Advancements in adenoviral based virotherapy for ovarian cancer

Developmental Landscape of Potential Vaccine Candidates Based on Viral Vector for Prophylaxis of COVID-19

Severe acute respiratory syndrome coronavirus 2, SARS-CoV-2, arose at the end of 2019 as a zoonotic virus, which is the causative agent of the novel coronavirus outbreak COVID-19. Without any clear indications of abatement, the disease has become a major healthcare threat across the globe, owing to prolonged incubation period, high prevalence, and absence of existing drugs or vaccines. Development of COVID-19 vaccine is being considered as the most efficient strategy to curtail the ongoing pandemic. Following publication of genetic sequence of SARS-CoV-2, globally extensive research and development work has been in progress to develop a vaccine against the disease. The use of genetic engineering, recombinant technologies, and other computational tools has led to the expansion of several promising vaccine candidates. The range of technology platforms being evaluated, including virus-like particles, peptides, nucleic acid (DNA and RNA), recombinant proteins, inactivated virus, live attenuated viruses, and viral vectors (replicating and non-replicating) approaches, are striking features of the vaccine development strategies. Viral vectors, the next-generation vaccine platforms, provide a convenient method for delivering vaccine antigens into the host cell to induce antigenic proteins which can be tailored to arouse an assortment of immune responses, as evident from the success of smallpox vaccine and Ervebo vaccine against Ebola virus. As per the World Health Organization, till January 22, 2021, 14 viral vector vaccine candidates are under clinical development including 10 nonreplicating and four replicating types. Moreover, another 39 candidates based on viral vector platform are under preclinical evaluation. This review will outline the current developmental landscape and discuss issues that remain critical to the success or failure of viral vector vaccine candidates against COVID-19.

Role of heat-shock proteins in infection of human adenocarcinoma cell line MCF-7 by tumor-adapted rotavirus isolates

Background:

Viruses are being used as alternative and complementary tools for treating cancers. Oncolytic viruses exhibit tumor tropism, ability to enhance anti-tumor immunity and ability to be used in combination with conventional chemotherapy and radiotherapy. We have recently selected some rotavirus isolates which are adapted to efficiently infect and kill tumor cell lines.

Aim:

We tested five tumor cell-adapted rotavirus isolates for their ability to infect the human adenocarcinoma cell line MCF-7.

Methods:

Cell surface membrane-associated proteins mediating virus particle attachment were characterized using ELISA, immunoprecipitation, FACS analysis, and antibody blocking.

Results:

It was found that heat shock proteins (HSPs) such as Hsp90, Hsp70, Hsp60, and Hsp40 are expressed on the cell surface forming complexes with protein disulfide isomerase (PDI), integrin β3, and heat shock cognate protein 70 (Hsc70) in lipid raft microdomains. Interaction of rotavirus isolates with these cellular proteins was further confirmed by a competition assay and an inhibition assay involving the HSPs tested.

Conclusion:

Our findings suggest that the tumor cell-adapted rotavirus isolates studied here offer a promising tool for killing tumor cells, thus encouraging further research into this topic, including animal models.

Guerrero C, Acosta O. Role of heat-shock proteins in infection of human adenocarcinoma cell line MCF-7 by tumor-adapted rotavirus isolates

Background: Viruses are being used as alternative and complementary tools for treating cancers. Oncolytic viruses exhibit tumor tropism, ability to enhance anti-tumor immunity and ability to be used in combination with conventional chemotherapy and radiotherapy. We have recently selected some rotavirus isolates which are adapted to efficiently infect and kill tumor cell lines. Aim: We tested five tumor cell-adapted rotavirus isolates for their ability to infect the human adenocarcinoma cell line MCF-7. Methods: Cell surface membrane-associated proteins mediating virus particle attachment were characterized using ELISA, immunoprecipitation, FACS analysis, and antibody blocking. Results: It was found that heat shock proteins (HSPs) such as Hsp90, Hsp70, Hsp60, and Hsp40 are expressed on the cell surface forming complexes with protein disulfide isomerase (PDI), integrin β3, and heat shock cognate protein 70 (Hsc70) in lipid raft microdomains. Interaction of rotavirus isolates with these cellular proteins was further confirmed by a competition assay and an inhibition assay involving the HSPs tested. Conclusion: Our findings suggest that the tumor cell-adapted rotavirus isolates studied here offer a promising tool for killing tumor cells, thus encouraging further research into this topic, including animal models.

