A Fiber-Modified, Secretory Leukoprotease Inhibitor Promoter-Based Conditionally Replicating Adenovirus for Treatment of Ovarian Cancer

Oncolytic virus immunotherapies in ovarian cancer: moving beyond adenoviruses

Ovarian cancer is the 5th most common cancer in UK women with a high relapse rate. The overall survival for ovarian cancer has remained low for decades prompting a real need for new therapies. Recurrent ovarian cancer remains confined in the peritoneal cavity in >80% of the patients, providing an opportunity for locoregional administration of novel therapeutics, including gene and viral therapy approaches. Immunotherapy is an expanding field, and includes oncolytic viruses as well as monoclonal antibodies, immune checkpoint inhibitors, and therapeutic vaccines. Oncolytic viruses cause direct cancer cell cytolysis and immunogenic cell death and subsequent release of tumor antigens that will prime for a potent tumor-specific immunity. This effect may be further enhanced when the viruses are engineered to express, or coadministered with, immunostimulatory molecules. Currently, the most commonly used and well-characterized vectors utilized for virotherapy purposes are adenoviruses. They have been shown to work synergistically with traditional chemotherapy and radiotherapy and have met with success in clinical trials. However, pre-existing immunity and poor in vivo models limit our ability to fully investigate the potential of oncolytic adenovirus as effective immunotherapies which in turn fosters the need to develop alternative viral vectors. In this review we cover recent advances in adenovirus-based oncolytic therapies targeting ovarian cancer and recent advances in mapping immune responses to oncolytic virus therapies in ovarian cancer.

A novel bladder cancer - specific oncolytic adenovirus by CD46 and its effect combined with cisplatin against cancer cells of CAR negative expression

BACKGROUND

Conditionally replicative oncolytic adenoviruses (CRAds) display significant anti-tumor effects. However, the traditional adenovirus of serotype 5 (Ad5) entering cancer cells via coxsackie virus and adenovirus receptor (CAR) can't be utilized for bladder cancer with low expression of CAR, which limits the application of Ad5.

METHODS

We utilized Ad5/F11p containing the chimeric fiber gene encoding the Ad5 fiber tail domain and Ad11p fiber shaft and knob domains to construct bladder cancer-specific chimeric type viruses Ad5/F11p-PSCAE-UPII-E1A, which can infect bladder cancer cells mediated by CD46 molecule. We carried out series of experiments in vitro to research anti-tumor effect of Ad5/F11p-PSCAE-UPII-E1A and the interaction in combination with cisplatin.

RESULTS

The results demonstrated Ad5/F11p-PSCAE-UPII-E1A could infect bladder cancer cells (T24, EJ and 5637) in a CAR-independent way, and exert anti-tumor effect by blocking the cancer cells in G1 phase and inducing apoptosis. Ad5/F11p-PSCAE-UPII-E1A plus cisplatin enhanced the anti-proliferative effect and increased the number of apoptotic cells compared with viruses or cisplatin alone. Ad5/F11p-PSCAE-UPII-E1A plus cisplatin could upregulate the proteins expression of p53, Bax, and cleaved caspase-3, and downregulated Bcl-2 protein expression in T24, EJ and 5637 cells.

CONCLUSION

We constructed a bladder cancer-specific oncolytic adenovirus and provided new combination treatment strategies for bladder cancer.

Antitumor Efficacy of SLPI Promoter-Controlled Expression of Artificial microRNA Targeting EGFR in a Squamous Cell Carcinoma Cell Line

The purpose of this study was to develop a recombinant adenovirus with secretory leukoprotease inhibitor (SLPI) promoter-controlled expression for gene therapy of squamous cell carcinoma (SCC). An artificial microRNA targeting epidermal growth factor receptor (EGFR) was designed, and used to construct a replication-defective recombinant adenovirus with SLPI promoter-controlled expression. The silencing efficiency of this vector (Ad-SLPI-EGFRamiR) was detected in Hep-2 cells. Western blotting showed that the expression of 170 kD EGFR was significantly reduced in Hep-2 cells 72 h after infection with Ad-SLPI-EGFRamiR. At a multiplicity of infection (MOI) of 200 pfu/cell, proliferation of Hep-2 cells was highly inhibited by Ad-SLPI-EGFRamiR (inhibition rate: ~70%). The apoptosis rate of Hep-2 cells at 72 h after infection with Ad-SLPI-EGFRamiR at a MOI 35 pfu/cell was 32.8%. The adenovirus constructed was able to specifically inhibit the growth of SCC cells in vitro.

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.

Treatment of endometriosis with a VEGF-targeted conditionally replicative adenovirus

OBJECTIVE

To evaluate a vascular endothelial growth factor (VEGF)-targeted gene therapy for the treatment of endometriosis.

DESIGN

Analysis of the VEGF gene expression and promoter activity in ectopic and eutopic endometrium. Evaluation of the specific replication and cell-killing effect of a VEGF-targeted adenovirus (Ad5VEGFE1) in endometriotic cells.

PATIENT(S)

Four patients who underwent hysterectomy for benign disease, 30 women with moderate superficial, and 30 women with deep infiltrating endometriosis.

INTERVENTION(S)

Immunostaining and gene expression of VEGF was examined in eutopic endometrium, endometriotic lesions, and normal peritoneum. The VEGF promoter activity was evaluated in eutopic endometrium and endometriotic lesions. A VEGF-targeted conditionally replicative adenovirus (Ad5VEGFE1) was evaluated regarding specific viral replication in endometriosis cells and induction of apoptosis. The biodistribution of the VEGF-targeted conditionally replicative adenovirus was examined in a mouse model.

RESULT(S)

The VEGF gene was highly expressed in ectopic endometrium compared with eutopic endometrium and normal peritoneum. The VEGF promoter was active in endometriotic cells. Ad5VEGFE1 showed efficient viral replication and induction of apoptosis in purified primary endometriotic cells and demonstrated a similar lower targeting to the liver and the uterus in a mouse model.

CONCLUSION(S)

Ad5VEGFE1 is a promising candidate for treating endometriosis and holds potential for clinical testing.

Gene therapy for gastric cancer: Is it promising?

Gastric cancer is one of the most common tumors worldwide. The therapeutic outcome of conventional therapies is inefficient. Thus, new therapeutic strategies are urgently needed. Gene therapy is a promising molecular alternative in the treatment of gastric cancer, including the replacement of defective tumor suppressor genes, the inactivation of oncogenes, the introduction of suicide genes, genetic immunotherapy, anti-angiogenetic gene therapy, and virotherapy. Improved molecular biological techniques and a better understanding of gastric carcinogenesis have allowed us to validate a variety of genes as molecular targets for gene therapy. This review provides an update of the new developments in cancer gene therapy, new principles, techniques, strategies and vector systems, and shows how they may be applied in the treatment of gastric cancer.

Recent progress in the battle between oncolytic viruses and tumours

In the past 5 years, the field of oncolytic virus research has matured significantly and is moving past the stage of being a laboratory novelty into a new era of preclinical and clinical trials. What have recent anticancer trials of oncolytic viruses taught us about this exciting new line of therapeutics?