Pfizer adds another product to its PAH franchise
pharmafile | May 14, 2010 | News story | Research and Development | Ergonex, PAH, Pfizer, Thelin, revatio, terguride, viagra
Pfizer has signed an agreement to acquire terguride, a drug for pulmonary arterial hypertension (PAH) currently in phase II testing, from Swiss company Ergonex GmbH.
The new compound extends Pfizer’s franchise in the fast-growing, $2.5 billion market for PAH drugs at a time when its main product is facing the threat of generic competition.
Terguride is an orally-active antagonist of serotonin 5-HT2B and 5-HT2A receptors, a different mechanism of action to Pfizer’s existing PAH therapies, Revatio (sildenafil citrate) and Thelin (sitaxsentan sodium).
Financial details have not been disclosed, but Pfizer said it will take over development of terguride outside Japan where it is already marketed for hyperprolactinaemia. It will also pay Ergonex milestone payments and royalties if the drug is successful.
Revatio has the same active phosphodiesterase-5 inhibitor ingredient as erectile dysfunction drug Viagra, and was the first of a new-generation of drugs specifically developed for PAH to reach the market back in 2005. Although Pfizer does not divulge Revatio sales in its earnings statements, it is estimated that the drug brings in around $120 million per quarter.
The company also launched a new intravenous version of Revatio to complement the original oral formulation in November 2009, but the impending expiry of the sildenafil citrate patent in 2012 in the key US market could mean that generic competition to the brand is on the way.
Pfizer also doesn’t divulge sales of Thelin, an orally-active once-daily endothelin A receptor antagonist which is currently approved in Europe but not the US, but they are thought to be around the $50 million mark per year.
The appeal of terguride for Pfizer also lies in its novel mechanism of action, which Geno Germano, president of Pfizer’s Specialty Care business unit, describes as “potentially disease modifying”.
It is known that serotonin stimulates the proliferation of pulmonary artery smooth muscle cells and induces fibrosis in the arterial walls, and Ergonex and Pfizer believe serotonin is central to the development of the increased vascular resistance seen in PAH patients.
If that hypothesis is proved correct, blocking serotonin with terguride could potentially halt or even reverse the vascular changes and slow down progression of PAH.
Terguride has been given orphan drug status in the US and EU for the treatment of PAH, which despite only affecting between 100,000 and 200,000 people in these regions is expected to drive a drugs market worth $3.6 billion in 2015, according to market research firm GlobalData.
Thereafter the growth in the market is expected to tail off as the current market leader, Actelion’s endothelin antagonist Tracleer (bosentan), loses patent protection.
Phil Taylor
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