18F-FDG and Fluorine F18 FDHT PET/MRI Imaging in Patients Metastatic Breast Cancer
This early phase I trial tests whether positron emission tomography/magnetic resonance imaging (PET/MRI) scans using the imaging agent F18-FDHT are an effective way of identifying androgen receptor (AR)-positive breast cancer that has spread from where it first started (primary site) to other places in the body (metastatic). Breast cancer is often positive for AR. The AR protein allows the body to respond to androgen hormones, such as testosterone, and researchers think the effects of AR may contribute to the growth of breast cancer. Currently, there are no Food and Drug Administration (FDA)-approved treatments that target and block AR for the treatment of breast cancer. One challenge in developing and studying treatments that target AR is that there is no accurate way to identify and detect AR in breast cancer. For many patients with breast cancer, an imaging test called a PET/computed tomography (CT) is used to evaluate the presence or absence of breast cancer in the body. Breast cancer often has high levels of glucose (sugar) in the tumor. Fludeoxyglucose F-18 ([18F]-FDG) is a standard glucose drug; it is made from radioactive chemicals similar to glucose. The glucose builds up in locations where cancer cells are located, and it helps the PET/CT scan show the cancer. However, differences in the tumors can affect how well 18F-FDG can detect the tumors. 18F-FDHT is a steroid analogue, which means it is made from radioactive chemicals similar to steroids (hormones such as androgen) and can detect cancer cells that have AR. 18F-FDHT binds to AR on cancer cells so the PET/MRI scans can specifically show AR-positive tumors. This study may help researchers learn whether 18F-FDHT may be better for taking pictures of tumors than 18F-FDG because AR can be more easily detected in those tumors than glucose.