M P Goetz, N A Bagegni, G Batist, A Brufsky, M A Cristofanilli, S Damodaran, B R Daniel, G F Fleming, W J Gradishar, S L Graff, M T Grosse Perdekamp, E Hamilton, S Lavasani, A Moreno-Aspitia, T O'Connor, T J Pluard, H S Rugo, S L Sammons, L S Schwartzberg, D G Stover, G A Vidal, G Wang, E Warner, R Yerushalmi, P V Plourde, D J Portman, E N Gal-Yam
BACKGROUND: Acquired estrogen receptor alpha (ER/ESR1) mutations commonly cause endocrine resistance in ER+ metastatic breast cancer (mBC). Lasofoxifene, a novel selective ER modulator, stabilizes an antagonist conformation of wild-type and ESR1-mutated ER-ligand binding domains, and has antitumor activity in ESR1-mutated xenografts. PATIENTS AND METHODS: In this open-label, randomized, phase II, multicenter, ELAINE 1 study (NCT03781063), we randomized women with ESR1-mutated, ER+/human epidermal growth factor receptor 2 negative (HER2-) mBC that had progressed on an aromatase inhibitor (AI) plus a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) to oral lasofoxifene 5 mg daily or IM fulvestrant 500 mg (days 1, 15, and 29, and then every 4 weeks) until disease progression/toxicity...
December 2023: Annals of Oncology: Official Journal of the European Society for Medical Oncology