An innovative new drug combination may help women with advanced breast cancer that no longer responds to trastuzumab (Herceptin), researchers report. The investigational drug lapatinib (Tykerb) slows cancer growth by about 50% when given with the drug capecitabine (Xeloda), researchers from Allegheny General Hospital in Pittsburgh announced .

They presented findings from their phase III clinical trial at the annual meeting of the American Society of Clinical Oncology, in Atlanta.

The study involved 321 women with breast cancer that expressed HER2/neu, a protein that makes tumors especially aggressive. About 20%-25% of breast cancers are HER2-positive. The drug Herceptin, which targets HER2, is very effective at treating these advanced cancers, but women eventually develop resistance to it and it stops working.

That was the case with the women in this study. All had tumors that had continued growing or spread, even though they had been treated with chemotherapy and Herceptin.