A Novel Therapeutic Peptide to Treat P. aeruginosa Infection in Cystic Fibrosis Patients

Project Summary Our objective is to develop 6K-F17 as an antimicrobial agent that can be prescribed with tobramycin for the treatment of chronic, antibiotic-resistant Pseudomonas aeruginosa infection in cystic fibrosis (CF) patients. CF affects over 70,000 people worldwide1. Even with the current array of antibiotics, 80-95% of CF patients will ultimately succumb to respiratory failure brought on by chronic bacterial infections3. As a result, there is a significant unmet need to develop new antimicrobials for chronic, antibiotic-resistant infections in CF patients. CF is a genetic disease arising from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that encodes a chloride ion transporter4. Impaired trans-epithelial chloride transport leads to dehydrated airway secretions and a lack of airway mucus clearance5, 6. As a result, individuals with CF are prone to chronic, biofilm-based bacterial infections, bronchiectasis and respiratory failure6, 7In particular, chronic infection with P. aeruginosa has been shown to lead to more rapid lung function decline, a lower quality of life, and premature death8-11. Chronic infection with P. aeruginosa is particularly challenging to treat as this strain continually adapts to environmental challenges, including the formation of a mucus-like biofilms. These biofilms protect bacteria from natural host defense mechanisms and make them more resistant to small molecule antibiotics 5, 12-18. Progress toward developing treatments for biofilm infections has been made through the use of cationic antimicrobial peptides (CAPs). CAPs are found naturally in a wide variety of organisms ranging from plants to humans and constitute a major component of the innate immune system19-21. Importantly, these natural CAPs kill bacteria by destroying their membranes – in effect ‘blowing up’ the bacteria by lodging and accumulating in their membranes - rather than by targeting a specific bacterial protein or biochemical pathway. This mechanism impedes the advent of bacterial resistance to CAPs. Recently, our team developed a novel peptide, called 6K-F17, that can disrupt biofilms created by P. aeruginosa and kill the bacteria using a novel mechanism of membrane association. Due to its unique mechanism of action, 6K-F17 synergizes with antibiotics, such as tobramycin, to kill antibiotic-resistant strains of P. aeruginosa. Building from this work, the objective of this proposal is to generate the optimal dose, pharmacokinetics and toxicology profiles for 6K-F17 in mice. The specific aims are to: 1) produce sufficient amounts of 6K-F17 and standardize analytical and potency assays; 2) determine the optimal effective dose of 6K-F17 to eliminate P. aeruginosa infection in mice; and 3) establish a preliminary acute toxicology profile for 6K-F17 in normal mice. Successful completion of these studies will advance an exciting antimicrobial agent for the treatment of antibiotic-resistant P. aeruginosa, and potentially other antibiotic-resistant lung infections, in CF patients.Project Narrative Individuals with cystic fibrosis (CF) are prone to repeated and chronic bacterial infections. In particular, chronic infection with Pseudomonas aeruginosa leads to more rapid lung function decline, respiratory failure and premature death. This project aims to develop the novel peptide 6K-F17 as an antimicrobial agent that can be prescribed with tobramycin to treat chronic, antibiotic-resistant P. aeruginosa infection. Successful commercialization of 6K-F17 would ultimately provide a profound advancement in the treatment of chronic infection in CF patients.