UPDATED: GlaxoSmithKline gains blockbuster FDA approval of lung drug Breo

GlaxoSmithKline ($GSK) and Theravance ($THRX) have won FDA approval for their drug Breo Ellipta for treating chronic obstructive pulmonary disease (COPD), the third-biggest killer of Americans, the agency announced. The approval comes with an undesirable boxed warning from the agency that LABA therapies boost risk of asthma-related deaths.

Cowen & Co. analysts wrote in a note to investors today that the label for Breo was "solid," and the LABA warning from the agency has become standard for drugs in the class and "does not necessarily reflect Breo-specific data."

Breo Ellipta contains the once-daily LABA therapy vilanterol (VI) and the approved corticosteroid fluticasone furoate, or FF. The VI ingredient was discovered through a partnership between the London drug giant and South San Francisco-based Theravance, which is expected to reap a 15% royalty from Glaxo on sales of the drug up to the first $3 billion in annual revenue for the product. Previous analyst estimates forecasted sales of more than $1 billion by 2018, Bloomberg reported.

GlaxoSmithKline and Theravance are partnered on a number of new respiratory drugs, but Breo is the first to win a major regulatory approval, and both companies have a lot riding on their partnership. With blockbuster sales of Advair, Glaxo's respirator business is the largest franchise in the company. Breo gives the company a once-daily LABA option to market alongside twice-daily Advair. And Theravance has only one other approved product, the antibiotic Vibativ.

The FDA approved Breo Ellipta after Glaxo studied the therapy in more than 7,000 patients with COPD, which is used as a blanket term for patients with breathing problems such as chronic bronchitis and emphysema. 

"COPD is a serious disease that makes breathing difficult," said Dr. Curtis Rosebraugh, director of the FDA's Office of Drug Evaluation II, Center for Drug Evaluation and Research. "The availability of new long-term maintenance medications provides additional treatment options for the millions of Americans who suffer with COPD."

The FDA noted that side effects of Breo have included increased risk of pneumonia and bone fractures.

Glaxo has full responsibility for development of Breo Ellipta as well as Anoro, which stemmed from a partnership with Theravance and is under review for potential approvals this year.

Theravance last month proposed a plan to split into two separate companies: one that would manage the moneymaking assets from the Glaxo partnership, and one to focus on the Vibativ business and development of drugs in the biotech company's pipeline.

- here's the release
- and the FDA's release

Editor's note: Updated with Cowen & Co.'s take on the LABA warning and product label.