This is a multi-center, single arm, phase II study of T-DM1 with or without palbociclib in the treatment of patients with metastatic HER2-positive breast cancer.~Hypotheses: Combination of T-DM1 with palbociclib improves progression free survival~Primary objective: Progression free survival of the combination of T-DM1 with palbociclib~Secondary objectives i) Response rates ii) Overall survival~Correlative objectives i) Investigate predictive biomarkers of response in blood and archived tumor tissue ii) Investigate mechanisms of resistance for palbociclib in blood and tumor tissue
This is a single arm, phase II study to evaluate if the combination of T-DM1 with palbociclib improves progression-free survival in patients with metastatic HER2 positive breast cancer. All patients will be treated with T-DM1 with palbociclib.