ERBB2 and neoplasm: Of note, although all patients were classified as HER2+ tumors by guidelines [4], based on clinical history and previous assessment of HER2 status on tumor samples, and were eligible for treatment with T-DM1, 8 of the 74 samples that were re-analyzed for HER2 had an IHC HER2 result of 0 (n = 5) or 1+ (n = 3).