The CNS activity of pyrotinib was also investigated in combination with capecitabine in a recent phase II trial of 61 HER2-positive ABC patients with untreated brain metastases (PERMEATE); the objective CNS response rate (defined by RECIST 1.1 criteria) was 74.6% (95%CI 61.1–85.0) [70]. The gene discussed is ERBB2; the disease is aneurysmal bone cyst.