TMEM16A (Anoctamin-1) calcium-activated chloride channel

Class

Small molecule TMEM16A potentiator

Pathway

Enhances calcium-induced anion transport, increasing airway fluid secretion and promoting mucus hydration/clearance (formerly ETD002; Genentech/Roche, muco-obstructive airway disease)

TMEM16A, also called Anoctamin-1, is a chloride channel found on the surface of cells that line the airway. It opens in response to a rise in calcium inside the cell, allowing chloride ions to exit; this pulls water along with it, keeping the thin fluid layer on the airway surface properly hydrated. In conditions such as cystic fibrosis and chronic obstructive pulmonary disease, this surface fluid becomes too thin or too thick, mucus becomes sticky and hard to clear, and airways become prone to plugging, infection, and inflammation. A small-molecule potentiator makes TMEM16A more responsive to the calcium signals that are already occurring in these cells, increasing chloride and fluid secretion without requiring an artificial calcium surge. Because TMEM16A works independently of CFTR, the chloride channel that is defective in cystic fibrosis, this approach offers a route to improving airway hydration regardless of a patient's underlying CFTR mutation, including cases not addressed by CFTR-directed therapies. This mechanism targets a shared feature of muco-obstructive airway disease, impaired mucus clearance, giving it potential relevance across several chronic respiratory conditions beyond cystic fibrosis.