Treatment of Metastatic Disease through Natural Killer Cell Modulation by Infected Cell Vaccines

Remodeling the tumor immune microenvironment with oncolytic viruses expressing miRNAs

MiRNAs (miRNA, miR) play important functions in the tumor microenvironment (TME) by silencing gene expression through RNA interference. They are involved in regulating both tumor progression and tumor suppression. The pathways involved in miRNA processing and the miRNAs themselves are dysregulated in cancer. Consequently, they have become attractive therapeutic targets as underscored by the plethora of miRNA-based therapies currently in pre-clinical and clinical studies. It has been shown that miRNAs can be used to improve oncolytic viruses (OVs) and enable superior viral oncolysis, tumor suppression and immune modulation. In these cases, miRNAs are empirically selected to improve viral oncolysis, which translates into decreased tumor growth in multiple murine models. While this infectious process is critical to OV therapy, optimal immunomodulation is crucial for the establishment of a targeted and durable effect, resulting in cancer eradication. Through numerous mechanisms, OVs elicit a strong antitumor immune response that can also be further improved by miRNAs. They are known to regulate components of the immune TME and promote effector functions, antigen presentation, phenotypical polarization, and varying levels of immunosuppression. Reciprocally, OVs have the power to overcome the limitations encountered in canonical miRNA-based therapies. They deliver therapeutic payloads directly into the TME and facilitate their amplification through selective tumoral tropism and abundant viral replication. This way, off-target effects can be minimized. This review will explore the ways in which miRNAs can synergistically enhance OV immunotherapy to provide the basis for future therapeutics based on this versatile combination platform.

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.

Harnessing the Immune System with Cancer Vaccines: From Prevention to Therapeutics

Prophylactic vaccination against infectious diseases is one of the most successful public health measures of our lifetime. More recently, therapeutic vaccination against established diseases such as cancer has proven to be more challenging. In the host, cancer cells evade immunologic regulation by multiple means, including altering the antigens expressed on their cell surface or recruiting inflammatory cells that repress immune surveillance. Nevertheless, recent clinical data suggest that two classes of antigens show efficacy for the development of anticancer vaccines: tumor-associated antigens and neoantigens. In addition, many different vaccines derived from antigens based on cellular, peptide/protein, and genomic components are in development to establish their efficacy in cancer therapy. Some vaccines have shown promising results, which may lead to favorable outcomes when combined with standard therapeutic approaches. This review provides an overview of the innate and adaptive immune systems, their interactions with cancer cells, and the development of various different vaccines for use in anticancer therapeutics.

Intravesical immunotherapy with a GM-CSF armed oncolytic vesicular stomatitis virus improves outcome in bladder cancer

A significant proportion of non-muscle invasive bladder cancer cases will progress to muscle invasive disease. Transurethral resection followed by Bacillus Calmette Guerin immunotherapy can reduce this risk, while cystectomy prior to muscle invasion provides the best option for survival. Currently, there are no effective treatments for Bacillus Calmette Guerin refractory disease. A novel oncolytic vesicular stomatitis virus containing the human GM-CSF transgene (VSVd51-hGM-CSF) was rescued and tested as a potential bladder-sparing therapy for aggressive bladder cancer. The existing variant expressing mouse GM-CSF was also used. Measurement of gene expression and protein level alterations of canonical immunogenic cell death associated events on mouse and human bladder cancer cell lines and spheroids showed enhanced release of danger signals and immunogenic factors following infection with VSVd51-m/hGM-CSF. Intravesical instillation of VSVd51-mGM-CSF into MB49 bladder cancer bearing C57Bl/6 mice demonstrated enhanced activation of peripheral and bladder infiltrating effector immune cells, along with improved survival and reduced tumor volume. Importantly, virus-mediated anti-tumor immunity was recapitulated in bladder cancer patient-derived organoids. These results suggest that VSVd51-hGM-CSF is a promising viro/immunotherapy that could benefit bladder cancer patients.