Waterfall plot of the best change from baseline in target lesions according to the best objective response per cohort in the FAS population ( n = 177). The confirmed ORR with T-DXd was 70.6% ( n = 68, 95% CI 58.3–81) in cohort 1, 37.5% ( n = 72, 95% CI 26.4–49.7) in cohort 2 and 29.7% ( n = 37, 95% CI 15.9–47) in cohort 3. The likelihood of confirmed objective response was higher in cohort 1 as compared to cohort 2 (adjusted OR: 3.96, 95% CI 1.78–8.77, P = 0.001) and not significantly different between cohort 3 and cohort 2 (adjusted OR: 0.63, 95% CI 0.25–1.54, P = 0.30). The adjusted OR and P value were derived from a multivariable logistic model taking as reference cohort 2 and adjusted for hormone receptor status, interval from initial diagnosis to metastatic disease, number and type of metastatic site, ECOG performance status and interval from diagnosis of metastatic disease to inclusion. All statistical tests were two-sided.
