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.

Doxorubicin-loaded PLGA nanoparticles for the chemotherapy of glioblastoma: Towards the pharmaceutical development.

Brain delivery of drugs by nanoparticles is a promising strategy that could open up new possibilities for the chemotherapy of brain tumors. As demonstrated in previous studies, the loading of doxorubicin in poly(lactide-co-glycolide) nanoparticles coated with poloxamer 188 (Dox-PLGA) enabled the brain delivery of this cytostatic that normally cannot penetrate across the blood-brain barrier in free form. The Dox-PLGA nanoparticles produced a very considerable anti-tumor effect against the intracranial 101.8 glioblastoma in rats, thus representing a promising candidate for the chemotherapy of brain tumors that warrants clinical evaluation. The objective of the present study, therefore, was the optimization of the Dox-PLGA formulation and the development of a pilot scale manufacturing process. Optimization of the preparation procedure involved the alteration of the technological parameters such as replacement of the particle stabilizer PVA 30-70 kDa with a presumably safer low molecular mass PVA 9-10 kDa as well as the modification of the external emulsion medium and the homogenization conditions. The optimized procedure enabled an increase of the encapsulation efficiency from 66% to >90% and reduction of the nanoparticle size from 250 nm to 110 nm thus enabling the sterilization by membrane filtration. The pilot scale process was characterized by an excellent reproducibility with very low inter-batch variations. The in vitro hematotoxicity of the nanoparticles was negligible at therapeutically relevant concentrations. The anti-tumor efficacy of the optimized formulation and the ability of the nanoparticles to penetrate into the intracranial tumor and normal brain tissue were confirmed by in vivo experiments.

Toxicological study of doxorubicin-loaded PLGA nanoparticles for the treatment of glioblastoma.

Doxorubicin loaded in poloxamer 188-coated PLGA nanoparticles (Dox-NP + P188) was shown to produce a high antitumor effect against the experimental orthotopic 101.8 glioblastoma in rats upon intravenous administration. The objective of the present study was to evaluate the acute and chronic toxicity of this nanoformulation. The parent drug was used as a reference formulation. Acute toxicity of doxorubicin-loaded nanoparticles in mice and rats was similar to that of free doxorubicin. The chronic toxicity study was conducted in Chinchilla rabbits; the treatment regimen consisted of 30 daily intravenous injections using two dosage levels: 0.22 mg/kg/day and 0.15 mg/kg/day. The study included assessment of the body weight, hematological parameters, blood biochemical parameters, urinalysis, and pathomorphological evaluation of the internal organs. The results of the study demonstrated that the hematological, cardiac, and testicular toxicity of doxorubicin could be reduced by binding the drug to PLGA nanoparticles. Coating of PLGA nanoparticles with poloxamer 188 contributed to the reduction of cardiotoxicity. Functional and morphological abnormalities caused by the nanoparticulate doxorubicin were dose-dependent and reversible. Altogether these results provide evidence that the PLGA-based nanoformulation not only might enable the broadening of the spectrum of doxorubicin activity but also an improvement of its safety profile.