Dry powder Inhalation of lytic mycobacteriophages for adjunct therapy in a mouse model of infection with Mycobacteriumtuberculosis

Abstract

Inhaled therapy of tuberculosis (TB) by a Dry Powder Inhalation (DPI) comprising mycobacteriophage D29 and TM4 was non-inferior to oral anti-tuberculosis therapy (ATT) with isoniazid and rifampicin in a mouse model of infection with Mycobacterium tuberculosis (Mtb). No pharmaceutical phage product of mycobacteriophages is approved for large-scale production. We scaled up preparation and downstream processing of phages, developed DPI formulations, and established methods for determining identity, purity, assay, stability, and critical quality attributes (CQA). We carried out cell-based assays of intracellular bactericidal activity and pharmacokinetics and comparative efficacy in Mtb-infected mice. Daily doses of the DPI containing ∼10¹⁰ Plaque Forming Units/dose DPI reduced Mtb colony forming units (CFU) in the lungs from 6.4 ± 0.3-log to 4.8 ± 0.7-log in four weeks, while oral human equivalent doses (HED) of isoniazid and rifampicin reduced CFU to 3.8 ± 0.8-log. Combining inhaled phages with oral drugs sterilized the lungs of one of four mice and reduced group mean CFU to 2.3-log. Inhalations significantly upregulated tumor necrosis factor (TNF) in lung tissue to ∼1500 pg/ml of homogenate, improved organ morphology, and reduced histopathology. The HD DPI may be a useful adjunct to oral drugs. Dose-finding animal efficacy studies are required before assessing preclinical safety.

Keywords: Dry powder inhalation; Efficacy; Mycobacterium tuberculosis; Phage therapy; Pharmacokinetics.