Overview of Current Immunotherapies Targeting Mutated KRAS Cancers

The occurrence of somatic substitution mutations of the KRAS proto-oncogene is highly prevalent in certain cancer types, which often leads to constant activation of proliferative pathways and subsequent neoplastic transformation. It is often seen as a gateway mutation in carcinogenesis and has been commonly deemed as a predictive biomarker for poor prognosis and relapse when conventional chemotherapeutics are employed. Additionally, its mutational status also renders EGFR targeted therapies ineffective owing to its downstream location. Efforts to discover new approaches targeting this menacing culprit have been ongoing for years without much success, and with incidences of KRAS positive cancer patients being on the rise, researchers are now turning towards immunotherapies as the way forward. In this scoping review, recent immunotherapeutic developments and advances in both preclinical and clinical studies targeting K-ras directly or indirectly via its downstream signal transduction machinery will be discussed. Additionally, some of the challenges and limitations of various K-ras targeting immunotherapeutic approaches such as vaccines, adoptive T cell therapies, and checkpoint inhibitors against KRAS positive cancers will be deliberated.

Perspective on Adenoviruses: Epidemiology, Pathogenicity, and Gene Therapy

Human adenoviruses are large (150 MDa) doubled-stranded DNA viruses that cause respiratory infections. These viruses are particularly pathogenic in healthy and immune-compromised individuals, and currently, no adenovirus vaccine is available for the general public. The purpose of this review is to describe (i) the epidemiology and pathogenicity of human adenoviruses, (ii) the biological role of adenovirus vectors in gene therapy applications, and (iii) the potential role of exosomes in adenoviral infections.

Defining a murine ovarian cancer model for the evaluation of conditionally-replicative adenovirus (CRAd) virotherapy agents

BACKGROUND

Virotherapy represents a promising approach for ovarian cancer. In this regard, conditionally replicative adenovirus (CRAd) has been translated to the context of human clinical trials. Advanced design of CRAds has sought to exploit their capacity to induce anti-tumor immunization by configuring immunoregulatory molecule within the CRAd genome. Unfortunately, employed murine xenograft models do not allow full analysis of the immunologic activity linked to CRAd replication.

RESULTS

We developed CRAds based on the Ad5/3-Delta24 design encoding cytokines. Whereas the encoded cytokines did not impact adversely CRAd-induced oncolysis in vitro, no gain in anti-tumor activity was noted in immune-incompetent murine models with human ovarian cancer xenografts. On this basis, we explored the potential utility of the murine syngeneic immunocompetent ID8 ovarian cancer model. Of note, the ID8 murine ovarian cancer cell lines exhibited CRAd-mediated cytolysis. The use of this model now enables the rational design of oncolytic agents to achieve anti-tumor immunotherapy.

CONCLUSIONS

Limits of widely employed murine xenograft models of ovarian cancer limit their utility for design and study of armed CRAd virotherapy agents. The ID8 model exhibited CRAd-induced oncolysis. This feature predicate its potential utility for the study of CRAd-based virotherapy agents.

Therapeutic effect of targeted Fas-expressing adenoviruses method combining γδ T cells in a mouse model of human ovarian carcinoma

The present study aimed to investigate the therapeutic effect and safety of targeted use of Fas-expressing adenoviruses combined with γδ T cell-mediated killing to treat human ovarian cancer xenografts in BALB/c mice. Shuttle plasmids containing control elements of human telomerase reverse transcriptase promoter and two-step transcriptional amplification system were constructed and packaged into adenovirus-5 vectors to generate expression of an exogenous Fas gene. A mouse xenograft model of human ovarian carcinoma was constructed. A total of 35 BALB/c mice were randomly divided into five groups, which were injected with PBS, γδ T cells, Fas-expressing adenoviruses, taxol, or Fas-expressing adenovirus and γδ T cells. The weight and volume of tumors in mice in each group was monitored. Tissue sections of the various tissues of mice in the Fas-expressing adenovirus and γδ T cells group was compared with those in the PBS group to evaluate the safety of Fas-expressing adenovirus and γδ T cells in the treatment of human ovarian cancer xenograft tumors. The results of the present study indicated that mice in all treatment groups were alive at the end of the treatment course. Tumor weight and volume was the highest in the PBS group, followed successively by the adenovirus group, the γδ T cell group, the adenovirus and γδ T cell group, and the taxol group. The weight and volume inhibition rate in adenovirus and γδ T cell group were significantly higher compared with in the PBS group (P<0.05). Pathological observation of tissue samples revealed that none of vital organs in the adenovirus and γδ T cell group developed any evident morphological changes during treatment, when compared with healthy controls. In conclusion, the combined therapy with Fas-expressing adenoviruses and γδ T cells is efficient and safe for the treatment of mouse human ovarian carcinoma xenografts.

