GlaxoSmithKline Plc. said a new study into breast cancer-causing stem cells showed its cancer drug Tykerb managed to reduce the number of stem cells that can cause breast cancer to recur.

Dr. Angel Rodriguez from the Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston conducted a trial involving 45 patients, which showed there was significant tumor regression after only six weeks of use.

The study found that Tykerb, currently under EU regulatory scrutiny, decreased cancer-causing stem cells from 10.6 percent to 4.7 percent.

The results of the study, presented at the sixth European Breast Cancer Conference in Berlin, could open up the possibility of Tykerb being used to help with the treatment of breast cancer and preventing the development of the disease.

”Rather than the broad brush approach, in which cells are killed indiscriminately, targeting the stem cells may be more effective and also prevent some of the unpleasant side effects associated with conventional chemotherapy treatment,” Rodriguez said, according to Reuters.

Although sales to date have been slow, Glaxo sees Tykerb as a potential blockbuster in the long term. According to Rodriguez, in the U.S., Tykerb costs between $2,000 and 3,000 a month. Tykerb rivals Herceptin from Roche Holding AG and Genentech Inc.