BackgroundThe phase III CLEOPATRA study demonstrated that combining pertuzumab with trastuzumab plus docetaxel significantly improves progression-free and overall survival in previously untreated HER2-positive metastatic breast cancer. Here, we report health-related quality-of-life (HRQoL) results from CLEOPATRA. Patients and methodsParticipants were randomly assigned to pertuzumab or placebo, each given with trastuzumab plus docetaxel every 3 weeks. Pertuzumab and trastuzumab were administered until progression and six or more docetaxel cycles were recommended. Time from randomization to a ≥5-point decrease in Trial Outcome Index-Physical/Functional/Breast (TOI-PFB) of the Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaire was analyzed as a prespecified secondary end point. A post hoc exploratory analysis investigated time to ≥2-point deterioration in Breast Cancer Subscale (BCS) score. ResultsTime to ≥5-point decline in TOI-PFB did not differ significantly between the pertuzumab and placebo arms [hazard ratio (HR), 0.97; P = 0.7161]. The median times to TOI-PFB deterioration were 18.4 and 18.3 weeks, respectively (approximately six cycles). The mean TOI-PFB declined slightly until week 18 and recovered thereafter. Pertuzumab increased time until BCS deterioration versus placebo (median 26.7 versus 18.3 weeks; HR, 0.77; P = 0.0061). ConclusionsCombining pertuzumab with trastuzumab and docetaxel had no adverse impact on HRQoL and may prolong time to worsening of breast cancer-specific symptoms.