Novel Antibacterial Activity of Febuxostat, an FDA-Approved Antigout Drug against Mycobacterium tuberculosis Infection

Accumulating evidence suggests that drug repurposing has drawn attention as an anticipative strategy for controlling tuberculosis (TB), considering the dwindling drug discovery and development pipeline. In this study, we explored the antigout drug febuxostat and evaluated its antibacterial activity against Mycobacterium species. Based on MIC evaluation, we found that febuxostat treatment significantly inhibited mycobacterial growth, especially that of Mycobacterium tuberculosis (Mtb) and its phylogenetically close neighbors, M. bovis, M. kansasii, and M. shinjukuense, but these microorganisms were not affected by allopurinol and topiroxostat, which belong to a similar category of antigout drugs. Febuxostat concentration-dependently affected Mtb and durably mediated inhibitory functions (duration, 10 weeks maximum), as evidenced by resazurin microtiter assay, time-kill curve analysis, phenotypic susceptibility test, and the Bactec MGIT 960 system. Based on these results, we determined whether the drug shows antimycobacterial activity against Mtb inside murine bone marrow-derived macrophages (BMDMs). Notably, febuxostat markedly suppressed the intracellular growth of Mtb in a dose-dependent manner without affecting the viability of BMDMs. Moreover, orally administered febuxostat was efficacious in a murine model of TB with reduced bacterial loads in both the lung and spleen without the exacerbation of lung inflammation, which highlights the drug potency. Taken together, unexpectedly, our data demonstrated that febuxostat has the potential for treating TB.