New frontiers in oncolytic viruses: optimizing and selecting for virus strains with improved efficacy

Oncolytic viruses have demonstrated selective replication and killing of tumor cells. Different types of oncolytic viruses – adenoviruses, alphaviruses, herpes simplex viruses, Newcastle disease viruses, rhabdoviruses, Coxsackie viruses, and vaccinia viruses – have been applied as either naturally occurring or engineered vectors. Numerous studies in animal-tumor models have demonstrated substantial tumor regression and prolonged survival rates. Moreover, clinical trials have confirmed good safety profiles and therapeutic efficacy for oncolytic viruses. Most encouragingly, the first cancer gene-therapy drug – Gendicine, based on oncolytic adenovirus type 5 – was approved in China. Likewise, a second-generation oncolytic herpes simplex virus-based drug for the treatment of melanoma has been registered in the US and Europe as talimogene laherparepvec.

Latest trends in cancer therapy applying viral vectors

Gene therapy based on viral vectors has demonstrated steady progress recently, not only in the area of cancers. A multitude of viral vectors has been engineered for both preventive and therapeutic applications. Two main approaches comprise of viral vector-based delivery of toxic or anticancer genes or immunization with anticancer antigens. Tumor growth inhibition and tumor regression have been observed, providing improved survival rates in animal tumor models. Furthermore, vaccine-based cancer immunotherapy has demonstrated both tumor regression and protection against challenges with lethal doses of tumor cells. Several clinical trials with viral vectors have also been conducted. Additionally, viral vector-based cancer drugs have been approved. This review gives an overview of different viral vector systems and their applications in cancer gene therapy.

Adenovirus-Mediated Gene Delivery: Potential Applications for Gene and Cell-Based Therapies in the New Era of Personalized Medicine

With rapid advances in understanding molecular pathogenesis of human diseases in the era of genome sciences and systems biology, it is anticipated that increasing numbers of therapeutic genes or targets will become available for targeted therapies. Despite numerous setbacks, efficacious gene and/or cell-based therapies still hold the great promise to revolutionize the clinical management of human diseases. It is wildly recognized that poor gene delivery is the limiting factor for most in vivo gene therapies. There has been a long-lasting interest in using viral vectors, especially adenoviral vectors, to deliver therapeutic genes for the past two decades. Among all currently available viral vectors, adenovirus is the most efficient gene delivery system in a broad range of cell and tissue types. The applications of adenoviral vectors in gene delivery have greatly increased in number and efficiency since their initial development. In fact, among over 2,000 gene therapy clinical trials approved worldwide since 1989, a significant portion of the trials have utilized adenoviral vectors. This review aims to provide a comprehensive overview on the characteristics of adenoviral vectors, including adenoviral biology, approaches to engineering adenoviral vectors, and their applications in clinical and pre-clinical studies with an emphasis in the areas of cancer treatment, vaccination and regenerative medicine. Current challenges and future directions regarding the use of adenoviral vectors are also discussed. It is expected that the continued improvements in adenoviral vectors should provide great opportunities for cell and gene therapies to live up to its enormous potential in personalized medicine.

Enhancing Adenoviral-Mediated Gene Transfer and Expression to Endometrial Cells

OBJECTIVE

Our aim was to screen a panel of modified adenoviral gene transfer vectors to identify those which can sustain high gene expression in human endometrial cells.

METHODS

Normal endometrial stromal cell cultures were established from endometrial lining of hysterectomy specimens performed for benign gynecologic indications. Human endometrial stromal cells were transfected by modified adenoviruses expressing luciferase reporter gene. Luciferase activity mediated by each virus was expressed as a percentage of adenovirus serotype 5 (Ad5-CMV-luc) activity. The 2-tailed Student t test was used to compare data.

