Randomized Phase 2 Trial of the Oncolytic Virus Pelareorep (Reolysin) in Upfront Treatment of Metastatic Pancreatic Adenocarcinoma

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.

CD200 is overexpressed in the pancreatic tumor microenvironment and predictive of overall survival

Pancreatic cancer is an aggressive disease with a 5 year survival rate of 13%. This poor survival is attributed, in part, to limited and ineffective treatments for patients with metastatic disease, highlighting a need to identify molecular drivers of pancreatic cancer to target for more effective treatment. CD200 is a glycoprotein that interacts with the receptor CD200R and elicits an immunosuppressive response. Overexpression of CD200 has been associated with differential outcomes, depending on the tumor type. In the context of pancreatic cancer, we have previously reported that CD200 is expressed in the pancreatic tumor microenvironment (TME), and that targeting CD200 in murine tumor models reduces tumor burden. We hypothesized that CD200 is overexpressed on tumor and stromal populations in the pancreatic TME and that circulating levels of soluble CD200 (sCD200) have prognostic value for overall survival. We discovered that CD200 was overexpressed on immune, stromal, and tumor populations in the pancreatic TME. Particularly, single-cell RNA-sequencing indicated that CD200 was upregulated on inflammatory cancer-associated fibroblasts. Cytometry by time of flight analysis of PBMCs indicated that CD200 was overexpressed on innate immune populations, including monocytes, dendritic cells, and monocytic myeloid-derived suppressor cells. High sCD200 levels in plasma correlated with significantly worse overall and progression-free survival. Additionally, sCD200 correlated with the ratio of circulating matrix metalloproteinase (MMP) 3: tissue inhibitor of metalloproteinase (TIMP) 3 and MMP11/TIMP3. This study highlights the importance of CD200 expression in pancreatic cancer and provides the rationale for designing novel therapeutic strategies that target this protein.

LOAd703, an oncolytic virus-based immunostimulatory gene therapy, combined with chemotherapy for unresectable or metastatic pancreatic cancer (LOKON001): results from arm 1 of a non-randomised, single-centre, phase 1/2 study

BACKGROUND

Pancreatic ductal adenocarcinoma is characterised by low immunogenicity and an immunosuppressive tumour microenvironment. LOAd703, an oncolytic adenovirus with transgenes encoding TMZ-CD40L and 4-1BBL, lyses cancer cells selectively, activates cytotoxic T cells, and induces tumour regression in preclinical models. The aim of this study was to evaluate the safety and feasibility of combining LOAd703 with chemotherapy for advanced pancreatic ductal adenocarcinoma.

METHODS

LOKON001 was a non-randomised, phase 1/2 study conducted at the Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA, and consisted of two arms conducted sequentially; the results of arm 1 are presented here. In arm 1, patients 18 years or older with previously treated or treatment-naive unresectable or metastatic pancreatic ductal adenocarcinoma were treated with standard 28-day cycles of intravenous nab-paclitaxel 125 mg/m2 plus gemcitabine 1000 mg/m2 (up to 12 cycles) and intratumoural injections of LOAd703 every 2 weeks. Patients were assigned using Bayesian optimal interval design to receive 500 μL of LOAd703 at 5 × 1010 (dose 1), 1 × 1011 (dose 2), or 5 × 1011 (dose 3) viral particles per injection, injected endoscopically or percutaneously into the pancreatic tumour or a metastasis for six injections. The primary endpoints were safety and treatment-emergent immune response in patients who received at least one dose of LOAd703, and antitumour activity was a secondary endpoint. This study was registered with ClinicalTrials.gov, NCT02705196, arm 2 is ongoing and open to new participants.

FINDINGS

Between Dec 2, 2016, and Oct 17, 2019, 23 patients were assessed for eligibility, leading to 22 patients being enrolled. One patient withdrew consent, resulting in 21 patients (13 [62%] men and eight [38%] women) assigned to a dose group (three to dose 1, four to dose 2, and 14 to dose 3). 21 patients were evaluable for safety. Median follow-up time was 6 months (IQR 4-10), and data cutoff was Jan 5, 2023. The most common treatment-emergent adverse events overall were anaemia (96 [8%] of 1237 events), lymphopenia (86 [7%] events), hyperglycaemia (70 [6%] events), leukopenia (63 [5%] events), hypertension (62 [5%] events), and hypoalbuminaemia (61 [5%] events). The most common adverse events attributed to LOAd703 were fever (14 [67%] of 21 patients), fatigue (eight [38%]), chills (seven [33%]), and elevated liver enzymes (alanine aminotransferase in five [24%], alkaline phosphatase in four [19%], and aspartate aminotransferase in four [19%]), all of which were grade 1-2, except for a transient grade 3 aminotransferase elevation occurring at dose 3. A maximum tolerated dose was not reached, thereby establishing dose 3 as the highest-evaluated safe dose when combined with nab-paclitaxel plus gemcitabine. Proportions of CD8+ effector memory cells and adenovirus-specific T cells increased after LOAd703 injections in 15 (94%) of 16 patients for whom T-cell assays could be performed. Eight (44%, 95% CI 25-66) of 18 patients evaluable for activity had an objective response.

INTERPRETATION

Combining LOAd703 with nab-paclitaxel plus gemcitabine in patients with advanced pancreatic ductal adenocarcinoma was feasible and safe. To build upon this novel chemoimmunotherapeutic approach, arm 2 of LOKON001, which combines LOAd703, nab-paclitaxel plus gemcitabine, and atezolizumab, is ongoing.

FUNDING

Lokon Pharma, the Swedish Cancer Society, and the Swedish Research Council.

Does oncolytic viruses-mediated metabolic reprogramming benefit or harm the immune microenvironment?

Oncolytic virus immunotherapy as a new tumor therapy has made remarkable achievements in clinical practice. And metabolic reprogramming mediated by oncolytic virus has a significant impact on the immune microenvironment. This review summarized the reprogramming of host cell glucose metabolism, lipid metabolism, oxidative phosphorylation, and glutamine metabolism by oncolytic virus and illustrated the effects of metabolic reprogramming on the immune microenvironment. It was found that oncolytic virus-induced reprogramming of glucose metabolism in tumor cells has both beneficial and detrimental effects on the immune microenvironment. In addition, oncolytic virus can promote fatty acid synthesis in tumor cells, inhibit oxidative phosphorylation, and promote glutamine catabolism, which facilitates the anti-tumor immune function of immune cells. Therefore, targeted metabolic reprogramming is a new direction to improve the efficacy of oncolytic virus immunotherapy.

NK cells as powerful therapeutic tool in cancer immunotherapy

BACKGROUND

Natural killer (NK) cells have gained considerable attention and hold great potential for their application in tumor immunotherapy. This is mainly due to their MHC-unrestricted and pan-specific recognition capabilities, as well as their ability to rapidly respond to and eliminate target cells. To artificially generate therapeutic NK cells, various materials can be utilized, such as peripheral blood mononuclear cells (PBMCs), umbilical cord blood (UCB), induced pluripotent stem cells (iPSCs), and NK cell lines. Exploiting the therapeutic potential of NK cells to treat tumors through in vivo and in vitro therapeutic modalities has yielded positive therapeutic results.

CONCLUSION

This review provides a comprehensive description of NK cell therapeutic approaches for tumors and discusses the current problems associated with these therapeutic approaches and the prospects of NK cell therapy for tumors.

An oncolytic system produces oxygen selectively in pancreatic tumor cells to alleviate hypoxia and improve immune activation

INTRODUCTION

Hypoxia is one of the important reasons for the poor therapeutic efficacy of current pancreatic cancer treatment, and the dense stroma of pancreatic cancer restricts the diffusion of oxygen within the tumor.

METHODS

A responsive oxygen-self-supplying adv-miRT-CAT-KR (adv-MCK) cascade reaction system to improve hypoxia in pancreatic cancer is constructed. We utilized various experiments at multiple levels (cells, organoids, in vivo) to investigate its effect on pancreatic cancer and analyzed the role of immune microenvironment changes in it through high-throughput sequencing.

