GSK and Theravance scored a win Wednesday when an FDA reviewing committee voted to recommend approval of their COPD drug Breo, which combines fluticasone furoate and vilanterol. The panel voted on a number of data points, with a 9-4 vote in favor of the drug being used as a maintenance treatment and 8-5 vote endorsing the drug’s use in handling COPD exacerbations.  A Thursday research note by Jefferies analyst Jeffery Holford indicates the “No” votes were over pneumonia concerns – inhaled steroids raise risk of pneumonia in COPD patients — and the question of just how much of a contribution fluticasone furoate made overall. Holford wrote that he anticipates the companies’ chances of getting a Complete Response Letter from the regulator at 50%.

FDA is set to review the drug by May 12. Regulatory approval would pit the it against AstraZeneca’s twice-a-day Symbicort and GSK’s twice-a-day Advair Diskus.

Yesterday’s endorsement was not a surprise — an early release of the committee’s notes and opinions primed the Street for a green light, but also fueled concern over the drug’s chances of winning acceptance, given that its benefits don’t trounce what’s already on the market. Bernstein analyst Tim Anderson wrote Wednesday that “Patients and physicians alike generally seem quite content with Advair,” and because the difference between the two is small, he expects GSK will have to work hard to corral payers to “adopt favorable reimbursement status and market access.”

Anderson projects that Breo, known as Relvar in Europe, could have about $706 million in sales by 2016. Advair, indicated for asthma and COPD, boasts $5.5 billion in sales. He expects generics will begin nibbling at Advair’s market share by the middle of 2016. AstraZeneca’s Symbicort, also indicated for both COPD and asthma, has added around $3 billion to the company’s sales every year for the past three years.

Anderson’s Breo enthusiasm is also tempered by what is now a COPD-only indication. GSK and Theravance have not pursued an asthma indication in the US but said in a joint statement that the companies are “reviewing the strategy for a future US filing for asthma.”

Anderson wrote that it’s unlikely the FDA will sign off on an asthma indication as well “because of the cautious nature of FDA’s respiratory division” over long acting beta agonists in the asthma space.

The advisory committee’s decision not binding, but is used as a reference point for when the drug goes up for approval.