Spectinamides: a new class of semisynthetic antituberculosis agents that overcome native drug efflux


Although the classical antibiotic spectinomycin is a potent bacterial protein synthesis inhibitor, poor antimycobacterial activity limits its clinical application for treating tuberculosis. Using structure-based design, we generated a new semisynthetic series of spectinomycin analogs with selective ribosomal inhibition and excellent narrow-spectrum antitubercular activity. In multiple murine infection models, these spectinamides were well tolerated, significantly reduced lung mycobacterial burden and increased survival. In vitro studies demonstrated a lack of cross resistance with existing tuberculosis therapeutics, activity against multidrug-resistant (MDR) and extensively drug-resistant tuberculosis and an excellent pharmacological profile. Key to their potent antitubercular properties was their structural modification to evade the Rv1258c efflux pump, which is upregulated in MDR strains and is implicated in macrophage-induced drug tolerance. The antitubercular efficacy of spectinamides demonstrates that synthetic modifications to classical antibiotics can overcome the challenge of intrinsic efflux pump-mediated resistance and expands opportunities for target-based tuberculosis drug discovery.

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Figure 1: Spectinomycin and spectinamide ribosome binding.
Figure 2: In vivo efficacy trial data showing bacterial burden (log10 CFU) in the lungs of M. tuberculosis–infected mice. (a) Bacterial burden in the lungs of interferon-γ (IFN-γ) receptor knockout mice acutely infected with M. tuberculosis (n = 5) treated with lead spectinamides and comparator drugs all subcutaneously dosed at 200 mg per kg body weight twice daily (BID) for 9 d (mean ± s.

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This study was supported by US National Institutes of Health (NIH) grant AI090810 (R.E.L., E.C.B., A.J.L. and B.M.), the National Institute of Allergy and Infectious Diseases (NIAID) Indefinite Delivery Indefinite Quantity (IDIQ) (R.E.L. and M.G.) Contract Task Order HHSN272201000009I/01, the American Lebanese Syrian Associated Charities (ALSAC) and St. Jude Children's Research Hospital (SJCRH) (R.E.L.) and in part by the Intramural Research Program of the NIAID, NIH (H.I.B.) and the Spanish Government (grant BIO-2009-09405) (J.A.A.). We thank L. Yang and J. Scarborough from SJCRH for their help with analysis of the final compounds, M. Maddox from SJCRH for technical assistance in determining MIC values, J. Ryman from the University of Tennessee Health Science Center for technical assistance in the performance of pharmacokinetic studies in mice, M. Butler from Microbiotix for coordination of the MDR tuberculosis testing and E. Tuomanen from SJCRH for critical evaluation of this manuscript.

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R.E.L. designed the compound series. J.G.H., D.F.B., R.B.L. and H.I.B. performed MIC testing and microbiology studies. J.L., J.Q., R., S.L.W. and D.S. performed the medicinal chemistry. T.M., R.A. and E.C.B. designed and performed MIC testing and ribosome inhibition studies. M.S.S., M.R.M., M.G.-J. and A.J.L. designed and performed the in vivo efficacy trials. P.K.V., C.R., D.B.M., A.T. and B.M. designed and performed the pharmacokinetic analysis. Z.Z. and S.D. performed the molecular modeling experiments. C.V., D.F.B. and J.A.A. designed and performed the efflux mutant testing. All authors discussed and analyzed the data. R.E.L., E.C.B., A.J.L., R.B.L., D.F.B., J.A.A. and B.M. wrote the manuscript.

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Correspondence to Richard E Lee.

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R.E.L., J.Q., J.G.H., B.M., P.K.V., R. and J.L. disclose intellectual property rights ownership associated with the spectinamide series.

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Supplementary Scheme 1, Supplementary Analytical Data, Supplementary Tables 1–12 and Supplementary Figures 1–3 (PDF 1822 kb)

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Lee, R., Hurdle, J., Liu, J. et al. Spectinamides: a new class of semisynthetic antituberculosis agents that overcome native drug efflux. Nat Med 20, 152–158 (2014). https://doi.org/10.1038/nm.3458

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