The purpose of this study is to determine whether a commonly used cholesterol-lowering therapies can help recruit antitumor immune cells into a prostate tumor. The study focuses on people with prostate cancer who have elected to monitor their cancer under active surveillance and who will have a standard-of-care biopsy in 3-6 months. Study procedures include receiving medication (usually Vytorin but can differ depending on cholesterol level and any current anti-cholesterol therapy), undergoing blood tests, and completing questionnaires. All study medications are approved by the U.S. Food and Drug Administration (FDA) for cholesterol-lowering, but their use in this study is considered experimental because it has not been approved to stop the growth of prostate cells in individuals with prostate cancer.