Datopotamab deruxtecan (Dato-DXd) vs chemotherapy (CT) in previously treated inoperable or metastatic hormone receptor-positive, HER2-negative (HR+/HER2–) breast cancer (BC): Patient-reported outcomes (PROs) from the TROPION-Breast01 study.

1006 Background: In the primary analysis of the Phase 3 TROPION-Breast01 study (NCT05104866), Dato-DXd showed a statistically significant and clinically meaningful improvement in progression-free survival vs investigator’s choice of CT (ICC) (HR 0.63 95% CI 0.52‒0.76; p<0.0001) (Bardia et al, ESMO 2023). Here we report PROs from TROPION-Breast01. Methods: Patients with inoperable or metastatic HR+/HER2‒ BC, with disease progression on endocrine therapy and for whom endocrine therapy was unsuitable and who had received 1‒2 prior lines of systemic CT, were randomized 1:1 to Dato-DXd (6 mg/kg Q3W, n=365) or ICC (eribulin/vinorelbine/capecitabine/gemcitabine, n=367). PROs were measured at prespecified timepoints, including secondary PRO endpoints of time to deterioration (TTD) in global health status (GHS)/QoL, physical functioning, and pain based on EORTC QLQ-C30, and exploratory PRO endpoints based on additional questionnaires. Results: PRO questionnaire compliance was 82.5% at baseline in both arms and remained similar across arms over time. TTD was delayed in Dato-DXd vs ICC arms for all secondary endpoints. In an analysis of time to first deterioration (primary analysis), median TTD (HR 95% CI) in GHS/QoL was 3.4 vs 2.1 months (0.85 0.68–1.06), physical functioning was 5.6 vs 3.5 months (0.77 0.61–0.99), and pain was 3.5 vs 2.8 months (0.85 0.68–1.07); in an analysis of time to confirmed deterioration (sensitivity analysis), median TTD in GHS/QoL was 9.0 vs 4.8 months (0.76 0.58–0.98), physical functioning was 12.5 vs 6.2 months (0.77 0.59–1.01), and pain was 9.0 vs 5.5 months (0.72 0.55–0.94). The Table shows TTD in other selected functioning and symptom scales from EORTC. Patient-reported symptomatic AEs (measured by PRO-CTCAE and EORTC) were generally consistent with clinician-reported safety data, and patient-reported treatment tolerability (measured by PGI-TT) was comparable between arms. Conclusions: In TROPION-Breast01, TTD was delayed in the Dato-DXd vs ICC arms for GHS/QoL, physical functioning, pain, and most other symptoms and functioning scales. PRO data complement the improvement in efficacy and manageable safety profile demonstrated with Dato-DXd vs ICC in the primary analysis, supporting Dato-DXd as a potential new, well tolerated therapeutic option in this setting. Clinical trial information: NCT05104866 . Table: see text