PURPOSE Develop and characterize a micellar formulations of N-{[(2-hydroxy-5-nitrophenyl)amino]carbonothioyl}-3,5-dimethylbenzamide (DM-PIT-1) – a new small molecule non-lipid antagonist of phopshotidylinositol-3.4.5-triphopshate and inhibitor of the PI3-kinase pathway. METHODS Micelle-forming PEG2000-PE was used to solubilize DM-PIT-1. To improve the specificity of the micellar DM-PIT-1, cancer-targeting anti-nucleosomal mAb2C5 antibodies as well as Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL) were attached to the surface of polymeric micelles. RESULTS DM-PIT-1 was effectively incorporated (>70%) into 14–16 nm micelles, which had a negative surface zeta potential of 4–5 mV. Micellar DM-PIT-1 demonstrated high in vitro cytotoxicity against various cancer cells. An improved potency of the dual-activity DM-PIT-1/TRAIL combination nanoparticles in inducing death of TRAIL-resistant cancer cells was shown. Efficacy of the TRAIL therapy was enhanced by combining it with the 2C5 antibody cancer-targeted micellar form of DM-PIT-1. CONCLUSIONS DM-PIT-1 micellar preparations can be used for targeted combination therapy against TRAIL-resistant cancers.

Polyethylene glycol (PEG)-diacyl lipid micelles have been prepared by loading with the hydrophobic meso-5,10,15,20-tetraphenyl-21H,23H-porphine (TPP) and used for the photodynamic treatment of B-16 melanoma cells in vitro and in vivo. The use of PEG-PE micelles allowed for a 150-fold increased the solubilization of TPP, compared with the native drug. The average size of the PEG-PE micelles was in the range of 10 -12 nm with a narrow size distribution. At 50 mg/ml of TPP in micelles with an irradiation intensity of 4.5 -21.5 mW/cm 2 , the viability of B-16 melanoma cells in vitro decreased in a fluencedependent manner. A highly effective outcome of photodynamic therapy (PDT) with TPP-loaded PEG-PE micelles can be further increased by modifying such micelles with cancer-specific monoclonal antibody 2C5 to TPP-loaded micelles to tumor cells. TPP-containing 2C5-modified micelles provided the strongest phototoxic effect against B-16 cells in vitro compared with TPP-loaded plain micelles at the same TPP concentration. The association of TPP-loaded immuno-targeted micelles with melanoma cells was also studied by flow cytometry. An increase in cell association was found for 2C5-targeted micelles compared with non-targeted micelles. In vivo, the PDT treatment of subcutaneous melanoma-bearing C57BL/6 mice with 100 mW/cm 2 of 630 nm laser light 9 h after the administration of the micellar TPP (1 mg/kg of TPP) resulted in a significant inhibition of tumor growth. Compared with controls, the weight of postmortem tumors was approx. 3.5-and 7.5-fold smaller with TPP-loaded PEG-PE micelles and TPP-loaded PEG-PE 2C5-immunomicelles, respectively.