Commenting on the studies evaluating novel agents in breast cancer, Nicholas Turner, MD, PhD, of the Royal Marsden Hospital in London, observed that for BKM120 plus trastuzumab (Herceptin), the “benefit appears to be in only a relatively small proportion of patients, but in those patients there is an impressive level of activity.” He said the response rates were similar to those seen with everolimus plus trastuzumab, which suggests this drug might be targeting the same subset.

There is a clear need to find biomarkers to guide future development of BKM120 in HER2-positive breast cancer, Dr. Turner said, including full analysis of PIK3CA mutations.

Regarding E-3810, Dr. Turner called the study results “highly impressive,” suggesting, “It’s hard to imagine a phase I trial that has generated more positive data than this one in breast cancer.”

He noted that nearly half the patients receiving the 15-mg dose required dose reductions during the first two cycles. Therefore, further work must be done to identify a “chronically tolerable” dose and schedule, he suggested. ■