GlaxoSmithKline halted trials of its breast cancer drug Tykerb in women whose cancer had spread to other body parts because of good results, the UK drug maker said.Tykerb showed a 50% slowdown of the progression of advanced breast cancer in women who have failed on ordinary chemotherapy and Herceptin.“A pre-planned interim analysis of 321 patients in the study yielded statistically significant results, exceeding the primary endpoint,” GlaxoSmithKline said in a statement.GlaxoSmithKline said it plans to file for regulatory approval for Tykerb in the US and Europe later this year.