InterMune plunges as US FDA calls for additional testing of IPF drug Esbriet; agency clears label change for Shire's Vyvanse

InterMune saw a melt-down in its share price, after it revealed that the US Food and Drug Administration had issued a complete response letter for the New Drug Application for its potential blockbuster Esbriet (pirfenidone) in the treatment of patients with idiopathic pulmonary fibrosis to reduce decline in lung function, calling for an additional clinical trial to support the efficacy of the drug in IPF patients.

InterMune's stock price plunged about 80% in after-hours trading yesterday to $9.47. The stock has been buoyant since an FDA advisory committee voted nine to three to recommend approval of the drug, jumping 59% to $37.65 on that news (The Pharma Letter March 10). Annual sales of pirfenidone capsules may reach $1.07 billion in 2014, according to the average estimate of six analysts surveyed by Bloomberg. InterMune reported $48.7 million in revenue last year.

"After the positive FDA Advisory Committee meeting of March 9 at which the Committee recommended the approval of the pirfenidone NDA by a nine-three margin, we are disappointed by this outcome," said Dan Welch, chairman, chief executive and president of InterMune. "We will meet with the FDA as soon as possible to understand their points of view and to determine the most appropriate path forward to expeditiously make Esbriet available to the approximately 100,000 patients with IPF and their families who suffer from this terrible disease and for whom no FDA-approved medicines exist,' he added.