Co-Administration of Vadimezan and Recombinant Coagulase-NGR Inhibits Growth of Melanoma Tumor in Mice.

Purpose: Tumor vascular targeting appeared as an appealing approach to fight cancer, though, the results from the clinical trials and drugs in the market were proved otherwise. The promise of anti-angiogenic therapy as the leading tumor vascular targeting strategy was negatively affected with the discovery that tumor vascularization can occur non-angiogenic mechanisms such as co-option. An additional strategy is induction of tumor vascular infarction and ischemia. Methods: Such that we used truncated coagulase (tCoa) coupled to tumor endothelial targeting moieties to produce tCoa-NGR fusion proteins. We showed that tCoa-NGR can bypass coagulation cascade to induce selective vascular thrombosis and infarction of mild and highly proliferative solid tumors in mice. Moreover, combination therapy can be used to improve the potential of cancer vascular targeting modalities. Herein, we report combination of tCoa-NGR with vascular disrupting agent (VDA), vadimezan. Results: Our results show that synergistic work of these two agents can significantly suppress growth of B16-F10 melanoma tumors in C57/BL6 mice. Conclusion: For the first time, we used the simultaneous benefits of two strategies for inducing thrombosis and destruction of tumor vasculature as spatial co-operation. The tCoa-NGR induce thrombosis which reduces blood flow in the peripheral tumor region. And combined with the action of DMXAA, which target inner tumor mass, growth and proliferation of melanoma tumors can be significantly suppressed.

An overview on Vadimezan (DMXAA): The vascular disrupting agent.

Vascular disrupting agents (VDAs), a group of cancer remedies, can cause a specific and irreversible destruction of established tumor vessels, and the complete halt of blood flow in the tumor. DMXAA (ASA404) or Vadimezan, a flavone-acetic acid-based drug, is the most promising VDAs that induces a rapid shutdown of blood flow in tumors but not in normal tissue. The exact mechanism of vascular disruption is unknown; however, proposed direct and indirect mechanisms of action for DMXAA comprises (i) inducing apoptosis in endothelial cells; (ii) hemorrhagic necrosis and ischemia in tumor; (iii) release of serotonin (5-HT); (vi) stimulation of innate immune system; (v) production of inflammatory cytokines, for example TNF, IL-6, GCSF, KC, IP-10, and MCP-1; (vi) activation of NFκB and p38 (MAPK); (vii) production of nitric oxide; and (viii) reducing tumor energetics and membrane turnover. Despite the remarkable results from preclinical and phase I/II, DMXAA has failed in phase III clinical trials. The reason for this surprising discrepancy, among others, was discovered to be STING receptor variations between mice and humans. In this review, the development, the mechanisms of DMXAA action, the clinical trials, the combination therapy, and the future of this drug will be discussed.

NGR (Asn-Gly-Arg)-targeted delivery of coagulase to tumor vasculature arrests cancer cell growth.

Induction of selective thrombosis and infarction in tumor-feeding vessels represents an attractive strategy to combat cancer. Here we took advantage of the unique coagulation properties of staphylocoagulase and genetically engineered it to generate a new fusion protein with novel anti-cancer properties. This novel bi-functional protein consists of truncated coagulase (tCoa) and an NGR (GNGRAHA) motif that recognizes CD13 and αvß3 integrin receptors, targeting it to tumor endothelial cells. Herein, we report that tCoa coupled by its C-terminus to an NGR sequence retained its normal binding activity with prothrombin and avß3 integrins, as confirmed in silico and in vitro. Moreover, in vivo biodistribution studies demonstrated selective accumulation of FITC-labeled tCoa-NGR fusion proteins at the site of subcutaneously implanted PC3 tumor xenografts in nude mice. Notably, systemic administration of tCoa-NGR to mice bearing 4T1 mouse mammary xenografts or PC3 human prostate tumors resulted in a significant reduction in tumor growth. These anti-tumor effects were accompanied by massive thrombotic occlusion of small and large tumor vessels, tumor infarction and tumor cell death. From these findings, we propose tCoa-NGR mediated tumor infarction as a novel and promising anti-cancer strategy targeting both CD13 and integrin αvß3 positive tumor neovasculature.