Shira Dorot1, James Tankel1, Victoria Doviner2, Hilary Shmeeda3, Yasmine Amitay4, Patricia Ohana4, Amir Dagan1, Menachem Ben-Haim1, Petachia Reissman1, Alberto Gabizon5,6. 1. Department of Surgery, Shaare Zedek Medical Center and Hebrew University-Faculty of Medicine, Jerusalem, Israel. 2. Department of Pathology, Shaare Zedek Medical Center and Hebrew University-Faculty of Medicine, Jerusalem, Israel. 3. Oncology Institute, Shaare Zedek Medical Center and Hebrew University-Faculty of Medicine, Jerusalem, Israel. 4. Lipomedix Pharmaceuticals Ltd., Jerusalem, Israel. 5. Oncology Institute, Shaare Zedek Medical Center and Hebrew University-Faculty of Medicine, Jerusalem, Israel. alberto.gabizon@gmail.com. 6. Shaare Zedek Nano-oncology Research Center, POB 3235, 12 Shmuel Bayit St., 91031, Jerusalem, Israel. alberto.gabizon@gmail.com.
Abstract
PURPOSE: To examine the ex- vivo ability of explanted human tumors and normal tissue to activate liposomal mitomycin C lipidic prodrug (MLP) by releasing the active free drug form, mitomycin C (MMC). METHODS: We tested conversion of MLP to MMC in an ex vivo assay using explanted tissues obtained during routine surgery to remove primary tumors or metastases. Tumor and adjacent normal tissue were obtained from freshly explanted tumors and were immediately deep frozen at - 70 °C. On test day, the fragments were thawed, homogenized and incubated in the presence of a fixed amount of liposomal MLP at 37 °C for 1 h. We measured MLP and its rate of conversion to MMC by HPLC. Controls included plasma, malignant effusions, red blood cells, tumor cell lines, mouse liver, and buffer with dithiothreitol, a potent reducing agent. RESULTS: Most patients tested (16/20) were diagnosed with colo-rectal carcinoma. The average fraction of MLP cleaved per 100-mg tumor tissue (21.1%, SEM = 1.8) was greater than per 100-mg normal tissue (16.6%, SEM = 1.3). When the tumor and normal tissue samples were paired by patient, the difference was statistically significant (p = 0.022, paired t test). Biological fluids did not activate liposomal MLP, while normal liver tissue strongly does. Interestingly, the omental fatty tissue also greatly activated MLP. CONCLUSIONS: Tumor tissue homogenates activate MLP with greater efficiency than the surrounding normal tissues, but far less than liver and adipose tissue. These observations demonstrate the bioavailability of liposomal MLP in human tumors, and its pharmacologic potential in cancer therapy.
PURPOSE: To examine the ex- vivo ability of explanted human tumors and normal tissue to activate liposomal mitomycin C lipidic prodrug (MLP) by releasing the active free drug form, mitomycin C (MMC). METHODS: We tested conversion of MLP to MMC in an ex vivo assay using explanted tissues obtained during routine surgery to remove primary tumors or metastases. Tumor and adjacent normal tissue were obtained from freshly explanted tumors and were immediately deep frozen at - 70 °C. On test day, the fragments were thawed, homogenized and incubated in the presence of a fixed amount of liposomal MLP at 37 °C for 1 h. We measured MLP and its rate of conversion to MMC by HPLC. Controls included plasma, malignant effusions, red blood cells, tumor cell lines, mouse liver, and buffer with dithiothreitol, a potent reducing agent. RESULTS: Most patients tested (16/20) were diagnosed with colo-rectal carcinoma. The average fraction of MLP cleaved per 100-mg tumor tissue (21.1%, SEM = 1.8) was greater than per 100-mg normal tissue (16.6%, SEM = 1.3). When the tumor and normal tissue samples were paired by patient, the difference was statistically significant (p = 0.022, paired t test). Biological fluids did not activate liposomal MLP, while normal liver tissue strongly does. Interestingly, the omental fatty tissue also greatly activated MLP. CONCLUSIONS: Tumor tissue homogenates activate MLP with greater efficiency than the surrounding normal tissues, but far less than liver and adipose tissue. These observations demonstrate the bioavailability of liposomal MLP in human tumors, and its pharmacologic potential in cancer therapy.
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Authors: Uma Prabhakar; Hiroshi Maeda; Rakesh K Jain; Eva M Sevick-Muraca; William Zamboni; Omid C Farokhzad; Simon T Barry; Alberto Gabizon; Piotr Grodzinski; David C Blakey Journal: Cancer Res Date: 2013-02-19 Impact factor: 12.701
Authors: Talia Golan; Tal Grenader; Patricia Ohana; Yasmine Amitay; Hilary Shmeeda; Ninh M La-Beck; Esther Tahover; Raanan Berger; Alberto A Gabizon Journal: Cancer Med Date: 2015-07-14 Impact factor: 4.452