FDA staff question efficacy data for GlaxoSmithKline, Theravance's COPD combination therapy

In documents released Monday ahead of an FDA advisory panel meeting on April 17, agency staff said that efficacy data supporting a regulatory filing for GlaxoSmithKline and Theravance's chronic obstructive pulmonary disease (COPD) drug Breo (fluticasone/vilanterol) are not entirely consistent. Reviewers said that studies examining vilanterol alone showed it was effective at improving a measure of lung function, although studies involving the combination therapy "are less robust."

The FDA staff questioned the contribution of the corticosteroid fluticasone in improving lung function, although they suggested the data appears to support a benefit in reducing COPD exacerbations. The reviewers noted that the safety profile of Breo appears generally consistent with that of similar drugs, although the once-daily treatment may be linked to side effects, including pneumonia and fractures, which outweigh any added benefit from the combination of the long-acting beta-agonist vilanterol and a corticosteroid. "Overall, the documents seem broadly supportive and propose questions in keeping with our expectation on efficacy and safety," remarked UBS analyst Andrew Whitney.

Jefferies analyst Jeffrey Holford noted that "on the positive side, the FDA appears happy with the dosing for Breo," while Berenberg Bank analyst Alistair Campbell suggested that "the main question mark appears to be the relative benefit of adding a steroid onto the bronchodilator." Campbell said that the advisory panel meeting "may be less contentious than feared and this should give Breo a very good chance of a positive recommendation." Shares of Theravance rose as much as 22 percent on the news.

GlaxoSmithKline and Theravance submitted Breo for regulatory approval in the US in July last year, and at the same time filed an application in Europe, where if approved the combination product will be sold as Relvar. The FDA previously postponed the advisory panel meeting for Breo in March ahead of a snowstorm, although the agency did not give an official reason for the cancellation. A final decision on the therapy is expected from the regulator by May 12. Holford predicts that if approved, Breo may generate peak annual sales of $1.5 billion in the COPD indication.

Additionally, GlaxoSmithKline and Theravance submitted the COPD drug Anoro (umeclidinium bromide/vilanterol) for regulatory approval in the US in December and in Europe in January. The anticipated approvals of Breo and Anoro have fuelled speculation that GlaxoSmithKline, which is currently Theravance's largest shareholder with a 27-percent stake, may attempt to acquire the company.

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