Patient-reported outcomes and hospitalization data in patients with HER2-positive metastatic breast cancer receiving trastuzumab deruxtecan or trastuzumab emtansine in the phase III DESTINY-Breast03 study

Background: In the DESTINY-Breast03 clinical trial, trastuzumab deruxtecan (T-DXd) showed superior progression-free survival and overall survival versus trastuzumab emtansine (T-DM1) and manageable safety in patients with human epidermal growth factor receptor 2 (HER2)-positive (HER2+) metastatic breast cancer. Here, patient-reported outcomes (PROs) are reported along with hospitalization data.

Patients and methods: Patients in DESTINY-Breast03 were assessed for prespecified PRO measures, including European Organization for Research and Treatment of Cancer quality of life (EORTC-QoL) questionnaires [the oncology-specific EORTC Quality of Life Questionnaire Core 30 (QLQ-C30) and breast cancer-specific EORTC QLQ-BR45] and the generic EuroQol 5-dimension 5-level questionnaire (EQ-5D-5L) visual analogue scale. Analyses included change from baseline, time to definitive deterioration (TDD), and hospitalization-related endpoints.

Results: EORTC QLQ-C30 baseline global health status (GHS) scores for T-DXd (n = 253) and T-DM1 (n = 260) were similar, with no clinically meaningful change (<10-point change from baseline) while on either treatment (median treatment duration: T-DXd, 14.3 months; T-DM1, 6.9 months). TDD analyses of QLQ-C30 GHS (primary PRO variable) and all other prespecified PROs (QLQ-C30 subscales, the QLQ-BR45 arm symptoms scale, and the EQ-5D-5L visual analogue scale) suggested T-DXd was numerically favored over T-DM1 based on TDD hazard ratios. Of all randomized patients, 18 (6.9%) receiving T-DXd versus 19 (7.2%) receiving T-DM1 were hospitalized, and the median time to first hospitalization was 219.5 versus 60.0 days, respectively.

Conclusions: In DESTINY-Breast03, EORTC GHS/QoL was maintained on both therapies throughout treatment, indicating that despite the longer treatment duration with T-DXd versus T-DM1, health-related QoL did not worsen on T-DXd. Furthermore, TDD hazard ratios numerically favored T-DXd over T-DM1 in all prespecified variables of interest including pain, suggesting T-DXd may delay time until health-related QoL deterioration compared with T-DM1. Median time to first hospitalization was three times longer with T-DXd versus T-DM1. Together with reported improved efficacy and manageable toxicity, these results support the overall benefit of T-DXd for patients with HER2+ metastatic breast cancer.