Neoadjuvant administration of Semliki Forest virus expressing interleukin-12 combined with attenuated Salmonella eradicates breast cancer metastasis and achieves long-term survival in immunocompetent mice

Abstract

BackgroundMetastatic breast cancer is a major cause of death among women worldwide; therefore efficient therapeutic strategies are extremely needed. In this work we have developed a gene therapy- and bacteria-based combined neoadjuvant approach and evaluated its antitumor effect in a clinically relevant animal model of metastatic breast cancer.Methods2×108 particles of a Semliki Forest virus vector expressing interleukin-12 (SFV-IL-12) and/or 2×107 units of an aroC− Samonella Typhimurium strain (LVR01) were injected into 4T1 tumor nodules orthotopically implanted in mice. Tumors were surgically resected and long-term survival was determined. IL-12 and interferon-γ were quantified by Enzyme-Linked ImmunoSorbent Assay, bacteria was visualized by inmunohistochemistry and the number of lung metastasis was calculated with a clonogenic assay.ResultsSFV-IL-12 and LVR01 timely inoculated and followed by surgical resection of tumors succeeded in complete inhibition of lethal lung metastasis and long-term survival in 90 % of treated mice. The combined therapy was markedly synergistic compared to each treatment alone, since SFV-IL-12 monotherapy showed a potent antiangiogenic effect, being able to inhibit tumor growth and extend survival, but could not prevent establishment of distant metastasis and death of tumor-excised animals. On the other hand, LVR01 alone also showed a significant, although limited, antitumor potential, despite its ability to invade breast cancer cells and induce granulocyte recruitment. The efficacy of the combined therapy depended on the order in which both factors were administered; inasmuch the therapeutic effect was only observed when SFV-IL-12 was administered previous to LVR01, whereas administration of LVR01 before SFV-IL-12 had negligible antitumor activity. Moreover, pre-treatment with LVR01 seemed to suppress SFV-IL-12 antiangiogenic effects associated to lower IL-12 expression in this group. Re-challenged mice were unable to reject a second 4T1 tumor; however 100 % of them could be totally cured by applying the same neoadjuvant combined regimen. To our knowledge, these are the most encouraging results obtained to date in a post-operatory setting using the highly aggressive 4T1 animal model.ConclusionsSFV-IL-12-based gene therapy combined with Salmonella LVR01 neoadjuvant administration has a synergic antitumor effect and may be a promising therapeutic option to prevent and/or eradicate pre-operatory metastasis in locally advanced breast cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1618-x) contains supplementary material, which is available to authorized users.

Salmonella Immunotherapy Improves the Outcome of CHOP Chemotherapy in Non-Hodgkin Lymphoma-Bearing Mice

“…8685718). LVR01 demonstrated also great potential as immunotherapy in the A20 mouse models of B-NHL ( 24 , 25 ) as well as in 4T1 breast cancer ( 26 ) and B16 melanoma (our own unpublished results).…”

Delivering safer immunotherapies for cancer

“…For example, i.t. injection of an adenovirus or alphavirus expressing IL-12 induced highly localized cytokine expression in tumors, leading to tumor regression and long-term immunity [181, 182]. Intralesional injection of adenovirus encoding human CC chemokine ligand (CCL) 16 inhibited mammary tumor growth and prevented metastatic spread in mice bearing 4T1 mammary adenocarcinoma [183].…”

Bacterial Therapy of Cancer: Promises, Limitations, and Insights for Future Directions

“…However, in most models bacteria mono-therapies are not sufficient to eliminate a primary tumor or the metastatic burden. Combined therapies including chemotherapy ( Dang et al, 2001 ; Yamamoto et al, 2016 ; Yano et al, 2016 ), radiotherapy ( Jiang et al, 2010 ), traditional herbal medicine ( Zhang et al, 2013 ), anti-angiogenic and/or immunotherapy ( Binder et al, 2013 ; Kramer et al, 2015 ) or the use of bacteria carrying plasmids coding for anti-tumor genes (reviewed in Moreno et al, 2010 ; Nguyen and Min, 2017 ) have shown enhanced results. Based on the use of eukaryotic gene-expression systems it has been suggested that bacteria can act as vector systems for plasmid transfer to mammalian cancer cells, a process known as “bactofection” ( Weiss and Chakraborty, 2001 ; Baban et al, 2010 ; Othman et al, 2013 ).…”

“… Direct and synergystic anti-tumor effects of attenuated S. Typhimurium integrating cellular and systemic immune responses. (A) Induction of cell death and granulocyte recruitment associated with intracellular replication of attenuated S. Typhimurium LVR01 ( Salmonella ), which previously showed a modest antitumor effect in the 4T1 metastatic breast cancer model ( Kramer et al, 2015 ). (a) Confocal microscopy indicates bacteria invasion and replication in breast cancer cell lines: 4T1 (ATCC-CRL2539) (upper line) and NMU (ATCC-CRL1743) (lower line) in a time-course experiment.…”

“…In tumors, bacterial infection is associated with tumor-tissue architecture deterioration, a rise in granulocytic cells and INF-γ induction and a decrease of intra-tumor macrophages ( Avogadri et al, 2005 ; Westphal et al, 2008 ; Zheng et al, 2017 ). Late effects (10–20 days after bacteria administration) are characterized by a moderate decrease in tumor size, adaptive immune responses including INF-γ production, antibody recognition of tumor antigens, and cytotoxic immune activities ( Avogadri et al, 2005 ; Kramer et al, 2015 ; Masner et al, unpublished results). Repeated administration of attenuated bacteria could result in a better targeting of metastases ( Zhao et al, 2012 ), while stimulating immune responses that enhance cancer-cell elimination.…”