<qa>  What is the recombinant DNA-derived humanized monoclonal antibody thatTrastuzumab Herceptin is a highly purified recombinant DNA-derived humanized monoclonal antibody that selectively binds with high affinity to the extracellular domain of the HER2 receptor. Pivotal multicenter efficacy trials in metastatic patients showed improved response rates and disease-free survival in patients who received trastuzumab in addition to chemotherapy. One of these studies was an open-labeled, multicenter, randomized phase III study evaluating the addition of trastuzumab to standard first-line chemotherapy in metastatic breast cancer. This study randomized 469 patients with metastatic disease to chemotherapy with or without trastuzumab. Results of this study showed survival in patients who received trastuzumab plus chemotherapy to be almost twice as long as chemotherapy alone 7.2 vs. 4.5 months, p0.0001. 