Tumor cells as cellular vehicles to deliver gene therapies to metastatic tumors

Abstract

A long-pursued goal in cancer treatment is to deliver a therapy specifically to metastases. As a result of the disseminated nature of the metastatic disease, carrying the therapeutic agent to the sites of tumor growth represents a major step for success. We hypothesized that tumor cells injected intravenously (i.v.) into an animal with metastases would respond to many of the factors driving the metastatic process, and would target metastases. Using a model of spontaneous metastases, we report here that i.v. injected tumor cells localized on metastatic lesions. Based on this fact, we used genetically transduced tumor cells for tumor targeting of anticancer agents such as a suicide gene or an oncolytic virus, with evident antitumoral effect and negligible systemic toxicity. Therefore, autologous tumor cells may be used as cellular vehicles for systemic delivery of anticancer therapies to metastatic tumors. Cancer Gene Therapy ( Keywords: neoplasm metastasis; delivery system; oncolytic virus; NOD SCID mice C ancer is often diagnosed when the disease has already disseminated and most of the patient deaths are related to metastatic disease. Current treatment options for metastatic tumors lack efficacy and metastases targeting remains a major challenge for curing cancer. Novel cell-and gene-based therapies have been developed aimed to deliver an antitumor effect specifically to metastases. Some strategies rely on the immune system for selectivity, such as the stimulation of effector immune cells 1 or the use of monoclonal antibodies that recognize tumor antigens. 2 Others target angiogenic 3-5 or anaerobic signals 6,7 that arise at the metastases. Recently, oncotropic viruses have been used to selectively kill the tumor cells with the advantage that once targeting is achieved the propagation of the virus amplifies the therapy. 8,9 These promising new therapies have fallen behind expectations mainly because of their limited capacity for effectively targeting in vivo. 2,10 The process of metastasis is a turning point in the progression of malignant solid tumors. Million tumor cells leave the primary tumor, reach the bloodstream and disseminate through the body. 11 Only a minority will eventually survive to become the origin of a new cancer nodule 12 at anatomical sites that are specific for the tumor type. 13 The dissemination of cancer cells from the primary tumor and their homing in specific organs involve several steps: invasion, detachment, circulation, cell adhesion, motility and invasion again. Cells must express a specific receptor molecule repertoire (cell adhesion molecules, chemokine receptors or integrin ligands among others) to complete this metastatic process. [14][15][16][17] We hypothesized that cancer cells may be good candidates to target established metastases in vivo because they express the receptor and effector molecules involved in the metastatic process. Autologous intravenously (i.v.) injected tumor cells should respond to metastasis-related cues as the cells leaving the primary tumor did when th...

Syncytia formation affects the yield and cytotoxicity of an adenovirus expressing a fusogenic glycoprotein at a late stage of replication

“…This cassette was placed directly downstream of the fiber gene, as an L6 unit ( Figure 1a). This strategy has been used previously 7,19 and cloning strategies are available upon request. Transfection of the AdwtRGD-GALV genome into 293 cells led to massive syncytia formation ( Figure 1b) and virus generation.…”

Osteosarcoma cells as carriers to allow antitumor activity of canine oncolytic adenovirus in the presence of neutralizing antibodies

“…We have previously demonstrated that tumor cells can be used to target tumors. 19 OCCAV-infected D17 carrier cells displayed a much more effective antitumoral effect as compared with Abrams carrier cells in systemic injections, probably because of a higher viral burst of D17 cells (Figure 1a, panel A) than of Abrams cells (Figure 1a, panel B), which offers increased potential for dose amplification. Moreover, further confirmation that viral production in carrier cells is linked to antitumoral activity comes from the observation that the homogeneous mix of infected cells showed an intermediate therapeutic efficacy between the D17 and Abrams-infected carrier cells.…”

“…injected tumor cells homed in metastatic lesions and were able to deliver OVs to the metastases with only localized and negligible systemic toxicity. 18,19 Moreover, in an immunocompetent model, tumor carrier cells loaded with adenovirus generated anti-adenovirus and antitumoral cytotoxic T-lymphocytes, the activity of which could be further enhanced by granulocyte-macrophage colony-stimulating factor expression. 10 In this study, we explored the potential of using canine tumor cells as carriers for delivery of oncolytic canine adenovirus to tumor sites in a xenograft animal model.…”

Cell carriers to deliver oncolytic viruses to sites of myeloma tumor growth

“…An assortment of cells have been explored in this regard, including tumor cells, [49][50][51][52] outgrowth endothelial cells, 53 mesenchymal progenitor cells, 54,55 T cells 56,57 and monocytes. 58 There are several criteria that need to be addressed when determining which cell type should be utilized as a carrier for the delivery of a given oncolytic virus: (i) susceptibility to oncolytic virus infection, (ii) protection of the cargo from antibody neutralization, (iii) homing to sites of tumor growth and (iv) transfer of virus progeny to tumor tissue.…”

“…Briefly, irradiated and non-irradiated cells were infected with VSV-GFP (MOI ¼ 0.5, 1 and 5) as described previously. At 48 h after infection, culture supernatants from infected cells were collected and virus titers were determined on Vero cells using TCID 50 titration method. As depicted in Figure 3e, cells exposed to 40 Gy were still able to produce significant amounts of VSV-GFP, although there was a slight decrease in progeny virus production compared to non-irradiated cells.…”