F-18 16 Alpha-Fluoroestradiol

This phase II trial tests how well stereotactic body radiation therapy (SBRT) works in treating patients with estrogen receptor positive (ER +) breast cancer that has spread from where it first started to other places in the body (metastatic) and has limited disease progression (oligoprogression). Currently, the standard of care for breast cancer patients with oligoprogressive disease is to change systemic therapy when progression occurs. Radiation therapy uses high energy x-rays, particles, or radioactive seeds to kill cancer cells and shrink tumors. SBRT is a type of external radiation therapy that uses special equipment to position a patient and precisely deliver radiation to tumors in the body (except the brain). The total dose of radiation is divided into smaller doses (fractions) given over several days. This type of radiation therapy helps spare normal tissue and has been shown to improve survival. SBRT may kill more tumor cells and allow patients with oligoprogressive ER + metastatic breast cancer to continue taking current systemic treatment. This trial also tests how well ER targeted positron emission tomography (PET)/ computed tomography (CT) imaging, using FES, works in identifying progressive disease in patients with ER + metastatic breast cancer. FES, a radiolabeled substance, binds to estrogen receptors and gives off radiation that can be detected by a PET scan. The PET scan, an established imaging technique that utilizes small amounts of radioactivity attached to very minimal amounts of tracer, FES, forms an image that shows where tumor cells with estrogen receptors can be found in the body. CT images use x-rays to provide an exact outline of organs. FES PET/CT may improve identification of progressive disease in patients with ER + metastatic breast cancer.

This phase II trial studies how well a vaccine, STEMVAC, works in combination with standard endocrine-based therapy (ET) with a CDK4/6 targeted drug therapy, or with the chemotherapy drug capecitabine, in treating patients with hormone receptor (HR)-positive, HER2-negative breast cancer that has spread from where it first started (primary site) to other places in the body (metastatic). STEMVAC is designed to target proteins that cancer cells use when they become more aggressive and start to spread, and it is believed to work by boosting the immune system to recognize and destroy the invader tumor cells that are causing the disease. Standard ET is treatment that adds, blocks, or removes hormones in order to slow or stop the growth of cancer. Standard CDK4/6 inhibitors, including abemaciclib, may stop the growth of tumor cells and may kill them by blocking some of the enzymes needed for cell growth. Capecitabine is in a class of medications called antimetabolites. It is taken up by tumor cells and breaks down into fluorouracil, a substance that kills tumor cells. Giving STEMVAC in combination with standard ET or chemotherapy may be an effective treatment for metastatic HR positive, HER2 negative breast cancer.