FDL169 for Cystic Fibrosis

FDL169 is an experimental therapy for cystic fibrosis (CF) that is being developed by Flatley Discovery Lab.

How FDL169 works

Cystic fibrosis is a heritable disease caused by mutations in the CFTR gene, which encodes for a protein that channels salts in and out of cells. Mutations in this gene can cause the protein to be made incorrectly, which results in the buildup of thick, sticky mucus in organs and tissues, thereby interfering with their function.

The most common mutation is the so-called F508del mutation, which causes the deletion of a single amino acid (the building blocks which make up proteins). This single change causes the CFTR protein to fold incorrectly.

FDL169 is designed to work as a CFTR corrector, a treatment that corrects the folding of the CFTR protein. It binds to CFTR as the protein is being made by the cell, and helps the protein fold into the correct shape. This increases the presence of CFTR at the cell membrane, meaning that more salt can be trafficked normally.

FDL169 in clinical trials for CF 

Four Phase 1 clinical trials (NCT03527095, NCT03424252, NCT02680418, and NCT02359357) evaluated the safety, bioavailability, and pharmacokinetics (movement in the body) of FDL169 in healthy adult volunteers. The results of these studies have not been published yet.

A Phase 1 clinical trial (NCT03516331) evaluated the safety and interactions between FDL169 and FDL176, another experimental treatment for CF being developed by Flatley Discovery Lab. FDL176 is designed to act as a CFTR potentiator — a molecule that holds the CFTR protein channel open, allowing higher rates of salt traffic across the cell membrane. A single site in Belfast, U.K., is currently recruiting adults for a similar study in healthy volunteers (NCT03756922).

A single Phase 1 clinical trial (NCT03093714) evaluated the safety, pharmacodynamics (how the body processes the treatment), and pharmacokinetics of FDL169 in patients with CF, but results have not been published.

A Phase 1/2 clinical trial (NCT02767297) of FDL169 has been completed, which examined the bioavailability and pharmacokinetics in healthy adults and CF patients. Its findings have not yet been published.


Cystic Fibrosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.