Priority review designation requires the U.S. Food and Drug Administration to decide on a drug application six months after submission. Tykerb was filed for U.S. approval on Sept. 18.
The oral cancer treatment is a potential rival to the blockbuster Herceptin, which is given by injection, and is a key new medicine for Europe's biggest drugmaker. Glaxo hopes it will confirm its arrival as a major force in oncology.
The British-based group is seeking approval to market Tykerb as a treatment for advanced breast cancer -- meaning cancer that has spread to other parts of the body -- in combination with Roche Holding AG's Xeloda cancer drug.
It would be given to women who test positive for the HER2 gene mutation and who have not responded to prior treatment such as Roche and Genentech Inc's Herceptin.
Some industry analysts believe Tykerb could eventually be a $4 billion-a-year seller. But this hinges on it competing against Herceptin in early-stage cancer, and analysts do not expect that data to be reported before 2010.
Tykerb, which works by blocking two enzymes called kinases that are believed to play a role in promoting cancer, is also being studied for other types of solid tumours.© Reuters 2006