GlaxoSmithKline's new asthma drug gets a split vote from FDA advisers

GSK pharma R&D president Patrick Vallance

A group of FDA advisers backed GlaxoSmithKline's ($GSK) latest asthma treatment for use in adults but balked at recommending it for adolescents, setting the stage for a likely approval in the fall.

GSK's injection, mepolizumab, works by blocking the protein interleukin-5 to prevent buildups of white blood cells in the lungs that can exacerbate asthma. The company is angling to get the drug approved as a treatment for sufferers of severe asthma who aren't getting the relief they need from inhaled therapies.

The FDA's independent pulmonary drugs committee signed off on mepolizumab in adults with severe asthma, voting 14-0 in favor of approval. But panelists took issue with the lack of data on adolescent patients in GSK's late-stage package, voting 10-4 against recommending the monthly treatment for asthmatics between 12 and 17.

The agency is not required to follow the votes of its advisers, though it commonly does. The FDA has promised to hand down a final decision on mepolizumab by Nov. 4.

GSK leads a group of drugmakers developing IL-5 antibodies for severe asthma, trailed by AstraZeneca ($AZN) and its Phase III benralizumab and by Teva ($TEVA), which plans to file its similar reslizumab this year. All three contenders are working to prove their antibodies can improve results in COPD as well, hoping to carve out a new market for injectable respiratory treatments that analysts have said could reach above $7 billion a year.

The IL-5 race is particularly important for GSK, whose banner respiratory business has come under fire in recent months. Advair, long the drugmaker's cash cow in the field, is finally facing generic competition, and the potential blockbusters expected to usurp it, Breo and Anoro Ellipta, have lagged analyst expectations since winning FDA approvals in 2013.

"Our clinical development program has demonstrated the potential of mepolizumab as a targeted treatment for difficult-to-treat adults with severe asthma, many of whom have been struggling to live with their condition for many years," GSK R&D President Patrick Vallance said in a statement. "These are patients who currently have very few treatment options, and our belief in this medicine as a new treatment option has today been reinforced by the advisory committee's decision."

- read the statement