Experimental drug slows HER2-positive cancer.(News)

ATLANTA -- The investigational drug lapatinib slows disease progression in women with advanced or metastatic HER2-positive breast cancer that has become resistant to targeted therapy with trastuzumab.

Lapatinib (Tykerb) nearly doubled the time to recurrence for heavily pretreated patients when combined with capecitabine in an international, multicenter, phase III trial presented at the annual meeting of the American Society of Clinical Oncology.

Dr. Charles E. Geyer Jr. reported the median time to progression was 37 weeks for 160 women treated with the two-drug combination, but only 20 weeks for 161 women given capecitabine alone.

"Cutting the hazard in half is really the bottom line," Dr. Geyer, director of breast oncology at Allegheny General Hospital, Pittsburgh, said during a press briefing immediately before his presentation. The hazard ratio for progression was 0.51.

The trial, originally slated to enroll 520 women, was stopped on March 20 after the interim analysis showed a "clinically meaningful" and "statistically significant advantage" in its primary end point.

Dr. Geyer said the investigators may not be able to show improved survival because many patients in the single-agent arm have since added lapatinib to their regimens.

"It is a price that has to be paid when you see improvement in time to progression," he said.