RESULTS

The adv-MCK system is an oncolytic adenovirus system expressing three special components of genes. The microRNA (miRNA) targets (miRTs) enable adv-MCK to selectively replicate in pancreatic cancer cells. Catalase catalyzes the overexpressed hydrogen peroxide in pancreatic cancer cells to generate endogenous oxygen, which is catalyzed by killerRed to generate singlet oxygen (1O2) and further to enhance the oncolytic effect. Meanwhile, the adv-MCK system can specifically improve hypoxia in pancreatic cancer, exert antitumor effects in combination with photodynamic therapy, and activate antitumor immunity, especially by increasing the level of γδ T cells in the tumor microenvironment.

CONCLUSION

The responsive oxygen-self-supplying adv-MCK cascade reaction system combined with photodynamic therapy can improve the hypoxic microenvironment of pancreatic cancer and enhance antitumor immunity, which provides a promising alternative treatment strategy for pancreatic cancer.

Advancements and challenges in oncolytic virus therapy for gastrointestinal tumors

BACKGROUND

Tumors of the gastrointestinal tract impose a substantial healthcare burden due to their prevalence and challenging prognosis.

METHODS

We conducted a review of peer-reviewed scientific literature using reputable databases (PubMed, Scopus, Web of Science) with a focus on oncolytic virus therapy within the context of gastrointestinal tumors. Our search covered the period up to the study's completion in June 2023.

INCLUSION AND EXCLUSION CRITERIA

This study includes articles from peer-reviewed scientific journals, written in English, that specifically address oncolytic virus therapy for gastrointestinal tumors, encompassing genetic engineering advances, combined therapeutic strategies, and safety and efficacy concerns. Excluded are articles not meeting these criteria or focusing on non-primary gastrointestinal metastatic tumors.

RESULTS

Our review revealed the remarkable specificity of oncolytic viruses in targeting tumor cells and their potential to enhance anti-tumor immune responses. However, challenges related to safety and efficacy persist, underscoring the need for ongoing research and improvement.

CONCLUSION

This study highlights the promising role of oncolytic virus therapy in enhancing gastrointestinal tumor treatments. Continued investigation and innovative combination therapies hold the key to reducing the burden of these tumors on patients and healthcare systems.

Immunotherapeutic Agents for Intratumoral Immunotherapy

Immunotherapy using systemic immune checkpoint inhibitors (ICI) and chimeric antigen receptor (CAR) T cells has revolutionized cancer treatment, but it only benefits a subset of patients. Systemic immunotherapies cause severe autoimmune toxicities and cytokine storms. Immune-related adverse events (irAEs) plus the immunosuppressive tumor microenvironment (TME) have been linked to the inefficacy of systemic immunotherapy. Intratumoral immunotherapy that increases immunotherapeutic agent bioavailability inside tumors could enhance the efficacy of immunotherapies and reduce systemic toxicities. In preclinical and clinical studies, intratumoral administration of immunostimulatory agents from small molecules to xenogeneic cells has demonstrated antitumor effects not only on the injected tumors but also against noninjected lesions. Herein, we review and discuss the results of these approaches in preclinical models and clinical trials to build the landscape of intratumoral immunotherapeutic agents and we describe how they stimulate the body's immune system to trigger antitumor immunity as well as the challenges in clinical practice. Systemic and intratumoral combination immunotherapy would make the best use of the body's immune system to treat cancers. Combining precision medicine and immunotherapy in cancer treatment would treat both the mutated targets in tumors and the weakened body's immune system simultaneously, exerting maximum effects of the medical intervention.

Anti-tumor activity of a recombinant measles virus against canine lung cancer cells

Canine primary lung cancer with metastasis has a poor prognosis with no effective treatment. We previously generated a recombinant measles virus (MV) that lost binding affinity to a principal receptor, SLAM, to eliminate its virulence as a new cancer treatment strategy. The virus, rMV-SLAMblind, targets nectin-4, recently listed as a tumor marker, and exerts antitumor activity against nectin-4-positive canine mammary cancer and urinary bladder transitional cell carcinoma cells. However, the effectivity of rMV-SLAMblind for other types of canine cancers is still unknown. Here we evaluated the antitumor effect of rMV-SLAMblind to canine lung cancer. Nectin-4 is expressed on three canine lung cancer cell lines (CLAC, AZACL1, AZACL2) and rMV-SLAMblind was able to infect these cell lines. CLAC cells showed reduced cell viability after virus infection. In the CLAC xenograft nude mouse model, intratumoral administration of rMV-SLAMblind significantly suppressed tumor growth. In rMV-SLAMblind-treated mice, natural killer cells were activated, and Cxcl10 and Il12a levels were significantly increased in comparison with levels in the control group. In addition, the depletion of NK cells reduced the anti-tumor effect. To understand difference in efficacy among canine lung cancer cell lines, we compared virus growth and gene expression pattern after virus treatment in the three canine lung cancer cell lines; virus growth was highest in CLAC cells compared with the other cell lines and the induction of interferon (IFN)-beta and IFN-stimulated genes was at lower levels in CLAC cells. These results suggested that rMV-SLAMblind exhibits oncolytic effect against some canine lung cancer cells and the cellular response after the virus infection may influence its efficacy.

Effectiveness and safety of pelareorep plus chemotherapy versus chemotherapy alone for advanced solid tumors: a meta-analysis

Background: Pelareorep is an oncolytic virus that causes oncolytic effects in many solid tumors, and it has shown therapeutic benefits. However, few studies have compared pelareorep combined with chemotherapy to traditional chemotherapy alone in advanced solid tumors. Consequently, we intended to evaluate the effectiveness and safety of pelareorep plus chemotherapy in this paper. Methods: We searched four databases including PubMed, Embase, Cochrane Library and Web of Science comprehensively for studies comparing pelareorep combined with chemotherapy to chemotherapy alone in the treatment of advanced solid tumors. The outcomes measures were 1-year overall survival (OS), 2-year OS, 4-month progression-free survival (PFS), 1-year PFS, objective response rate (ORR), any-grade adverse events (any-grade AEs), and severe AEs (grade ≥ 3). Results: There were five studies involving 492 patients included in the study. Combination therapy did not significantly improve clinical outcomes in terms of 1-year OS [RR = 1.02, 95%CI = (0.82-1.25)], 2-year OS [RR = 1.00, 95%CI = (0.67-1.49)], 4-month PFS [RR = 1.00, 95%CI = (0.67-1.49)], 1-year PFS [RR = 0.79, 95%CI = (0.44-1.42)], and ORR [OR = 0.79, 95%CI = (0.49-1.27)] compared to chemotherapy alone, and the subgroup analysis of 2-year OS, 1-year PFS, and ORR based on countries and tumor sites showed similar results. In all grades, the incidence of AEs was greater with combination therapy, including fever [RR = 3.10, 95%CI = (1.48-6.52)], nausea [RR = 1.19, 95%CI = (1.02-1.38)], diarrhea [RR = 1.87, 95%CI = (1.39-2.52)], chills [RR = 4.14, 95%CI = (2.30-7.43)], headache [RR = 1.46, 95%CI = (1.02-2.09)], vomiting [RR = 1.38, 95%CI = (1.06-1.80)] and flu-like symptoms [RR = 4.18, 95%CI = (2.19-7.98)]. However, severe adverse events did not differ significantly between the two arms. Conclusion: Pelareorep addition to traditional chemotherapy did not lead to significant improvements in OS, PFS, or ORR in advanced solid tumor patients, but it did partially increase AEs in all grades, with no discernible differences in serious AEs. Therefore, the combination treatment is not recommended in patients with advanced solid tumors. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=400841, identifier CRD42023400841.

