Abstract 3844: A novel liposomal Clodronate depletes tumor-associated macrophages in primary and metastatic melanoma: anti-angiogenic and anti-tumor effects

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Abstract The depletion of tumor-associated macrophages (TAMs), involved in different stages of cancer development and progression, is an appealing strategy in cancer therapy. We developed novel Clodronate-containing liposomes (Clo-Lipo-DOTAP) presenting good physicochemical properties (size distribution, polidispersity index and Z-potential). In vitro, Clo-Lipo-DOTAP inhibited proliferation, reduced viability and induced apoptosis of a macrophage-like cell line in a dose- and time-dependent manner. In proof of functionality experiments, Clo-Lipo-DOTAP depleted macrophages in a genetic mouse model of chronic hepatitis and hepatocellular carcinoma leading to a significant reduction of F4/80-positive cells in the liver and spleen of treated mice compared to PBS-treated controls. The number of granulocytes, B and T lymphocytes was not affected. In B16/F10 subcutaneous melanoma-bearing mice, Clo-Lipo-DOTAP significantly reduced the volume of primary tumors (P < 0.001). Within the tumors, the expression F4/80 and α-SMA was significantly lowered. Plasma levels of IL-10, Mo KC, TNF-α, VEGF and PDGF-bb were statistically decreased. In B16/F10 lung metastatic melanoma model, treatment with Clo-Lipo-DOTAP significantly reduced the number of pulmonary nodules (P < 0.05). F4/80-positive cells and microvessel density were statistically decreased. In conclusion, the depletion of TAMs in primary and metastatic melanoma presents anti-tumor efficacy via inhibition of angiogenesis and modulation of inflammation related cytokines. Citation Format: Chiara Brignole, Patrizia Perri, Francesca Piaggio, Fabio Pastorino, Daniela Di Paolo, Laura Emionite, Antonio Daga, Vangelis Kondylis, Manolis Pasparakis, Domenico Ribatti, Mirco Ponzoni. A novel liposomal Clodronate depletes tumor-associated macrophages in primary and metastatic melanoma: anti-angiogenic and anti-tumor effects. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3844.