ESR1 and breast cancer: Use of vemurafenib, dabrafenib in BRAF-mutated melanoma; gefitinib, erlotinib in EGFR-mutant NSCLC and crizotinib in ALK-mutated NSCLC; cetuximab, panitumumab in EGFR-amplified colorectal cancer; or tamoxifen, letrozole, and fulvestrant in ER+ BC (38, 39) have revolutionized the therapeutic outcome in patients, consolidating the rationale for oncodriver targeting.