Towards a new combination therapy for tuberculosis with next generation benzothiazinones

Vadim Makarov,Koen Andries,Anthony Vocat,Ming Zhang,Benoit Lechartier,Paul J Dyson,Thierry Buclin,Florence Pojer,Susanne A Raadsen,Astrid M Van Der Sar,Stewart T Cole,Wilbert Bitter,Laurent A Decosterd,João Neres,Nicolas Widmer,Ruben C Hartkoorn,Olga B Ryabova

doi:10.1002/emmm.201303575

Abstract

The benzothiazinone lead compound, BTZ043, kills Mycobacterium tuberculosis by inhibiting the essential flavo-enzyme DprE1, decaprenylphosphoryl-beta-D-ribose 2-epimerase. Here, we synthesized a new series of piperazine-containing benzothiazinones (PBTZ) and show that, like BTZ043, the preclinical candidate PBTZ169 binds covalently to DprE1. The crystal structure of the DprE1-PBTZ169 complex reveals formation of a semimercaptal adduct with Cys387 in the active site and explains the irreversible inactivation of the enzyme. Compared to BTZ043, PBTZ169 has improved potency, safety and efficacy in zebrafish and mouse models of tuberculosis (TB). When combined with other TB drugs, PBTZ169 showed additive activity against M. tuberculosis in vitro except with bedaquiline (BDQ) where synergy was observed. A new regimen comprising PBTZ169, BDQ and pyrazinamide was found to be more efficacious than the standard three drug treatment in a murine model of chronic disease. PBTZ169 is thus an attractive drug candidate to treat TB in humans.Subject Categories Microbiology, Virology & Host Pathogen Interaction; Pharmacology & Drug Discovery

Highlights

The benzothiazinone lead compound, BTZ043, kills Mycobacterium tuberculosis by inhibiting the essential flavo-enzyme DprE1, decaprenylphosphoryl-beta-D-ribose 2-epimerase
During our structure-activity relationship (SAR) analysis of the first generation benzothiazinone (BTZ) compounds we discovered a direct correlation between lipophilicity and antimycobacterial activity (Makarov et al, 2009)
PBTZ169 is less cytotoxic than BTZ043 and showed significantly better efficacy at lower concentrations in the murine model of chronic TB (Fig 7) and this may be attributed to the fact that PBTZ169 inhibits DprE1 more efficiently than BTZ043 does

Summary

Introduction

The benzothiazinone lead compound, BTZ043, kills Mycobacterium tuberculosis by inhibiting the essential flavo-enzyme DprE1, decaprenylphosphoryl-beta-D-ribose 2-epimerase. We synthesized a new series of piperazine-containing benzothiazinones (PBTZ) and show that, like BTZ043, the preclinical candidate PBTZ169 binds covalently to DprE1. The crystal structure of the DprE1-PBTZ169 complex reveals formation of a semimercaptal adduct with Cys387 in the active site and explains the irreversible inactivation of the enzyme. Compared to BTZ043, PBTZ169 has improved potency, safety and efficacy in zebrafish and mouse models of tuberculosis (TB). When combined with other TB drugs, PBTZ169 showed additive activity against M. tuberculosis in vitro except with bedaquiline (BDQ) where synergy was observed. A new regimen comprising PBTZ169, BDQ and pyrazinamide was found to be more efficacious than the standard three drug treatment in a murine model of chronic disease. PBTZ169 is an attractive drug candidate to treat TB in humans

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Results

Conclusion