ERBB2 and metastatic neoplasm: Additionally, a group of researchers from Memorial Sloan-Kettering Cancer Center evaluated a group of 63 patients with HER2+ BC with disease recurrence after adjuvant trastuzumab treatment, or progressive metastatic disease on a trastuzumab-containing regimen.[20] All patients underwent biopsy of at least a single local or distant site to document progressive disease.