Therapeutic potential of gene therapy for gastrointestinal diseases: Advancements and future perspectives

Advancements in understanding the pathogenesis mechanisms underlying gastrointestinal diseases, encompassing inflammatory bowel disease, gastrointestinal cancer, and gastroesophageal reflux disease, have led to the identification of numerous novel therapeutic targets. These discoveries have opened up exciting possibilities for developing gene therapy strategies to treat gastrointestinal diseases. These strategies include gene replacement, gene enhancement, gene overexpression, gene function blocking, and transgenic somatic cell transplantation. In this review, we introduce the important gene therapy targets and targeted delivery systems within the field of gastroenterology. Furthermore, we provide a comprehensive overview of recent progress in gene therapy related to gastrointestinal disorders and shed light on the application of innovative gene-editing technologies in treating these conditions. These developments are fueling a revolution in the management of gastrointestinal diseases. Ultimately, we discuss the current challenges (particularly regarding safety, oral efficacy, and cost) and explore potential future directions for implementing gene therapy in the clinical settings for gastrointestinal diseases.

Advances in Immunotherapeutics in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for up to 95% of all pancreatic cancer cases and is the seventh-leading cause of cancer death. Poor prognosis is a result of late presentation, a lack of screening tests and the fact some patients develop resistance to chemotherapy and radiotherapy. Novel therapies like immunotherapeutics have been of recent interest in pancreatic cancer. However, this field remains in its infancy with much to unravel. Immunotherapy and other targeted therapies have yet to yield significant progress in treating PDAC, primarily due to our limited understanding of the disease immune mechanisms and its intricate interactions with the tumour microenvironment (TME). In this review we provide an overview of current novel immunotherapies which have been studied in the field of pancreatic cancer. We discuss their mechanisms, evidence available in pancreatic cancer as well as the limitations of such therapies. We showcase the potential role of combining novel therapies in PDAC, postulate their potential clinical implications and the hurdles associated with their use in PDAC. Therapies discussed with include programmed death checkpoint inhibitors, Cytotoxic T-lymphocyte-associated protein 4, Chimeric Antigen Receptor-T cell therapy, oncolytic viral therapy and vaccine therapies including KRAS vaccines, Telomerase vaccines, Gastrin Vaccines, Survivin-targeting vaccines, Heat-shock protein (HSP) peptide complex-based vaccines, MUC-1 targeting vaccines, Listeria based vaccines and Dendritic cell-based vaccines.

The clinical terrain of immunotherapies in heterogeneous pancreatic cancer: unravelling challenges and opportunities

Pancreatic ductal adenocarcinoma (PDAC) is the most common and aggressive type of pancreatic cancer and has abysmal survival rates. In the past two decades, immunotherapeutic agents with success in other cancer types have gradually been trialled against PDACs at different stages of cancer progression, either as a monotherapy or in combination with chemotherapy. Unfortunately, to this day, chemotherapy still prolongs the survival rates the most and is prescribed in clinics despite the severe side effects in other cancer types. The low success rates of immunotherapy against PDAC have been attributed most frequently to its complex and multi-faceted tumour microenvironment (TME) and low mutational burden. In this review, we give a comprehensive overview of the immunotherapies tested in PDAC clinical trials thus far, their limitations, and potential explanations for their failure. We also discuss the existing classification of heterogenous PDACs into cancer, cancer-associated fibroblast, and immune subtypes and their potential opportunity in patient selection as a form of personalisation of PDAC immunotherapy. © 2023 The Pathological Society of Great Britain and Ireland.

Vaccinating against cancer: getting to prime time

Immunotherapies, such as immune checkpoint inhibitors, cellular therapies, and T-cell engagers, have fundamentally changed our approach to treating cancer. However, successes with cancer vaccines have been more difficult to realize. While vaccines against specific viruses have been widely adopted to prevent the development of cancer, only two vaccines can improve survival in advanced disease: sipuleucel-T and talimogene laherparepvec. These represent the two approaches that have the most traction: vaccinating against cognate antigen and priming responses using tumors in situ. Here, we review the challenges and opportunities researchers face in developing therapeutic vaccines for cancer.

Next-Generation Approaches to Immuno-Oncology in GI Cancers

Immunotherapy has only had a modest impact on the treatment of advanced GI malignancies. Microsatellite-stable colorectal cancer and pancreatic adenocarcinoma, the most common GI tumors, have not benefited from treatment with standard immune checkpoint inhibitors. With this huge unmet need, multiple approaches are being tried to overcome barriers to better anticancer outcomes. This article reviews a number of novel approaches to immunotherapy for these tumors. These include the use of novel checkpoint inhibitors such as a modified anti-cytotoxic T lymphocyte-associated antigen-4 antibody and antibodies to lymphocyte-activation gene 3, T cell immunoreceptor with immunoglobulin and ITIM domains, T-cell immunoglobulin-3, CD47, and combinations with signal transduction inhibitors. We will discuss other trials that aim to elicit an antitumor T-cell response using cancer vaccines and oncolytic viruses. Finally, we review attempts to replicate in GI cancers the frequent and durable responses seen in hematologic malignancies with immune cell therapies.

Oncolytic virotherapy: basic principles, recent advances and future directions

Oncolytic viruses (OVs) have attracted growing awareness in the twenty-first century, as they are generally considered to have direct oncolysis and cancer immune effects. With the progress in genetic engineering technology, OVs have been adopted as versatile platforms for developing novel antitumor strategies, used alone or in combination with other therapies. Recent studies have yielded eye-catching results that delineate the promising clinical outcomes that OVs would bring about in the future. In this review, we summarized the basic principles of OVs in terms of their classifications, as well as the recent advances in OV-modification strategies based on their characteristics, biofunctions, and cancer hallmarks. Candidate OVs are expected to be designed as "qualified soldiers" first by improving target fidelity and safety, and then equipped with "cold weapons" for a proper cytocidal effect, "hot weapons" capable of activating cancer immunotherapy, or "auxiliary weapons" by harnessing tactics such as anti-angiogenesis, reversed metabolic reprogramming and decomposing extracellular matrix around tumors. Combinations with other cancer therapeutic agents have also been elaborated to show encouraging antitumor effects. Robust results from clinical trials using OV as a treatment congruously suggested its significance in future application directions and challenges in developing OVs as novel weapons for tactical decisions in cancer treatment.

Exploiting RIG-I-like receptor pathway for cancer immunotherapy

RIG-I-like receptors (RLRs) are intracellular pattern recognition receptors that detect viral or bacterial infection and induce host innate immune responses. The RLRs family comprises retinoic acid-inducible gene 1 (RIG-I), melanoma differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2) that have distinctive features. These receptors not only recognize RNA intermediates from viruses and bacteria, but also interact with endogenous RNA such as the mislocalized mitochondrial RNA, the aberrantly reactivated repetitive or transposable elements in the human genome. Evasion of RLRs-mediated immune response may lead to sustained infection, defective host immunity and carcinogenesis. Therapeutic targeting RLRs may not only provoke anti-infection effects, but also induce anticancer immunity or sensitize "immune-cold" tumors to immune checkpoint blockade. In this review, we summarize the current knowledge of RLRs signaling and discuss the rationale for therapeutic targeting RLRs in cancer. We describe how RLRs can be activated by synthetic RNA, oncolytic viruses, viral mimicry and radio-chemotherapy, and how the RNA agonists of RLRs can be systemically delivered in vivo. The integration of RLRs agonism with RNA interference or CAR-T cells provides new dimensions that complement cancer immunotherapy. Moreover, we update the progress of recent clinical trials for cancer therapy involving RLRs activation and immune modulation. Further studies of the mechanisms underlying RLRs signaling will shed new light on the development of cancer therapeutics. Manipulation of RLRs signaling represents an opportunity for clinically relevant cancer therapy. Addressing the challenges in this field will help develop future generations of cancer immunotherapy.

