ERBB2 and breast cancer: However, the clinical response between groups did not reach statistical significance.677 The NeopalAna study, a single-arm Phase II study in 50 HR+/HER2- breast cancer patients, evaluated the antiproliferative effect (complete cell cycle arrest, CCCA, Ki67 <= 2.7%) of sequentially administered endocrine and palbociclib treatment as the primary endpoint.678 This study demonstrated that the addition of palbociclib imposes an antiproliferative effect regardless of menopausal state, luminal subtype, histology, stage, grade, PI3K, P53, PTEN, and RUNX1 mutational status.