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

Philip J Kuehl,Steven A Belinsky,Devon Dubose,Aaron Badenoch,Larry M Mallis,Carmen S Tellez,Marcie J Grimes,David A Revelli,Thomas H March,Mathewos Tessema,Michael Burke,Maria A Picchi,David T Vodak,Tyler Sniegowski,Wendy W Dye

doi:10.1038/s41416-020-0765-2

Philip J Kuehl, Steven A Belinsky + Show 13 more

Open Access

https://doi.org/10.1038/s41416-020-0765-2

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Abstract

BackgroundEpigenetic 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.MethodsPharmacokinetics 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.ResultsInhaled 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.ConclusionsThese 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.

Highlights

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)
Development and characterisation of a dry powder formulation of 5AZA The key to development of an inhalable formulation of 5AZA is maintaining its stability during the spray drying process, since 5AZA rapidly degrades in aqueous solution at room temperature
HPLC analysis revealed purity greater than 92% with no degradation peaks detected after spray drying or following vacuum desiccation

Summary

Introduction

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). METHODS: Pharmacokinetics of inhaled dry powder and aqueous formulations of 5AZA were compared to an injected formulation. 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. 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. Cytosine methylation is dominant in transcriptional repression, and inhibitors of the cytosine DNA-methyltransferases, 5-azacytidine (5AZA) and 5-aza-2’-deoxyazacytidine (DAC), can induce re-expression of genes silenced through promoter hypermethylation.[8,9] These drugs, delivered at doses much lower than the maximum tolerated dose, are serving as potent therapy for myelodysplasia with an overall response rate (ORR) of >60%, leading to FDA approval for treatment of these diseases.[10,11]

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