ESR1 and breast cancer: The objective response rate (ORR) was 0%, 16% (four partial responses (PRs) including an estrogen-receptor-positive breast cancer patient who received a first-line combination of ridaforolimus, dalotuzumab, and exemestane) and 21% (one complete response (CR) and four PRs) in Arms A, B, and C, respectively (Table 4).