Other agents entered early clinical trials, such as LSZ102 (NCT02734615) combined with CDK4/6i in ER+/HER2− ABC patients who progressed on ET, and the oral SERD elacestrant (RAD1901, NCT03778931) [80] in ER+/HER2− ABC patients who experienced disease progression on combined CDK4/6i and ET (AI or fulvestrant). The gene discussed is ESR1; the disease is aneurysmal bone cyst.