Inclusion Criteria:  Patient ≥ 18 years of age  Patient with locally advanced or metastatic urothelial carcinoma (irrespective of tumor histology) whose disease has not progressed (ongoing stable disease, partial response or complete response) following completion of first-line platinum-based chemotherapy and who has been (restrospective), is (retropsectifve and prospective), will be (prospective) treated with avelumab.  For a patient alive at the moment of the inclusion in the study : the patient must be informed of the study, he/she must be given an information letter signed by the investigator and must not be opposed to the collection of his/her data For a patient who died before the inclusion in the study : the family of the patient must be informed and the patient (during his lifetime) must not be opposed to the collection of his data.  Patient benefiting from a social security scheme according to local regulations  Exclusion Criteria:  For a patient alive at the moment of the inclusion in the study: patient without liberty, under tutelage, or unable to give oral consent. Patient enrolled in a prospective interventional clinical trial assessing an investigational product.