LeuRS-Targeting Prodrug, MRX-5, Expresses Anti-Mycobacterium abscessus Activity

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Mycobacterium abscessus is a multi-drug resistant bacterium causing challenging infections.
• Novel therapeutic strategies are crucial for effective M. abscessus treatment.

Purpose of the Study:

• To evaluate the in vitro and in vivo efficacy of MRX-5, an oral prodrug of MRX-6038, against Mycobacterium abscessus.
• To assess the stability, pharmacokinetics, and lung distribution of MRX-5.

Main Methods:

• MRX-5 stability was tested in broth using liquid chromatography-tandem mass spectrometry.
• Minimum inhibitory concentrations (MICs) were determined against M. abscessus strains.
• In vivo studies involved pharmacokinetic assessment and efficacy testing in a mouse model of lung infection.

Main Results:

• MRX-5 efficiently converted to MRX-6038 in broth and in vivo, with 83.95% oral bioavailability.
• MRX-5 showed reduced in vitro potency compared to MRX-6038 but achieved significant lung distribution.
• In vivo, MRX-5 effectively reduced bacterial load in a mouse lung infection model, comparable to linezolid.

Conclusions:

• MRX-5 demonstrates favorable pharmacokinetic properties and significant in vivo efficacy against M. abscessus lung infections.
• MRX-5 is a promising oral candidate for treating M. abscessus infections.
• Further development of MRX-5 could address treatment challenges posed by this resistant pathogen.