FDL176 is an experimental therapy for cystic fibrosis (CF) that is being developed by Flatley Discovery Lab.

How FDL176 works

CF is caused by mutations in the CFTR gene, which provides instructions for making a protein that channels salts in and out of cells. Mutations in CFTR cause the protein to be made incorrectly, meaning that salt is not trafficked normally. This results in the buildup of thick mucus in different organs and tissues.

FDL176 is a CFTR potentiator, a small molecule designed to bind to the CFTR protein and hold the channel open, allowing more salt to move through it.

CF can be treated with a combination of CFTR modulator therapies — two or more medications that work together to address the underlying cause of the disease. The Flatley Discovery Lab is testing FDL176 with FDL169, a CFTR corrector designed to help CFTR fold correctly.

FDL176 in clinical trials for CF

A Phase 1 clinical trial (NCT03173573) to establish the safety, tolerability, and pharmacokinetics (movement in the body) of FDL176 in healthy volunteers and CF patients has been completed. The trial consisted of five parts. The first part was a double-blind, placebo-controlled, dose-escalation study in healthy male volunteers. The second part was a single-dose, open-label study in healthy male participants. The third part was a single-dose, double-blind, placebo-controlled study in healthy female participants. The fourth part was a randomized, double-blind, placebo-controlled, dose-escalation study in healthy male and female participants. Finally, the fifth part was a single-dose, open-label study in male and female participants with CF. Although the trial has been completed, the results have not been made public yet.

Another Phase 1 clinical trial (NCT03516331) evaluated the safety and interactions between FDL176 and FDL169. This trial has also been completed, but the results have not been published. A single site in Belfast, U.K., is currently recruiting adults for a similar study in healthy volunteers (NCT03756922).


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