDAC cell lines. However, some PDAC cell lines are resistant to VSV. Upregulated type I IFN signaling and constitutive expression of a subset of interferon-simulated genes (ISGs) play a major role in such resistance, while other mechanisms, such as inefficient viral attachment and resistance to VSV-mediated apoptosis, also play a role in some PDACs. Several alternative approaches have been shown to break the resistance of PDACs to VSV without compromising VSV oncoselectivity, including (i) combinations of VSV with JAK1/2 inhibitors (such as ruxolitinib); (ii) triple combinations of VSV with ruxolitinib and polycations improving both VSV replication and attachment; (iii) combinations of VSV with chemotherapeutic drugs (such as paclitaxel) arresting cells in the G2/M phase; (iv) arming VSV with p53 transgenes; (v) directed evolution approach producing more effective OVs. The latter study demonstrated impressive long-term genomic stability of complex VSV recombinants encoding large transgenes, supporting further clinical development of VSV as safe therapeutics for PDAC.

Patient-Derived Organoids for Precision Cancer Immunotherapy

Cancer immunotherapy has revolutionized the way tumors are treated. Nevertheless, efficient and robust testing platforms are still missing, including clinically relevant human ex vivo tumor assays that allow pretreatment testing of cancer therapies and selection of the most efficient and safe therapy for a specific patient. In the case of immunotherapy, this testing platform would require not only cancer cells, but also the tumor microenvironment, including immune cells. Here, we discuss the applications of patient-derived tumor organoid cultures and the possibilities in using complex immune-organoid cultures to provide preclinical testing platforms for precision cancer immunotherapy.

Pancreatic Ductal Adenocarcinoma (PDAC) Organoids: The Shining Light at the End of the Tunnel for Drug Response Prediction and Personalized Medicine

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) causes massive medical problems because of late diagnosis and limited responsiveness to standard chemotherapeutic treatments. This makes PDAC one of the major causes of death by cancer. To address this problem, novel tools for early diagnosis and therapy are needed. The recent development of PDAC organoids, which represent micro-scale mini-tumors, offers promising new options for personalized drug-testing based on primary PDAC patient material. This overview article summarizes and discusses the current state-of-the-art in exploiting the organoid technology to improve clinical management of PDAC.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) represents 90% of pancreatic malignancies. In contrast to many other tumor entities, the prognosis of PDAC has not significantly improved during the past thirty years. Patients are often diagnosed too late, leading to an overall five-year survival rate below 10%. More dramatically, PDAC cases are on the rise and it is expected to become the second leading cause of death by cancer in western countries by 2030. Currently, the use of gemcitabine/nab-paclitaxel or FOLFIRINOX remains the standard chemotherapy treatment but still with limited efficiency. There is an urgent need for the development of early diagnostic and therapeutic tools. To this point, in the past 5 years, organoid technology has emerged as a revolution in the field of PDAC personalized medicine. Here, we are reviewing and discussing the current technical and scientific knowledge on PDAC organoids, their future perspectives, and how they can represent a game change in the fight against PDAC by improving both diagnosis and treatment options.

Oncolytic virotherapy for pancreatic ductal adenocarcinoma: A glimmer of hope after years of disappointment?

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and highly lethal malignancies. Existing therapeutic interventions have so far been unsuccessful in improving prognosis, and survival remains very poor. Oncolytic virotherapy represents a promising, yet not fully explored, alternative strategy for the treatment of PDAC. Oncolytic viruses (OVs) infect, replicate within and lyse tumor cells specifically and stimulate antitumor immune responses. Multiple challenges have hampered the efficacy of oncolytic virotherapy for PDAC, the most significant being the desmoplastic and immunosuppressive pancreatic tumor microenvironment (TME). The TME limits the access of therapeutic drugs and the infiltration of effector T cells and natural killer (NK) cells into the tumor mass. Additionally, cancer cells promote the secretion of immunosuppressive factors and develop mechanisms to evade the host immune system. Because of their oncolytic and immune-stimulating properties, OVs are the ideal candidates for counteracting the pancreatic immunosuppressive TME and for designing combination therapies that can be clinically exploited in clinical trials that seek to improve the prognosis of PDAC.