Pre-treatment of oncolytic reovirus improves tumor accumulation and intratumoral distribution of PEG-liposomes

PEGylated liposomes (PEG-liposomes) are a promising drug delivery vehicle for tumor targeting because of their efficient tumor disposition profiles via the enhanced permeability and retention (EPR) effect. However, tumor targeting of PEG-liposomes, particularly their delivery inside the tumors, is often disturbed by physical barriers in the tumor, including tumor cells themselves, extracellular matrices, and interstitial pressures. In this study, B16 melanoma tumor-bearing mice were injected intravenously with oncolytic reovirus before administration of PEG-liposomes to enhance PEG-liposomes' tumor disposition. Three days after reovirus administration, significant expression of reovirus sigma 3 protein, elevation of apoptosis-related gene expression, and activation of caspase 3 in the tumors were found. Apoptotic cells were found inside the tumors. These data indicated that reovirus efficiently replicated in the tumors and induced apoptosis of tumor cells. The tumor disposition levels of PEG-liposomes were approximately doubled by reovirus pre-administration, compared with a PBS-pretreated group. PEG-liposomes were widely distributed in the tumors of reovirus-pretreated mice, whereas in the PBS-pretreated group, PEG-liposomes were found mainly around or inside the blood vessels in the tumors. Pre-treatment with reovirus also improved the tumor accumulation of PEG-liposomes in human pancreatic BxPC-3 tumors. 3D imaging analysis of whole BxPC-3 tumors demonstrated that pretreatment with reovirus led to the enhancement of PEG-liposome accumulation inside the tumors. Combination treatment with reovirus and paclitaxel-loaded PEG-liposomes (PTX-PEG-liposomes) significantly suppressed B16 tumor growth. These results provide important information for clinical use of combination therapy of reovirus and nanoparticle-based drug delivery system (DDS).

Tumour microenvironment and heterotypic interactions in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is a disease with a survival rate of 9%; this is due to its chemoresistance and the large tumour stroma that occupies most of the tumour mass. It is composed of a large number of cells of the immune system, such as Treg cells, tumour-associated macrophages (TAMs), myeloid suppressor cells (MDCs) and tumour-associated neutrophiles (TANs) that generate an immunosuppressive environment by the release of inflammatory cytokines. Moreover, cancer-associated fibroblast (CAFs) provide a protective coverage that would difficult the access of chemotherapy to the tumour. According to this, new therapies that could remodel this heterogeneous tumour microenvironment, such as adoptive T cell therapies (ACT), immune checkpoint inhibitors (ICI), and CD40 agonists, should be developed for targeting PDA. This review organizes the different cell populations found in the tumour stroma involved in tumour progression in addition to the different therapies that are being studied to counteract the tumour.

VG161 activates systemic antitumor immunity in pancreatic cancer models as a novel oncolytic herpesvirus expressing multiple immunomodulatory transgenes

The VG161 represents the first recombinant oncolytic herpes simplex virus type 1 carrying multiple synergistic antitumor immuno-modulating factors. Here, we report its antitumor mechanisms and thus provide firm theoretical foundation for the upcoming clinical application in pancreatic cancer. Generally, the VG161-mediated antitumor outcomes were analyzed by a collaboration of techniques, namely the single-cell sequencing, airflow-assisted desorption electrospray ionization-mass spectrometry imaging (AFADSI-MSI) and nanostring techniques. In vitro, the efficacy of VG161 together with immune checkpoint inhibitors (ICIs) has been successfully shown to grant a long-term antitumor effect by altering tumor immunity and remodeling tumor microenvironment (TME) metabolisms. Cellular functional pathways and cell subtypes detected from patient samples before and after the treatment had undergone distinctive changes including upregulated CD8+ T and natural killer cells. More importantly, significant antitumor signals have emerged since the administration of VG161 injection. In conclusion, VG161 can systematically activate acquired and innate immunity in pancreatic models, as well as improve the tumor immune microenvironment, indicative of strong antitumor potential. The more robusting antitumor outcome for VG161 monotherapy or in combination with other therapies on pancreatic cancer is worth of being explored in further clinical trials.

Clinical trial-identified inflammatory biomarkers in breast and pancreatic cancers

Breast cancer and pancreatic cancer are two common cancer types characterized by high prevalence and high mortality rates, respectively. However, breast cancer has been more well-studied than pancreatic cancer. This narrative review curated inflammation-associated biomarkers from clinical studies that were systematically selected for both breast and pancreatic cancers and discusses some of the common and unique elements between the two endocrine-regulated malignant diseases. Finding common ground between the two cancer types and specifically analyzing breast cancer study results, we hoped to explore potential feasible methods and biomarkers that may be useful also in diagnosing and treating pancreatic cancer. A PubMed MEDLINE search was used to identify articles that were published between 2015-2022 of different kinds of clinical trials that measured immune-modulatory biomarkers and biomarker changes of inflammation defined in diagnosis and treatment of breast cancer and pancreatic cancer patients. A total of 105 papers (pancreatic cancer 23, breast cancer 82) were input into Covidence for the title and abstract screening. The final number of articles included in this review was 73 (pancreatic cancer 19, breast cancer 54). The results showed some of the frequently cited inflammatory biomarkers for breast and pancreatic cancers included IL-6, IL-8, CCL2, CD8+ T cells and VEGF. Regarding unique markers, CA15-3 and TNF-alpha were two of several breast cancer-specific, and CA19 and IL-18 were pancreatic cancer-specific. Moreover, we discussed leptin and MMPs as emerging biomarker targets with potential use for managing pancreatic cancer based on breast cancer studies in the future, based on inflammatory mechanisms. Overall, the similarity in how both types of cancers respond to or result in further disruptive inflammatory signaling, and that point to a list of markers that have been shown useful in diagnosis and/or treatment method response or efficacy in managing breast cancer could potentially provide insights into developing the same or more useful diagnostic and treatment measurement inflammatory biomarkers for pancreatic cancer. More research is needed to investigate the relationship and associated inflammatory markers between the similar immune-associated biological mechanisms that contribute to breast and pancreatic cancer etiology, drive disease progression or that impact treatment response and reflect survival outcomes.

Perioperative oncolytic virotherapy to counteract surgery-induced immunosuppression and improve outcomes in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a high fatality cancer with one of the worst prognoses in solid tumors. Most patients present with late stage, metastatic disease and are not eligible for potentially curative surgery. Despite complete resection, the majority of surgical patients will recur within the first two years following surgery. Postoperative immunosuppression has been described in different digestive cancers. While the underlying mechanism is not fully understood, there is compelling evidence to link surgery with disease progression and cancer metastasis in the postoperative period. However, the idea of surgery-induced immunosuppression as a facilitator of recurrence and metastatic spread has not been explored in the context of pancreatic cancer. By surveying the existing literature on surgical stress in mostly digestive cancers, we propose a novel practice-changing paradigm: alleviate surgery-induced immunosuppression and improve oncological outcome in PDAC surgical patients by administering oncolytic virotherapy in the perioperative period.

Emerging Nano-/Biotechnology Drives Oncolytic Virus-Activated and Combined Cancer Immunotherapy

Oncolytic viruses (OVs) as one promising antitumor methods have made important contributions to tumor immunotherapy, which arouse increasing attention. They provide the dual mechanisms including direct killing effect toward tumor cells and immune activation for elevating antitumor responses, which have been proved in many preclinical studies. Especially, natural or genetically modified viruses as clinical immune preparations have emerged as a new promising approach objective to oncology treatment. The approval of talimogene laherparepvec (T-VEC) by the U.S. Food and Drug Administration (FDA) for the therapy of advanced melanoma could be considered as a milestone achievement in the clinical translation of OV. In this review, we first discussed the antitumor mechanisms of OVs with an emphasis on targeting, replication, and propagation. We further outlined the state of the art of current OVs in tumor and underlined the activated biological effects especially including immunity. More significantly, the enhanced immune responses based on OVs were systematically discussed from different perspectives such as combination with immunotherapy, genetic engineering of OVs, integration with nanobiotechnology or nanoparticles, and antiviral response counteraction, where their principles were shed light on. The development of OVs in the clinics was also highlighted to analyze the actuality and concerns of different OV applications in clinical trials. At last, the future perspectives and challenges of OVs as an already widely accepted treatment means were discussed. This review will provide a systematic review and deep insight into OV development and also offer new opportunities and guidance pathways to drive the further clinical translation.