RESULTS

At a multiplicity of infection (MOI) of 10 pfu/cell, of the transductionally modified adenoviruses, adenovirus-RGD (Ad-RGD-luc) mediated highest level of endometrial cell transduction with transgene expression around 4 times higher when compared to Ad5 (P < .001). Of the transcriptionally targeted adenoviruses, adenovirus under secretory leukocyte protease inhibitor promoter (Ad-SLPI-luc) and adenovirus under heparanase promoter (Ad-heparanase-luc)-mediated luciferase activation were 5.8- and 4.3-folds higher than Ad5-CMV-luc, respectively (P = .02 and .03, respectively). At MOI of 50 pfu/cell, Ad-RGD-luc and AD-SLPI-luc mediated significantly higher gene transfer efficiency compared to Ad5-CMV-luc (P values < .001, for each virus). Ad-heparanase-luc achieved higher gene activity, but difference was not significant (P = .1). Ad-SLPI-luc, at low viral dose (10 pfu/ cell), mediated gene expression effect comparable to Ad5-CMV-luc at a high dose (50 pfu/cell), with no significant difference.

CONCLUSIONS

We conclude that when compared to the wild-type adenovirus, Ad-RGD-luc, Ad-SLPI-luc, and Ad-heparanase-luc mediate higher reporter gene activity in endometrial cells and can work as effective gene transfer vectors in gene therapy applications to the endometrium.

Gene therapy in endocrine tumors: a comprehensive overview

Effective treatment strategies that help tackle the complex problems associated with managing endocrine cancers are in great demand. Because of the shortcomings in current treatments and the problems associated with the treatment strategies used in the cure and/or management of endocrine cancers, considerable effort must be devoted to developing new and effective therapeutic strategies. Gene therapy represents an area of both basic and clinical research that can potentially be considered a therapeutic option in treating endocrine cancers. Therefore, we consider it timely to summarize the studies related to gene-therapy interventions that are available for treating endocrine cancers and to highlight the major limitations of and the recent progress made in these therapies. After systematically reviewing the literature, we provide a comprehensive overview of distinct studies conducted to evaluate gene-therapy approaches in various endocrine cancers. Some of these successful studies have been extended toward translational investigations. The emerging view is that an integrative approach is required to combat the pitfalls associated with gene-therapy studies, especially in endocrine cancers.

Oncolytic myxoma virus: the path to clinic

Many common neoplasms are still noncurative with current standards of cancer therapy. More therapeutic modalities need to be developed to significantly prolong the lives of patients and eventually cure a wider spectrum of cancers. Oncolytic virotherapy is one of the promising new additions to clinical cancer therapeutics. Successful oncolytic virotherapy in the clinic will be those strategies that best combine tumor cell oncolysis with enhanced immune responses against tumor antigens. The current candidate oncolytic viruses all share the common property that they are relatively nonpathogenic to humans, yet they have the ability to replicate selectively in human cancer cells and induce cancer regression by direct oncolysis and/or induction of improved anti-tumor immune responses. Many candidate oncolytic viruses are in various stages of clinical and preclinical development. One such preclinical candidate is myxoma virus (MYXV), a member of the Poxviridae family that, in its natural setting, exhibits a very restricted host range and is only pathogenic to European rabbits. Despite its narrow host range in nature, MYXV has been shown to productively infect various classes of human cancer cells. Several preclinical in vivo modeling studies have demonstrated that MYXV is an attractive and safe candidate oncolytic virus, and hence, MYXV is currently being developed as a potential therapeutic for several cancers, such as pancreatic cancer, glioblastoma, ovarian cancer, melanoma, and hematologic malignancies. This review highlights the preclinical cancer models that have shown the most promise for translation of MYXV into human clinical trials.

HER3 targeting of adenovirus by fiber modification increases infection of breast cancer cells in vitro, but not following intratumoral injection in mice

Despite the tremendous potential of adenovirus (Ad) as a delivery vector for cancer gene therapy, its use in clinical settings has been limited, mainly as a result of the limited infectivity in many tumors and the wide tissue tropism associated with Ad. To modify the tropism of the virus, we have inserted the epidermal growth factor-like domain of the human heregulin-α (HRG) into the HI loop of Ad5 fiber. This insertion had no adverse effect on fiber trimerization nor did it affect incorporation of the modified fiber into infectious viral particles. Virions bearing modified fiber displayed growth characteristics and viral yields indistinguishable from those of wild-type (wt) virus. Most importantly, HRG-tagged virions showed enhanced infection of cells expressing the cognate receptors HER3/ErbB3 and HER4/ErbB4. This was significantly reduced in the presence of soluble HRG. Furthermore, HER3-expressing Chinese hamster ovary (CHO) cells were transduced by the HRG-modified virus, but not by wt virus. In contrast, CHO cells expressing the coxsackie-Ad receptor were transduced with both viruses. However, infection of an in vivo breast cancer xenograft model after intratumoral injection was similar with both viruses, suggesting that the tumor microenvironment and/or the route of delivery have important roles in infection of target cells with fiber-modified Ads.

