The evaluation of Intra-bronchial and Nebulised Bacteriophage Treatment in Children with Pseudomonas aeruginosa (CHIP-CF)

This is an open-label, single-arm study of bacteriophage that has demonstrated obligate lytic activity against each of the study participants’ Pseudomonas aeruginosa. This selected bacteriophage will be prepared according to established protocols and instilled endo-bronchially (first dose) using an appropriately sized bronchoscope, followed by twice a day of bacteriophage nebulisation for a duration of 7 consecutive days as an inpatient. The bacteriophages will be obtained through and tested in the Westmead Institute of Medical Research (Iredell Lab). Sterile transfer of the final lysate into sterile vials will be conducted in the sterile medication preparation room in the pharmacy of the Children’s Hospital at Westmead prior to administration. Phages that exceed titres of 10*8 PFU/mL when tested using the participant’s own bacterial isolate will be selected. Each selected phage will be amplified using the participants' own bacterial strain to avoid any contamination. Bacterial isolate obtained from participants will be tested using spot plaque testing. Phages selected must not only have lytic activity as demonstrated by the plaque formation but will need to be more than or equal to 10*8 PFU/mL to be considered for therapy. As for the participants’ bacterial strain, genomics will be performed on the initial bacterial isolate used to perform spot testing on available phages, BAL isolates at the start and at the end of treatment ( if pseudomonas continues to be isolated). Each participant will be treated with a bespoke bacteriophage. This trial has an element of compassionate/magisterial use as these participants have previously been treated with standard treatment available to treat the infection and continue to isolate Pseudomonas aeruginosa. The phage solution will undergo regular monitoring throughout the entire study following processes that may reduce the phage titres. Examples of steps that may cause a reduction in phage titres include litre scale cultivation, filtration of phage solution, following exposure to medications (mannitol, dornase alfa and nebulised antibiotics), nebulisation and storage process. In order to test these bespoke phage solutions, any nebulised medication that the participant is on during the trial will be tested against the selected phage prior to commencing treatment to ensure stability and maintenance of potency. A time-kill curve will be performed before and after in vitro exposure of the medications and phage solution. Additionally, phage titre will be assessed following the addition of these medications to ensure titres remain high (more than or equal to 10*8 PFU/mL ). Nebuliser used in this study will be a TGA-approved mesh nebuliser. In order to confirm the viability of the phage-nebuliser pairing, all candidate phage will undergo testing to ensure titres remain more than or equal to 10*8 PFU/mL prior to administration. Candidate phage will be nebulised and the nebulised aerosol will be collected and phage titration (spot plaque testing will be performed). The dose of phage administered will be 10*8 PFU/mL of a single individually tailored phage (bespoke), diluted as appropriate in Pharmacy. Primary packaging of phage solution that is sterile will be in sealed sterile glass flasks. This flask will then be transported to a sterile medication preparation room (in the pharmacy of the Children’s Hospital at Westmead). The solution (1mL of 1x10*8 PFU/mL of phage and added with 3mL of sterile normal saline) will be decanted into non-pyrogenic sterile Type 1 glass vials and sealed. These vials will be stored in a 4°C fridge and labelled. Solution from the vial will be transferred into the nebuliser chamber using a sterile syringe and diluted with sterile saline. Bronchoscopy will be performed using 1 mL/kg of lavage fluid of normal saline 0.9% will be prepared in total to obtain lavage fluid for microbiology and to aid the bronchoscopy. The remaining 1 mL/kg will be made up of 0.9% normal saline with 8 mL of phage solution (equivalent to 2x10*8 PFU in the total solution or 2 sterile vials of phage solution that contain 1x10*8 PFU/4mL ), therefore 2mL/kg of fluid used during the bronchoscopy. The final solution of 1 mL/kg of phage and saline solution will be instilled in equal aliquots in all five lobes of the lung. This translates to 0.2mL/kg in each lobe. The subsequent bacteriophage dose will be administered via nebulisation. Phage nebulisation must occur after physiotherapy sessions and/or nebulised mannitol and/or nebulised hypertonic saline and/or nebulised dornase alfa and/or nebulised antibiotics The nebulised solution will contain 1 x10*8 PFU/4mL and be administered twice daily. The ideal timing of phage dosing should be 12 hours apart (range 10 to 14 hours). This therapy will be continued to complete 7 days of phage treatment ( a total of 14 vials of bacteriophages will be administered) Therapy for intravenous anti-pseudomonal antibiotics will be done concurrently and will be based on the sensitivity of the most recent Pseudomonas aeruginosa isolate and current dosing and guideline as per the Children’s Hospital Westmead existing antibiotic stewardship and treatment protocols. IV antibiotics and physiotherapy will be continued after completion of phage therapy (to complete 10 to 14 days of inpatient treatment). Following completion of treatment, regular clinical assessments and repeat lung function will be performed at 3, 6, 9 and 12 months.