Combined Treatment of a Murine Breast Cancer Model with Type 5 Adenovirus Vectors Expressing Murine Angiostatin and IL-12: A Role for Combined Anti-Angiogenesis and Immunotherapy

Abstract

In this study, we used intratumor delivery of adenoviral vectors to induce a selective anti-tumor response by combining the potent angiogenesis inhibitor murine angiostatin (adenovirus (Ad)-angiostatin) with the powerful immune simulator and angiostatic cytokine murine IL-12 (Ad-IL-12). In a murine model of breast carcinoma, intratumor injection of Ad-angiostatin delayed mean tumor growth, as compared with control virus with an initial regression of tumor growth, in 65% of treated animals. However, all treated animals eventually succumbed to the tumors. Mice injected with Ad-IL-12 alone responded with an initial regression in 20% of treated animals, with only 13% developing a total regression. Coinjection of the vectors resulted in 96% of the treated animals developing an initial regression, with 54% undergoing a total regression of the tumor. These mice were resistant to tumor rechallenge and developed a strong CTL response. Frozen tumor sections were stained for microvessel density using an Ab against murine CD31, an endothelial cell marker. Automated image analysis revealed the mean microvessel density following the administration of Ad-angiostatin and Ad-IL-12 alone or in combination was significantly reduced compared with the control-treated tumor. In summary, we have shown that a short-term course of antiangiogenic therapy combined with immunotherapy can effectively shrink a solid tumor and vaccinate the animal against rechallenge. The rationale for this therapy is to limit the tumor size by attacking the vasculature with angiostatin, thereby allowing IL-12 to mount a T cell-specific response against the tumor Ag.

Immunotherapy of cancer by IL-12-based cytokine combinations

“…IL-12 has been combined with other anti-angiogenic factors, such as Angiostatin [92], vasostatin [93], and soluble receptors for vascular endothelial growth factor (VEGF) [94]. Similar to the studies involving IP-10+IL-12, the combination of IL-12 with each of these factors was also able to achieve increased tumor regression that was generally associated with reduced microvessel density in tumor sections as well as T cell mediated protection against subsequent tumor rechallenge.…”

New insights into IL-12-mediated tumor suppression

“…71,74 Nevertheless, synergistic antitumor responses in breast cancer have been achieved by combining local adenovirus-mediated gene transfer of IL-12 with T-cell chemoattractants (lymphotactin, CXCL10), costimulatory molecules (B7.1, glucocorticoid induced TNF receptor ligand, 4-1BB ligands), GM-CSF, radiotherapy or antiangiogenic therapy. [77][78][79][80][81][82][83] Furthermore, the combination with chemotherapeutic or antiangiogenic agents in lung, skin and colorectal cancer, or with antiangiogenic agents in prostate cancer proved to be more efficient than viral-mediated IL-12 gene therapy alone in different types of tumors. [84][85][86][87][88][89] Even though local delivery of IL-12 by gene therapy resulted in a more sustained expression of IL-12 in comparison with the levels obtained by injecting the recombinant protein, the lack of selectivity and the occurrence of non-specific immune responses associated with the use of viral vectors remain a major concern when using this strategy to deliver IL-12.…”

Intratumoral coinjection of two adenoviral vectors expressing functional interleukin-18 and inducible protein-10, respectively, synergizes to facilitate regression of established tumors

“…27 Recently, IP -10 was reported necessary for effector T-cell trafficking and function and host survival in Toxoplasma gondii infection. 28 Neutralization of IP-10 inhibited the influx of T cells into spleens and livers of mice infected by T. gondii, resulting in a simultaneous 3 -log increase in the parasite burden and a significant decrease in survival.…”