[The effect of lipid derivative of anti-tumor drug sarcolysin embedded in phospholipid nanoparticles in the experiments in vivo]

To improve the therapeutic properties of the antitumor agent Sarcolysin, we have previously developed and characterized a dosage form representing its ester conjugate with decanol embedded in ultra-small phospholipid nanoparticles less than 30 nm in size ("Sarcolysin-NP"). The effect of the resulting composition was investigated in vivo in comparison with the free substance of sarcolysin. The composition intravenous administration to mice showed an improvement in the pharmacokinetic parameters of sarcolysin associated with its initial higher (by 22%) level in the blood and prolonged circulation, which was also observed in mice with P388 tumor. In mice with three types of tumors - lymphocytic leukemia P388, lymphocytic leukemia L1210, and adenocarcinoma of the mammary gland Ca755 - administration of two doses of sarcolysin over a period of 7 days showed its predominant antitumor effect. The maximum tumor growth inhibition was noted for lymphocytic leukemia L1210 and adenocarcinoma of the mouse mammary gland Ca755 (at a dose of Sarcolysin-NP - 8,4 mg/kg), which was higher in comparison with free substance by more than 24% and 17%, respectively. Differences in the life span of the treated animals were revealed significantly at a dose of 10 mg/kg and amounted to 25% and 17,4% for lymphocytic leukemia P388 and L1210, respectively, and 11% for adenocarcinoma Ca755. In an experiment on rats, acute toxicity of Sarcolysin-NP administered intravenously showed that an average LD50 value 2-3 times exceeded a similar parameter for commercial preparations of free sarcolysin (Melphalan and Alkeran), which indicates its lower toxicity.

Liposomal Formulation of a Melphalan Lipophilic Prodrug: Studies of Acute Toxicity, Tolerability, and Antitumor Efficacy

BACKGROUND

Recently we developed a scalable scheme of synthesis of melphalan ester conjugate with 1,2-dioleoyl-sn-glycerol (MlphDG) and a protocol for the fabrication of its lyophilized liposomal formulation.

OBJECTIVE

Herein we compared this new convenient in use formulation of MlphDG with parent drug Alkeran® in rats concerning several toxicological parameters and evaluated its antitumor efficacy in the model of breast cancer in mice.

METHOD

Liposomes of approximately 100 nm in diameter, consisting of egg phosphatidylcholine, soybean phosphatidylinositol, and MlphDG, or placebo liposomes without the drug were produced by extrusion and lyophilized. Alkeran® or liposomes recovered by the addition of water were injected into the tail vein of animals. Clinical examination of rats consisted of detailed inspection of the behavior, general status, and hematological parameters. Mice with transplanted breast cancer WNT-1 were subjected to multiple treatments with the drugs; tumor growth inhibition was assessed, together with cellular immunity parameters.

RESULTS

Liposomes showed approximately two times lower acute toxicity and better tolerability than Alkeran® in terms of behavioral criteria. The toxic effects of liposomes on hemopoiesis were manifested at higher doses than in the case of Alkeran®, proportionally to the difference in LD50 values. The formulation inhibited tumor growth significantly more effectively than Alkeran®, delaying the start of the exponential growth phase and exhibiting no additional toxic effects toward bone marrow.

CONCLUSION

Lower toxicity of the liposomal formulation of MlphDG promises improved quality of life for cancer patients in need of treatment with melphalan. Presumably, the list of indications for melphalan therapy could be extended.

Fragment-based approach to novel bioactive purine derivatives

Using purine as a scaffold, the methods for preparation of novel 2-aminopurine and purine derivatives substituted at position C 6 by the fragments of natural amino acids, short peptides, and N-heterocycles, including enantiopure ones, have been proposed. The methods for determination of the enantiomeric purity of the obtained chiral compounds have been developed. Conjugates exhibiting high antimycobacterial or anti-herpesvirus activity against both laboratory and multidrug-resistant strains were revealed among the obtained compounds.

Multi-targeted approach by 2-benzimidazolylquinoxalines-loaded cationic arginine liposomes against сervical cancer cells in vitro

Multi-targeted approaches for inhibition of сervical cancer cells in vitro were developed by implementing two different strategies and drug combination for creation of new therapeutic target agents and for nanotechnological-enhancement of intracellular delivery. New 2-benzimidazolylquinoxalines derivatives were synthesized and characterized by combining two different pharmacophores - benzimidazole and quinoxaline rings directly bonded in their structures. Spectrophotometric technique for determination of content of compounds in various media was developed to evaluate their solubility in water and micellar solutions of surfactants. The bioavailability of poorly water-soluble 2-benzimidazolylquinoxalines was improved by PEGylated liposomes as antitumor drug delivery carriers. 2-benzimidazolylquinoxalines-loaded PEGylated liposomes, with size close to 100 nm and negative zeta potential ranging from -13 mV to -27 mV, were time-stable at room temperature. The design of liposomal formulations for improving cellular uptake and in vitro antitumor efficacy was performed by modification of liposome surface with the new arginine surfactant. The cell viability of 2-benzimidazolylquinoxalines-loaded arginine liposomes on human cancer M-Hela cells was 16% at the concentration 0.15 mg/ml. Moreover, these liposomes showed a lower toxicity (40%) against normal human Gang liver cells both at the lowest and highest tested concentrations.

Targeting liposomes loaded with melphalan prodrug to tumour vasculature via the Sialyl Lewis X selectin ligand

Earlier we showed that liposome formulation of DL-melphalan lipophilic prodrug bearing tetrasaccharide Sialyl Lewis X (SiaLe^X) caused prolonged therapeutic effect on mammary cancer in mice. Here, we compare antivascular effect of SiaLe^X-liposomes loaded with diglyceride ester of melphalan (Mlph) against SiaLe^X-free formulation in Lewis lung carcinoma model.

METHODS

Liposomes of egg phosphatidylcholine/yeast phosphatidylinositol/1,2-dioleoyl glycerol (DOG) conjugate of Mlph/±SiaLe^X-PEG_8-15-DOG, 8:1:1:0.2 by mol, were prepared by standard extrusion. After two intravenous injections with Mlph or liposomes under either standard or delayed treatment protocols, vascular-disrupting effects of the preparations were evaluated basing on tumour section histomorphology, lectin perfusion assay and immunohistochemistry (anti-CD31 staining) data. Also, untreated mice were administered with fluorescently-labelled liposomes to assess their distribution in tumour sections with confocal laser scanning microscopy.

RESULTS

Two injections of SiaLe^X-liposomes reproducibly caused severe injuries of tumour vessels. SiaLe^X-liposomes co-localized with CD31 marker on vascular endothelium while the non-targeted formulation extravasated into tumour.

DISCUSSION

Cytotoxic SiaLe^X-liposomes exhibit superior vascular-disrupting properties compared to non-targeted liposomes, yet the effect starts to transform into gain in tumour growth inhibition only under delayed treatment regimen.

CONCLUSION

SiaLe^X-ligand provides targeting of cytotoxic liposomes to tumour endothelium and subsequent antivascular effect.