Atezolizumab With or Without Eribulin Mesylate in Treating Patients With Recurrent Locally Advanced or Metastatic Urothelial Cancer

This phase II trial studies the side effects of atezolizumab with or without eribulin mesylate and how well they work in treating patients with urothelial cancer that has come back (recurrent), spread to nearby tissues or lymph nodes (locally advanced), or spread from where it first started (primary site) to other places in the body (metastatic). Immunotherapy with monoclonal antibodies, such as atezolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Chemotherapy drugs, such as eribulin mesylate, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving atezolizumab and eribulin mesylate may work better at treating urothelial cancer compared to atezolizumab alone.