ERBB2 and breast cancer: Updates from the study Palbociclib plus Letrozole versus Placebo plus Letrozole in Postmenapausal Women with Hormone Receptors Positive/HER2 Negative in Advanced Breast Cancer (PALOMA-2) which explored the efficacy of combining Palbociclib plus Letrozole versus placebo plus Letrozole [2] showed that Palbociclib extended the PFS from 14 to 28 months.