Combining Monoclonal Antibodies in HER2-Positive Breast Cancer
The addition of pertuzumab to trastuzumab and capecitabine did not significantly improve independent review facility–assessed progression-free survival, in a randomized phase III trial of patients with HER2-positive metastatic breast cancer who experienced disease progression after trastuzumab-based therapy and received a prior taxane. These findings were reported by Urruticoechea et al in the Journal of Clinical Oncology.
Patients were randomly assigned to one of two arms and treated with either trastuzumab plus capecitabine (arm A=218) or pertuzumab plus trastuzumab plus capecitabine (arm B=228). The increase in median independent review facility–assessed progression-free survival was modest: 9 months in arm A versus 11.1 months in arm B. Interim overall survival was 28.1 in arm A versus 36.1 months in arm B. Although statistical significance cannot be claimed for overall survival, the investigators concluded that their findings suggest clinical relevance.
The most common adverse events associated with the combination therapies were hand-foot syndrome, nausea, and neutropenia in those who received trastuzumab plus capecitabine and diarrhea, rash, and nasopharyngitis in those who received pertuzumab, trastuzumab, and capecitabine.