Simvastatin increases the antineoplastic actions of paclitaxel carried in lipid nanoemulsions in melanoma-bearing mice.

PURPOSE: Lipid nanoemulsions (LDEs) that bind to low-density lipoprotein (LDL) receptors used as carriers of paclitaxel (PTX) can decrease toxicity and increase PTX antitumoral action. The administration of simvastatin (Simva), which lowers LDL-cholesterol, was tested as an adjuvant to commercial PTX and to PTX associated with LDE (LDE-PTX). MATERIALS AND METHODS: B16F10 melanoma-bearing mice were treated with saline solution or LDE (controls), Simva, PTX, PTX and Simva, LDE-PTX, and LDE-PTX and Simva: PTX dose 17.5 µmol/kg (three intraperitoneal injections, 3 alternate days): Simva 50 mg/kg/day by gavage, 9 consecutive days. RESULTS: Compared with saline controls, 95% tumor-growth inhibition was achieved by LDE-PTX and Simva, 61% by LDE-PTX, 44% by PTX and Simva, and 43% by PTX. Simva alone had no effect. Metastasis developed in only 37% of the LDE-PTX and Simva, 60% in LDE-PTX, and 90% in PTX and Simva groups. Survival rates were higher in LDE-PTX and Simva and in LDE-PTX groups. The LDE-PTX and Simva group presented tumors with reduced cellular density and increased collagen fibers I and III. Tumors from all groups showed reduction in immunohistochemical expression of ICAM, MCP-1, and MMP-9; LDE-PTX and Simva presented the lowest MMP-9 expression. Expression of p21 was increased in the Simva, LDE-PTX, and LDE-PTX and Simva groups. In the Simva and LDE-PTX and Simva groups, expression of cyclin D1, a proliferation and survival promoter of tumor cells, was decreased. Therapy with LDE-PTX and Simva showed negligible toxicity compared with PTX and Simva, which resulted in weight loss and myelosuppression. CONCLUSION: Simva increased the antitumor activity of PTX carried in LDE but not of PTX commercial presentation, possibly because statins increase the expression of LDL receptors that internalize LDE-PTX.

Association of daunorubicin to a lipid nanoemulsion that binds to low-density lipoprotein receptors enhances the antitumour action and decreases the toxicity of the drug in melanoma-bearing mice.

OBJECTIVES: To test the toxicity and antitumoral activity of the compound N-oleyl-daunorubicin (oDNR) with a cholesterol-rich nanoemulsion (LDE) formulation. METHODS: LDE-oDNR was prepared by high-pressure homogenisation of lipid mixtures. B16F10 melanoma cells and NIH/3T3 fibroblasts were used for cytotoxicity tests. The maximum tolerated dose (MTD) of both commercial and LDE-oDNR was determined in mice, and melanoma-bearing mice were used for the antitumoral activity tests. KEY FINDINGS: CC50 for LDE-oDNR and DNR in melanoma cells were 200 µm and 15 µm, respectively, but LDE-oDNR was less toxic against fibroblasts than DNR. MTD for LDE-oDNR was 65-fold higher than commercial DNR. In tumour-bearing mice, LDE-oDNR (7.5 µmol/kg) reduced tumour growth by 59 ± 2%, whereas the reduction by DNR was only 23 ± 2%. LDE-oDNR increased survival rates (P < 0.05), which was not achieved by DNR treatment. The number of mice with metastasis was only 30% in LDE-oDNR-treated mice, compared with 82% under DNR treatment. By flow cytometry, there were 9% viable cells in tumours of animals treated with LDE-oDNR compared with 27% in DNR-treated animals. Less haematological toxicity was observed in LDE-oDNR-treated mice. CONCLUSIONS: Compared with DNR, LDE-oDNR improved tumour growth inhibition and survival rates with pronouncedly less toxicity, and thus may become a new tool for cancer treatment.

Drug-targeting in combined cancer chemotherapy: tumor growth inhibition in mice by association of paclitaxel and etoposide with a cholesterol-rich nanoemulsion.

BACKGROUND: Lipid nanoemulsions (LDE) may be used as carriers of paclitaxel (PTX) and etoposide (ETP) to decrease toxicity and increase the therapeutic action of those drugs. The current study investigates the combined chemotherapy with PTX and ETP associated with LDE. METHODS: Four groups of 10-20 B16F10 melanoma-bearing mice were treated with LDE-PTX and LDE-ETP in combination (LDE-PTX + ETP), commercial PTX and ETP in combination (PTX + ETP), single LDE-PTX, and single LDE-ETP. PTX and ETX doses were 9 µmol/kg administered in three intraperitoneal injections on three alternate days. In two control groups mice were treated with saline solution or LDE alone. Tumor growth, metastasis presence, cell-cycle distribution, blood cell counts and histological data were analyzed. Toxicity of all treatments was evaluated in mice without tumors. RESULTS: Tumor growth inhibition was similarly strong in all treatment groups. However, there was a greater reduction in the number of animals bearing metastases in the LDE-PTX + ETP group (30 %) in comparison to the PTX + ETP group (82 %, p < 0.05). Reduction of cellular density, blood vessels and increase of collagen fibers in tumor tissues were observed in the LDE-PTX + ETP group but not in the PTX + ETP group, and in both groups reduced melanoma-related anemia and thrombocytosis were observed. Flow cytometric analysis suggested that LDE-PTX + ETP exhibited greater selectivity to neoplastic cells than PTX-ETP, showing arrest (65 %) in the G(2)/M phase of the cell cycle (p < 0.001). Toxicity manifested by weight loss and myelosuppression was markedly milder in the LDE-PTX + ETP than in the PTX + ETP group. CONCLUSION: LDE-PTX + ETP combined drug-targeting therapy showed markedly superior anti-cancer properties and reduced toxicity compared to PTX + ETP.

