It has been evaluated in clinical trials primarily for its antineoplastic potential, with ongoing Phase I studies focusing on cancers such as breast, lung and fallopian tube carcinoma[102,112,113], alongside one completed Phase II trial, highlighting its relevance in treating various malignant solid tumors with specific biomarker profiles such as estrogen receptor (ER) negative and HER-2 deficient expression. The gene discussed is ESR1; the disease is cancer.