Copper Cu 64-DOTA-Trastuzumab PET in Predicting Response to Treatment With Ado-Trastuzumab Emtansine in Patients With Metastatic HER2 Positive Breast Cancer

This pilot clinical trial studies how well copper Cu 64-tetra-azacyclododecanetetra-acetic acid (DOTA)-trastuzumab positron emission tomography (PET) works in predicting response to treatment with ado-trastuzumab emtansine in patients with human epidermal growth factor receptor 2 (HER2) positive breast cancer that has spread to other places in the body. Copper Cu 64-DOTA-trastuzumab is a chemotherapy drug (trastuzumab) attached to a radioactive substance. Diagnostic procedures using PET may allow scanners to take pictures of where the drug travels in the body and may help doctors identify which patients may benefit from treatment with ado-trastuzumab emtansine.