5-Azacytidine inhaled dry powder formulation profoundly improves pharmacokinetics and efficacy for lung cancer therapy through genome reprogramming.

BACKGROUND: Epigenetic therapy through demethylation of 5-methylcytosine has been largely ineffective in treating lung cancer, most likely due to poor tissue distribution with oral or subcutaneous delivery of drugs such as 5-azacytidine (5AZA). An inhalable, stable dry powder formulation of 5AZA was developed. METHODS: Pharmacokinetics of inhaled dry powder and aqueous formulations of 5AZA were compared to an injected formulation. Efficacy studies and effect of therapy on the epigenome were conducted in an orthotopic rat lung cancer model for inhaled formulations. RESULTS: Inhaled dry powder 5AZA showed superior pharmacokinetic properties in lung, liver, brain and blood compared to the injected formulation and for all tissues except lung compared to an inhaled aqueous formulation. Only dry powder 5AZA was detected in brain (~4-h half-life). Inhaled dry powder was superior to inhaled aqueous 5AZA in reducing tumour burden 70-95%. Superiority of inhaled 5AZA dry powder was linked to effectively reprogramming the cancer genome through demethylation and gene expression changes in cancer signalling and immune pathways. CONCLUSIONS: These findings could lead to widespread use of this drug as the first inhaled dry powder therapeutic for treating local and metastatic lung cancer, for adjuvant therapy, and in combination with immunotherapy to improve patient survival.

Inhalation delivery dramatically improves the efficacy of topotecan for the treatment of local and distant lung cancer.

Topotecan is potent anti-cancer drug approved for various malignancies but hematopoietic toxicities undermine its wider application and use of its most effective dose. This study aims to improve these limitations through inhalation-delivery. The pharmacokinetics, efficacy, and toxicity of 2-5 times lower inhalation doses of topotecan dry-powder were compared with the standard intravenous (IV) delivery once/twice-a-week. Human-derived EGFR-mutant (H1975), KRAS-mutant (A549), and EGFR/KRAS wild-type (H358) orthotopic and distant lung tumors were evaluated in murine models. Inhalation of 1 mg/kg topotecan significantly improved the half-life and drug exposure (area under the curve, AUC) compared to 5 mg/kg via IV-delivery. AUCs (h*ng/mL) for inhaled/IV topotecan in plasma, lung, liver, and brain were, 831/888, 60,000/1080, 8380/4000, and 297/15, respectively; while the half-life was also greatly increased in these tissues. The average lung tumor burden of H358-derived tumors was reduced from 15.0 g to 8.4 g (44%) in rats treated once-a-week with 2 mg/kg IV and 1.8 g (88%) with 1 mg/kg inhaled topotecan, corroborating previous findings using A549- and H1975-derived orthotopic lung tumors. Importantly, inhaled topotecan showed superior efficacy in suppressing lung tumors at distant sites. The growth of H1975- and H358-derived subcutaneous xenografts were completely arrested and A549-derived tumors were significantly reduced in mice treated twice-a-week with 1 mg/kg inhaled topotecan compared to a minor (H1975 and H358) or no reduction (A549) with twice-a-week 5 mg/kg IV topotecan.

Inhalation delivery of topotecan is superior to intravenous exposure for suppressing lung cancer in a preclinical model.

Intravenous (IV) topotecan is approved for the treatment of various malignancies including lung cancer but its clinical use is greatly undermined by severe hematopoietic toxicity. We hypothesized that inhalation delivery of topotecan would increase local exposure and efficacy against lung cancer while reducing systemic exposure and toxicity. These hypotheses were tested in a preclinical setting using a novel inhalable formulation of topotecan against the standard IV dose. Respirable dry-powder of topotecan was manufactured through spray-drying technology and the pharmacokinetics of 0.14 and 0.79 mg/kg inhalation doses were compared with 0.7 mg/kg IV dose. The efficacy of four weekly treatments with 1 mg/kg inhaled vs. 2 mg/kg IV topotecan were compared to untreated control using an established orthotopic lung cancer model for a fast (H1975) and moderately growing (A549) human lung tumors in the nude rat. Inhalation delivery increased topotecan exposure of lung tissue by approximately 30-fold, lung and plasma half-life by 5- and 4-folds, respectively, and reduced the maximum plasma concentration by 2-fold than the comparable IV dose. Inhaled topotecan improved the survival of rats with the fast-growing lung tumors from 7 to 80% and reduced the tumor burden of the moderately-growing lung tumors over 5- and 10-folds, respectively, than the 2-times higher IV topotecan and untreated control (p < .00001). These results indicate that inhalation delivery increases topotecan exposure of lung tissue and improves its efficacy against lung cancer while also lowering the effective dose and maximum systemic concentration that is responsible for its dose-limiting toxicity.

A non-invasive intratracheal inoculation method for the study of pulmonary melioidosis.

Pulmonary melioidosis, a disease manifestation caused by the bacterium Burkholderia pseudomallei, has been studied using aerosols or intranasal (IN) inoculation in small animal models. Both have inherent disadvantages which may not accurately model primary pulmonary melioidosis in humans. Intratracheal inoculation (IT) by direct visualization of the tracheal opening offers an alternative technique for infection that overcomes the disadvantages of aerosol and IN challenge. In this study, we describe a method which requires relatively inexpensive equipment, little training, and is compliant with the operational constraints of a BSL3 laboratory. Results obtained using trypan blue demonstrated that an inoculum can be accurately delivered into the lungs of mice within a biosafety cabinet (BSC). Whole body imaging and histopathology confirmed that mice inoculated intratracheally with B. pseudomallei develop the primary focus of infection in the lungs, and not the nasal passages which can lead to invasion of the central nervous system and potential neurologic complications. Further, based on colony counts and bioluminescent imaging, dissemination to secondary organs occurred as expected. Taken together, this intratracheal method of inoculation fulfills four goals: (1) to accurately deliver B. pseudomallei into the lungs of the animal model, (2) to avoid potentially confounding complications due to primary infections at sites other than the lung, (3) to maintain normal organ dissemination, and (4) to be BSL3 compliant.