Efficacy and safety of oncolytic virus combined with chemotherapy or immune checkpoint inhibitors in solid tumor patients: A meta-analysis

Background: In recent years, several clinical trials have focused on oncolytic virus (OVs) combined with chemotherapy or immune checkpoint inhibitors (ICIs) in solid tumor patients, which showed encouraging effects. However, few studies have concentrated on the summary on the safety and efficacy of the combined treatments. Therefore, we conducted this meta-analysis to explore the safety and curative effect of the combined therapy. Methods: We searched the PubMed, Cochrane Library, Embase, and Clinicaltrials.gov databases to comprehensively select articles on OVs combined with chemotherapy or ICIs for the solid tumor treatment. Overall survival (OS), progression-free survival (PFS), 1-year survival rate, 2-year survival rate, objective response rate (ORR), and adverse events (AEs) were the outcomes. Results: Fifteen studies with 903 patients were included in this meta-analysis. The pooled ORR was 32% [95% confidence interval (CI): 27-36%, I2 = 24.9%, p = 0.239]. Median OS and median PFS were 6.79 months (CI: 4.29-9.30, I2 = 62.9%, p = 0.044) and 3.40 months (CI: 2.59-4.22, I2 = 0.0%, p = 0.715), respectively. The 1-year survival rate was 38% (CI: 0.29-0.47, I2 = 62.9%, p = 0.044), and the 2-year survival rate was 24% (CI: 12-37%, I2 = 0.0%, p = 0.805). The most common AEs were fever (63%, CI: 57-69%, I2 = 2.3%, p = 0.402), fatigue (58%, CI: 51-65%, I2 = 49.2%, p = 0.096), chill (52%, CI: 43-60%, I2 = 0.0%, p = 0.958), and neutropenia (53%, CI: 47-60%, I2 = 0.0%, p = 0.944). Conclusion: OVs combined with ICIs showed a better efficacy than OVs combined with chemotherapy, which lends support to further clinical trials of OVs combined with ICIs. In addition, OVs combined with pembrolizumab can exert increased safety and efficacy. The toxicity of grades ≥3 should be carefully monitored and observed. However, high-quality, large-scale clinical trials should be completed to further confirm the efficacy and safety of OVs combined with ICIs. Systematic Review Registration: [https://www.crd.york.ac.uk/PROSPERO/login.php], identifier [RD42022348568].

Modern approaches to treating cancer with oncolytic viruses

According to the World Health Organization, cancer is the second leading cause of death in the world. This serves as a powerful incentive to search for new effective cancer treatments. Development of new oncolytic viruses capable of selectively destroying cancer cells is one of the modern approaches to cancer treatment. The advantage of this method – the selective lysis of tumor cells with the help of viruses – leads to an increase in the antitumor immune response of the body, that in turn promotes the destruction of the primary tumor and its metastases. Significant progress in development of this method has been achieved in the last decade. In this review we analyze the literature data on families of oncolytic viruses that have demonstrated a positive therapeutic effect against malignant neoplasms in various localizations. We discuss the main mechanisms of the oncolytic action of viruses and assess their advantages over other methods of cancer therapy as well as the prospects for their use in clinical practice.

The Role of Immunotherapy in Pancreatic Cancer

Pancreatic adenocarcinoma remains one of the most lethal cancers globally, with a significant need for improved therapeutic options. While the recent breakthroughs of immunotherapy through checkpoint inhibitors have dramatically changed treatment paradigms in other malignancies based on considerable survival benefits, this is not so for pancreatic cancer. Chemotherapies with modest benefits are still the cornerstone of advanced pancreatic cancer treatment. Pancreatic cancers are inherently immune-cold tumors and have been largely refractory to immunotherapies in clinical trials. Understanding and overcoming the current failures of immunotherapy through elucidating resistance mechanisms and developing novel therapeutic approaches are essential to harnessing the potential durable benefits of immune-modulating therapy in pancreatic cancer patients.

Current clinical landscape of oncolytic viruses as novel cancer immunotherapeutic and recent preclinical advancements

Oncolytic viruses (OVs) have been gaining attention in the pharmaceutical industry as a novel immunotherapeutic and therapeutic adjuvant due to their ability to induce and boost antitumor immunity through multiple mechanisms. First, intrinsic mechanisms of OVs that enable exploitation of the host immune system (e.g., evading immune detection) can nullify the immune escape mechanism of tumors. Second, many types of OVs have been shown to cause direct lysis of tumor cells, resulting in an induction of tumor-specific T cell response mediated by release of tumor-associated antigens and danger signal molecules. Third, armed OV-expressing immune stimulatory therapeutic genes could be highly expressed in tumor tissues to further improve antitumor immunity. Last, these OVs can inflame cold tumors and their microenvironment to be more immunologically favorable for other immunotherapeutics. Due to these unique characteristics, OVs have been tested as an adjuvant of choice in a variety of therapeutics. In light of these promising attributes of OVs in the immune-oncology field, the present review will examine OVs in clinical development and discuss various strategies that are being explored in preclinical stages for the next generation of OVs that are optimized for immunotherapy applications.

GOBLET: a phase I/II study of pelareorep and atezolizumab +/- chemo in advanced or metastatic gastrointestinal cancers

Most gastrointestinal (GI) cancers have microsatellite-stable (MSS) tumors, which have an immunologically 'cold' phenotype with fewer genetic mutations, reduced immune cell infiltration and downregulated immune checkpoint proteins. These attributes make MSS tumors resistant to conventional immunotherapy including checkpoint blockade therapy. Pelareorep is a naturally occurring, nongenetically modified reovirus. Upon intravenous administration, pelareorep selectively kills tumor cells and promotes several immunologic changes that prime tumors to respond to checkpoint blockade therapy. Given its demonstrated synergy with checkpoint blockade, as well as its encouraging efficacy in prior GI cancer studies, pelareorep plus atezolizumab will be evaluated in the GOBLET study in multiple GI cancer indications.

An Extensive Review on Preclinical and Clinical Trials of Oncolytic Viruses Therapy for Pancreatic Cancer

Chemotherapy resistance and peculiar tumor microenvironment, which diminish or mitigate the effects of therapies, make pancreatic cancer one of the deadliest malignancies to manage and treat. Advanced immunotherapies are under consideration intending to ameliorate the overall patient survival rate in pancreatic cancer. Oncolytic viruses therapy is a new type of immunotherapy in which a virus after infecting and lysis the cancer cell induces/activates patients’ immune response by releasing tumor antigen in the blood. The current review covers the pathways and molecular ablation that take place in pancreatic cancer cells. It also unfolds the extensive preclinical and clinical trial studies of oncolytic viruses performed and/or undergoing to design an efficacious therapy against pancreatic cancer.

