Cemiplimab and Transarterial Radioembolization With Y-90 SIR-S Spheres for the Treatment of Liver Directed Metastatic Breast Cancer

This phase II trial tests how well cemiplimab and transarterial radioembolization (TARE) with yttrium-90 (Y90) SIR-Spheres, registered trademark, works in treating breast cancer that has spread from where it first started (primary site) to the liver (metastatic). Immunotherapy with monoclonal antibodies, such as cemiplimab, may help the body's immune system attack the tumor, and may interfere with the ability of tumor cells to grow and spread. TARE is a treatment that uses radioactive microspheres, such as Y90 SIR-S Spheres, to both cause hepatic artery embolization and to deliver regional radiotherapy. Y90 SIR-S Spheres is an injectable form of the radioisotope yttrium Y 90 encapsulated in resin microspheres. When injected into the artery supplying the tumor, yttrium Y 90 resin microspheres block the tumor blood vessels and deliver the yttrium Y 90 directly to the tumor site, which may kill or slow tumor growth. Giving cemiplimab and Y90 SIR-Spheres by TARE to the tumor in the liver may kill more tumor cells in patients with metastatic breast cancer.