Opsumit: Pfizer's PAH franchise passes the baton

Opsumit
Project name: macitentan
Disease: Pulmonary arterial hypertension (PAH)
Peak sales estimate: $1.4 billion
Approved: Oct. 18
Company: Actelion

The Scoop:
Actelion's ($ATLN) injectable Tracleer brought in $1.6 billion in 2012 treating pulmonary arterial hypertension. But with its patent expiring in 2015 and a new generation of oral competitors on the way, efforts to update the drug were seen as crucial to protecting the Swiss drugmaker's aging PAH franchise. 

Enter Opsumit (macitentan). The drug's approval on Oct. 18 came not a day too soon, following competitor Bayer's expedited approval of Adempas (riociguat) by just 10 days. Like Adempas, Opsumit will carry a boxed warning alerting patients and physicians that the drug should not be used in pregnant women because it can harm the developing fetus. 

Adempas and Opsumit join Gilead Sciences' ($GILD) Letairis (ambrisentan), an existing oral treatment for PAH. Letairis brought in $410 million last year. A fourth pill, Pfizer's ($PFE) Revatio, contains the same active ingredient as the erectile dysfunction drug Viagra.

Analysts at Jefferies forecast peak Opsumit sales of $1.4 billion, Reuters reported, assuming a 40% share of new PAH patients at a 15% price discount to Tracleer and Letairis. The news of FDA approval sent Actelion's shares up more than 5% to a 6-year high, according to Reuters.

In late December, the FDA handed a third competitor a surprise approval. After two complete response letters, United Therapeutics ($UTHR) got a green light for an oral successor to its own PAH bestseller, Remodulin. Analysts don't expect peak sales to surpass $250 million in this crowded market, but after its earlier setbacks the money looks like manna from heaven.

Opsumit's safety and effectiveness were established in a long-term clinical trial lasting about two years on average, involving 742 participants taking Opsumit or placebo. The trial found Opsumit effective in delaying disease progression.

PAH causes elevated pressure in the pulmonary arteries, which carry blood from the heart to the lungs. Symptoms include shortness of breath, fatigue, chest pain and racing heartbeat, according to the NIH. Heart failure is the most common cause of death in PAH patients. -- Galen Moore (email | Twitter)

For more:
Actelion wins crucial FDA approval for next-gen lung disease drug Opsumit 
Bayer's now-approved Adempas girds for market-share battle in PAH 
Strike two: FDA hands United Therapeutics another snub on oral Remodulin

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Opsumit: Pfizer's PAH franchise passes the baton