Coupling of 5-fluoro 2'-deoxyuridine to lactosaminated poly-l-lysine: an approach to a regional, non-invasive chemotherapy of liver micrometastases

Therapeutic efficacy of DNA-Loaded PLGA microspheres in tumor-bearing mice

In vivo gene therapy was attempted using poly-(D,L-lactic-co-glycolic acid) microspheres containing the interleukin-12 gene (p2CMVmlL12) in colon adenocarcinoma (CT-26)-bearing Balb/ c mice. Treatment with IL-12-loaded microspheres inhibited tumor growth significantly compared to a control group treated with free IL-12 DNA, though the degree of tumor inhibition was not dependent on the amount of IL-12 gene loaded. Combining gene therapy with 5-fluorouracil (50 mg/kg) treatment further inhibited tumor growth compared with gene therapy alone. The results indicate that microsphere formulations of pDNA may provide an efficient gene delivery system.

Inducing a change in the pharmacokinetics and biodistribution of poly-L-lysine in rats by complexation with heparin

The aim of our study was to induce changes in the plasma elimination half-life (t(1/2)(elim)), rate and extent of urinary excretion, and biodistribution of a model macromolecule, poly-L-lysine, in rats following complexation with heparin. Male Sprague-Dawley rats were dosed intravenously with either unfractionated [(3)H]heparin, FITC-labelled poly-L-lysine, or an [(3)H]heparin:FITC-labelled poly-L-lysine complex. Serum and blood concentration vs time and urinary excretion profiles were determined as well as the resulting patterns of biodistribution to liver, spleen, kidney, and muscle tissue. While the mean values for the total body clearance of poly-L-lysine and the complex were not significantly different, the volume of distribution and the half-life associated with elimination from the serum were increased greater than 2-fold for the complex compared with free poly-L-lysine. The rate and extent of elimination in the urine followed the relative rank order; heparin > poly-L-lysine> heparin:poly-L-lysine complex. Thirty minutes following intravenous administration, there was significantly more tissue deposition/uptake of the complex in the liver, kidney, and muscle, but not the spleen, when compared with poly-L-lysine administered alone. Complexation of heparin to poly-L-lysine effectively increased the fraction of an administered dose of poly-L-lysine that was deposited in liver, kidney, and muscle tissue. Due to the macromolecular complex being nontoxic and uncharged, potentially it might serve as a suitable carrier for both conventional and peptidic drugs to increase drug distribution to liver, kidney, or muscle tissue.

Floxuridine coupling with lactosaminated human albumin to increase drug efficacy on liver micrometastases

BACKGROUND

Conjugates of nucleoside analogues with galactosyl terminating peptides selectively enter hepatocytes through the asialoglycoprotein receptor. After intracellular release from the carrier, the drugs partly exit from hepatic cells into hepatic blood.

AIMS

To establish whether administration of a conjugate of floxuridine with lactosaminated human albumin selectively enhances drug concentrations in hepatic blood. Floxuridine is a fluoropyrimidine active on human colorectal cancer, a tumour which metastasises first to the liver.

METHODS

In rats injected with free or conjugated floxuridine, plasma levels of the drug were determined in hepatic veins and in inferior vena cava, in order to measure drug concentrations in hepatic blood and in the systemic circulation, respectively.

RESULTS

Ratios between floxuridine levels in hepatic veins and those in systemic circulation were found to be seven times higher in rats injected with the conjugate (p=0.000).

CONCLUSIONS

The present results suggest that coupling to lactosaminated albumin might improve the effect of floxuridine in adjuvant chemotherapy of colorectal cancer by exposing the cells of liver micrometastases (nourished by hepatic sinusoids) to enhanced drug concentrations.