Engaging Pattern Recognition Receptors in Solid Tumors to Generate Systemic Antitumor Immunity

Malignant tumors frequently exploit innate immunity to evade immune surveillance. The priming, function, and polarization of antitumor immunity fundamentally depends upon context provided by the innate immune system, particularly antigen presenting cells. Such context is determined in large part by sensing of pathogen specific and damage associated features by pathogen recognition receptors (PRRs). PRR activation induces the delivery of T cell priming cues (e.g. chemokines, co-stimulatory ligands, and cytokines) from antigen presenting cells, playing a decisive role in the cancer immunity cycle. Indeed, endogenous PRR activation within the tumor microenvironment (TME) has been shown to generate spontaneous antitumor T cell immunity, e.g., cGAS-STING mediated activation of antigen presenting cells after release of DNA from dying tumor cells. Thus, instigating intratumor PRR activation, particularly with the goal of generating Th1-promoting inflammation that stokes endogenous priming of antitumor CD8⁺ T cells, is a growing area of clinical investigation. This approach is analogous to in situ vaccination, ultimately providing a personalized antitumor response against relevant tumor associated antigens. Here I discuss clinical stage intratumor modalities that function via activation of PRRs. These approaches are being tested in various solid tumor contexts including melanoma, colorectal cancer, glioblastoma, head and neck squamous cell carcinoma, bladder cancer, and pancreatic cancer. Their mechanism (s) of action relative to other immunotherapy approaches (e.g., antigen-defined cancer vaccines, CAR T cells, dendritic cell vaccines, and immune checkpoint blockade), as well as their potential to complement these approaches are also discussed. Examples to be reviewed include TLR agonists, STING agonists, RIG-I agonists, and attenuated or engineered viruses and bacterium. I also review common key requirements for effective in situ immune activation, discuss differences between various strategies inclusive of mechanisms that may ultimately limit or preclude antitumor efficacy, and provide a summary of relevant clinical data.

Biological causes of immunogenic cancer cell death (ICD) and anti-tumor therapy; Combination of Oncolytic virus-based immunotherapy and CAR T-cell therapy for ICD induction

Chimeric antigen receptor (CAR) T-cell therapy is a promising and rapidly expanding therapeutic option for a wide range of human malignancies. Despite the ongoing progress of CAR T-cell therapy in hematologic malignancies, the application of this therapeutic strategy in solid tumors has encountered several challenges due to antigen heterogeneity, suboptimal CAR T-cell trafficking, and the immunosuppressive features of the tumor microenvironment (TME). Oncolytic virotherapy is a novel cancer therapy that employs competent or genetically modified oncolytic viruses (OVs) to preferentially proliferate in tumor cells. OVs in combination with CAR T-cells are promising candidates for overcoming the current drawbacks of CAR T-cell application in tumors through triggering immunogenic cell death (ICD) in cancer cells. ICD is a type of cellular death in which danger-associated molecular patterns (DAMPs) and tumor-specific antigens are released, leading to the stimulation of potent anti-cancer immunity. In the present review, we discuss the biological causes of ICD, different types of ICD, and the synergistic combination of OVs and CAR T-cells to reach potent tumor-specific immunity.

Nanobugs as Drugs: Bacterial Derived Nanomagnets Enhance Tumor Targeting and Oncolytic Activity of HSV-1 Virus

The survival strategies of infectious organisms have inspired many therapeutics over the years. Indeed the advent of oncolytic viruses (OVs) exploits the uncontrolled replication of cancer cells for production of their progeny resulting in a cancer-targeting treatment that leaves healthy cells unharmed. Their success against inaccessible tumors however, is highly variable due to inadequate tumor targeting following systemic administration. Coassembling herpes simplex virus (HSV1716) with biocompatible magnetic nanoparticles derived from magnetotactic bacteria enables tumor targeting from circulation with magnetic guidance, protects the virus against neutralizing antibodies and thereby enhances viral replication within tumors. This approach additionally enhances the intratumoral recruitment of activated immune cells, promotes antitumor immunity and immune cell death, thereby inducing tumor shrinkage and increasing survival in a syngeneic mouse model of breast cancer by 50%. Exploiting the properties of such a nanocarrier, rather than tropism of the virus, for active tumor targeting offers an exciting, novel approach for enhancing the bioavailability and treatment efficacy of tumor immunotherapies for disseminated neoplasms.

Priming stroma with a vitamin D analog to optimize viroimmunotherapy for pancreatic cancer

Pancreatic cancer resistance to immunotherapies is partly due to deficits in tumor-infiltrating immune cells and stromal density. Combination therapies that modify stroma and recruit immune cells are needed. Vitamin D analogs such as calcipotriol (Cal) decrease fibrosis in pancreas stroma, thus allowing increased chemotherapy delivery. OVs infect, replicate in, and kill cancer cells and recruit immune cells to immunodeficient microenvironments. We investigated whether stromal modification with Cal would enhance oncolytic viroimmunotherapy using recombinant orthopoxvirus, CF33. We assessed effect of Cal on CF33 replication using pancreas ductal adenocarcinoma (PDAC) cell lines and in vivo flank orthotopic models. Proliferation assays showed that Cal did not alter viral replication. Less replication was seen in cell lines whose division was slowed by Cal, but this appeared proportional to cell proliferation. Three-dimensional in vitro models demonstrated decreased myofibroblast integrity after Cal treatment. Cal increased vascular lumen size and immune cell infiltration in subcutaneous models of PDAC and increased viral delivery and replication. Cal plus serial OV dosing in the syngeneic Pan02 model caused more significant tumor abrogation than other treatments. Cal-treated tumors had less dense fibrosis, enhanced immune cell infiltration, and decreased T cell exhaustion. Calcipotriol is a possible adjunct for CF33-based oncolytic viroimmunotherapy against PDAC.

Altered Plasma Fatty Acid Abundance Is Associated with Cachexia in Treatment-Naïve Pancreatic Cancer

Cachexia occurs in up to 80% of pancreatic ductal adenocarcinoma (PDAC) patients and is characterized by unintentional weight loss and tissue wasting. To understand the metabolic changes that occur in PDAC-associated cachexia, we compared the abundance of plasma fatty acids (FAs), measured by gas chromatography, of subjects with treatment-naïve metastatic PDAC with or without cachexia, defined as a loss of > 2% weight and evidence of sarcopenia (n = 43). The abundance of saturated, monounsaturated, and polyunsaturated FAs was not different between subjects with cachexia and those without. Oleic acid was significantly higher in subjects with cachexia (p = 0.0007) and diabetes (p = 0.015). Lauric (r = 0.592, p = 0.0096) and eicosapentaenoic (r = 0.564, p = 0.015) acids were positively correlated with age in cachexia patients. Subjects with diabetes (p = 0.021) or both diabetes and cachexia (p = 0.092) had low palmitic:oleic acid ratios. Linoleic acid was lower in subjects with diabetes (p = 0.018) and correlated with hemoglobin (r = 0.519, p = 0.033) and albumin (r = 0.577, p = 0.015) in subjects with cachexia. Oleic or linoleic acid may be useful treatment targets or biomarkers of cachexia in patients with metastatic PDAC, particularly those with diabetes.

Uncovering key targets of success for immunotherapy in pancreatic cancer

INTRODUCTION

Despite available treatment options, pancreatic ductal adenocarcinoma (PDAC) is frequently lethal. Recent immunotherapy strategies have failed to yield any notable impact. Therefore, research is focussed on unearthing new drug targets and therapeutic strategies to tackle this malignancy and attain more positive outcomes for patients.

AREAS COVERED

In this perspective article, we evaluate the main resistance mechanisms to immune checkpoint inhibitors (ICIs) and the approaches to circumvent them. We also offer an assessment of concluded and ongoing trials of PDAC immunotherapy. Literature research was performed on Pubmed accessible through keywords such as: 'pancreatic ductal adenocarcinoma,' 'immunotherapy,' 'immunotherapy resistance,' 'immune escape,' 'biomarkers.' Papers published between 2000 and 2021 were selected.

EXPERT OPINION

The tumor microenvironment is a critical variable of treatment resistance because of its role as a physical barrier and inhibitory immune signaling. Promising therapeutic strategies appear to be a combination of immunotherapeutics with other targeted treatments. Going forward, predictive biomarkers are required to improve patient selection. Biomarker-driven trials could enhance approaches for assessing the role of immunotherapy in PDAC.

