Reshaping the tumor microenvironment of cold soft-tissue sarcomas with oncolytic viral therapy: a phase 2 trial of intratumoral JX-594 combined with avelumab and low-dose cyclophosphamide

Most soft-tissue sarcomas (STS) exhibit an immunosuppressive tumor microenvironment (TME), leading to resistance against immune checkpoint inhibitors (ICIs) and limited therapeutic response. Preclinical data suggest that oncolytic viral therapy can remodel the TME, facilitating T cell accumulation and enhancing the immunogenicity of these tumors.We conducted the METROMAJX, a phase II clinical trial, to investigate the combination of JX-594, an oncolytic vaccinia virus engineered for selective tumor cell replication, with metronomic cyclophosphamide and the PD-L1 inhibitor avelumab in patients with advanced, 'cold' STS, characterized by an absence of tertiary lymphoid structures. The trial employed a two-stage Simon design. JX-594 was administered intratumorally at a dose of 1.109 pfu every 2 weeks for up to 4 intra-tumoral administrations. Cyclophosphamide was given orally at 50 mg twice daily in a week-on, week-off schedule, and avelumab was administered at 10 mg/kg biweekly. The primary endpoint was the 6-month non-progression rate.Fifteen patients were enrolled, with the most frequent toxicities being grade 1 fatigue and fever. Fourteen patients were assessable for efficacy analysis. At 6 months, only one patient remained progression-free, indicating that the trial did not meet the first stage endpoint of Simon's design. Analysis of sequential tissue biopsies and plasma samples revealed an increase in CD8 density and upregulation of immune-related protein biomarkers, including CXCL10.Intra-tumoral administration of JX-594 in combination with cyclophosphamide and avelumab is safe and capable of modulating the TME in cold STS. However, the limited efficacy observed warrants further research to define the therapeutic potential of oncolytic viruses, particularly in relation to specific histological subtypes of STS.

Phase 2 trial of intravenous oncolytic virus JX-594 combined with low-dose cyclophosphamide in patients with advanced breast cancer

Breast cancer is one the most common cause of cancer death in women worldwide. We report here the first phase II study investigating a virus genetically engineered for tumor-selective replication in patients with breast cancer. Ten patients were treated with a combination of low-dose oral cyclophosphamide and intra-venous JX-594, a thymidine kinase gene-inactivated oncolytic vaccinia virus engineered for the expression of transgenes encoding human granulocyte-macrophage colony-stimulating factor (GM-CSF) and β-galactosidase. Best response as per RECIST criteria was stable disease for 2 patients and progressive disease for 8 patients. Median progression-free and overall survival were 1.6 months (95% CI: [1.1-1.9]) and 14.4 months (95% CI: [2.0 - NA]) respectively. High throughput analysis of sequential plasma samples revealed an upregulation of protein biomarkers reflecting immune induction such as IFN gamma. Whether the combination of JX-594 with an immune checkpoint inhibitor is associated with meaningful clinical activity is therefore worth to investigate.

Randomized phase 2 trial of intravenous oncolytic virus JX-594 combined with low-dose cyclophosphamide in patients with advanced soft-tissue sarcoma

JX-594 is an oncolytic vaccinia virus genetically modified to replicate selectively in tumor cells. Metronomic chemotherapy has shown preclinical synergy with oncolytic viruses. We report here the results of the METROMAJX which is a randomized phase II clinical trial investigating the combination of JX-594 combined with metronomic cyclophosphamide (arm 1) or metronomic cyclophosphamide (arm 2) in patients with advanced STS. A two-stage Simon design was used. JX-594 was administered intra-venously at the dose 1.109 every 2 weeks for the first 3 injections and then every 3 weeks. Cyclophosphamide was given orally at the dose of 50 mg BID 1 week on 1 week off. The primary endpoint was the 6-month non progression rate. 20 patients were included (arm 1:15, arm 2:5). The two most frequent toxicities were grade 1 fatigue and fever and grade 2 fatigue and grade 2 lymphopenia in arms 1 and 2, respectively. In arm 1, 12 patients were assessable for the efficacy analysis. None of them were progression-free at 6 months indicating that the first stage of the Simon's design was not satisfied. One patient out 4 assessable for efficacy was progression-free at 6 months in arm 2. High throughput analysis of sequential plasma samples revealed an upregulation of protein biomarkers reflecting immune induction such as CXCL10 and soluble CD8 antigen in arm 1. Systemic treatment with JX-594 is safe in patients with advanced STS. Further investigations are needed to improve immune response to oncolytic viruses and define their therapeutic potential in patients with STS.

Early Experience of Oncolytic Virus Injection Combined with Sorafenib in a Patient with Advanced Hepatocellular Carcinoma and Portal Vein Thrombosis

JX-594 is a modified oncolytic poxvirus designed to selectively replicate in and destroy cancer cells. In a pilot study, JX-594 injection followed by sorafenib was well-tolerated in three patients and associated with objective tumor responses. In this study, we report a case in which a patient with advanced hepatocellular carcinoma and portal vein thrombosis was treated with a combination of JX-594 and sorafenib.

Engineered oncolytic viruses to treat melanoma: where are we now and what comes next?

INTRODUCTION

Melanoma treatments have evolved rapidly in the past decade and have included the use of intratumoral injections of engineered oncolytic viruses. One such oncolytic virus is talimogene laherparepvec (T-VEC), which is the first approved therapy of its kind for use in recurrent, unresectable stage IIIB-IVM1a melanoma. Additional oncolytic viruses and their uses in combination with other interventions are currently under investigation.

