This is a Phase II, single cohort study designed to evaluate outcomes in patients with muscle invasive bladder cancer (MIBC) with variant histology who receive neoadjuvant chemotherapy (NAC) with or without immunotherapy (IO) followed by trimodal therapy (TMT). Enrolled patients will undergo at least 3 cycles of NAC +/- IO (oncologist's choice) followed by a four- or six-week course of concurrent standard of care chemotherapy and radiation therapy. These patients will be compared with historical controls of patients with a diagnosis of pure urothelial carcinoma who have undergone TMT. This study has been designed to test the hypothesis that variant histology TMT can be delivered within 45 days of NAC +/- IO and is therefore a viable option in patients who are risk of systemic disease spread.