Ma F et al. -The safety, tolerability, pharmacokinetics, anti-tumor activity, and predictive biomarkers of pyrotinib in patients with HER2–positive metastatic breast cancer were determined In the current study it was shown that daily pyrotinib was well-tolerated with good anti-tumor activity in HER2-positive patients with metastatic breast cancer. The maximum tolerated dose was shown to be 400 mg.