AREAS COVERED

Oncolytic viruses are being evaluated as immunotherapies for a variety of advanced malignancies. In this article, we review T-VEC, the only FDA-approved engineered oncolytic virus, in addition to ongoing research regarding other oncolytic viruses for the treatment of advanced melanomas. Finally, we discuss opportunities to improve these therapies through viral, host, and tumor-related modifications.

EXPERT OPINION

Engineered and naturally oncolytic viruses have demonstrable local and systemic efficacy as immunotherapies in cancer. T-VEC leads the way with improved survival outcomes for unresectable, stage IIIB-IVM1a melanoma as a monotherapy, and is demonstrating superior results in combination with systemic checkpoint inhibitors. Additional viral vectors show acceptable safety profiles and varying degrees of efficacy in targeting melanoma. The indications for use of oncolytic viruses will expand as their efficacy and appropriate usage is better understood in coming years.

Trial Watch-Oncolytic viruses and cancer therapy

Oncolytic virotherapy relies on the administration of non-pathogenic viral strains that selectively infect and kill malignant cells while favoring the elicitation of a therapeutically relevant tumor-targeting immune response. During the past few years, great efforts have been dedicated to the development of oncolytic viruses with improved specificity and potency. Such an intense wave of investigation has culminated this year in the regulatory approval by the US Food and Drug Administration (FDA) of a genetically engineered oncolytic viral strain for use in melanoma patients. Here, we summarize recent preclinical and clinical advances in oncolytic virotherapy.

The emerging therapeutic potential of the oncolytic immunotherapeutic Pexa-Vec (JX-594)

Oncolytic immunotherapeutics (OIs) are viruses designed to preferentially replicate in and lyse cancer cells, thereby triggering antitumor immunity. Numerous oncolytic platforms are currently in clinical development. Here we review preclinical and clinical experience with Pexa-Vec (pexastimogene devacirepvec, JX-594). Pexa-Vec is derived from a vaccinia vaccine strain that has been engineered to target cancer cells and express the therapeutic transgene granulocyte macrophage colony-stimulating factor (GM-CSF) in order to stimulate antitumor immunity. Key to its ability to target metastatic disease is the evolution of unique vaccinia virus characteristics that allow for effective systemic dissemination. Multiple mechanisms of action (MOA) for Pexa-Vec have been demonstrated in preclinical models and patients: 1) tumor cell infection and lysis, 2) antitumor immune response induction, and 3) tumor vascular disruption. This review will summarize data on the Pexa-Vec MOA as well as provide an overview of the Pexa-Vec clinical development program from multiple Phase I studies, Phase II studies in renal cell cancer and colorectal cancer, through Phase IIb clinical testing in patients with advanced hepatocellular carcinoma (primary liver cancer).

Oncolytic virotherapy as emerging immunotherapeutic modality: potential of parvovirus h-1

Human tumors develop multiple strategies to evade recognition and efficient suppression by the immune system. Therefore, a variety of immunotherapeutic strategies have been developed to reactivate and reorganize the human immune system. The recent development of new antibodies against immune check points may help to overcome the immune silencing induced by human tumors. Some of these antibodies have already been approved for treatment of various solid tumor entities. Interestingly, targeting antibodies may be combined with standard chemotherapy or radiation protocols. Furthermore, recent evidence indicates that intratumoral or intravenous injections of replicative oncolytic viruses such as herpes simplex-, pox-, parvo-, or adenoviruses may also reactivate the human immune system. By generating tumor cell lysates in situ, oncolytic viruses overcome cellular tumor resistance mechanisms and induce immunogenic tumor cell death resulting in the recognition of newly released tumor antigens. This is in particular the case of the oncolytic parvovirus H-1 (H-1PV), which is able to kill human tumor cells and stimulate an anti-tumor immune response through increased presentation of tumor-associated antigens, maturation of dendritic cells, and release of pro-inflammatory cytokines. Current research and clinical studies aim to assess the potential of oncolytic virotherapy and its combination with immunotherapeutic agents or conventional treatments to further induce effective antitumoral immune responses.

Viral warfare! Front-line defence and arming the immune system against cancer using oncolytic vaccinia and other viruses

BACKGROUND

Despite mankind's many achievements, we are yet to find a cure for cancer. We are now approaching a new era which recognises the promise of harnessing the immune system for anti-cancer therapy. Pathogens have been implicated for decades as potential anti-cancer agents, but implementation into clinical therapy has been plagued with significant drawbacks. Newer 'designer' agents have addressed some of these concerns, in particular, a new breed of oncolytic virus: JX-594, a genetically engineered pox virus, is showing promise.

OBJECTIVE

To review the current literature on the use of oncolytic viruses in the treatment of cancer; both by direct oncolysis and stimulation of the immune system. The review will provide a background and historical progression for the surgeon on tumour immunology, and the interplay between oncolytic viruses, immune cells, inflammation on tumourigenesis.

METHODS

A literature review was performed using the Medline database.

CONCLUSIONS

Viral therapeutics hold promise as a novel treatment modality for the treatment of disseminated malignancy. It provides a multi-pronged attack against tumour burden; direct tumour cell lysis, exposure of tumour-associated antigens (TAA), induction of immune danger signals, and recognition by immune effector cells.