A Real-World Study on the Effectiveness and Safety of Elacestrant in Patients with ESR1-Mutated Metastatic Breast Cancer Progressing After CDK4/6 Inhibitors and Endocrine Therapy

Advanced hormone receptor-positive (HR+), epidermal growth factor 2-negative (HER2) breast carcinoma (BC) patients receive frontline therapy with cyclin-dependent tyrosine kinase 4/6 inhibitors + endocrine therapy. At progression, the best management includes mutational analysis for ESR-1, allowing second-line therapy with elacestrant. This paper reports results of an observational study of elacestrant efficacy and safety in a real-world setting. The results for objective response rate, progression-free survival, and overall survival were within the ranges reported in the registrational studies. The type and severity of adverse events associated with elacestrant were also within the range reported by other authors. Further studies are needed to understand primary resistance to elacestrant.