Gunter von Minckwitz, MD, PhD, of the German Breast Group and the University of Frankfurt, discussed the findings of the NSABP B-41 trial. He observed that lapatinib was not more effective than trastuzumab, which is in line with increasing evidence in various breast cancer settings showing greater activity for trastuzumab. “There is initial high efficacy of lapatinib that might be impaired by rapid development of secondary resistance,” he said.

Lapatinib is also associated with toxicity that results in diminished dose intensity and exposure, he noted, but he does not believe this compromises efficacy. “In GeparQuinto, we showed that only in patients receiving less than 700 mg/d was the [pathologic complete response] rate decreased,” he said. “The therapeutic window of lapatinib is quite wide, and therefore, discontinuation of treatment may not be so relevant for patients.”

Anticipated Results

The emphasis should be on dual HER2 blockade, he emphasized. “This is the most promising approach for the future,” he said, adding that highly anticipated results from the ALLTO and APHINITY studies will be informative as to whether neoadjuvant results are predictive of outcomes in the adjuvant and metastatic settings. If this proves to be the case, he said, “this might open the regulatory pathway for conditional approval of agents in early development.” ■

Disclosure: Dr. von Minckwitz reported no potential conflicts of interest.