GlaxoSmithKline said approval of Cervarix will be delayed in the US after FDA regulators requested more information on the vaccine in a “complete response letter” to the drugmaker.
Complete response letters are usually issued by the agency when the review of a file is complete and questions remain to be answered prior to approval.
GSK did not say publicly what questions were asked in the letter.
"We have already started addressing the questions and will be engaged in discussions with the FDA to finalize our responses," said Barbara Howe, MD, VP and director, North American vaccine development, GlaxoSmithKline in a statement. "Our discussions with the agency continue to be positive and constructive, and we are working diligently to resolve any outstanding questions to bring Cervarix to the US market."
Cervarix is already approved in 45 countries, including the 27 member countries of the European Union, Mexico and Australia.
GSK's vaccine competes with Merck's Gardasil, which has been available for a year in the US and is prescribed for use by girls and women aged nine to 26.
In early trading in New York, GSK shares fell 80 cents, or 1.5%, to $52.20, while Merck shares rose 88 cents, or 1.5%, to $60.45.
Gardasil brought in $418 million in sales for Whitehouse Station, NJ-based Merck in the third quarter.
Lehman Brothers analyst Tony Butler last year estimated Gardasil may generate $3 billion in peak annual sales for Merck.
Cervical cancer is the second-most common malignancy among women after breast cancer and kills 250,000 a year worldwide, according to the World Health Organization.