ERBB2 and aneurysmal bone cyst: In this phase 1 trial, clinical activity of single agent dalpiciclib in HR-positive and HER2-negative ABC was demonstrated with an overall DCR of 62.5% (95% CI: 45.8–77.3) across all dose levels, consistent with the preclinical evidence that dalpiciclib could overcome the resistance to an endocrine agent (tamoxifen) [18].