Oncolytic reovirus-mediated killing of mouse cancer-associated fibroblasts

Oncolytic viruses, which mediate tumor cell-specific infection, resulting in efficient tumor cell killing, have attracted much attention as a novel class of anti-cancer biopharmaceutical agents. Cancer-associated fibroblasts (CAFs) are an important component of the tumor microenvironment that strongly supports the growth, survival, and metastasis of tumor cells, suggesting that CAFs would have influence to the antitumor effects of oncolytic viruses; however, it remains to be fully evaluated whether oncolytic viruses affect the viabilities and properties of CAFs following treatment. Oncolytic reovirus, which is a non-enveloped virus that contains 10-segmented double-stranded RNA genome, shows efficient tumor cell lysis without apparent cytotoxicity to normal cells and has been tested worldwide in clinical trials against various types of tumors. In this study, we demonstrated that reovirus exhibited cytotoxicity against mouse primary CAFs isolated from subcutaneous tumors, but not against tail-tip fibroblasts. Infection with reovirus resulted in activation of caspase 3 and up-regulation of apoptosis-related gene expression, indicating that reovirus induced apoptosis of mouse primary CAFs. Intratumoral administration of reovirus induced apoptosis of mouse CAFs in the tumor. Taken together, these results indicate that reovirus has the potential to mediate antitumor effects by killing not only cancer cells but also CAFs.

Mutations in key driver genes of pancreatic cancer: molecularly targeted therapies and other clinical implications

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, with a minimal difference between its incidence rate and mortality rate. Advances in oncology over the past several decades have dramatically improved the overall survival of patients with multiple cancers due to the implementation of new techniques in early diagnosis, therapeutic drugs, and personalized therapy. However, pancreatic cancers remain recalcitrant, with a 5-year relative survival rate of <9%. The lack of measures for early diagnosis, strong resistance to chemotherapy, ineffective adjuvant chemotherapy and the unavailability of molecularly targeted therapy are responsible for the high mortality rate of this notorious disease. Genetically, PDAC progresses as a complex result of the activation of oncogenes and inactivation of tumor suppressors. Although next-generation sequencing has identified numerous new genetic alterations, their clinical implications remain unknown. Classically, oncogenic mutations in genes such as KRAS and loss-of-function mutations in tumor suppressors, such as TP53, CDNK2A, DPC4/SMAD4, and BRCA2, are frequently observed in PDAC. Currently, research on these key driver genes is still the main focus. Therefore, studies assessing the functions of these genes and their potential clinical implications are of paramount importance. In this review, we summarize the biological function of key driver genes and pharmaceutical targets in PDAC. In addition, we conclude the results of molecularly targeted therapies in clinical trials and discuss how to utilize these genetic alterations in further clinical practice.

Pharmacology-based ranking of anti-cancer drugs to guide clinical development of cancer immunotherapy combinations

The success of antibodies targeting Programmed cell death protein 1 (PD-1) and its ligand L1 (PD-L1) in cancer treatment and the need for improving response rates has led to an increased demand for the development of combination therapies with anti-PD-1/PD-L1 blockers as a backbone. As more and more drugs with translational potential are identified, the number of clinical trials evaluating combinations has increased considerably and the demand to prioritize combinations having potential for success over the ones that are unlikely to be successful is rising. This review aims to address the unmet need to prioritize cancer immunotherapy combinations through comprehensive search of potential drugs and ranking them based on their mechanism of action, clinical efficacy and safety. As lung cancer is one of the most frequently studied cancer types, combinations that showed potential for the treatment of lung cancer were prioritized. A literature search was performed to identify drugs with potential in combination with PD-1/PD-L1 blockers and the drugs were ranked based on their mechanism of action and known clinical efficacy. Nineteen drugs or drug classes were identified from an internal list of lead molecules and were scored for their clinical potential. Efficacy and safety data from pivotal studies was summarized for the selected drugs. Further, overlap of mechanisms of action and adverse events was visualized using a heat map illustration to help screen drugs for combinations. The quantitative scoring methodology provided in this review could serve as a template for preliminary ranking of novel combinations.

Pancreatic cancer in 2021: What you need to know to win

Pancreatic cancer is one of the solid tumors with the worst prognosis. Five-year survival rate is less than 10%. Surgical resection is the only potentially curative treatment, but the tumor is often diagnosed at an advanced stage of the disease and surgery could be performed in a very limited number of patients. Moreover, surgery is still associated with high post-operative morbidity, while other therapies still offer very disappointing results. This article reviews every aspect of pancreatic cancer, focusing on the elements that can improve prognosis. It was written with the aim of describing everything you need to know in 2021 in order to face this difficult challenge.

Pancreatic Cancer and Immunotherapy: A Clinical Overview

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with high mortality. The vast majority of patients present with unresectable, advanced stage disease, for whom standard of care chemo(radio)therapy may improve survival by several months. Immunotherapy has led to a fundamental shift in the treatment of several advanced cancers. However, its efficacy in PDAC in terms of clinical benefit is limited, possibly owing to the immunosuppressive, inaccessible tumor microenvironment. Still, various immunotherapies have demonstrated the capacity to initiate local and systemic immune responses, suggesting an immune potentiating effect. In this review, we address PDAC's immunosuppressive tumor microenvironment and immune evasion methods and discuss a wide range of immunotherapies, including immunomodulators (i.e., immune checkpoint inhibitors, immune stimulatory agonists, cytokines and adjuvants), oncolytic viruses, adoptive cell therapies (i.e., T cells and natural killer cells) and cancer vaccines. We provide a general introduction to their working mechanism as well as evidence of their clinical efficacy and immune potentiating abilities in PDAC. The key to successful implementation of immunotherapy in this disease may rely on exploitation of synergistic effects between treatment combinations. Accordingly, future treatment approaches should aim to incorporate diverse and novel immunotherapeutic strategies coupled with cytotoxic drugs and/or local ablative treatment, targeting a wide array of tumor-induced immune escape mechanisms.

Efficacy and safety of oncolytic viruses in advanced or metastatic cancer: a network meta-analysis

BACKGROUND

Oncolytic viruses (OVs) have shown prospects in advanced and metastatic cancer, and many clinical trials have been carried out. To compare OV therapies comprehensively and provide a categorized profile and ranking of efficacy and safety, a network meta-analysis was conducted.

METHODS

A total of 5948 studies were screened and 13 randomized controlled trials with 1939 patients, of whom 1106 patients received OV therapies, comparing four OVs (NTX-010, pexastimogene devacirepvec (Pexa-Vec), talimogene laherparepvec (T-VEC), and pelareorep) were included in a Bayesian network meta-analysis. Eligible studies reported at least one of the following clinical outcome measures: objective response rate (ORR) and grade ≥ 3 adverse events.

RESULTS

Compared to systemic treatments alone, talimogene laherparepvec (T-VEC) (OR 7.00, 95% CI 1.90-26.00) and T-VEC plus systemic treatment (2.90, 0.80-11.00) showed better objective response rates (ORRs), whereas Pexa-Vec 1 * 109 pfu plus systemic treatment (0.91, 0.26-3.00) and pelareorep plus systemic treatment (1.10, 0.61-2.00) were found to be comparable. The grade ≥ 3 adverse event ranking of the treatments from worst to best was as follows: T-VEC (ranking probability 24%), Pexa-Vec 1 * 109 pfu plus systemic treatment (21%), Pexa-Vec 1 * 109 pfu (17%), T-VEC plus systemic treatment (13%), pelareorep plus systemic treatment (13%), systemic treatments (18%), Pexa-Vec 1 * 108 pfu (12%), and NTX-010 (20%).

CONCLUSIONS

Compared with other oncolytic virus therapies for patients with advanced or metastatic cancer, T-VEC and T-VEC plus systemic treatment appear to provide the best ORR therapy in terms of monotherapy and combination respectively, but should be given with caution to grade ≥ 3 adverse events. Conversely, combining OVs with chemotherapy or target agents was demonstrated not to improve efficacy compared with chemotherapy or target agents alone. Combining OV therapies with immune-checkpoint inhibitors, instead of chemotherapy or target agents, tended to provide better ORRs without causing severe adverse events. This study will guide treatment choice and optimize future trial designs for investigations of advanced or metastatic cancer.

