Urinary pH Warrants Therapeutic Window of EBL-1003 (Apramycin) in the Treatment of Complicated Urinary Tract Infections and Acute Pyelonephritis

Background: The clinical-stage drug candidate EBL-1003 (apramycin) represents a distinct new subclass of aminoglycoside antibiotics for the treatment of drug-resistant infections. It has demonstrated best-in-class coverage of resistant isolates, and preclinical efficacy in lung infection models. However, preclinical evidence for its utility in other disease indications has yet to be provided. Here we studied the therapeutic potential of EBL-1003 in the treatment of complicated urinary tract infection and acute pyelonephritis (cUTI/AP). Methods: A combination of data-base mining, antimicrobial susceptibility testing, time-kill experiments, and four murine infection models was used in a comprehensive assessment of the microbiological coverage and efficacy of EBL-1003 against Gram-negative uropathogens. The pharmacokinetics and renal toxicology of EBL-1003 in rats was used to assess the therapeutic window of EBL-1003 in cUTI/AP.  Results: EBL-1003 demonstrated broad-spectrum activity and rapid multi-log CFU reduction against a phenotypic variety of bacterial uropathogens including aminoglycoside-resistant clinical isolates. The basicity of amines in the apramycin molecule suggested a higher increase in positive charge at urinary pH when compared to gentamicin or amikacin, resulting in sustained drug uptake and bactericidal activity, and consequently in potent efficacy in mouse infection models. Renal pharmacokinetics, biomarkers for toxicity, and kidney histopathology in adult rats all indicated a significantly lower nephrotoxicity of EBL-1003 than of gentamicin.  Conclusions: This study provides preclinical proof-of-concept for the efficacy of EBL-1003 in cUTI/AP. Similar efficacy but lower nephrotoxicity of EBL-1003 in comparison to gentamicin may thus translate into a higher safety margin and a wider therapeutic window in the treatment of cUTI/API. Funding Information: Some of the research leading to these results was conducted as part of the ND4BB European Gram-Negative Antibacterial Engine (ENABLE) Consortium (www.nd4bb-enable.eu) and has received funding from the Innovative Medicines Initiative Joint Undertaking (www.imi.europa.eu) under grant agreement n°115583, resources of which are composed of financial contribution from the European Union's Seventh Framework Programme (FP7/2007-2013) and The European Federation of Pharmaceutical Industries and Associations (EFPIA) companies in-kind contribution. The ENABLE project is also financially supported by contributions from Academic and Small and medium-sized enterprise (SME) partners. The University of Zurich has utilized the non-clinical and pre-clinical services program offered by the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health (NIH). This work was further supported by the Swedish Research Council [grant number 2018–05501]; the Swedish Foundation for Strategic Research [grant number RIF14-0078], and the Science for Life Laboratory to PEA. This work was further supported by the University of Zurich, Institute of Medical Microbiology. Declaration of Interests: Authors ECB, DC, and SNH are co-founders of and shareholders in Juvabis AG. All other authors declare no conflict of interest. Ethical Approval: No serum or tissue samples were used other than those described for the mouse and rat models (kidney, bladder, plasma, urine). Further ethical approval Information below. Figure 3 All aspects of this work, including housing, experimentation, and disposal of animals were performed in general accordance with the Guide for the Care and Use of Laboratory Animals (National Academy Press, Washington, D. C., 2011). The study was performed in our AAALAC accredited ABSL2 laboratory under the supervision of the veterinarians and the animal care and use protocol was approved by the IACUC at Eurofins Panlabs Taiwan. Figures 5A, 5B, 5C, S5, S6, S7, S8, and S9 The experimental procedures were carried out in accordance with the guidelines of the European Community and local laws and policies and were approved by the Latvian Animal Protection Ethical Committee, Food and Veterinary Service, Riga, Latvia. Figure 5E Animal experiments were performed under the Swedish national ethical license S7-15. Figure S2 Standards for housing and care of animals comply to the latest and most comprehensive international guidelines, Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the protection of animals used for scientific purposes. All animal experiments are approved by the National Committee of Animal Ethics, Ministry of Environment and Food of Denmark.