Aerosolised 5-azacytidine suppresses tumour growth and reprogrammes the epigenome in an orthotopic lung cancer model.

BACKGROUND: Epigenetic silencing by promoter methylation and chromatin remodelling affects hundreds of genes and is a causal event for lung cancer. Treatment of patients with low doses of the demethylating agent 5-azacytidine in combination with the histone deacetylase inhibitor entinostat has yielded clinical responses. The subcutaneous dosing route for consecutive days and reduced bioavailability of 5-azacytidine because of inactivation by cytidine deaminase may limit the expansion of epigenetic therapy into Phase III trials. To mitigate these barriers, an aerosol of 5-azacytidine was generated and characterised. METHODS: The effect of aerosol vs systemic delivery of 5-azacytidine on tumour burden and molecular response of engrafted lung tumours in the nude rat was compared. RESULTS: Pharmacokinetics revealed major improvement in the half-life of 5-azacytidine in lung tissue with aerosol delivery. Aerosolised 5-azacytidine significantly reduced lung tumour burden and induced global demethylation of the epigenome at one-third of the comparable effective systemic dose. High commonality for demethylation of genes was seen in tumours sampled throughout lung lobes and across treated animals receiving the aerosolised drug. CONCLUSION: Collectively, these findings show that aerosolised 5-azacytidine targets the lung, effectively reprogrammes the epigenome of tumours, and is a promising approach to combine with other drugs for treating lung cancer.

Mechanistic models facilitate efficient development of leucine containing microparticles for pulmonary drug delivery.

Mechanistic models of the spray drying and particle formation processes were used to conduct a formulation study with minimal use of material and time. A model microparticle vehicle suitable for respiratory delivery of biological pharmaceutical actives was designed. L-leucine was chosen as one of the excipients, because of its ability to enhance aerosol dispersibility. Trehalose was the second excipient. The spray drying process parameters used to manufacture the particles were calculated a priori. The kinetics of the particle formation process were assessed using a constant evaporation rate model. The experimental work was focused on the effect of increasing L-leucine mass fraction in the formulation, specifically its effect on leucine crystallinity in the microparticles, on powder density, and on powder dispersibility. Particle, powder and aerosol properties were assessed using analytical methods with minimal sample requirement, namely linear Raman spectroscopy, scanning electron microscopy, time-of-flight aerodynamic diameter measurements, and a new technique to determine compressed bulk density of the powder. The crystallinity of leucine in the microparticles was found to be correlated with a change in particle morphology, reduction in powder density, and improvement in dispersibility. It was demonstrated that the use of mechanistic models in combination with selected analytical techniques allows rapid formulation of microparticles for respiratory drug delivery using batch sizes of less than 80 mg.

Effects of novel 5-lipoxygenase inhibitors on the incidence of pulmonary adenomas in the A/J murine model when administered via nose-only inhalation.

The objective of this study was to determine the effects of 5-lipoxygenase (5-LO) inhibitors on the incidence of benzo(a)pyrene-induced pulmonary adenomas in female A/J mice. Two novel compounds, S-29606 and S-30621, and the Food and Drug Administration-approved Zileuton were investigated. S-29606 and S-30621 were selected from a group of similar active structures on the basis of local versus systemic 5-LO inhibitory activity. Preliminary studies found them to lack oral bioavailability, in direct contrast to Zileuton. Treatment was initiated 1 week following exposure to the carcinogen benzo(a)pyrene. Both S-29606 and S-30621 were dosed via nose-only inhalation 5 days a week, for 16 weeks, whereas Zileuton was administered orally. Dose levels for S-29606 and S-30621 were determined to be 220 and 430 microg/kg for the low- and high-dose groups, respectively, whereas the dose of Zileuton was 245 mg/kg. Both test compounds exhibited a significant reduction of pulmonary adenomas, compared with a positive control for high and low doses, P < 0.05. Additionally, a dose response for both S-29606 and S-30621 was observed when compared with placebo. Despite a dose 575 times greater than that of the novel test compounds, orally administered Zileuton did not produce a reduction in adenoma occurrence. The findings of this study offer compelling preliminary data for the use of S-29606 and S-30621 in further investigations of the treatment of pulmonary adenomas and support the use of inhalation drug delivery as an alternate to oral delivery for these compounds.

Preformulation studies on imexon.

Imexon is an aziridine containing iminopyrrolidone that, through aziridine ring opening, is able to induce oxidative stress resulting in apoptosis. The main objective of this research was to conduct extensive preformulation studies on Imexon in order to understand the factors that affect its stability. The results obtained indicate that the stability of Imexon is dependent on pH, ionic strength, temperature, buffer species, and initial concentration. Degradation of Imexon follows apparent first-order degradation kinetics with the primary degradation product resulting from opening of the aziridine ring. In order to maximize stability, ionic strength, temperature, and initial concentration should be minimized, with an optimal range pH between 7.2 and 9.0. Experimentation with other aqueous solutions indicates that Imexon has increased stability in D5W as opposed to normal saline, while it undergoes rapid degradation in 6% H(2)O(2). Imexon is not ionizable between pH 5.0 to 8.5 and has an aqueous solubility of approximately 25 mg/mL over this range. Solid-state characterization has concluded that Imexon is a crystalline solid that begins decomposition at 165 degrees C, prior to melting.