This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Trastuzumab all are true EXCEPT: \nSelect and explain. \nA. Shows better response in combination with paclitaxel, B. Used in metastatic breast cancer, C. Causes upregulation of HER2/neu, D. Do not causes bone marrow toxicity', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Causes upregulation of HER2/neu REF: Lippincott\'s pharmacology 6th edition 653, Goodman & Gillman\'s 11\'1\' edition page 901, http://en.wikipedia.org/wiki/Trastuzumab "It has been suggested that trastuzumab induces some of its effect by downregulation of HER2/neu not upregulation" Trastuzumab: Herceptin (Trastuzumab) is a humanized antibody directed against the HER-2 antigen that is overexpressed on the tumor cell surface in approximately 25% of breast cancer patients. Trastuzumab is approved as intravenous infusion in HER2/neu overexpressing metastatic breast cancer in combination with paclitaxel as initial treatment or as monotherapy following chemotherapy relapse. Trastuzumab also is synergistic with other cytotoxic agents, but only in HER2/neuoverexpressing cancers. Trastuzumab is a humanized monoclonal antibody that binds to the domain IV of the extracellular segment of the HER2/neu receptor It has been suggested that trastuzumab induces some of its effect by downregulation of HER2/ neu Herceptinus e is associated withinfusion-relatedhypotension , flushing andbronchoconstriction, and skin rash but no bone marrow toxicity Herceptin appears to sensitize patients to cardiotoxicity, an impoant concern in patients also receiving doxorubicin.', 'role': 'assistant'}]