Testing the Addition of the Anti-cancer Drug, Cabozantinib, to the Usual Immunotherapy Treatment, Avelumab, in Patients With Metastatic Urothelial Cancer, MAIN-CAV Study

Inclusion Criteria: * Histologically or cytologically-confirmed diagnosis of advanced or metastatic urothelial cancer of the renal pelvis, ureter, bladder, or urethra (transitional cell and mixed transitional/non-transitional cell histologies except for small-cell histology), including N3 only disease prior to start of first-line platinum-based chemotherapy * Prior first-line treatment must have consisted of 4-6 cycles of 1st-line therapy (platinum-based chemotherapy; gemcitabine-cisplatin, gemcitabine-carboplatin, methotrexate, vinblastine, doxorubicin and cisplatin \[MVAC\] or dose-dense \[dd\]MVAC) * No more than 1 line of prior chemotherapy for metastatic or locally advanced disease (neoadjuvant or adjuvant chemotherapy will be allowed if given 12 or more months prior to registration) * Tumor objective response of CR, PR, or SD upon completion of first line platinum-based chemotherapy by treating physician's assessment * The last dose of first-line chemotherapy must have been received no less than 3 weeks, and no more than 10 weeks, prior to randomization in the present study * No prior immunotherapy with IL-2, IFN-alpha, or an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or CTLA-4 antibody (including ipilimumab), or any other antibody or drug specifically targeting T-cell co-stimulation or immune checkpoint pathways * Age \>= 18 years * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Not pregnant and not nursing, because this study involves an…