UPDATED: Theravance rallies after FDA's mixed Breo briefing

As GlaxoSmithKline ($GSK) gears up for an advisory committee meeting on Breo, the British drug giant can expect to face questions about the efficacy of the inhaled once-daily combo of fluticasone furoate (FF) and vilanterol (VI). In an FDA briefing document, agency staff highlighted a lack in consistent data to support the benefits of combining the approved corticosteroid FF with the long-acting beta-agonist VI. Yet some analysts saw the briefing as an overall positive for the program.

GlaxoSmithKline, which is developing Breo via a partnership with Theravance ($THRX), has undertaken a massive development program to advance the candidate for COPD and asthma. Yet the large and extensive trials for the candidate have produced mixed results as Breo failed to best GSK's twice-daily respiratory med Advair. FDA staff point out that the program lacks "robust" data to support the benefit of the combo concerning bronchodilation in patients. And the staff harped on the previously known increased risk of pneumonia in patients on Breo.

"While the submitted data are extensive," the FDA briefing document says, "the data to support the benefit of FF/VI 100/25 over VI 25 is not entirely consistent. Whether there is substantial evidence of efficacy of FF/VI to balance the identified safety concerns is a topic for discussion at the meeting."

The non-agency experts will consider this and other questions at an advisory committee meeting slated for Wednesday--rescheduled after bad weather prompted the agency to postpone the meeting from its previous date in March. Glaxo, which is applying for approval of the FF/VI combo as Relvar in Europe, aims to gain the panel's support for the therapy as a new option for patients with COPD, which includes breathing problems such as smoker's cough and chronic bronchitis.

London-based Glaxo pulls in more money from respiratory drugs led by Advair sales than any other therapeutic category, and Breo is one of the leading drug candidates in its pipeline of new therapies for breathing disorders. South San Francisco-based Theravance is watching the FDA AdComm meeting closely from the sidelines, seeking to gain its second product approval ever and a 15% royalty on sales of Breo that could help move the loss-making biotech company into the black.

Theravance shares jumped 17.5% to $27.92 as of early this afternoon. Analytst seemed bullish on the company's prospects in the respiratory arena, especially if Breo makes it to market. The FDA is due to decide whether to approve the drug for COPD by May 12.

"We had expected the documents to focus on dose selection, trials statistics, the rule of combinations, and the safety profile of fluticasone furoate," Cowen & Co. analysts wrote this morning. "Our initial read of the briefing documents is very positive and suggests that none these issues are likely to be hurdles to approval."

In addition to Breo, Theravance and Glaxo are collaborating on several respiratory drugs, including Anoro, which has been submitted for regulatory approval and faces regulatory decisions later this year. With many major pipeline events in store, GSK CEO Andrew Witty acknowledged earlier this year that he will have many "nervous" moments in 2013.

- here's the FDA briefing doc
- see Reuters article