Additional subgroup analyses suggest that among patients with ESR1-mutated tumors who received prior ET+CDK4/6i ≥12 months, single-agent elacestrant was associated with a prolonged PFS versus SOC for patients in clinically relevant subgroups, including patients with bone metastases, liver and/or lung metastases, <3 or ≥3 metastatic sites, or tumors with PIK3CA-mut, TP53-mut, HER2-low tumor expression, or ESR1 mutation variants D538G or Y537S/N. Here, CDK4 is linked to neoplasm.