TROPION-Breast01 China cohort: datopotamab deruxtecan versus chemotherapy in previously treated HR-positive, HER2-negative breast cancer

Prespecified analysis of the 83 patients enrolled in mainland China in TROPION-Breast01, the global phase 3 trial of datopotamab deruxtecan (6 mg/kg every three weeks) against investigator's choice of chemotherapy (eribulin, capecitabine, vinorelbine or gemcitabine) in inoperable or metastatic hormone receptor-positive, HER2-negative breast cancer after progression on endocrine therapy and one or two lines of chemotherapy. Dual primary endpoints were progression-free survival by blinded independent central review and overall survival.

In the China cohort (44 on datopotamab deruxtecan, 39 on chemotherapy) median progression-free survival was 8.1 against 4.2 months (hazard ratio 0.54, 95 percent CI 0.30 to 0.96, nominal p 0.0329). Overall survival numerically favoured datopotamab deruxtecan (hazard ratio 0.83, 95 percent CI 0.49 to 1.43, nominal p 0.5028). Grade 3 or worse treatment-related adverse events occurred in 29.5 percent against 58.3 percent; nausea (47.7 percent) and raised aspartate aminotransferase (40.9 percent) were the commonest with datopotamab deruxtecan, and oral mucositis or stomatitis and ocular surface events affected 43.2 and 47.7 percent.