A tumor-stroma targeted oncolytic adenovirus replicated in human ovary cancer samples and inhibited growth of disseminated solid tumors in mice

Targeting the tumor stroma in addition to the malignant cell compartment is of paramount importance to achieve complete tumor regression. In this work, we modified a previously designed tumor stroma-targeted conditionally replicative adenovirus (CRAd) based on the SPARC promoter by introducing a mutated E1A unable to bind pRB and pseudotyped with a chimeric Ad5/3 fiber (Ad F512v1), and assessed its replication/lytic capacity in ovary cancer in vitro and in vivo. AdF512v1 was able to replicate in fresh samples obtained from patients: (i) with primary human ovary cancer; (ii) that underwent neoadjuvant treatment; (iii) with metastatic disease. In addition, we show that four intraperitoneal (i.p.) injections of 5 × 10(10) v.p. eliminated 50% of xenografted human ovary tumors disseminated in nude mice. Moreover, AdF512v1 replication in tumor models was enhanced 15-40-fold when the tumor contained a mix of malignant and SPARC-expressing stromal cells (fibroblasts and endothelial cells). Contrary to the wild-type virus, AdF512v1 was unable to replicate in normal human ovary samples while the wild-type virus can replicate. This study provides evidence on the lytic capacity of this CRAd and highlights the importance of targeting the stromal tissue in addition to the malignant cell compartment to achieve tumor regression.

Myxoma virus-mediated oncolysis of ascites-derived human ovarian cancer cells and spheroids is impacted by differential AKT activity

OBJECTIVE

We propose that metastatic epithelial ovarian cancer (EOC) is a potential therapeutic target for the oncolytic agent, Myxoma virus (MYXV).

METHODS

Primary EOC cells were isolated from patient ascites and cultured as adherent cells or in suspension using Ultra Low-Attachment dishes. MYXV expressing green fluorescent protein was used to infect cells and spheroids. Infection was monitored by fluorescence microscopy, viral titering and immunoblotting for M-T7 and M130 virus protein expression, and cell viability by alamarBlue assay. Akti-1/2 (5 μM) and rapamycin (20 nM) were used to assay the role of PI3K-AKT signaling in mediating MYXV infection.

RESULTS

Ascites-derived EOC cells grown in adherent culture are effectively killed by MYXV infection. EOC cells grown in suspension to form three-dimensional EOC spheroids readily permit MYXV entry into cells, yet are protected from the cytopathic effects of late MYXV infection. Upon reattachment (to model secondary metastasis), EOC spheroids are re-sensitized to MYXV-mediated oncolysis. The critical determinant that facilitates efficient MYXV infection is the presence of an activated PI3K-AKT signaling pathway. Treatment with the specific AKT inhibitor Akti-1/2 reduces infection of monolayer EOC cells and spheroids. Direct infection of freshly-collected ascites demonstrated that 54.5% of patient samples were sensitive to MYXV-mediated oncolytic cell killing. We also demonstrate that factor(s) present in ascites may negatively impact MYXV infection and oncolysis of EOC cells, which may be due to a down-regulation in endogenous AKT activity.

CONCLUSIONS

Differential activity of AKT serves as the mechanistic basis for regulating MYXV-mediated oncolysis of EOC spheroids during key steps of the metastatic program. In addition, we provide the first evidence that MYXV oncolytic therapy may be efficacious for a significant proportion of ovarian cancer patients with metastatic disease.