Drugging the Undruggable: Advances on RAS Targeting in Cancer

Around 20% of all malignancies harbour activating mutations in RAS isoforms. Despite this, there is a deficiency of RAS-targeting agents licensed for therapeutic use. The picomolar affinity of RAS for GTP, and the lack of suitable pockets for high-affinity small-molecule binding, precluded effective therapies despite decades of research. Recently, characterisation of the biochemical properties of KRAS-G12C along with discovery of its 'switch-II pocket' have allowed development of effective mutant-specific inhibitors. Currently seven KRAS-G12C inhibitors are in clinical trials and sotorasib has become the first one to be granted FDA approval. Here, we discuss historical efforts to target RAS directly and approaches to target RAS effector signalling, including combinations that overcome limitations of single-agent targeting. We also review pre-clinical and clinical evidence for the efficacy of KRAS-G12C inhibitor monotherapy followed by an illustration of combination therapies designed to overcome primary resistance and extend durability of response. Finally, we briefly discuss novel approaches to targeting non-G12C mutant isoforms.

Oncolytic adeno-immunotherapy modulates the immune system enabling CAR T-cells to cure pancreatic tumors

High expression levels of human epidermal growth factor receptor 2 (HER2) have been associated with poor prognosis in patients with pancreatic adenocarcinoma (PDAC). However, HER2-targeting immunotherapies have been unsuccessful to date. Here we increase the breadth, potency, and duration of anti-PDAC HER2-specific CAR T-cell (HER2.CART) activity with an oncolytic adeno-immunotherapy that produces cytokine, immune checkpoint blockade, and a safety switch (CAdTrio). Combination treatment with CAdTrio and HER2.CARTs cured tumors in two PDAC xenograft models and produced durable tumor responses in humanized mice. Modifications to the tumor immune microenvironment contributed to the antitumor activity of our combination immunotherapy, as intratumoral CAdTrio treatment induced chemotaxis to enable HER2.CART migration to the tumor site. Using an advanced PDAC model in humanized mice, we found that local CAdTrio treatment of primary tumor stimulated systemic host immune responses that repolarized distant tumor microenvironments, improving HER2.CART anti-tumor activity. Overall, our data demonstrate that CAdTrio and HER2.CARTs provide complementary activities to eradicate metastatic PDAC and may represent a promising co-operative therapy for PDAC patients.

Immunotherapy for pancreatic cancer: chasing the light at the end of the tunnel

BACKGROUND

Checkpoint blockade immunotherapy has had a significant impact on the survival of a subset of patients with advanced cancers. It has been particularly effective in immunogenic cancer types that present large numbers of somatic mutations in their genomes. To date, all conventional immunotherapies have failed to produce significant clinical benefits for patients diagnosed with pancreatic cancer, probably due to its poor immunogenic properties, including low numbers of neoantigens and highly immune-suppressive microenvironments.

CONCLUSIONS

Herein, we discuss advances that have recently been made in cancer immunotherapy and the potential of this field to deliver effective treatment options for pancreatic cancer patients. Preclinical investigations, combining different types of therapies, highlight possibilities to enhance anti-tumor immunity and to generate meaningful clinical responses in pancreatic cancer patients. Results from completed and ongoing (pre)clinical trials are discussed.

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.

Envisioning the immune system to determine its role in pancreatic ductal adenocarcinoma: Culprit or victim?

Pancreatic ductal adenocarcinoma has a poor 5-year survival rate that makes it one of the most fatal human malignancies. Unfortunately, despite the serious improvement in the survival of most cancers, there has been a minor advance in pancreatic cancer (PC). Major advances in PC treatment have been assessed over the bygone twenty-year time span, yet some complications make the survival of the patients shorter. Getting to know the PC tumor microenvironment (TME) and the immunosuppression that happens during the pathogenesis of this malignancy could be a great help to understand the nature of the immune system and find better treatment modalities based on it. Although many immune cells are present in PC, immunosuppression of the TME leads to severe immune dysfunction in the patients, therefore immune effectors fail to do their functions. Lately, immunotherapy has been presented as one of the promising treatment strategies for different malignancies including hepatocellular carcinoma, melanoma, non-small cell lung cancer, and kidney cancer. In PC, there has been shown promising results centered around the TME, immune checkpoint inhibitors, cancer vaccines, and other approaches especially when used as combinational therapy. Here we dig a little deeper into the role of the immune system and possible therapeutic options in the treatment of PC.

Oncolytic Virotherapy in Solid Tumors: The Challenges and Achievements

Oncolytic virotherapy (OVT) is a promising approach in cancer immunotherapy. Oncolytic viruses (OVs) could be applied in cancer immunotherapy without in-depth knowledge of tumor antigens. The capability of genetic modification makes OVs exciting therapeutic tools with a high potential for manipulation. Improving efficacy, employing immunostimulatory elements, changing the immunosuppressive tumor microenvironment (TME) to inflammatory TME, optimizing their delivery system, and increasing the safety are the main areas of OVs manipulations. Recently, the reciprocal interaction of OVs and TME has become a hot topic for investigators to enhance the efficacy of OVT with less off-target adverse events. Current investigations suggest that the main application of OVT is to provoke the antitumor immune response in the TME, which synergize the effects of other immunotherapies such as immune-checkpoint blockers and adoptive cell therapy. In this review, we focused on the effects of OVs on the TME and antitumor immune responses. Furthermore, OVT challenges, including its moderate efficiency, safety concerns, and delivery strategies, along with recent achievements to overcome challenges, are thoroughly discussed.

Dilemma and Challenge of Immunotherapy for Pancreatic Cancer

Pancreatic cancer is a tumor with a high degree of malignancy, morbidity, and mortality. Immunotherapy is another important treatment for pancreatic cancer in addition to surgery and chemotherapy, but its application in pancreatic cancer is very limited, which is related to the unique biological behavior of pancreatic cancer and the tumor microenvironment. The immunosuppressive microenvironment of pancreatic cancer is highly heterogeneous and presents challenges for immunotherapy. The transformation of tumor immunosuppressive microenvironment contributes to the response to tumor immunotherapy, such that the tumor undergoes functional reprogramming to change from immunologically "cold" to immunologically "hot." In this review, we summarized the research and progress in immunotherapy for pancreatic cancer, including immune checkpoint inhibitors, vaccines, adoptive T cell therapy, oncolytic viruses, and immunomodulators, and suggest that individualized, combination, and precise therapy should be the main direction of future immunotherapy in pancreatic cancer.

The Present Status of Immuno-Oncolytic Viruses in the Treatment of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is the fifth leading cause of cancer-related death in Western countries. The incidence of PDAC has increased over the last 40 years and is projected to be the second leading cause of cancer death by 2030. Despite aggressive treatment regimens, prognosis for patients diagnosed with PDAC is very poor; PDAC has the lowest 5-year survival rate for any form of cancer in the United States (US). PDAC is very rarely detected in early stages when surgical resection can be performed. Only 20% of cases are suitable for surgical resection; this remains the only curative treatment when combined with adjuvant chemotherapy. Treatment regimens excluding surgical intervention such as chemotherapeutic treatments are associated with adverse effects and genetherapy strategies also struggle with lack of specificity and/or efficacy. The lack of effective treatments for this disease highlights the necessity for innovation in treatment options for patients diagnosed with early- to late-phase PDAC and immuno-oncolytic viruses (OVs) have been of particular interest since 2006 when the first oncolytic virus was approved as a therapy for nasopharyngeal cancers in China. Interest resurged in 2015 when T-Vec, an oncolytic herpes simplex virus, was approved in the United States for treatment of advanced melanoma. While many vectors have been explored, few show promise as treatment for pancreatic cancer, and fewer still have progressed to clinical trial evaluation. This review outlines recent strategies in the development of OVs targeting treatment of PDAC, current state of preclinical and clinical investigation and application.