Health-related quality of life with pertuzumab retreatment: Secondary analysis of the PRECIOUS trial

BACKGROUND: Retreatment with pertuzumab has demonstrated survival benefit in previously treated human epidermal growth factor receptor 2 (HER2)-positive locally advanced or metastatic breast cancer, but its effect on health-related quality of life (HRQoL) is not well established. METHODS: This secondary analysis of the randomized, open-label phase III PRECIOUS trial evaluated HRQoL in women previously treated with pertuzumab, trastuzumab, and chemotherapy. Patients were randomized 1:1 to pertuzumab plus trastuzumab plus chemotherapy (PTC) or trastuzumab plus chemotherapy (TC). HRQoL was assessed using the Functional Assessment of Cancer Therapy-Breast (FACT-B). The primary endpoint was time-to-deterioration (TTD) in the Breast-Trial Outcome Index (B-TOI), defined as a ≥5-point decline. Secondary endpoints included TTD in the FACT-B total score, General Subscale, and Breast Cancer Subscale. Longitudinal changes were analyzed using linear mixed-effects models. RESULTS: Of 217 eligible patients, 178 were included in the HRQoL analysis (median age: 57 years in PTC and 60 years in TC). No significant between-group differences in TTD for B-TOI were observed (hazard ratio, 1.22; 95% CI, 0.86-1.90; p = 0.23). Secondary TTD endpoints also showed no differences. Mixed-effects models indicated that TC had better B-TOI and Breast Cancer Subscale scores at week 6, but these early differences were not sustained beyond week 12. CONCLUSION: Pertuzumab retreatment was not associated with clinically meaningful deterioration in HRQoL. These findings support the use of dual HER2 blockade beyond progression in appropriately selected patients.