A new generation of serotype chimeric infectivity-enhanced conditionally replicative adenovirals: the safety profile of ad5/3-Δ24 in advance of a phase I clinical trial in ovarian cancer patients

Conditionally replicative adenoviral (CRAd) virotherapy represents a promising therapeutic approach for cancer. We have demonstrated that a serotype chimeric adenoviral 5/3 fiber-knob modification achieves enhanced ovarian cancer infectivity, conditional replication, and oncolytic activity. This study evaluated the safety of intraperitoneal (IP) Ad5/3-Δ24 in advance of a phase I clinical trial in gynecologic cancers. Syrian hamster cohorts were treated with IP Ad5/3-Δ24 or control buffer for 3 consecutive days and euthanized on study days 8, 17, 57, and 89. Blood and tissue samples were harvested from each animal. For biodistribution studies, presence and quantitation of viral levels within samples were determined via quantitative polymerase chain reaction. For safety studies, animals were assessed for adverse vector-related tissue or laboratory effects. In the biodistribution study, low levels of Ad5/3-Δ24 DNA were noted outside of the abdominal cavity. Viral DNA levels in tissues obtained from the peritoneal cavity peaked at day 8 and declined thereafter. In the safety study, no specific histopathologic changes were attributable to virus administration. Hematologic findings noted in the 1 × 10(11) viral particles (vp)/dose group on Days 4 and/or 8 were indicative of an Ad5/3-Δ24-specific generalized inflammatory response; these findings resolved by day 56. The no observable adverse effect level was determined to be 1 × 10(10) vp/dose. This study elucidates the safety profile of IP administration of the serotype chimeric infectivity-enhanced CRAd, Ad5/3-Δ24, and provides guidance for a planned phase I trial for patients with recurrent gynecologic cancers.

Therapeutic vaccination in chronic hepatitis B: preclinical studies in the woodchuck

Recommended treatment of chronic hepatitis B with interferon-α and/or nucleos(t)ide analogues does not lead to a satisfactory result. Induction of HBV-specific T cells by therapeutic vaccination or immunotherapies may be an innovative strategy to overcome virus persistence. Vaccination with commercially available HBV vaccines in patients did not result in effective control of HBV infection, suggesting that new formulations of therapeutic vaccines are needed. The woodchuck (Marmota monax) is a useful preclinical model for developing the new therapeutic approaches in chronic hepadnaviral infections. Several innovative approaches combining antiviral treatments with nucleos(t)ide analogues, DNA vaccines, and protein vaccines were tested in the woodchuck model. In this paper we summarize the available data concerning therapeutic immunization and gene therapy using recombinant viral vectors approaches in woodchucks, which show encouraging results. In addition, we present potential innovations in immunomodulatory strategies to be evaluated in this animal model.

Scavenger receptors and their potential as therapeutic targets in the treatment of cardiovascular disease

Scavenger receptors act as membrane-bound and soluble proteins that bind to macromolecular complexes and pathogens. This diverse supergroup of proteins mediates binding to modified lipoprotein particles which regulate the initiation and progression of atherosclerotic plaques. In vascular tissues, scavenger receptors are implicated in regulating intracellular signaling, lipid accumulation, foam cell development, and cellular apoptosis or necrosis linked to the pathophysiology of atherosclerosis. One approach is using gene therapy to modulate scavenger receptor function in atherosclerosis. Ectopic expression of membrane-bound scavenger receptors using viral vectors can modify lipid profiles and reduce the incidence of atherosclerosis. Alternatively, expression of soluble scavenger receptors can also block plaque initiation and progression. Inhibition of scavenger receptor expression using a combined gene therapy and RNA interference strategy also holds promise for long-term therapy. Here we review our current understanding of the gene delivery by viral vectors to cells and tissues in gene therapy strategies and its application to the modulation of scavenger receptor function in atherosclerosis.

Targeted activation of RNA helicase retinoic acid-inducible gene-I induces proimmunogenic apoptosis of human ovarian cancer cells

Most malignant cells are poorly immunogenic and fail to elicit an effective antitumor immune response. In contrast, viral infections of cells are promptly detected and eliminated by the immune system. Viral recognition critically hinges on cytosolic nucleic acid receptors that include the proinflammatory RNA helicase retinoic acid-inducible gene-I (RIG-I). Here, we show that targeted delivery of RIG-I agonists induced ovarian cancer cells to upregulate HLA class I and to secrete the proinflammatory cytokines CXCL10, CCL5, interleukin-6, tumor necrosis factor-alpha, and IFN-beta. Ovarian cancer cells stimulated via RIG-I became apoptotic and were readily phagocytosed by monocytes and monocyte-derived dendritic cells, which in turn upregulated HLA class I/II and costimulatory molecules and released CXCL10 and IFN-alpha. Our findings offer proof of principle that mimicking viral infection in ovarian cancer cells triggers an immunogenic form of tumor cell apoptosis that may enhance immunotherapy of ovarian cancer.