Real-world outcomes of adding pertuzumab to trastuzumab plus chemotherapy for metastatic breast cancer

The CLEOPATRA study found median overall survival of 57.1 months in metastatic breast cancer (MBC) patients receiving pertuzumab, trastuzumab and chemotherapy, compared with 40.8 months in patients receiving trastuzumab and chemotherapy alone (HR 0.68; p<0.001). However, studies examining the real-world use of pertuzumab have found conflicting results. A population-based retrospective study of MBC-patients in Ontario compared pertuzumab-trastuzumab-chemotherapy versus trastuzumab-chemotherapy. The median OS was 40.2 months (95% CI 35.6-47.8) with pertuzumab versus 25.3 months (95% CI 22.8-27.6) without pertuzumab. The authors conclude that although the median OS in both groups were shorter in this study than what was seen in CLEOPATRA, there appears to be a similar significant OS benefit with pertuzumab in the real-world setting.