Real-World Patient-Reported Outcome Comparing Antibody-Drug Conjugates and Conventional Chemotherapy in Metastatic Breast Cancer.

BACKGROUND: Antibody-drug conjugates (ADCs) have transformed second-line metastatic breast cancer (MBC) therapy, yet their multidimensional quality-of-life impact versus conventional intravenous chemotherapy in real-world practice, particularly on lifestyle and caregiver burden, remains poorly characterized. MATERIALS AND METHODS: This prospective cohort enrolled 122 consecutive patients with MBC starting second-line therapy: 51 received ADCs and 71 conventional intravenous chemotherapy, allocated by tumor biology and clinical factors. The DAMA (Digital Antibody drug conjugate Modulator in breAst cancer) framework collected electronic patient-reported outcome measures (ePROMs) on anthropometric, lifestyle, symptom, psychosocial, and caregiver-burden domains at baseline, 3 and 6 months, analyzed with linear mixed-effects models. RESULTS: At baseline, measured lifestyle, symptom, psychosocial and caregiver variables were broadly similar between cohorts, although treatment-related characteristics differed. At 3 months, ADC patients had greater mean weight loss (-3.1 vs - 1.2 kg), a larger decline in weekly physical activity (-41 vs - 22 minutes/week), higher stress and caregiver burden, but lower pain scores (3.7 vs 5.3). By 6 months, several differences attenuated. In pooled descriptive analyses, weekly physical activity showed little association with pain (r = 0.03, p = 0.56), stress (r = -0.12, p = 0.03), anxiety (r = -0.02, p = 0.73), caregiver emotional wellbeing (r = 0.00, p = 0.97), or sleep duration (r = 0.04, p = 0.47). CONCLUSION: In this prospective real-world cohort, ADC and conventional chemotherapy cohorts showed different longitudinal patterns of patient- and caregiver-reported burden. Because treatment allocation was biology- and clinically driven, these findings are exploratory and should not be interpreted as causal treatment effects. Systematic ePROM collection within the DAMA framework was feasible and may support identification of supportive-care needs.