ERBB2 and neoplasm: Another explanation to the response of patients with negative BiotHER immunoreaction is that mechanisms of HER-2 shedding might change under Trastuzumab therapy and chemotherapy, with less of the HER-2 protein fragment being released to the serum, which would make the c-erbB-2-positive tumour cells a better target for anti-HER-2 antibody treatment (Luftner et al, 1999; Molina et al, 2001).