This research study is a double-blind, randomized phase II clinical trial of brain-directed stereotactic radiation with or without AGuIX (Activation and Guidance of Irradiation by X-ray) gadolinium-based nanoparticles in the management of brain metastases at higher-risk of local recurrence with radiation alone.~The study agent (AGuIX gadolinium-based nanoparticles) has two main parts. The first is gadolinium, also known as contrast, which is typically injected into a vein during a MRI scan. The second part is a nanoparticle (linked to the gadolinium) that may make focused radiation work more effectively. The AGuIX gadolinium-based nanoparticles are deposited within the brain metastases via the bloodstream and then the brain metastases are radiated.~The U.S. Food and Drug Administration (FDA) has not approved AGuIX gadolinium-based nanoparticles as a treatment for any disease. AGuIX gadolinium-based nanoparticles have been tested in other studies for safety and efficacy in patients with brain metastases who are also receiving radiation.~This study seeks to determine whether AGuIX gadolinium-based nanoparticles improve outcomes relative to placebo.Participants will be randomized into one of the study groups:~Group A: Radiation plus AGuIX gadolinium-based nanoparticles~Group B: Radiation plus placebo~The research study procedures include screening for eligibility and study treatment including evaluations and follow up visits.~NH TherAguix, the manufacturer of the AGuIX gadolinium-based nanoparticles, is supporting this research study by providing the AGuIX gadolinium-based nanoparticles that will be evaluated in this study.~NH TherAguix is also covering the cost of the study.~It is expected that about 134 people will take part in this research study.
The purpose of this study is to determine whether AGuIX (Activation and Guidance of Irradiation by X-ray) gadolinium-based nanoparticles make radiation work more effectively in the treatment of patients with brain metastases that are more difficult to control with stereotactic radiation alone.