The PALOMA-2 trial is a randomized, multicenter, double-blind, phase III study comparing the clinical benefit following treatment with letrozole in combination with palbociclib versus letrozole in combination with placebo in postmenopausal women with ER+/HER2− advanced BC who have not received prior systemic anti-cancer therapies for their advanced/metastatic disease [26]. The gene discussed is ERBB2; the disease is breast cancer.