Gunter von Minckwitz, MD, PhD from the German Breast Group Research Institute, Neu-Isenburg, Germany discusses the efficacy of pertuzumab in HER2 positive breast cancer. Pertuzumab is a novel drug that has demonstrated significant improvements in survival outcome for patients with metastatic or locally advanced HER2 positive breast cancer. In the APHINITY trial (NCT01358877) patients received pertuzumab or placebo, and many factors were investigated including safety and side effects. The results produced from this trial showed that pertuzumab can significantly reduce invasive disease events however, the side effect profile showed an increase in the number of patients that suffered from diarrhea. However, it was a positive overall study and supports the use of pertuzumab in HER2 positive breast cancer. Recorded at the American Society of Oncology (ASCO) 2017 Annual Meeting held in Chicago, IL.