Health-related quality of life in older patients with HER2+ metastatic breast cancer: Comparing pertuzumab plus trastuzumab with or without metronomic chemotherapy in a randomised open-label phase II clinical trial

Introduction: European Organisation for Research and Treatment of Cancer (EORTC) phase II trial (75111-10114) demonstrated that combining pertuzumab with trastuzumab plus cyclophosphamide (TPM) improved median progression-free survival by seven months compared with pertuzumab and trastuzumab (TP) in older/frail patients with HER2-positive metastatic breast cancer (MBC). This publication reports the findings of the health-related quality-of-life (HRQoL) outcomes. Material and methods: HRQoL was assessed using the EORTC QLQ-C30 and the EORTC Elderly specific module (QLQ-ELD14 at baseline, week 9, 27, and 52. The primary HRQoL domains were global health status/QoL scale (GHQs), fatigue and pain. Treatment differences of ≥10 points were considered clinically significant. Correlations between change in GHQs and other HRQoL scales were obtained to identify domains impacting patients' overall perception. Results: Eighty patients were randomised to TP or TPM. Compliance with completing HRQoL forms ranged from 90% at baseline to 45% at week 52. HRQoL domains showed no statistically significant differences in the change scores over time between the two treatment arms. Improvement of ≥10 points was found at week 9 in favor of the TPM for the pain scores. This was reversed oat week 27. Sensitivity analyses, including imputation of missing data and area-under-the-curve analyses, revealed no meaningful differences between the arms for the primary HRQoL domains. ELD14 was systematically scored lower in the TPM arm. Discussion: TPM regimen in older and frail patients with HER2-positive MBC increased PFS with no impact on HRQoL. However, given the limited sample size and dropout in our study, further research is critical to confirm these results.