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Trabectedin is a marine-derived antineoplastic drug. Besides targeting the cancer cells, trabectedin has a peculiar activity on the tumor microenvironment with marked effects on the vasculature and the immune response. Because a favorable microenvironment is a key factor in the progression of cutaneous melanoma, we hypothesized that trabectedin might affect the growth and metastasis of this highly aggressive cancer. This study shows that trabectedin inhibited the subcutaneous growth of the murine melanoma B16-BL6 and K1735-M2. In line with its known activities on the environment of other tumor types, it caused a significant reduction of tumor blood vessel density and tumor-associated macrophages. Trabectedin had a significant antimetastatic activity, inhibiting the formation of lung colonies following intravenous injection of B16-BL6 or K1735-M2 cells. The drug was also active in a clinically relevant spontaneous metastasis assay, where it inhibited lung metastasis when administered before (neoadjuvant) or after (adjuvant) surgical removal of the primary tumor. Relevant to its antimetastatic activity, trabectedin inhibited melanoma cell invasiveness in vitro, associated with increased tissue inhibitor of metalloproteinase-1 production and alteration in cell shape and cytoskeleton organization. This study shows that trabectedin affects melanoma growth and metastasis, acting with tumor-dependent mechanisms on both the tumor cells and the vascular and the inflammatory tumor microenvironment. [ABSTRACT FROM AUTHOR]

The tubulin-binding agent ZD6126 is a novel vascular-targeting agent in clinical development for the treatment of solid tumors. In vivo, ZD6126 is rapidly converted into N-acetylcolchinol (ZD6126 phenol). In this study, we have explored the antivascular property of N-acetylcolchinol in vitro and ZD6126 in vivo. In cell culture, N-acetylcolchinol induced rapid changes in the morphology of human umbilical vein and lung microvessel endothelial cells. Within 40 min, the compound induced endothelial cell contraction, destabilization of the tubulin cytoskeleton, induction of actin stress fibers, and membrane blebbing. These effects occurred at noncytotoxic concentrations and were rapidly reversed on removal of the drug. Nonconfluent endothelial cells were more sensitive than confluent, quiescent cells. Among different cell types, endothelial cells were the most sensitive to the induction of morphological changes, whereas smooth muscle cells were not affected. In vitro, N-acetylcolchinol rapidly disrupted a network of newly formed cords. In vivo, ZD6126 caused shut down of newly formed vessels in the Matrigel plug assay, shortly after injection. This study indicates that rapid alteration of endothelial cell morphology may be responsible for the loss of tumor blood vessel integrity, vessel shut down, and extensive tumor necrosis induced by ZD6126 in experimental tumor models.

Purpose: We previously reported that paclitaxel, a microtubule-stabilizing drug, inhibited angiogenesis, mainly by inhibiting endothelial cell motility (D. Belotti et al., Clin. Cancer Res., 2: 1843-1849, 1996). The aim of this study was to select a taxane with little cytotoxicity but with antimotility and hence antiangiogenic activity., Experimental Design: Different taxanes, seco derivatives, and 14-beta-hydroxy-10-deacetyl baccatin III derivatives were tested for their effects on the proliferation and motility of human umbilical vein endothelial cells. The antiangiogenic and antineoplastic activities of the compound selected from this screening were further investigated in experimental models in vitro and in vivo., Results: From the screening of different taxanes, we selected IDN 5390, a seco derivative that showed potent antimotility activity and less cytotoxicity than paclitaxel. In comparable experimental conditions, IDN 5390 inhibited endothelial cell migration without affecting proliferation. This compound dose-dependently inhibited the capacity of human umbilical vein endothelial cells plated on Matrigel to organize into a network of cords. In vivo, IDN 5390 significantly inhibited fibroblast growth factor-2-induced angiogenesis in Matrigel implants. Daily treatment with IDN 5390 in mice bearing established lung micrometastases from the B16BL6 murine melanoma caused a reduction in the size of metastases. Finally, IDN 5390 slowed the s.c. growth of the paclitaxel-resistant human ovarian carcinoma, 1A9/PTX22, xenografted in nude mice., Conclusions: The seco derivative IDN 5390 might represent the prototype of a new class of taxane derivatives with antiangiogenic properties.