Datopotamab deruxtecan versus chemotherapy in previously treated inoperable/metastatic hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer: results from the TROPION-Breast01 China cohort

BACKGROUND: In the global phase III TROPION-Breast01 study, datopotamab deruxtecan (Dato-DXd) demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (PFS) by blinded independent central review (BICR) versus investigator's choice of chemotherapy (ICC) in patients with previously treated, inoperable/metastatic hormone receptor(HR)-positive human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer. At the final analysis, overall survival (OS) was not statistically significant. We report final results from the prespecified analysis of patients enrolled in mainland China. PATIENTS AND METHODS: Patients with inoperable/metastatic HR+/HER2- breast cancer, who had disease progression on endocrine therapy and for whom endocrine therapy was unsuitable and who had received 1-2 prior lines of chemotherapy in the inoperable/metastatic setting, were randomly assigned 1 : 1 to Dato-DXd (6 mg/kg every 3 weeks) or ICC (eribulin/capecitabine/vinorelbine/gemcitabine). Dual primary endpoints were PFS by BICR and OS. RESULTS: Overall, 83 patients were enrolled in mainland China (Dato-DXd, n = 44; ICC, n = 39). PFS by BICR numerically favored Dato-DXd versus ICC [hazard ratio (HR) 0.54, 95% confidence interval (CI) 0.30-0.96, nominal P = 0.0329; median PFS: 8.1 versus 4.2 months]. OS numerically favored Dato-DXd versus ICC [HR 0.83 (95% CI 0.49-1.43), nominal P = 0.5028]. The rate of grade ≥3 treatment-related adverse events (TRAEs) was lower with Dato-DXd versus ICC (29.5% versus 58.3%). The most common TRAEs (any grade/grade 3-4) were nausea (47.7%/4.5%) and increased aspartate aminotransferase (40.9%/2.3%) with Dato-DXd, and neutropenia (grouped term, 58.3%/36.1%) and anemia (52.8%/8.3%) with ICC. With Dato-DXd, treatment-related AEs of special interest (grouped terms) oral mucositis/stomatitis and ocular surface events occurred in 43.2% and 47.7% of patients, respectively. CONCLUSION: In this China cohort, Dato-DXd demonstrated numerically improved efficacy versus ICC and a manageable safety profile, consistent with the global population, supporting Dato-DXd as a new treatment option for Chinese patients with previously treated metastatic HR+/HER2- breast cancer.