Lead Compound timapiprant

Timapiprant1 is a highly potent and selective CRTH2 antagonist which is active on both the recombinant and native human receptor.

Preclinical studies have highlighted the following properties of timapiprant:

  • Inhibition of eosinophil activation in isolated leukocytes and in whole blood
  • Inhibition of chemotaxis of human Th2 lymphocytes
  • Inhibition of Th2 cytokine production in vitro and in vivo
  • Promotion of apoptosis of Th2 lymphocytes leading to long-lasting anti-allergic activity
  • Inhibition of the production of IgE
  • Inhibition of mast cell dependent activation of both Th2 lymphocytes and eosinophils
  • Excellent safety profile demonstrated in long term toxicology studies

Prostaglandin D2 - the natural ligand for the CRTH2 receptor

The Atopix lead compound timapiprant is effective in improving lung function and symptoms in patients with atopic eosinophilic asthma. This group represents 40-50% of all asthmatics and the magnitude of improvement in the responder population is equivalent to high dose inhaled corticosteroids.

Timapiprant has also been shown to reduce both nasal and eye symptoms in allergic subjects exposed to grass pollen. Of particular interest is the ability of timapiprant to reduce the rate of respiratory infections, an effect related to reduction in Th2 immunity which has a damaging effect on host defence. This will be studied by Professor Sebastian Johnston at the National Heart and Lung Institute, Imperial College London, who won a £1.3M Biomedical Catalyst Grant for this innovative research.

Timapiprant has also demonstrated an excellent safety profile in around 800 subjects exposed drug and no safety issues have been highlighted in long term toxicology.


1Timapiprant is the international name for OC459 / OC000459

Clinical Studies