Novel formulation of a methotrexate derivative with a lipid nanoemulsion.

BACKGROUND: Lipid nanoemulsions that bind to low-density lipoprotein receptors can concentrate chemotherapeutic agents in tissues with low-density lipoprotein receptor overexpression and decrease the toxicity of the treatment. The aim of this study was to develop a new formulation using a lipophilic derivative of methotrexate, ie, didodecyl methotrexate (ddMTX), associated with a lipid nanoemulsion (ddMTX-LDE). METHODS: ddMTX was synthesized by an esterification reaction between methotrexate and dodecyl bromide. The lipid nanoemulsion was prepared by four hours of ultrasonication of a mixture of phosphatidylcholine, triolein, and cholesteryloleate. Association of ddMTX with the lipid nanoemulsion was performed by additional cosonication of ddMTX with the previously prepared lipid nanoemulsion. Formulation stability was evaluated, and cell uptake, cytotoxicity, and acute animal toxicity studies were performed. RESULTS: The yield of ddMTX incorporation was 98% and the particle size of LDE-ddMTX was 60 nm. After 48 hours of incubation with plasma, approximately 28% ddMTX was released from the lipid nanoemulsion. The formulation remained stable for at least 45 days at 4°C. Cytotoxicity of LDE-ddMTX against K562 and HL60 neoplastic cells was higher than for methotrexate (50% inhibitory concentration [IC(50)] 1.6 versus 18.2 mM and 0.2 versus 26 mM, respectively), and cellular uptake of LDE-ddMTX was 90-fold higher than that of methotrexate in K562 cells and 75-fold in HL60 cells. Toxicity of LDE-ddMTX, administered at escalating doses, was higher than for methotrexate (LD(50) 115 mg/kg versus 470 mg/kg; maximum tolerated dose 47 mg/kg versus 94 mg/kg) in mice. However, the hematological toxicity of LDE-ddMTX was lower than for methotrexate. CONCLUSION: LDE-ddMTX was stable, and uptake of the formulation by neoplastic cells was remarkably greater than of methotrexate, which resulted in markedly greater cytotoxicity. LDE-ddMTX is thus a promising formulation to be tested in future animal models of cancer or rheumatic disease, wherein methotrexate is widely used.

Novel formulation of a methotrexatederivative with a lipid nanoemulsion

Lipid nanoemulsions that bind to low-density lipoprotein receptors can concentrate chemotherapeutic agents in tissues with low-density lipoprotein receptor overexpression anddecrease the toxicity of the treatment. The aim of this study was to develop a new formulation using a lipophilic derivative of methotrexate, ie, didodecyl methotrexate (ddMTX), associatedwith a lipid nanoemulsion (ddMTX-LDE).ddMTX was synthesized by an esterification reaction between methotrexate and dodecyl bromide. The lipid nanoemulsion was prepared by four hours of ultrasonication of a mixture of phosphatidylcholine, triolein, and cholesteryloleate. Association of ddMTX with the lipid nanoemulsion was performed by additional cosonication of ddMTX with the previously prepared lipid nanoemulsion. Formulation stability was evaluated, and cell uptake, cytotoxicity, and acute animal toxicity studies were performed. The yield of ddMTX incorporation was 98% and the particle size of LDE-ddMTX was 60 nm. After 48 hours of incubation with plasma, approximately 28% ddMTX was released from the lipid nanoemulsion. The formulation remained stable for at least 45 days at 4°C. Cytotoxicity of LDE-ddMTX against K562 and HL60 neoplastic cells was higher than for methotrexate (50% inhibitory concentration [IC50] 1.6 versus 18.2 mM and 0.2 versus 26 mM, respectively), and cellular uptake of LDE-ddMTX was 90-fold higher than that of methotrexate in K562 cells and75-fold in HL60 cells. Toxicity of LDE-ddMTX, administered at escalating doses, was higher than for methotrexate (LD50 115 mg/kg versus 470 mg/kg; maximum tolerated dose 47 mg/kgversus 94 mg/kg) in mice. However, the hematological toxicity of LDE-ddMTX was lower than for methotrexate.LDE-ddMTX was stable, and uptake of the formulation by neoplastic cells wasremarkably greater than of methotrexate, which resulted in markedly greater cytotoxicity.